WO2022061810A1

WO2022061810A1 - Electrochemical device and electronic device comprising electrochemical device

Info

Publication number: WO2022061810A1
Application number: PCT/CN2020/118094
Authority: WO
Inventors: 严坤; 张益博; 丁宇; 刘道林
Original assignee: 宁德新能源科技有限公司
Priority date: 2020-09-27
Filing date: 2020-09-27
Publication date: 2022-03-31
Also published as: CN114631221A; CN114631221B

Abstract

The present application relates to an electrochemical device and an electronic device comprising the electrochemical device. Specifically, the present application provides an electrochemical device, comprising an outer package, a partition plate, and electrode assemblies respectively provided at two sides of the partition plate. The partition plate and the electrode assemblies are located in the outer package, the partition plate protrudes from one of seal edges of the outer package, and a heat dissipation device is provided at the portion of the partition plate protruding from the outer package. By means of the design of the heat conduction mode of the partition plate, overheating caused by heat accumulation during the use of the electrochemical device is effectively avoided.

Description

An electrochemical device and an electronic device comprising the electrochemical device

technical field

The present application relates to the field of electrochemistry, and in particular, to an electrochemical device and an electronic device including the electrochemical device.

Background technique

Lithium-ion batteries have many advantages such as high energy density, long cycle life, high nominal voltage, low self-discharge rate, small size, and light weight, and are widely used in consumer electronics. With the rapid development of electric vehicles (EVs) and mobile electronic devices in recent years, people have higher and higher requirements for battery energy density, safety, cycle performance, etc., and look forward to the development of new lithium-ion batteries with comprehensive performance improvements appear.

In the existing lithium-ion battery system, due to the limitations of the electrochemical system, such as the limited voltage difference between the positive and negative electrode materials, and the limited redox resistance of the electrolyte, the operating voltage of the lithium-ion battery is difficult to exceed 5V. However, in actual use, there are many scenarios that need to use more than 5V voltage, such as electric vehicles (EV), voltage transformers (PT), energy storage systems (ESS) and other application scenarios.

In order to improve the output voltage of lithium-ion batteries, the existing technology usually connects multiple lithium-ion batteries in series when they are stacked in the thickness direction. However, in this series structure, due to the close contact between adjacent lithium-ion batteries in the thickness direction, The reduction of the heat dissipation surface area may easily lead to an excessively high temperature of the lithium-ion battery, thereby causing the lithium-ion battery to overheat and even cause a safety accident.

SUMMARY OF THE INVENTION

The present application provides an electrochemical device and an electronic device including the electrochemical device to avoid overheating during use of the electrochemical device.

A first aspect of the present application provides an electrochemical device, comprising an outer package, a separator, and electrode assemblies disposed on both sides of the separator, wherein the separator and the electrode assembly are located in the outer package, and the separator The board protrudes from one side of the outer package sealing edge, and the length of the separator protruding from the outer package sealing edge is 3 mm to 30 mm.

In some embodiments of the present application, the separator protrudes from a bottom edge or side edge of the outer package seal.

In some embodiments of the present application, a part of the partition extending out of the outer package is provided with a heat dissipation device, and the heat dissipation device includes a fin type heat sink or a fin type heat sink.

In some embodiments of the present application, the separator is connected to the outer package, and sealed cavities are respectively formed on both sides of the separator, and each sealed cavity is encapsulated with an electrode assembly and an electrolyte.

In some embodiments of the present application, the electrode assemblies are provided with tabs of different polarities, the tabs extend out of the outer package, and the adjacent electrode assemblies are connected in series through the tabs.

In some embodiments of the present application, the material of the separator includes at least one of a polymer film, a metal foil, and a carbon material.

In some embodiments of the present application, each electrode assembly has two tabs with opposite polarities, the two tabs protrude from the outer package, and two adjacent electrode assemblies are connected in series through the tabs.

In some embodiments of the present application, the separator is a bipolar separator, and the bipolar separator includes at least one of Cu-Al composite current collectors, stainless steel foil current collectors or polymer conductive current collectors .

In some embodiments of the present application, one side of the bipolar separator is provided with an electrode active material layer, and the outermost layer of the electrode assembly adjacent to the electrode active material layer is provided with electrode active materials with opposite polarities layer, a separator is provided between one side of the bipolar separator provided with the electrode active material layer and the adjacent electrode assembly, and the other side of the bipolar separator is electrically connected to the adjacent electrode assembly Insulation, the bipolar separator leads out a tab, and the tab is connected with the tabs connected in series with the electrode assemblies on both sides.

In some embodiments of the present application, one side of the bipolar separator is provided with an electrode active material layer, and the outermost layer of the electrode assembly adjacent to the electrode active material layer is provided with electrode active materials with opposite polarities layer, a separator is provided between the side of the bipolar separator with the electrode active material layer and the adjacent electrode assembly, and the other side of the bipolar separator is connected with the adjacent electrode assembly. electrical connection.

In some embodiments of the present application, electrode active material layers of different polarities are respectively provided on both sides of the bipolar separator, and the outermost layer of the electrode assembly adjacent to each electrode active material layer is provided with polar electrodes. In contrast to the electrode active material layer, a separator is provided between the electrode active material layer of the bipolar separator and the electrode active material layer of the outermost layer of the electrode assembly.

In some embodiments of the present application, the separator is hermetically connected to the outer package, and the part where the separator and the outer package are encapsulated includes an encapsulation material, and the encapsulation material includes polypropylene, acid anhydride modified polypropylene , polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-acrylic acid copolymer, ethylene-vinyl alcohol copolymer, polyvinyl chloride, polystyrene, polyether nitrile, polyurethane, polyamide, poly At least one of esters, amorphous alpha-olefin copolymers and derivatives thereof. In some embodiments of the present application, the separator has a thickness of 6 μm to 100 μm.

In some embodiments of the present application, it has at least one of the following features:

a. The electrochemical device comprises 2 to 3 separators;

b. The thickness of the separator is 10 μm to 40 μm;

c. The length of the separator protruding from the sealing edge of the outer package is 5mm to 20mm.

In some embodiments of the present application, the structure of the electrode assembly includes at least one of a wound structure or a laminated structure.

A second aspect of the present application provides an electronic device, including the electrochemical device provided in the first aspect of the present application.

The electrochemical device provided by the present application separates the lithium ion battery into a plurality of independent sealed cavities through the introduction of the separator and the sealed connection between the separator and the outer package, so as to realize the ion isolation between different sealed cavities and avoid internal leakage. The safety hazard of short circuit or high-voltage decomposition of the electrolyte can be avoided, thereby improving the safety performance of the electrochemical device and ensuring the effective power output of the electrochemical device. At the same time, by extending the separator from one of the sealing edges of the outer packaging, a heat dissipation device is provided at the part of the separator extending out of the outer packaging, so that part of the heat inside the electrochemical device can be exported through contact heat transfer, which can avoid the use of An overheating condition resulting from the accumulation of heat in an electrochemical device.

Description of drawings

In order to more clearly illustrate the embodiments of the present application and the technical solutions of the prior art, the following briefly introduces the drawings required in the embodiments and the prior art. Obviously, the drawings in the following description are only the For some embodiments of the application, for those of ordinary skill in the art, other embodiments can also be obtained according to these drawings.

1 is a top view of an electrochemical device according to an embodiment of the present application;

2 is a schematic diagram of an electrochemical device according to an embodiment of the application;

Fig. 3 is a schematic diagram of the decomposition structure of the electrochemical device of Fig. 2;

4 is a schematic diagram of an electrochemical device according to an embodiment of the present application;

FIG. 5 is a partial schematic view of the internal structure section of the electrochemical device of FIG. 4;

6 is a partial schematic cross-sectional view of an internal structure of an electrochemical device according to an embodiment of the present application;

7 is a partial schematic cross-sectional view of an internal structure of an electrochemical device according to an embodiment of the present application.

detailed description

In order to make the objectives, technical solutions and advantages of the present application more clearly understood, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all of the embodiments. All other embodiments obtained based on the embodiments in the present application fall within the protection scope of the present application.

The electrochemical device described in the present application is not particularly limited, and can be any electrochemical device that can use the present application, such as lithium-ion batteries, sodium-ion batteries, magnesium-ion batteries, supercapacitors, and the like. For the convenience of description, a lithium ion battery is used as an example for description, but this does not mean that the electrochemical device of the present application is limited to a lithium ion battery.

A first aspect of the present application provides an electrochemical device, comprising an outer package, a separator, and electrode assemblies disposed on both sides of the separator, wherein the separator and the electrode assembly are located in the outer package, and the separator a panel protrudes from one of the sealing edges of the outer package;

The length of the partition extending from the sealing edge of the outer package is 3 mm to 30 mm, preferably 5 mm to 20 mm; when the length of the partition extending from the sealing edge of the outer packaging is less than 3 mm, the extended part of the partition is too short, The heat dissipation effect is poor, or it is difficult to be fully and effectively connected with the heat dissipation device, so that the effective heat dissipation effect cannot be achieved; when the length of the partition extending beyond the sealing edge of the outer package is greater than 30mm, the extended part of the partition is too long, which will reduce the Energy density of electrochemical devices.

Usually, the "sealing edge of the outer package" refers to the sealing area formed around the outer package after the outer package is sealed and encapsulated, wherein the sealing edge protruding from the side of the tab is the top sealing edge, and the side opposite to the top sealing edge is Bottom sealing edge, two opposite sealing edges in the width direction of the outer package perpendicular to the top sealing edge are side sealing edges.

In the present application, the separator may extend from the bottom edge or the side edge of the outer package seal. The outer package sealing edge includes two side sealing edges, and in one embodiment, the separator of the present application may protrude from one of the two side sealing edges. Referring to FIG. 1, the "overpack seal edge" includes the bottom edge 52 and the two

side edges

51, 53, and does not include the top edge 54.

In some embodiments of the present application, the specific number of separators included in the electrochemical device is not limited, and those skilled in the art can choose according to actual needs, as long as the purpose of the present application can be achieved. 3 of said separators.

In some embodiments of the present application, the part of the partition extending out of the outer package is provided with a heat dissipation device. In this application, the type of the heat dissipation device is not particularly limited, as long as the purpose of the application can be achieved, For example, the heat dissipation device may include one of a chip heat sink, a fin heat sink, and the like.

In some embodiments of the present application, the separator is hermetically connected to the outer package, and sealed cavities are respectively formed on both sides of the separator, each sealed cavity is encapsulated with an electrode assembly and an electrolyte, and each sealed cavity It can realize ionic insulation between the two parts, avoid the problem of internal short circuit of the electrochemical device and the problem of the decomposition of the electrolyte under high voltage, thereby improving the safety performance of the electrochemical device and ensuring the effective power output of the electrochemical device. The separator protrudes from one side of the sealing edge of the outer package, and a heat dissipation device is arranged on the part of the separator protruding from the outer package, so as to realize the timely dissipation of the heat inside the electrochemical device.

In some embodiments of the present application, the electrode assemblies are provided with tabs of different polarities, the tabs extend out of the outer package, and the adjacent electrode assemblies are connected in series through the tabs. When all the tabs of the electrode assembly are drawn out of the outer packaging for welding, the welding effect of the tabs can be monitored at any time, reducing the risk of tab breakage and avoiding the problem of increasing the internal resistance of the electrochemical device due to poor tab welding results. ; Connecting adjacent electrode assemblies in series can effectively improve the output voltage of the electrochemical device.

FIG. 2 shows an embodiment of the present application, and FIG. 3 is a schematic diagram of the exploded structure of the electrochemical device in FIG. 2 . Referring to FIGS. 2 and 3 , the electrode assembly 31 and the electrode assembly 32 are separated by a separator 40 . 40 protrudes from the side sealing edge 53, and the part of the partition extending out of the outer package 10 is connected to an external heat sink, so as to dissipate the internal heat. The separator 40 is hermetically connected to the outer package 10, and independent sealed cavities are formed on both sides of the separator 40. The sealed cavities are ionically insulated, and each sealed cavity contains an electrode assembly and an electrolyte. The negative electrode tab 22 of the electrode assembly 31 and the positive electrode tab 23 of the electrode assembly 32 extend out of the outer package 10 and are connected in series to form a tab 25. The positive electrode tab 21 of the electrode assembly 31 and the negative electrode tab 24 of the electrode assembly 32 are used as positive and negative terminals. , for connection during charging and discharging.

The polymer film is not particularly limited, as long as it can achieve the purpose of the present application, for example, it may include polyethylene terephthalate (PET), polybutylene terephthalate, polyethylene naphthalate Alcohol ester, polyetheretherketone, polyimide (PI), polyamide (PA), polyethylene glycol, polyamideimide, polycarbonate, cyclic polyolefin (PO), polyphenylene sulfide, Polyvinyl acetate, polytetrafluoroethylene, polymethylene naphthalene, polyvinylidene fluoride, polyethylene naphthalate, polypropylene carbonate, poly(vinylidene fluoride-hexafluoropropylene), poly(vinylidene fluoride-hexafluoropropylene) Vinylidene fluoride-co-chlorotrifluoroethylene), silicone resin, vinylon, polypropylene (PP), polyethylene (PE), polyvinyl chloride, polystyrene, polyether nitrile, polyurethane, polyphenylene ether, At least one of polysulfone, amorphous alpha-olefin copolymer and derivatives thereof.

The metal foil is not particularly limited, as long as it can achieve the purpose of the present application, for example, it may include Ni, Ti, Cu, Ag, Au, Pt, Fe, Co, Cr, W, Mo, Al, Mg, K , at least one of Na, Ca, Sr, Ba, Si, Ge, Sb, Pb, In, Zn, stainless steel (SUS), and combinations or alloys thereof. Preferably, a metal foil with better oxidation-reduction resistance in the lithium-ion battery environment can be selected. More preferably, a metal or alloy-based metal foil with good thermal conductivity can be selected.

The carbon material is not particularly limited as long as it can achieve the purpose of the present application, for example, it can include single-walled carbon nanotubes, multi-walled carbon nanotubes (MWCNT), carbon felt, carbon film, carbon black, acetylene black, At least one of lerene, conductive graphite film or graphene film.

In some embodiments of the present application, the material of the separator is preferably a polymer film. Since the polymer film has a low density, the weight of the inactive material can be reduced, thereby increasing the mass energy density of the electrode assembly. In addition, the material of the separator is made of polymer material, under the condition of mechanical abuse (piercing nails, impact, extrusion, etc.), the probability of generating debris is smaller, and the effect of wrapping the surface of mechanical damage is better, so it can improve the above mechanical Abuse the security boundary in the case of abuse to improve the security test pass rate.

In some embodiments of the present application, the material of the separator is preferably metal foil, which has strong isolation reliability, and the toughness and compactness of the metal foil are better than those of polymer materials, and the processing thickness can also be made thinner.

In some embodiments of the present application, the material of the separator is preferably a carbon material, which has excellent safety performance, especially good thermal conductivity and excellent high temperature reliability.

In some embodiments of the present application, the material of the separator may further include a composite material formed by compounding at least two of a polymer film, a metal foil, and a carbon material. The type of the composite material is not particularly limited, any material known to those skilled in the art can be used, as long as the purpose of the application can be achieved, for example, it can include Ni metal surface layer composite PP film, Ag metal surface layer composite PET film, etc.

In some embodiments of the present application, the separator is a bipolar separator, and the bipolar separator includes at least one of a Cu-Al composite current collector, a stainless steel foil current collector or a polymer conductive current collector .

The polymer conductive current collector includes a composite material composed of a polymer material and a conductive material. The application does not specifically limit the polymer conductive current collector, as long as the purpose of the application can be achieved. For example, a polymer conductive current collector includes A polymer matrix and a conductive agent, wherein the conductive agent is a one-dimensional or two-dimensional conductive material, and the conductive material is distributed in the polymer matrix at an angle of 0° to 30° with the thickness direction of the polymer matrix. Another polymer conductive current collector includes conductive layers respectively arranged on two surfaces of the polymer matrix, and the two conductive layers are electrically connected. Another polymer conductive current collector includes a porous polymer matrix, and the conductive material is located in the pores of the porous polymer matrix, so that the two surfaces of the polymer conductive current collector can achieve electronic conduction. Another typical example of a polymer conductive current collector is the presence of the same or different metal material layers on both surfaces of the polymer material.

There is no particular limitation on the preparation method of the polymer conductive current collector, as long as the purpose of the application can be achieved. For example, it can be obtained by the following method: spraying a polymer material on a stainless steel substrate to obtain a polymer material layer, heating the polymer material Then, the one-dimensional or two-dimensional conductive material is implanted, and then the polymer material is sprayed again to form a polymer material film, and the obtained polymer material film is superheated and rolled. Next, roll up to obtain a polymer conductive current collector.

The conductive material includes at least one of carbon material or metal material.

The polymer conductive current collector can also be formed by other methods. For example, conductive agent particles and the like are dispersed in a polymer material.

In some embodiments of the present application, one side of the bipolar separator is provided with an electrode active material layer, and the outermost layer of the electrode assembly adjacent to the electrode active material layer is provided with electrode active materials with opposite polarities layer, a separator is provided between one side of the bipolar separator provided with the electrode active material layer and the adjacent electrode assembly, and the other side of the bipolar separator is electrically connected to the adjacent electrode assembly Insulation, the bipolar separator leads out a tab, and the tab is connected with the tabs connected in series with the electrode assemblies on both sides. In this embodiment, the first side of the bipolar separator and the outermost electrode piece of the adjacent electrode assembly constitute an electrochemical unit, which participates in the charging and discharging process of the electrochemical device and improves the energy of the electrochemical device density. An electrode lug is drawn out from the bipolar separator, and the electrode lug is connected with the electrode lugs connected in series with the electrode assemblies on both sides, thereby providing a high output voltage.

FIG. 4 is a schematic diagram of an electrochemical device according to another embodiment of the present application, and FIG. 5 is a partial schematic cross-sectional view of the internal structure of the electrochemical device of FIG. 4 . Referring to FIGS. 4 and 5 , the separator 40 of this embodiment is a bipolar separator. Plate, the A side of the bipolar separator is provided with a positive electrode active material layer 71, the outermost electrode assembly 31 adjacent to the positive electrode active material layer 71 is provided with a negative electrode active material layer 72, and the A side of the bipolar separator is provided with a negative electrode active material layer 72. A separator 80 is arranged between the positive electrode active material layer 71 and the negative electrode active material layer 72 of the outermost layer of the adjacent electrode assembly 31; The outer layer is provided with a separator 80, so as to electrically insulate the B side of the bipolar separator from the adjacent electrode assembly 32; the bipolar separator leads out a positive tab 27, the negative tab 22 of the electrode assembly 31 and the electrode The positive tab 23 of the assembly 32 is connected in series outside the outer package 10 to form a tab 25 (as shown in FIG. 2 ), the positive tab 27 is connected to the tab 25 to provide a high output voltage, and the positive tab 21 of the electrode assembly 31 and the electrode assembly The negative tabs 24 of 32 are used as positive and negative terminals for connection during charging and discharging. Those skilled in the art can understand that the positive electrode active material layer on the A side of the bipolar separator can also be the negative electrode active material layer. In this case, the outermost layer of the electrode assembly adjacent to the A side includes the positive electrode active material layer. .

In some embodiments of the present application, one side of the bipolar is provided with an electrode active material layer, and the outermost layer of the electrode assembly adjacent to the electrode active material layer is provided with an electrode active material layer with opposite polarity, A separator is arranged between one side of the bipolar separator provided with the electrode active material layer and the adjacent electrode assemblies, and the other side of the bipolar separator is electrically connected to the adjacent electrode assemblies. connect.

In the present application, the above-mentioned "electrical connection" means that the side of the bipolar separator without electrode active material realizes circuit connection through physical contact with the outermost current collector of its adjacent electrode assembly, that is, with the bipolar separator. There is no electrode active material on the surface of the electrode pads that are electrically connected by the separator.

In some embodiments of the present application, the bipolar separator may not lead out the tabs. In this case, the electrode assemblies on both sides of the bipolar separator are directly connected in series through the bipolar separator, and the electrochemical The device can only lead out two polar tabs with opposite polarities. When the electrochemical device contains more than two electrode assemblies, all the electrode assemblies are connected in series between the above two polar tabs with opposite polarities through bipolar separators. .

In some embodiments of the present application, the bipolar separator may also lead out a tab, and the tab is connected to the tab of the same polarity on the electrode assembly on the side where the electrode active material is arranged on the bipolar separator, A parallel connection is formed, and then it is connected with the opposite polarity tabs on the electrode assembly on the other side to form a series connection. At this time, the two electrode assemblies can be connected in series through the bipolar separator inside and through the outside of the tabs. In addition, the tabs of the bipolar separator may not be connected to the tabs of the electrode assembly, and are only used to monitor the voltage of the electrochemical device, which can timely check the faulty electrode assembly, find the cause of failure, and improve the manufacturing yield of the electrochemical device. and production efficiency.

FIG. 6 shows a partial schematic cross-sectional view of the internal structure of an electrochemical device according to an embodiment of the present application. As shown in FIG. 6 , the separator 40 of this embodiment is a bipolar separator, and the A side of the bipolar separator is arranged There is a negative electrode active material layer 72, the outermost electrode assembly 31 adjacent to the negative electrode active material layer 72 is provided with a positive electrode active material layer 71, the negative electrode active material layer 72 on the A side of the bipolar separator and the adjacent electrode assembly 31 A separator 80 is arranged between the outermost positive electrode active material layers 71; the B side of the bipolar separator has no electrode active material layer, and the outermost layer of the electrode assembly 32 adjacent to the B side of the bipolar separator is the positive electrode The current collector 61 , the positive electrode current collector 61 is electrically connected to the B side of the bipolar separator 0 . The electrode assembly 31 and the electrode assembly 32 can be connected in series directly through the bipolar separator, and only the positive tab of the electrode assembly 31 and the negative tab of the electrode assembly 32 are drawn out as positive and negative terminals for connection during charging and discharging. A negative electrode lug can also be provided on the bipolar separator. The electrode lug is connected to the negative electrode lug of the electrode assembly 31 to form a parallel connection, and then connected to the positive electrode lug of the electrode assembly 32 to form a series connection. At this time, the two electrodes The

components

31 and 32 are connected in series both internally through the bipolar separator and externally through the tabs. In addition, the tabs on the bipolar separator may not be connected to the tabs of the electrode assembly, and are only used for monitoring the voltage of the electrochemical device.

Those skilled in the art can understand that the negative electrode active material layer on the A side of the bipolar separator can also be a positive electrode active material layer. In this case, the outermost layer of the electrode assembly adjacent to the A side is provided with a negative electrode active material layer. In the material layer, the outermost layer of the electrode assembly adjacent to the B side of the bipolar separator is the negative electrode current collector 62, and the adjacent electrode assemblies can be connected in series directly through the bipolar separator.

In some embodiments of the present application, electrode active material layers of different polarities are respectively provided on both sides of the bipolar separator, and the outermost layer of the electrode assembly adjacent to each electrode active material layer is provided with polar electrodes. In contrast to the electrode active material layer, a separator is provided between the electrode active material layer of the bipolar separator and the electrode active material layer of the outermost layer of the electrode assembly. Two sides of the bipolar separator are respectively provided with electrode active material layers with different polarities, and the two sides respectively form electrochemical cells with the outermost electrode plates of adjacent electrode assemblies, thereby further improving the energy density of the battery.

The electrode assemblies on both sides of the bipolar separator can be directly connected in internal series through the bipolar separator, or can be connected in series internally and externally simultaneously through the bipolar separator and two polar tabs with opposite polarities.

FIG. 7 shows a partial schematic cross-sectional view of the internal structure of an electrochemical device according to an embodiment of the present application. As shown in FIG. 7 , the separator 40 of this embodiment is a bipolar separator, and the A side of the bipolar separator is provided There is a negative electrode active material layer 72, the outermost layer of the electrode assembly 31 adjacent to the A side of the bipolar separator is a positive electrode active material layer 71, and the B side of the bipolar separator is provided with a positive electrode active material layer 71, and the bipolar separator. The outermost layer of the electrode assembly 32 adjacent to the B side of the polar separator is the negative electrode active material layer 72, the electrode active material layer on the A and B sides of the bipolar separator and the electrode active material layer of the outermost layer of the adjacent electrode assembly. Separators 80 are respectively arranged between the material layers, and the electrode assembly 31 and the electrode assembly 32 are connected in series directly through the bipolar separator.

In some embodiments of the present application, electrode active material layers with different polarities are respectively provided on both sides of the bipolar separator, and a tab is provided on the bipolar separator, and the tab can be used For monitoring the voltage of the electrochemical device, or insulating the tabs. The tabs can also be connected to the series tabs of the electrode assemblies on both sides of the bipolar separator.

In some embodiments of the present application, the separator is hermetically connected to the outer package, and the part where the separator and the outer package are encapsulated includes an encapsulation material, and the encapsulation material includes polypropylene, acid anhydride modified polypropylene , polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-acrylic acid copolymer, ethylene-vinyl alcohol copolymer, polyvinyl chloride, polystyrene, polyether nitrile, polyurethane, polyamide, poly At least one of esters, amorphous alpha-olefin copolymers and derivatives thereof. The selection of the above-mentioned encapsulation material can more effectively seal the connection with the outer package, thereby helping to improve the safety of the electrochemical device.

In the present application, the size of the sealing edge formed after the separator and the outer package are encapsulated is not particularly limited, as long as the purpose of the present application can be achieved. For example, the thickness T (unit: mm) and the width W (unit: mm) of the sealing edge satisfy 0.01≤T/W≤0.05. When the ratio of T/W is within the above range, the sealing of the battery can be ensured and the service life of the battery can be improved. When the T/W is too small, the thickness of the seal may be insufficient and the sealing effect is not good, resulting in a decrease in the environmental stability of the battery. For example, the water vapor in the environment easily penetrates into the interior of the battery, resulting in an increase in the moisture content in the battery, the decomposition of the electrolyte, and the reduction of the battery. If the ratio of T/W is too large, the sealing width W may be too small, and the sealing effect is also not good, which will reduce the environmental stability of the battery. The increase of the content and the decomposition of the electrolyte will reduce the service life of the battery. In the present application, the seal thickness and the seal width are not particularly limited, as long as the purpose of the present application can be achieved, for example, the width W of the seal edge is preferably 1 mm to 7 mm.

In the packaging process of the present application, the polymer material in the outer package and the polymer material in the sealing material are sealed together by hot pressing. Therefore, the seal thickness includes the thickness after the polymer material in the sealing material is fused with the polymer material in the inner layer of the outer package. The sealing width refers to the width of the sealing area formed by the combination of the polymer material in the sealing material and the polymer material in the inner layer of the outer package after heat-press sealing. In some embodiments of the present application, the thickness of the separator is 6 μm to 100 μm, preferably 10 μm to 40 μm, and more preferably 20 μm to 30 μm. When the thickness of the separator is less than 6 μm, the mechanical strength of the separator may be insufficient, and it is easy to cause damage, which affects the performance and even the safety of the electrochemical device; when the thickness of the separator is greater than 100 μm, the quality of the introduced inactive substances increases, reducing the electrochemical performance. The energy density of the device.

In some embodiments of the present application, the structure of the electrode assembly is a winding structure, and the electrode assembly draws out at least one positive electrode tab and one negative electrode tab from the positive electrode tab and the negative electrode tab, respectively.

In some embodiments of the present application, the structure of the electrode assembly is a laminated structure, and the electrode assembly includes a plurality of tabs, which may be one positive tab and one negative electrode drawn from each layer of positive electrode and negative electrode respectively. Tabs, and finally a laminated structure electrode assembly includes multiple sets of positive tabs and negative tabs, and then lead out metal sheets through transfer welding and turning tabs.

In this application, the above-mentioned "electrode tab" generally refers to a metal conductor drawn from the positive electrode piece or the negative electrode piece, which is used to connect other parts of the electrochemical device in series or in parallel. The positive tab is drawn from the positive pole piece, and the negative pole tab is drawn from the negative pole piece.

In the present application, the material of the tab is not particularly limited, as long as the purpose of the present application can be achieved. For example, the positive electrode tab material includes at least one of aluminum (Al) or an aluminum alloy, and the negative electrode tab material includes at least one of nickel (Ni), copper (Cu), or nickel-plated copper (Ni-Cu).

In the present application, the welding method of the tab is not particularly limited, as long as the purpose of the present application can be achieved. For example, at least one of laser welding, ultrasonic welding, resistance welding, and the like.

In the present application, the direction in which the tabs are drawn out is not particularly limited, as long as the purpose of the present application can be achieved. For example, the lead-out directions of the tabs can be the same direction or different directions.

In some embodiments of the present application, the electrode assembly may comprise a separator, a positive electrode sheet and a negative electrode sheet, the separator is used to separate the positive electrode sheet and the negative electrode sheet, prevent internal short circuit of the electrochemical device, and allow free passage of electrolyte ions, Complete the role of the electrochemical charge and discharge process. In the present application, the number of separators, positive electrode pieces and negative electrode pieces is not particularly limited, as long as the purpose of the present application can be achieved.

In some embodiments of the present application, the separator is not particularly limited, as long as the purpose of the present application can be achieved. For example, polyethylene (PE), polypropylene (PP)-based polyolefin (PO) separators, polyester films (such as polyethylene terephthalate (PET) films), cellulose films, polyimide Amine film (PI), polyamide film (PA), spandex or aramid film, woven film, non-woven film (non-woven fabric), microporous film, composite film, diaphragm paper, rolled film, spinning film, etc. at least one of.

For example, the separator may include a substrate layer and a surface treatment layer. The substrate layer can be a non-woven fabric, film or composite film with a porous structure, and the material of the substrate layer can include at least one of polyethylene, polypropylene, polyethylene terephthalate, polyimide, etc. kind. Optionally, polypropylene porous membranes, polyethylene porous membranes, polypropylene non-woven fabrics, polyethylene non-woven fabrics, or polypropylene-polyethylene-polypropylene porous composite membranes may be used. Optionally, at least one surface of the substrate layer is provided with a surface treatment layer, and the surface treatment layer can be a polymer layer or an inorganic layer, or a layer formed by mixing a polymer and an inorganic substance.

For example, the inorganic layer includes inorganic particles and a binder, the inorganic particles are not particularly limited, and can be selected from aluminum oxide, silicon oxide, magnesium oxide, titanium oxide, hafnium dioxide, tin oxide, ceria, nickel oxide, for example , at least one of zinc oxide, calcium oxide, zirconium oxide, yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide and barium sulfate. The binder is not particularly limited, for example, it can be selected from polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, polyethylene One or a combination of rolidone, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene and polyhexafluoropropylene. The polymer layer contains a polymer, and the material of the polymer includes polyamide, polyacrylonitrile, acrylate polymer, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl ether, polyvinylidene fluoride or poly( At least one of vinylidene fluoride-hexafluoropropylene) and the like.

In some embodiments of the present application, the positive electrode sheet is not particularly limited, as long as the purpose of the present application can be achieved. For example, the positive electrode sheet typically includes a positive electrode current collector and a positive electrode active material. In the present application, the positive electrode current collector is not particularly limited, and can be any positive electrode current collector known in the art, such as copper foil, aluminum foil, aluminum alloy foil, composite current collector, and the like. The positive electrode active material is not particularly limited, and can be any positive electrode active material in the prior art. For example, the positive electrode active material includes nickel-cobalt lithium manganate, nickel-cobalt lithium aluminate, lithium iron phosphate, lithium cobaltate, manganic acid At least one of lithium or lithium iron manganese phosphate and the like. In the present application, the thicknesses of the positive electrode current collector and the positive electrode active material are not particularly limited as long as the purpose of the present application can be achieved. For example, the thickness of the cathode current collector is 8 μm to 12 μm, and the thickness of the cathode active material is 30 μm to 120 μm.

Optionally, the positive electrode sheet may further comprise a conductive layer located between the positive electrode current collector and the positive electrode active material layer. The composition of the conductive layer is not particularly limited, and may be a conductive layer commonly used in the art. The conductive layer includes a conductive agent and an adhesive.

In some embodiments of the present application, the negative pole piece is not particularly limited, as long as the purpose of the present application can be achieved. For example, the negative electrode sheet generally includes a negative electrode current collector and a negative electrode active material. In the present application, the negative electrode current collector is not particularly limited, and any negative electrode current collector known in the art can be used, such as copper foil, aluminum foil, aluminum alloy foil, composite current collector, and the like. The negative electrode active material is not particularly limited, and any negative electrode active material known in the art may be used. For example, at least one of artificial graphite, natural graphite, mesocarbon microspheres, silicon, silicon carbon, silicon oxide, soft carbon, hard carbon, lithium titanate or niobium titanate, and the like may be included. In the present application, the thicknesses of the negative electrode current collector and the negative electrode active material are not particularly limited as long as the purpose of the present application can be achieved. For example, the thickness of the anode current collector is 6 μm to 10 μm, and the thickness of the anode active material is 30 μm to 120 μm.

Optionally, the negative electrode sheet may further comprise a conductive layer located between the negative electrode current collector and the negative electrode active material layer. The composition of the conductive layer is not particularly limited, and may be a conductive layer commonly used in the art. The conductive layer includes a conductive agent and an adhesive.

The above-mentioned conductive agent is not particularly limited as long as the purpose of the present application can be achieved. For example, the conductive agent may include at least one of conductive carbon black (Super P), carbon nanotubes (CNTs), carbon fiber or graphene, and the like. The above-mentioned adhesive is not particularly limited, and any adhesive known in the art can be used as long as the purpose of the present application can be achieved. For example, the adhesive may include at least one of styrene-butadiene rubber (SBR), polyvinyl alcohol (PVA), polytetrafluoroethylene (PTFE), sodium carboxymethyl cellulose (CMC-Na), and the like. For example, styrene-butadiene rubber (SBR) can be selected as the adhesive.

In the present application, the electrolyte is not particularly limited as long as the purpose of the present application can be achieved. For example, the electrolyte is selected from any one of gel state, solid state and liquid state. For example, the liquid electrolyte includes a lithium salt and a non-aqueous solvent.

The lithium salt is not particularly limited as long as the purpose of the present application can be achieved. For example, lithium salts may include LiPF ₆ , LiBF ₄ , LiAsF ₆ , LiClO ₄ , LiB(C ₆ H ₅ ) ₄ , LiCH ₃ SO ₃ , LiCF ₃ SO ₃ , LiN(SO ₂ CF ₃ ) ₂ , LiC(SO ₂ ) At least one of CF ₃ ) ₃ or LiPO ₂ F ₂ and the like. For example, LiPF ₆ can be selected as the lithium salt.

The non-aqueous solvent is not particularly limited as long as the purpose of the present application can be achieved. For example, the non-aqueous solvent may include at least one of carbonate compounds, carboxylate compounds, ether compounds, nitrile compounds, other organic solvents, and the like.

For example, the carbonate compound may include diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), ethyl methyl carbonate Ester (MEC), Ethylene Carbonate (EC), Propylene Carbonate (PC), Butylene Carbonate (BC), Vinyl Ethylene Carbonate (VEC), Fluoroethylene Carbonate (FEC), Carbonic Acid 1 ,2-difluoroethylene carbonate, 1,1-difluoroethylene carbonate, 1,1,2-trifluoroethylene carbonate, 1,1,2,2-tetrafluoroethylene carbonate, 1,1,2,2-tetrafluoroethylene carbonate -Fluoro-2-methylethylene carbonate, 1-fluoro-1-methylethylene carbonate, 1,2-difluoro-1-methylethylene carbonate, 1,1,2-trifluorocarbonate- At least one of 2-methylethylene, trifluoromethylethylene carbonate, and the like.

In this application, the outer packaging is not particularly limited, as long as the purpose of the application can be achieved.

For example, the outer package can include an inner layer and an outer layer, and the inner layer is sealed with the bipolar current collector, so the material of the inner layer can include a polymer material, so as to achieve a good sealing effect; at the same time, the combination of the inner layer and the outer layer can Effectively protect the internal structure of electrochemical devices. In this application, the material of the inner layer is not particularly limited, as long as the purpose of the application can be achieved, for example, the material of the inner layer includes polypropylene, polyester, p-hydroxybenzaldehyde, polyamide, polyphenylene ether, polyurethane at least one of etc. In the present application, the material of the outer layer is not particularly limited, as long as the purpose of the present application can be achieved. For example, the material of the outer layer includes at least one of aluminum foil, aluminum oxide layer, silicon nitride layer, and the like.

For example, the outer package can be an aluminum-plastic film, and the aluminum-plastic film includes a nylon layer, an aluminum foil layer and a PP layer.

In the present application, the thickness of the outer package is not particularly limited, as long as the purpose of the present application can be achieved. For example, the thickness of the outer package may be 60 μm to 500 μm, preferably 60 μm to 300 μm, more preferably 60 μm to 200 μm. The outer packaging with the above thickness can effectively protect the internal structure of the electrochemical device.

The application does not specifically limit the sealing connection method between the separator and the outer package, as long as the purpose of the application can be achieved. For example, the sealing method includes one of hot pressing, glue sealing, and welding. In the present application, the hot pressing conditions are not particularly limited, as long as the purpose of the present application can be achieved. For example, for the polypropylene inner layer material, the hot pressing temperature is 150°C to 220°C, and the hot pressing pressure is 0.1 MPa to 0.6 MPa.

A second aspect of the present application provides an electronic device comprising the electrochemical device provided in the first aspect of the present application.

The electronic devices described in this application include general electronic devices in the art, such as notebook computers, pen input computers, mobile computers, e-book players, portable telephones, portable fax machines, portable copiers, portable printers, and headsets. , VCR, LCD TV, Portable Cleaner, Portable CD Player, Mini CD, Transceiver, Electronic Notepad, Calculator, Memory Card, Portable Recorder, Radio, Backup Power, Motor, Automobile, Motorcycle, Power-assisted Bicycle, Bicycle , lighting equipment, toys, game consoles, clocks, power tools, flashes, cameras, large household batteries and lithium-ion capacitors, etc.

The terms used in the art are generally those commonly used by those skilled in the art. If there is any inconsistency with the commonly used terms, the terms in this application shall prevail.

testing method:

0.1C discharge energy density:

The electrochemical device was allowed to stand at room temperature for 30 minutes, charged at a constant current rate of 0.05C to a voltage of 4.4V (rated voltage), and then discharged to 3.0V at a rate of 0.05C, repeating the above charging/discharging Step 3 cycles to complete the formation of the electrochemical device to be tested. After completing the formation of the electrochemical device, the electrochemical device was charged to a voltage of 4.4V at a constant current charging rate of 0.1C, and then the electrochemical device was discharged to 3.0V at a discharge rate of 0.1C, and its discharge capacity was recorded, and then its 0.1C discharge rate was calculated. Energy Density:

Energy density (Wh/L)=discharge capacity (Wh)/volume size of electrochemical device (L)

2C discharge temperature rise:

Put the fully charged chemical device in the terminal heat sink, one side is in contact with the terminal heat sink, and one side is exposed; paste a temperature probe on the surface of the exposed side to monitor the temperature of the electrochemical device; The partition part and the heat dissipation device are attached with adhesive tape. If there is no part protruding from the partition, no treatment will be done; discharge with 2C current for 15 minutes, and monitor the highest value of the surface temperature.

Hereinafter, the embodiment of the present application will be described more specifically with reference to Examples and Comparative Examples. Various tests and evaluations were performed according to the following methods. In addition, unless otherwise specified, "%" and "part" are based on mass.

Example 1

The negative electrode active material graphite (Graphite), conductive carbon black (Super P), and styrene-butadiene rubber (SBR) were mixed in a weight ratio of 96:1.5:2.5, and then deionized water was added as a solvent to prepare a solid content of 70%. slurry and mix well. The slurry was uniformly coated on one surface of the negative current collector copper foil with a thickness of 8 μm, and dried at 110° C. to obtain a negative electrode sheet with a coating thickness of 130 μm coated with negative active material on one side. After the above steps are completed, the single-side coating of the negative pole piece has been completed. Afterwards, the above steps are repeated on the other surface of the negative electrode pole piece to obtain a negative electrode pole piece coated with negative electrode active material on both sides. After the coating is completed, the pole piece is cut into a size of 41mm×61mm for use.

The positive active material lithium cobalt oxide (LiCoO ₂ ), conductive carbon black (Super P), and polyvinylidene fluoride (PVDF) were mixed in a weight ratio of 97.5:1.0:1.5, and N-methylpyrrolidone (NMP) was added as a solvent. , prepare a slurry with a solid content of 75%, and stir evenly. The slurry was uniformly coated on one surface of a positive electrode current collector aluminum foil with a thickness of 10 μm, and dried at 90° C. to obtain a positive electrode sheet with a coating thickness of 110 μm. After the above steps are completed, the single-side coating of the positive electrode sheet is completed. After that, the above steps are repeated on the other surface of the positive electrode sheet to obtain a positive electrode sheet coated with positive active material on both sides. After the coating is completed, the pole piece is cut into a size of 38mm×58mm for use.

In a dry argon atmosphere, organic solvents ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC) were first mixed in a mass ratio of EC:EMC:DEC=30:50:20, and then Lithium salt lithium hexafluorophosphate (LiPF ₆ ) is added to the organic solvent to dissolve and mix uniformly to obtain an electrolyte solution with a lithium salt concentration of 1.15 mol/L.

A PP separator of 15 μm was placed between the above-prepared positive pole piece and negative pole piece, and the four corners were fixed after lamination to form a laminated electrode assembly, wherein the number of layers of the positive pole piece and the negative pole piece were 13 and 14 respectively. .

The encapsulating material polystyrene is uniformly dispersed in the dispersant N-methylpyrrolidone (NMP) to prepare a suspension of encapsulating material; using a glue applicator, the separator PP film with a thickness of 30 μm is encapsulated with the outer packaging. Parts are coated with encapsulation material; the dispersant NMP in the encapsulation material suspension is dried at 130° C. to complete the preparation of the separator. The melting point of the separator is 150°C, and the melting point of the packaging material is 240°C.

A piece of outer packaging (aluminum-plastic film with a thickness of 90 μm) formed by punching was placed in the assembly jig with the pit surface facing up, and an electrode assembly (hereinafter referred to as electrode assembly A) was placed in the pit. One positive tab and one negative tab are drawn from the electrode assembly A.

Then, place the separator on the electrode assembly A, make it contact with the electrode assembly A, and apply external force to press, wherein the separator is aligned with the edges of the top sealing edge, bottom sealing edge and the first side sealing edge of the outer package , protruding from the second side sealing edge of the outer package, and the length of the extended part of the partition is 5mm.

An electrode assembly (hereinafter referred to as electrode assembly B) is placed on the separator, so that it is in contact with the separator, and is pressed by an external force. One positive tab and one negative tab are drawn from the electrode assembly B.

Then, the negative electrode tab of electrode assembly A and the positive electrode tab of electrode assembly B are welded together by laser welding, so that the two are connected in series, and the connected tabs are extended out of the outer package.

Then, the positive tab of electrode assembly A and the negative tab of electrode assembly B were pulled out of the outer package.

Then, cover another piece of outer packaging (aluminum-plastic film with a thickness of 90 μm) on the electrode assembly B with the pit face down, leaving the liquid injection port side and other positions of the outer packaging to be heat-sealed to obtain an assembled electrode. Two independent cavities are formed on both sides of the separator. Among them, the heat-sealing temperature was 180°C, and the heat-sealing pressure was 0.5MPa.

Electrolyte is injected separately into the two cavities of the assembled electrode assembly, and sealed after injection.

The charging and discharging process only needs to connect the positive electrode tab of electrode assembly A and the negative electrode tab of electrode assembly B.

Example 2

Except that the separator material shown in Table 1 is Ti metal foil, the rest is the same as that of Example 1.

Example 3

Except that the separator material shown in Table 1 is SUS, the rest is the same as that of Example 1.

Example 4

Except that the separator material as shown in Table 1 is Ni metal surface layer composite PP film, the rest is the same as that of Example 1.

Example 5

Except that the separator material shown in Table 1 is a carbon nanotube (CNT) thin film, the rest is the same as that of Example 1.

Example 6

<Preparation of Negative Electrode Sheet>, <Preparation of Positive Electrode Sheet>, <Preparation of Electrolyte Solution>, <Preparation of Electrode Assembly>, the same as Example 1.

An aluminum foil with a thickness of 15 μm was obtained, copper magnetron sputtering was performed on one side, and the surface layer was coated with a homogeneous and equal-thickness copper material with a thickness of 15 μm to obtain a copper-aluminum metal composite current collector.

Then, the lower side of the Cu-Al composite current collector (hereinafter referred to as separator) prepared above is placed on the electrode assembly A, and an external force is applied to press, wherein there is no electrode active material on the lower side of the separator, and the lower side of the separator is pressed. A 15μm PP separator is arranged between the electrode assembly A, and the separator is aligned with the edges of the top sealing edge, bottom sealing edge and the first side sealing edge of the outer package, and protrudes from the second side sealing edge of the outer packaging, The length of the baffle protruding portion is 5 mm.

An electrode assembly (hereinafter referred to as electrode assembly B) is placed on the upper side of the separator, so that the outermost positive electrode piece is in contact with the upper side of the separator, and an external force is applied to press it, wherein the positive electrode piece is provided with a positive electrode active material , a negative active material is arranged on the upper side of the separator, and a 15 μm PP separator is arranged between the positive electrode and the upper side of the separator. A positive electrode tab and a negative electrode tab are drawn out from the electrode assembly B, and a positive electrode tab is drawn out from the separator.

Then, the negative electrode tab of electrode assembly A and the positive electrode tab of electrode assembly B are welded together by laser welding, so that the two are connected in series, and the positive electrode tab of the separator and the above-mentioned series-connected tab are welded together by laser welding. The connected tabs stick out of the outer package.

Then, cover another piece of outer packaging (aluminum-plastic film with a thickness of 90 μm) on the electrode assembly B with the pit face down, leaving the liquid injection port side and heat-sealing other positions of the outer packaging to obtain the assembled electrode. Two independent cavities are formed on both sides of the separator. Among them, the heat-sealing temperature was 180°C, and the heat-sealing pressure was 0.5MPa.

Example 7

<Preparation of Negative Electrode Sheet>, <Preparation of Positive Electrode Sheet>, <Preparation of Electrolyte Solution>, <Preparation of Electrode Assembly>, <Preparation of Separator>, the same as Example 3.

A piece of outer packaging (aluminum-plastic film with a thickness of 90 μm) formed by punching was placed in the assembly jig with the pit surface facing up, and an electrode assembly (hereinafter referred to as electrode assembly A) was placed in the pit. A positive tab is drawn from the electrode assembly A.

Then, the stainless steel foil current collector (hereinafter referred to as separator) prepared above is placed on the electrode assembly A, and the lower side of the separator is brought into contact with the outermost positive electrode piece of the electrode assembly A, and an external force is applied to press, wherein , there is no electrode active material on the lower side of the separator, and the above-mentioned positive electrode sheet has no positive electrode active material. And the separator is aligned with the edges of the top sealing edge, the bottom sealing edge and the first side sealing edge of the outer package, and protrudes from the second side sealing edge of the outer packaging, and the length of the extended part of the separator is 5mm.

An electrode assembly (hereinafter referred to as electrode assembly B) is placed on the upper side of the separator, so that the outermost positive electrode piece is in contact with the upper side of the separator, and an external force is applied to press it, wherein the positive electrode piece is provided with a positive electrode active material , a negative active material is arranged on the upper side of the separator, and a 15 μm PP separator is arranged between the positive electrode and the upper side of the separator. One negative tab is drawn from the electrode assembly B, and one negative tab is drawn from the separator.

Then, the positive tab of the electrode assembly A, the negative tab of the electrode assembly B, and the negative tab of the separator are extended out of the outer package.

Example 8

Spray the PET material on the stainless steel substrate to obtain a PET layer, heat the PET layer to soften it, implant the conductive material MWCNT, then spray the PET material again to form a PET film, overheat the PET film obtained by rolling, and use a scraper to remove the PET film from the stainless steel substrate. The surface is removed and rolled to obtain a polymer conductive current collector composed of PET and MWCNT.

Then, the polymer conductive current collector (hereinafter referred to as the separator) prepared above is placed on the electrode assembly A, so that the lower side of the separator is in contact with the negative pole piece of the outermost layer of the electrode assembly A, and an external force is applied to press, Wherein, the lower side of the separator is provided with positive active material, the negative electrode is provided with negative active material, and a 15 μm PP separator is provided between the negative electrode and the lower side of the separator. And the separator is aligned with the edges of the top sealing edge, bottom sealing edge and the first side sealing edge of the outer package, and protrudes from the second side sealing edge of the outer packaging, and the length of the extended part of the separator is 5mm.

An electrode assembly (hereinafter referred to as electrode assembly B) is placed on the upper side of the separator, so that the outermost positive electrode piece is in contact with the upper side of the separator, and an external force is applied to press it, wherein the positive electrode piece is provided with a positive electrode active material , a negative active material is arranged on the upper side of the separator, and a 15 μm PP separator is arranged between the positive electrode and the upper side of the separator. Lead out a negative tab from electrode assembly B.

Example 9

Except that the thickness of the separator shown in Table 1 is 6 μm, the rest is the same as that of Example 2.

Example 10

Except that the thickness of the separator shown in Table 1 was 10 μm, the rest was the same as that of Example 1.

Example 11

Except that the thickness of the separator shown in Table 1 is 15 μm, the rest is the same as that of Example 1.

Example 12

Except that the thickness of the separator shown in Table 1 is 20 μm, the rest is the same as that of Example 1.

Example 13

Except that the thickness of the separator shown in Table 1 was 40 μm, the rest was the same as that of Example 1.

Example 14

Except that the thickness of the separator shown in Table 1 is 100 μm, the rest is the same as that of Example 1.

Example 15

Except that the extension length of the separator shown in Table 1 is 3 mm, the rest is the same as that of Example 3.

Example 16

The rest is the same as in Example 3, except that the extension length of the separator shown in Table 1 is 10 mm.

Example 17

The rest is the same as that of Example 3, except that the extension length of the separator shown in Table 1 is 20 mm.

Example 18

The rest is the same as that of Example 3, except that the extension length of the separator is 30 mm as shown in Table 1.

Example 19

Except that the thickness of the aluminum-plastic film shown in Table 1 is 115 μm, the rest is the same as that of Example 3.

Example 20

Except that the preparation process of the lithium ion battery is different from that of Example 1, the rest is the same as that of Example 1.

Then place the separator (hereinafter referred to as separator a) on the electrode assembly A, make it contact with the electrode assembly A, and apply external force to press, wherein the separator a is sealed with the top edge and two side edges of the outer package. The edges of the baffles are aligned and protrude from the bottom edge of the outer package, and the length of the protruding part of the partition a is 5mm.

An electrode assembly (hereinafter referred to as electrode assembly C) is placed on the separator a, so that it is in contact with the separator a, and is pressed by an external force. A positive electrode tab and a negative electrode tab are led out from the electrode assembly C.

Then place the separator (hereinafter referred to as separator b) on the electrode assembly C, make it contact with the electrode assembly C, and apply external force to press, wherein the separator b is sealed with the top edge and two side edges of the outer package. The edges of the baffles are aligned and protrude from the bottom sealing edge of the outer package, and the length of the protruding part of the partition b is 5mm.

An electrode assembly (hereinafter referred to as electrode assembly B) is placed on the separator b, so that it is in contact with the separator b, and is pressed by an external force. One positive tab and one negative tab are drawn from the electrode assembly B.

Then, the negative electrode tab of electrode assembly A and the positive electrode tab of electrode assembly C are welded together by laser welding, so that the two are connected in series; the negative electrode tab of electrode assembly C and the positive electrode tab of electrode assembly B are welded by laser welding. together, so that the two are connected in series.

Then, extend the positive tab of electrode assembly A, the series tab of electrode assembly A and electrode assembly C, the series tab of electrode assembly C and electrode assembly B, and the negative tab of electrode assembly B out of the outer package.

Then, cover another piece of outer packaging (aluminum-plastic film with a thickness of 90 μm) on the electrode assembly B with the pit face down, leaving the liquid injection port side and heat-sealing other positions of the outer packaging to obtain the assembled electrode. The two sides of the separator form three independent cavities. Among them, the heat-sealing temperature was 180°C, and the heat-sealing pressure was 0.5MPa.

Electrolyte is separately injected into the three cavities of the assembled electrode assembly, and sealed after injection.

Example 21

Except that the negative pole piece is cut into a size of 465 mm×92 mm for use, the rest is the same as that of Example 1.

Except that the positive pole piece was cut into a size of 480 mm×90 mm for use, the rest was the same as that of Example 1.

Same as Example 1.

The positive pole piece and the negative pole piece prepared above, and the PP separator of 15 μm are stacked in the order of the positive pole piece, the separator and the negative pole piece, so that the separator is in the middle of the positive pole piece and the negative pole piece to isolate the Acting, winding to obtain a wound electrode assembly.

Same as Example 1.

Except that the electrode assembly is the above-mentioned wound electrode assembly, the rest is the same as that of Example 1.

The data and test results of Examples 1-21 are shown in Table 1.

Comparative Example 1

The rest is the same as in Example 1, except that the extension length of the separator is 0 mm as shown in Table 1.

The data and test results of Comparative Example 1 are shown in Table 1.

The preparation parameters and test results of each embodiment and comparative example of table 1

It can be seen from Examples 1-21 and Comparative Example 1 of the present application that by extending the separator from one of the sealing edges of the outer package, the 2C discharge temperature rise of the electrochemical device during use is significantly reduced.

It can be seen that the electrochemical device provided by the present application, through the introduction of the separator and the sealing connection between the separator and the outer package, the electrochemical device is divided into a plurality of independent sealed cavities to achieve ion isolation between different cavities and avoid internal The problem of short circuit and the problem of electrolyte decomposition under high voltage, thereby improving the safety performance of the electrochemical device and ensuring the effective power output of the electrochemical device. At the same time, by extending the separator from one of the sealing edges of the outer package, part of the heat inside the electrochemical device is carried out through contact heat transfer, which effectively avoids the overheating caused by the accumulated heat of the electrochemical device during use. According to needs, a heat dissipation device can be provided on the part of the separator extending out of the outer package, so as to further improve the heat dissipation capability of the electrochemical device.

The above are only preferred embodiments of the present application, and are not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included in the protection of the present application. within the range.

Claims

An electrochemical device, comprising an outer package, a separator, and electrode assemblies disposed on both sides of the separator, wherein the separator and the electrode assembly are located in the outer package, and the separator extends from the outer package. One side of the sealing edge of the package protrudes, and the length of the separator protruding from the sealing edge of the outer package is 3 mm to 30 mm.
The electrochemical device of claim 1, wherein the separator protrudes from a bottom edge or a side edge of the outer package seal.
The electrochemical device according to claim 1, wherein a part of the separator protruding from the outer package is provided with a heat dissipation device, and the heat dissipation device comprises a fin type heat sink or a fin type heat sink.
The electrochemical device according to claim 1, wherein the separator is connected to the outer package, and sealed cavities are respectively formed on both sides of the separator, and each sealed cavity encapsulates the electrode assembly and the electrolyte. liquid.
The electrochemical device according to claim 1, wherein the electrode assemblies are provided with tabs of different polarities, the tabs extend out of the outer package, and the adjacent electrode assemblies are connected in series through the tabs .
The electrochemical device according to claim 1, wherein the material of the separator comprises at least one of a polymer film, a metal foil, and a carbon material.
6. The electrochemical device of claim 6, wherein each electrode assembly has two tabs with opposite polarities, the two tabs protrude from the outer package, and two adjacent electrode assemblies pass through the electrode The ears are connected in series.
The electrochemical device according to claim 1, wherein the separator is a bipolar separator, and the bipolar separator comprises a Cu-Al composite current collector, a stainless steel foil current collector or a polymer conductive current collector at least one of.
The electrochemical device according to claim 8, wherein one side of the bipolar separator is provided with an electrode active material layer, and an outermost layer of the electrode assembly adjacent to the electrode active material layer is provided with an opposite polarity. The electrode active material layer of the bipolar separator is provided with a separator between one side of the bipolar separator provided with the electrode active material layer and the adjacent electrode assembly, and the other side of the bipolar separator is adjacent to the The electrode assemblies are electrically insulated, the bipolar separator leads out a tab, and the tab is connected to the tabs connected in series with the electrode assemblies on both sides.
The electrochemical device according to claim 8, wherein one side of the bipolar separator is provided with an electrode active material layer, and an outermost layer of the electrode assembly adjacent to the electrode active material layer is provided with an opposite polarity. The electrode active material layer of the bipolar separator is provided with a separator between one side of the bipolar separator with the electrode active material layer and the adjacent electrode assembly, and the other side of the bipolar separator is adjacent to the electrical connection between the electrode assemblies.
The electrochemical device according to claim 8, wherein electrode active material layers of different polarities are respectively provided on both sides of the bipolar separator, and the outermost layer of the electrode assembly adjacent to each electrode active material layer is Electrode active material layers with opposite polarities are provided, and a separator is provided between the electrode active material layer of the bipolar separator and the electrode active material layer of the outermost layer of the electrode assembly.
The electrochemical device according to claim 1, wherein the separator is hermetically connected to the outer package, and the part where the separator and the outer package are encapsulated comprises an encapsulation material, and the encapsulation material comprises polypropylene, acid anhydride Modified polypropylene, polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-acrylic acid copolymer, ethylene-vinyl alcohol copolymer, polyvinyl chloride, polystyrene, polyether nitrile, polyurethane, At least one of polyamides, polyesters, amorphous alpha-olefin copolymers and derivatives thereof.
The electrochemical device of claim 1, wherein the separator has a thickness of 6 μm to 100 μm.
The electrochemical device of claim 1 having at least one of the following features:

a. The electrochemical device comprises 2 to 3 separators;

b. The thickness of the separator is 10 μm to 40 μm;

c. The length of the separator protruding from the sealing edge of the outer package is 5mm to 20mm.
The electrochemical device of claim 1, wherein the structure of the electrode assembly includes at least one of a rolled structure or a laminated structure.
An electronic device comprising the electrochemical device of any one of claims 1-15.