WO2019082696A1

WO2019082696A1 - Separator, bag-shape separator, packaged electrode and lithium ion secondary battery

Info

Publication number: WO2019082696A1
Application number: PCT/JP2018/038146
Authority: WO
Inventors: 健人高橋; 文昭小保内
Original assignee: Ｎｅｃエナジーデバイス株式会社
Priority date: 2017-10-25
Filing date: 2018-10-12
Publication date: 2019-05-02
Also published as: JP7244431B2; JPWO2019082696A1

Abstract

This separator (20), for producing a bag-shape separator obtained by thermally fusing the separator (20), is provided with a resin layer (21) and a ceramic layer (23) provided on at least one surface of the resin layer (21). A planned thermal fusion site (25) for producing a bag-shape separator is present on the ceramic layer (23) side, and the planned thermal fusion site (25) has an exposed part (27) where a portion of the ceramic layer (23) has been removed and a portion of the resin layer (21) is exposed on the ceramic layer (23) side.

Description

Separator, bag-shaped separator, packaged electrode and lithium ion secondary battery

The present invention relates to a separator, a bag-shaped separator, a packaged electrode and a lithium ion secondary battery.

In a lithium ion secondary battery, a porous resin film mainly composed of a polyolefin resin or a polyester resin is used as a separator. Such a porous resin film has a shutdown function of blocking the flow of current by blocking the fine pores of the porous resin film when an abnormal current is generated and the temperature of the battery rises. Therefore, the porous membrane is effective from the viewpoint of avoiding thermal runaway of the battery.

As a technique regarding such a separator, the thing of patent document 1 is mentioned, for example.

Patent Document 1 (Japanese Unexamined Patent Publication No. 2011-71009) describes a separator for a lithium ion secondary battery including a porous resin film and an insulating ceramic layer applied to at least the first surface thereof. ing.
In general, a separator provided with such a ceramic layer is considered to be excellent in heat resistance because thermal contraction is suppressed.

JP, 2011-71009, A

The separator may be used as a bag-like separator by fusing a part of the separator. In this case, the electrode is accommodated in the inside of the bag-like separator to form a packaged electrode.
According to the study of the present inventor, it has become clear that the bag-like separator constituted by the separator provided with the ceramic layer has the following problems.
First, a separator provided with a ceramic layer generally has a resin layer such as a polyolefin resin layer or a polyester resin layer, and a ceramic layer provided on one surface of the resin layer. When the separator having such a multilayer structure is heat-sealed into a bag, it is difficult to heat-seal the ceramic layers of the separators stably, so the resin-layers of the separators are heat-sealed. It had a bag shape.
However, according to the study of the present inventor, when the resin layer sides of the separators are heat-sealed to form a bag, the ceramic layer side contacts the heater block surface at the time of heat-sealing. It was revealed that adhesion of ceramic particles to the block surface and the like would occur. In addition, since the ceramic layer is disposed on the outside of the bag, there is a possibility that the ceramic layer may come off.

The present invention has been made in view of the above circumstances, and provides a bag-like separator in which the ceramic layer is prevented from falling off.

The present inventors diligently studied to solve the above problems. As a result, the ceramic layer side of the separator is stably stabilized by removing a part of the ceramic layer at the portion to be heat-sealed of the separator before forming into a bag shape and exposing a part of the resin layer to the ceramic layer side. As a result, it has been found that a bag-like separator which can be heat-fused and as a result can be stably obtained in which the dropping of the ceramic layer is suppressed, and the present invention has been completed.

The present invention was devised based on such knowledge.
That is, according to the present invention, the following separator, bag-like separator, bag electrode and lithium ion secondary battery are provided.

According to the invention
The above separator for producing a bag-like separator obtained by heat-sealing the separator,
A resin layer, and a ceramic layer provided on at least one surface of the resin layer;
Equipped with
It has a heat fusion scheduled portion for producing a bag-like separator on the side of the ceramic layer,
The heat-sealable portion is provided with a separator having an exposed portion in which a portion of the resin layer is exposed and a portion of the resin layer is exposed while the portion of the ceramic layer is removed.

Moreover, according to the present invention,
There is provided a bag-like separator obtained by heat-sealing the site to be heat-fused in the separator of the present invention.

Moreover, according to the present invention,
There is provided a packaged electrode comprising the above-described pouched separator of the present invention and an electrode accommodated in the pouched separator.

Furthermore, according to the invention,
A lithium ion battery in which a positive electrode that absorbs and releases lithium, a negative electrode that absorbs and releases lithium, a non-aqueous electrolytic solution containing a lithium salt, and a separator sandwiched between the positive electrode and the negative electrode are accommodated in a container. The next battery,
There is provided a lithium ion secondary battery in which the separator comprises the bag-like separator of the present invention.

ADVANTAGE OF THE INVENTION According to this invention, the bag-like separator in which drop-off | omission of the ceramic layer was suppressed can be provided.

The objects described above, and other objects, features and advantages will become more apparent from the preferred embodiments described below and the following drawings associated therewith.

It is the top view which showed typically an example of the structure of the separator of embodiment which concerns on this invention. It is sectional drawing which showed typically an example of the structure of the separator of embodiment which concerns on this invention in the position which follows the A-A 'line | wire shown in FIG. BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which showed typically an example of the structure of the packaged electrode of embodiment which concerns on this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which showed typically an example of the structure of the packaged electrode of embodiment which concerns on this invention. It is the schematic which showed typically an example of the structure of the laminated type battery of embodiment which concerns on this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is the schematic which showed typically an example of the structure of the winding type | mold battery of embodiment which concerns on this invention.

Hereinafter, embodiments of the present invention will be described using the drawings. In all the drawings, similar components are denoted by the same reference numerals, and the description thereof will be omitted as appropriate. Further, in the drawings, each component schematically shows the shape, size and arrangement relationship to the extent that the present invention can be understood, and is different from the actual size. Further, unless otherwise noted, the numerical range “to” represents the above to the following.

<Separator>
FIG. 1 is a plan view schematically showing an example of the structure of a separator 20 according to an embodiment of the present invention. FIG. 2 is a cross-sectional view schematically showing an example of the structure of the separator 20 according to the embodiment of the present invention at a position along the line AA 'shown in FIG.

The separator 20 according to the present embodiment is a separator for producing a bag-like separator obtained by heat-sealing the separator 20, and is provided on at least one surface of the resin layer 21 and the resin layer 21. A ceramic layer 23 is provided, and a heat fusion scheduled portion 25 for producing a bag-like separator is provided on the ceramic layer 23 side, and a part of the ceramic layer 23 is removed from the heat sealing planned region 25 At the same time, an exposed portion 27 where a part of the resin layer 21 is exposed is provided on the ceramic layer 23 side.
The separator 20 according to the present embodiment can be used, for example, as a separator for a lithium ion secondary battery.

According to the study of the present inventor, it has become clear that the bag-like separator constituted by the separator provided with the ceramic layer has the following problems.
First, a separator provided with a ceramic layer generally has a resin layer such as a polyolefin resin layer or a polyester resin layer, and a ceramic layer provided on one surface of the resin layer. When the separator having such a multilayer structure is heat-sealed into a bag, it is difficult to heat-seal the ceramic layers of the separators stably, so the resin-layers of the separators are heat-sealed. It had a bag shape.
However, according to the study of the present inventor, when the resin layer sides of the separators are heat-sealed to form a bag, the ceramic layer side contacts the heater block surface at the time of heat-sealing. It was revealed that adhesion of ceramic particles to the block surface and the like would occur. In addition, since the ceramic layer is disposed on the outside of the bag, there is a possibility that the ceramic layer may come off.
Therefore, as a result of intensive investigations, the inventor of the present invention removed a portion of the ceramic layer 23 at the portion 25 to be heat-sealed of the separator 20 before forming the bag shape and exposed a portion of the resin layer 21 on the ceramic layer 23 side. As a result, it has been found that the ceramic layer 23 side of the separator 20 can be stably heat-sealed as a result, and as a result, a bag-like separator in which the ceramic layer 23 is suppressed from dropping is stably obtained.
In such a separator 20, although the reason why the ceramic layer 23 side can be stably heat-sealed is not clear, it has an exposed portion 27 on the ceramic layer 23 side where a part of the resin layer 21 is exposed. As a result, the amount of the melted resin component relatively exposed on the surface of the ceramic layer 23 at the time of heat sealing relatively increases, and as a result, the heat melting of the ceramic layer 23 is stably performed by the exposed resin component. It is thought that it can be done.
According to the separator 20 according to the present embodiment, since the ceramic layer 23 side can be stably heat-fused, the side in contact with the heater block surface can be the resin layer 21 side when forming the bag shape. it can. Alternatively, in the case where the ceramic layer 23 is provided on both sides of the resin layer 21, the ratio of the ceramic layer 23 in contact with the heater block surface can be reduced.
As a result, it is possible to suppress the detachment of the ceramic layer 23 and the adhesion of the ceramic particles to the surface of the heater block at the time of heat fusion.
As mentioned above, according to the separator 20 which concerns on this embodiment, the bag-like separator by which drop-off | omission of the ceramic layer 23 was suppressed can be implement | achieved by heat-fusing the heat-fusion plan part 25 by heat.

The exposed portion 27 according to the present embodiment may be continuously extended without any gap in the region 25 to be heat-fused, or may be intermittently disposed with a gap, but is obtained. From the viewpoint of suppressing the generation of wrinkles due to the thermal contraction of the bag-like separator, it is preferable that the exposed portion 27 according to the present embodiment is intermittently disposed with a gap.
Here, the separator 20 according to this embodiment, is preferably, 5 mm ² or more that the sum of the areas of the resin layer 21 exposed in all of the exposed portion 27 in the separator 20 is 2 mm ² or more Is more preferably 10 mm ² or more, still more preferably 50 mm ² or more, particularly preferably 100 mm ² or more, and preferably 2000 mm ² or less, and 1500 mm ² or less. Some are more preferable, 1000 mm ² or less is more preferable, and 500 mm ² or less is particularly preferable.
The heat fusion of the ceramic layer 23 side of the separator 20 is performed more stably when the total value of the areas of the exposed resin layers 21 in all the exposed portions 27 in the separator 20 is equal to or more than the above lower limit. As a result, the welding strength of the separators 20 can be enhanced, and a bag-like separator in which the ceramic layer 23 is suppressed from dropping can be obtained more stably, which is preferable.
In addition, when the total value of the areas of the exposed resin layers 21 in all the exposed portions 27 in the separator 20 is equal to or less than the upper limit value, the insulation of the separator 20 can be enhanced. It is preferable because a bag-like separator in which the dropout is suppressed can be obtained more stably.
In addition, when the total value of the areas of the exposed resin layers 21 in all the exposed portions 27 in the separator 20 is equal to or less than the upper limit value, the ceramic layer 23 in the heat fusion scheduled portion 25 of the separator 20 described later. Since the process of removing at least a part can be shortened, the productivity of the separator 20 can be improved. In particular, when the size of the target lithium ion secondary battery is increased, the size of the separator is also increased. Therefore, the total value of the areas of the exposed resin layers 21 in all the exposed portions 27 in the separator 20 is the above upper limit It is preferable because the heat fusion can be stably performed and the production time can be shortened if the value is less than the value.
Here, the heat fusion scheduled part 25 is a part heated by the heating device at the time of heat fusion of the separator 20, and is, for example, the peripheral part of the separator 20 as shown in FIG. Further, the heat fusion planned site 25 may be only around the exposed portion 27.

The method of manufacturing the separator 20 having the exposed portion 27 where a part of the resin layer 21 is exposed on the ceramic layer 23 side is not particularly limited, but, for example, at least one of the ceramic layers 23 at the heat fusion scheduled portion 25 of the separator 20 It can obtain by the manufacturing method including the process of removing the part.

The method for removing at least a part of the ceramic layer 23 at the portion 25 to be heat-sealed of the separator 20 is not particularly limited. For example, the method for removing it with a heat cutter or heat wire, or removing with a pressing blade or rotary blade Methods include removal by laser irradiation.
Among these, from the viewpoint of being able to accurately remove a part of the ceramic layer 23 at the heat fusion planned site 25 of the separator 20, the ceramic layer at the heat fusion planned site 25 of the separator 20 by irradiating the ceramic layer 23 with a laser. The method of removing at least one part of 23 is preferable.

The laser to be used is not particularly limited, but the wavelength of the laser is preferably 300 nm or more and 600 nm or less, more preferably 350 nm or more and 550 nm or less, from the viewpoint of being able to remove a part of the ceramic layer 23 with much lower output and short time. Or 532 nm is more preferred. Further, from the viewpoint of excellent cost, a 532 nm laser is particularly preferable.
By setting the wavelength of the laser to the upper limit value or less, the energy absorption rate with respect to the ceramic layer 23 can be increased, and as a result, the ceramic layer 23 can be removed in a still lower output and in a short time.
Further, by setting the wavelength of the laser to the lower limit value or more, the energy output can be increased or the laser equipment can be simplified, so that the ceramic layer 23 can be removed more efficiently. Furthermore, the cost can be reduced.

Examples of the laser having a wavelength of 300 nm or more and 600 nm or less include a laser in which a YVO ₄ fundamental wave (wavelength 1064 nm), a YAG fundamental wave (wavelength 1064 nm) or the like is divided into integer multiples. Here, a laser having a wavelength of 532 nm is, for example, a YVO ₄ fundamental wave (wavelength 1064 nm) or a YAG fundamental wave (wavelength 1064 nm) converted to a half wavelength, and a laser having a wavelength of 355 nm is The YVO ₄ fundamental wave (wavelength 1064 nm) and the YAG fundamental wave (wavelength 1064 nm) are converted to a wavelength of 1/3.

The planar shape of the separator 20 according to the present embodiment is not particularly limited, and can be appropriately selected according to the shapes of the electrode and the current collector, and can be, for example, rectangular.

The thickness of the resin layer 21 is preferably 1 μm or more and 50 μm or less, more preferably 5 μm or less, from the viewpoint of balance between mechanical strength and lithium ion conductivity, and from the viewpoint of being able to improve the energy density of the obtained lithium ion secondary battery. The thickness is 40 μm or more, and more preferably 10 μm to 30 μm.

Examples of the resin for forming the resin layer 21 include polyolefin resins such as polypropylene resins and polyethylene resins, and polyester resins such as polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate. Among these, polyolefin resins are preferable, and polypropylene resins are more preferable, from the viewpoint of being excellent in balance of heat resistance, shutdown function, cost and the like. These resins may be used alone or in combination of two or more.
Here, the resin layer 21 preferably contains at least one selected from a polyolefin resin and a polyester resin as a main component. Here, the term "main component" means that the proportion in the porous resin layer is 50% by mass or more, preferably 70% by mass or more, more preferably 90% by mass or more, and 100% by mass It means that it may be.

It does not specifically limit as said polypropylene resin, For example, a propylene homopolymer, the copolymer of propylene and other olefins, etc. are mentioned, A propylene homopolymer (homo polypropylene) is preferable. The polypropylene resins may be used alone or in combination of two or more.
The olefins copolymerized with propylene include, for example, ethylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-nonene, 1-decene, etc. -An olefin etc. are mentioned.

It does not specifically limit as said polyethylene-type resin, For example, an ethylene homopolymer, the copolymer of ethylene and other olefins, etc. are mentioned, An ethylene homopolymer (homo polyethylene) is preferable. The polyethylene resins may be used alone or in combination of two or more.
Examples of olefins copolymerized with ethylene include α-olefins such as 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-nonene and 1-decene. Etc.

The resin layer 21 is preferably a porous resin layer. As a result, abnormal current is generated in the lithium ion secondary battery, and when the temperature of the battery rises, etc., the fine pores of the porous resin film can be blocked and the flow of current can be blocked, thereby causing thermal runaway of the battery. It can be avoided.

From the viewpoint of the balance between mechanical strength and lithium ion conductivity, the porosity of the porous resin layer is preferably 20% to 80%, more preferably 30% to 70%, and still more preferably 40% to 60%. Is particularly preferred.
The porosity can be determined from the following equation.
ε = {1-Ws / (ds · t)} × 100
Here, ε: porosity (%), Ws: basis weight (g / m ² ), ds: true density (g / cm ³ ), t: film thickness (μm).

The separator 20 according to the present embodiment has a ceramic layer 23 on at least one surface of the resin layer 21 from the viewpoint of improving the heat resistance. Here, the ceramic layer 23 is preferably provided only on one side of the resin layer 21 from the viewpoint of the handleability and productivity of the separator 20 according to the present embodiment, but the heat resistance of the separator 20 is preferable. May be provided on both sides of the resin layer 21 from the viewpoint of further improving the
By having the ceramic layer 23, the separator 20 according to the present embodiment can further reduce the thermal contraction of the separator 20, and can further prevent a short circuit between electrodes.

The ceramic layer 23 can be formed, for example, by applying and drying a ceramic layer forming material on the resin layer 21. As the ceramic layer forming material, for example, a material in which ceramic particles and a binder are dissolved or dispersed in an appropriate solvent can be used.

The ceramic particles used for the ceramic layer 23 can be appropriately selected from known materials used for a separator of a lithium ion secondary battery. For example, oxides or nitrides or sulfides or carbides having high insulating properties are preferable, and one or more selected from aluminum oxide, titanium oxide, silicon oxide, magnesium oxide, barium oxide, zirconium oxide, zinc oxide, iron oxide and the like It is more preferable to adjust two or more kinds of ceramics into particles. Among these, aluminum oxide and titanium oxide are preferable.

The binder is not particularly limited, and examples thereof include cellulose resins such as carboxymethyl cellulose (CMC); acrylic resins; fluorine resins such as polyvinylidene fluoride (PVDF); and the like. The binder may be used alone or in combination of two or more.

The solvent for dissolving or dispersing these components is not particularly limited, and is appropriately selected from, for example, water, alcohols such as ethanol, N-methylpyrrolidone (NMP), toluene, dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), etc. Can be used.

The thickness of the ceramic layer 23 is preferably 0.1 μm or more and 50 μm or less, more preferably 0.5 μm or more and 30 μm or less, from the viewpoint of the balance of heat resistance, mechanical strength, handleability and lithium ion conductivity. More preferably, it is 1 μm or more and 15 μm or less.

<Sacky separator and bagging electrode>
3 and 4 are cross-sectional views schematically showing an example of the structure of the packaged electrode 80 according to the embodiment of the present invention.
The bag-like separator 50 according to the present embodiment can be obtained by heat-sealing the heat-fusion intended portion 25 of the separator 20. Here, a portion joined by thermally fusing the portion 25 to be thermally fused in the separator 20 is referred to as a junction portion 53.
The method for producing the bag-like separator 50 according to the present embodiment is not particularly limited, but for example, as shown in FIG. Alternatively, as shown in FIG. 4, it can be produced by folding one separator 20 and thermally fusing the portion 25 of the separator 20 to be fused by heat.
Here, the portion 25 to be thermally fused is, for example, the peripheral portion of the separator 20.
When the separator 20 has a rectangular shape, the exposed portion 27 at the heat sealing scheduled portion 25 may be three or more of the peripheral portions of the four sides of the separator 20, and is preferably at four sides.
In addition, the bag-like separator 50 according to the present embodiment includes a state in which the peripheral edge is only heat-welded so as to suppress the movement of the electrode 83 accommodated therein, and the bag is not a complete bag. .

The packaged electrode 80 according to the present embodiment includes the bag-like separator 50 according to the present embodiment, and an electrode 83 accommodated in the bag-like separator 50. Here, after the bag-like separator 50 is manufactured using the separator 20 according to the present embodiment, the electrode 83 may be accommodated in the bag, or the electrode 83 is sandwiched between the separators 20, and then, The electrode 83 may be accommodated in the bag by heat-sealing the separator 20 to produce the bag-like separator 50.
As an electrode 83 accommodated in a bag, the positive electrode and negative electrode which are mentioned later are mentioned, for example.
Here, in the packaged electrode 80 according to the present embodiment, when the bag-like separator 50 has a rectangular shape, the bonding portion 53 may be at three or more sides in the peripheral portion at four sides, and at four sides preferable.

<Lithium ion secondary battery>
The lithium ion secondary battery according to the present embodiment has the following configuration.
The lithium ion secondary battery includes a positive electrode that inserts and receives lithium, a negative electrode that inserts and receives lithium, a non-aqueous electrolyte containing a lithium salt, and a separator sandwiched between the positive electrode and the negative electrode. It accommodates in a container and the said separator contains the bag-like separator which concerns on this embodiment. Here, the bag-like separator according to the present embodiment accommodates the positive electrode and the negative electrode.
Here, in the lithium ion battery according to the present embodiment, in the case where the bag-like separator has a rectangular shape, the bonding portion 53 may be at three or more sides in the peripheral portion of four sides, preferably at four sides. .
The form and type of the lithium ion secondary battery of the present embodiment are not particularly limited, but, for example, the following configuration can be made.

[Stacked battery]
FIG. 5 is a schematic view schematically showing an example of the structure of the stacked battery 100 according to the embodiment of the present invention. Stacked battery 100 includes battery elements in which positive electrode 1 and negative electrode 6 are alternately laminated in multiple layers with separator 20 interposed therebetween, and these battery elements are a flexible film together with an electrolytic solution (not shown). It is housed in a 30 container. The positive electrode terminal 11 and the negative electrode terminal 16 are electrically connected to the battery element, and a part or all of the positive electrode terminal 11 and the negative electrode terminal 16 are drawn out of the flexible film 30. .

The positive electrode 1 is provided with the coated part 2 and the uncoated part of the positive electrode active material on the front and back of the positive electrode current collector 3, and the negative electrode 6 is coated on the front and back of the negative electrode current collector 8. 7 and an uncoated part are provided.

A negative electrode for connecting the uncoated portion of the negative electrode active material in the negative electrode current collector 8 to the negative electrode terminal 16 with the uncoated portion of the positive electrode active material in the positive electrode current collector 3 as the positive electrode tab 10 for connecting to the positive electrode terminal 11 It is referred to as tab 5.
The positive electrode tabs 10 are assembled on the positive electrode terminal 11 and connected together by ultrasonic welding etc. together with the positive electrode terminal 11, and the negative electrode tabs 5 are assembled on the negative electrode terminal 16 connected together by ultrasonic welding etc. together with the negative electrode terminal 16. Be done. In addition, one end of the positive electrode terminal 11 is drawn out of the flexible film 30, and one end of the negative electrode terminal 16 is also drawn out of the flexible film 30.

If necessary, an insulating member can be formed at the boundary 4 between the coated part 2 and the non-coated part of the positive electrode active material, and the insulating member is not only the boundary 4 but also the positive electrode tab 10 and the positive electrode active material. It can be formed near both boundaries.

Similarly, an insulating member can be formed at the boundary 9 between the coated part 7 and the non-coated part of the negative electrode active material as necessary, and formed near the boundary between both the negative electrode tab 5 and the negative electrode active material. Can.

Usually, the external dimension of the application part 7 of a negative electrode active material is larger than the external dimension of the application part 2 of a positive electrode active material, and smaller than the external dimension of the separator 20.

[Wound battery]
FIG. 6 is a schematic view schematically showing an example of the structure of the wound battery 101 according to the embodiment of the present invention. The wound battery 101 includes a battery element in which a positive electrode 1 and a negative electrode 6 are stacked via a separator 20 and wound, and this battery element is made of a flexible film together with an electrolytic solution (not shown). Contained in the
The positive electrode terminal and the negative electrode terminal are also electrically connected to the battery element of the wound battery 101, and the other configuration is substantially the same as that of the laminated battery 100, and thus further description is omitted here.

It continues and demonstrates each structure used for the lithium ion secondary battery of this embodiment.

(Positive electrode for absorbing and desorbing lithium)
The positive electrode 1 used in the present embodiment can be appropriately selected from among positive electrodes that can be used for known lithium ion secondary batteries, according to the application and the like. The active material used for the positive electrode 1 is preferably a material having high electron conductivity so that lithium ions can be reversibly released and stored, and electron transport can be easily performed.

As an active material used for the positive electrode 1, for example, a complex oxide of lithium and transition metal such as lithium nickel complex oxide, lithium cobalt complex oxide, lithium manganese complex oxide, lithium-manganese-nickel complex oxide, etc .; Transition metal sulfides such as TiS ₂ , FeS, MoS _{2 and the} like; transition metal oxides such as MnO, V ₂ O ₅ , V ₆ O ₁₃ , TiO ₂ , and olivine-type lithium phosphorus oxide.
The olivine-type lithium phosphorus oxide is, for example, at least one member of the group consisting of Mn, Cr, Co, Cu, Ni, V, Mo, Ti, Zn, Al, Ga, Mg, B, Nb, and Fe. It contains elements, lithium, phosphorus and oxygen. These compounds may be obtained by partially replacing some elements with other elements in order to improve their properties.

Among these, olivine-type lithium iron phosphorus oxide, lithium cobalt composite oxide, lithium nickel composite oxide, lithium manganese composite oxide, and lithium-manganese-nickel composite oxide are preferable. These positive electrode active materials have large capacity in addition to high action potential and large energy density.
The positive electrode active material may be used alone or in combination of two or more.

A binder, a conductive agent, etc. can be suitably added to the positive electrode active material. As the conductive agent, carbon black, carbon fiber, graphite or the like can be used. Further, polyvinylidene fluoride (PVdF), polytetrafluoroethylene (PTFE), carboxymethyl cellulose, modified acrylonitrile rubber particles and the like can be used as the binder.

As the positive electrode current collector 3 used for the positive electrode 1, aluminum, stainless steel, nickel, titanium or an alloy thereof can be used. Among these, aluminum is particularly preferable.

In addition, the positive electrode 1 in the present embodiment can be manufactured by a known method. For example, after a positive electrode active material, a conductive agent, and a binder are dispersed in an organic solvent to obtain a slurry, a method of applying and drying this slurry on the positive electrode current collector 3 can be employed.

(Anode that occludes and releases lithium)
The negative electrode 6 used in the present embodiment can be appropriately selected from among negative electrodes that can be used for known lithium ion secondary batteries, depending on the application and the like. The active material used for the negative electrode 6 can also be appropriately set according to the application etc. as long as it can be used for the negative electrode.

Specific examples of the material that can be used as the negative electrode active material include artificial graphite, natural graphite, amorphous carbon, diamond-like carbon, fullerenes, carbon materials such as carbon nanotubes and carbon nanohorns; lithium metal materials; silicon, tin, etc. Alloy-based materials; oxide-based materials such as Nb ₂ O ₅ and TiO ₂ ; or composites of these can be used.
The negative electrode active material may be used alone or in combination of two or more.

Moreover, a binder, a conductive agent, etc. can be suitably added to a negative electrode active material similarly to a positive electrode active material. The same binder and conductive agent as those added to the positive electrode active material can be used.

As the negative electrode current collector 8, copper, stainless steel, nickel, titanium or an alloy thereof can be used. Among these, copper is particularly preferable.

In addition, the negative electrode 6 in the present embodiment can be manufactured by a known method. For example, after a negative electrode active material and a binder are dispersed in an organic solvent to obtain a slurry, a method of applying and drying this slurry on the negative electrode current collector 8 can be employed.

(Non-aqueous electrolyte containing lithium salt)
The non-aqueous electrolytic solution containing a lithium salt used in the present embodiment can be appropriately selected from known ones depending on the type of active material, the use of the lithium ion secondary battery, and the like.

Specific examples of the lithium salt, for _{_{_{example, LiClO 4, LiBF 6, LiPF}}} 6, LiCF 3 SO 3, LiCF 3 CO 2, LiAsF 6, LiSbF 6, LiB 10 Cl 10, LiAlCl 4, LiCl, LiBr, LiB Examples include (C ₂ H ₅ ) ₄ , CF ₃ SO ₃ Li, CH ₃ SO ₃ Li, LiC ₄ F ₉ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, and lower fatty acid carboxylate lithium.

The solvent for dissolving the lithium salt is not particularly limited as long as it is generally used as a liquid for dissolving the electrolyte, and ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (MEC), vinylene carbonate (VC) and other carbonates; γ-butyrolactone, γ-valerolactone and other lactones; trimethoxymethane, 1,2-dimethoxyethane Ethers such as diethyl ether, tetrahydrofuran and 2-methyltetrahydrofuran; Sulfoxides such as dimethyl sulfoxide; Oxolanes such as 1,3-dioxolane and 4-methyl-1,3-dioxolane; acetonitrile Nitrogenous solvents such as nitromethane, formamide and dimethylformamide; methyl formate, methyl acetate, ethyl acetate, butyl acetate, methyl propionate, ethyl propionate and the like organic acid esters; phosphoric acid triesters and diglymes; triglymes; Sulfolanes such as sulfolane and methyl sulfolane; oxazolidinones such as 3-methyl-2-oxazolidinone; sultones such as 1,3-propane sultone, 1,4-butane sultone, and naphtha sultone. These may be used singly or in combination of two or more.

(container)
A well-known member can be used for a container in this embodiment, and it is preferable to use the flexible film 30 from a viewpoint of weight reduction of a battery. The flexible film 30 can use what provided the resin layer in front and back of the metal layer used as a base material. The metal layer can be selected to have a barrier property to prevent leakage of the electrolytic solution and entry of moisture from the outside, and aluminum, stainless steel, etc. can be used. A heat-sealable resin layer such as modified polyolefin is provided on at least one surface of the metal layer, and the heat-sealable resin layers of the flexible film 30 are opposed to each other through the battery element to make the battery element The sheath is formed by heat-sealing the periphery of the part to be stored. A resin layer such as a nylon film or a polyester film can be provided on the surface of the exterior body opposite to the surface on which the heat-fusible resin layer is formed.

(Terminal)
In the present embodiment, the positive electrode terminal 11 may be made of aluminum or an aluminum alloy, and the negative electrode terminal 16 may be copper or a copper alloy, or those plated with nickel. Each terminal is drawn to the outside of the container, but a heat fusible resin can be provided in advance in a portion located at a portion of the respective terminal where the periphery of the package is heat welded.

(Insulation member)
In the case of forming the insulating member at the boundary portions 4 and 9 between the coated portion and the non-coated portion of the active material, polyimide, glass fiber, polyester, polypropylene or those containing these in the structure can be used. Heat can be applied to these members to weld them to the boundaries 4 and 9, or a gel-like resin can be applied to the boundaries 4 and 9 and dried to form an insulating member.

(Separator)
The separator 20 according to this embodiment is used as the separator. The description here is omitted.

As mentioned above, although this invention was demonstrated based on embodiment, these are the illustrations of this invention, and various structures other than the above can also be employ | adopted.
Further, the present invention is not limited to the above-described embodiment, and modifications, improvements, and the like within the range in which the object of the present invention can be achieved are included in the present invention.

Hereinafter, the present invention will be described by way of Examples and Comparative Examples, but the present invention is not limited thereto.

<Evaluation>
(1) Porosity of separator It calculated | required from the following formula.
ε = {1-Ws / (ds · t)} × 100
Here, ε: porosity (%), Ws: basis weight (g / m ² ), ds: true density (g / cm ³ ), t: film thickness (μm).

(2) Observation of Exposed Portion at Thermal Fusion Planned Site Using an electron microscope (SEM), the exposed area at the thermal fusion planned site of the separator is observed, and the area of the exposed resin layer at all exposed areas. The total value was calculated.

(3) Evaluation of falling off of the ceramic layer The surface of the ceramic layer in the bag-like separator was observed using an electron microscope (SEM), and the falling off of the ceramic layer was examined and evaluated according to the following criteria.
:: Drop-off of ceramic particles is not observed on the surface of the ceramic layer.
Fair: Falling of ceramic particles is observed on part of the surface of the ceramic layer.
X: Drop-off of ceramic particles is observed on the entire surface of the ceramic layer.

(4) Evaluation of adhesion of ceramic particles to the surface of the heater block The surface of the heater block was visually observed to examine the adhesion of the ceramic particles and evaluated according to the following criteria.
○: No adhesion of ceramic particles on the surface of the heater block.
X: Adhesion of ceramic particles is observed on the heater block surface.

Example 1
A separator (size: 20 cm) comprising a porous resin layer having a thickness of 18 μm made of a polypropylene resin and having a porosity of 50%, and a ceramic layer having a thickness of 5 μm formed of aluminum oxide particles on one surface of the porous resin layer Two pieces of × 20 cm were prepared.
Next, the peripheral portions of the two prepared separators are respectively irradiated from the ceramic layer side with a YVO ₄ laser having a wavelength of 532 nm, in which the YVO ₄ fundamental wave (wavelength 1064 nm) is converted to a half wavelength, Each part of the ceramic layer at the planned adhesion site was removed.
Here, the total value of the areas of the exposed resin layers in all the exposed portions was 245 mm ² (the total value of the areas of the exposed portions of the two separators).
Next, two separators are stacked so that the ceramic layer sides are respectively inside, and the two separators are heat-sealed by heating the heat-sealable portion using a heater block to obtain a bag-like separator 1 The Each evaluation was performed with respect to the obtained bag-like separator 1. The obtained evaluation results are shown in Table 1.

(Example 2)
A separator (size: 20 cm) comprising a porous resin layer having a thickness of 18 μm made of a polypropylene resin and having a porosity of 50%, and a ceramic layer having a thickness of 5 μm formed of aluminum oxide particles on one surface of the porous resin layer Two pieces of × 20 cm were prepared.
Next, with respect to the central portion in the lengthwise direction of the four sides of the peripheral portion of one of the two prepared separators, the YVO ₄ fundamental wave (wavelength 1064 nm) is halved from the ceramic layer side The YVO ₄ laser having a wavelength of 532 nm converted to each was irradiated to remove a portion of the ceramic layer at the heat fusion scheduled portion, and a total of four exposed portions of 0.5 mm ² were provided. Here, the total value of the areas of the exposed resin layers in all the exposed portions was 2 mm ² .
Next, two separators are stacked so that the ceramic layer sides are respectively inside, and the two separators are heat-sealed by heating the heat-sealable portion using a heater block to obtain a bag-like separator 2 The Each evaluation was performed with respect to the obtained bag-like separator 2. The obtained evaluation results are shown in Table 1.

(Comparative example 1)
A separator (size: 20 cm) comprising a porous resin layer having a thickness of 18 μm made of a polypropylene resin and having a porosity of 50%, and a ceramic layer having a thickness of 5 μm formed of aluminum oxide particles on one surface of the porous resin layer Two pieces of × 20 cm were prepared.
Next, two separators were stacked so that the porous resin layer side was inside, and the two separators were heat-sealed using a heater block, to obtain a bag-like separator 3. Each evaluation was performed with respect to the obtained bag-like separator 3. The obtained evaluation results are shown in Table 1.

(Comparative example 2)
A separator (size: 20 cm) comprising a porous resin layer having a thickness of 18 μm made of a polypropylene resin and having a porosity of 50%, and a ceramic layer having a thickness of 5 μm formed of aluminum oxide particles on one surface of the porous resin layer Two pieces of × 20 cm were prepared.
Next, two separators were stacked so that the ceramic layer side was on the inside, and the two separators were thermally fused using a heater block. However, the two separators were not sufficiently bonded, and the bonding was insufficient. Therefore, each evaluation is not performed about comparative example 2.

This application claims priority based on Japanese Patent Application No. 2017-205855 filed Oct. 25, 2017, the entire disclosure of which is incorporated herein.

Claims

The separator for producing a bag-like separator obtained by heat-sealing a separator, comprising:
A resin layer, and a ceramic layer provided on at least one surface of the resin layer;
Equipped with
It has a heat fusion scheduled portion for producing a bag-like separator on the ceramic layer side,
The separator to which the portion to be heat-fused is an exposed portion in which a portion of the ceramic layer is removed and a portion of the resin layer is exposed on the ceramic layer side.
In the separator according to claim 1,
The separator whose sum total of the area of the said resin layer exposed in all the said exposed parts in the said separator is 2 mm 2 or more.
In the separator according to claim 1 or 2,
The said resin layer is a separator containing at least 1 type selected from polyolefin resin and polyester resin.
In the separator according to any one of claims 1 to 3,
The separator whose said resin layer is a porous resin layer.
In the separator according to claim 4,
The separator in which the porosity of the porous resin layer is 20% or more and 80% or less.
In the separator according to any one of claims 1 to 5,
The separator whose thickness of the said resin layer is 1 micrometer-50 micrometers.
The separator according to any one of claims 1 to 6.
The ceramic layer is a separator made of ceramic particles.
In the separator according to claim 7,
The separator in which the ceramic particles contain one or more selected from aluminum oxide, titanium oxide, silicon oxide, magnesium oxide, barium oxide, zirconium oxide, zinc oxide and iron oxide.
The separator according to any one of claims 1 to 8.
The separator whose thickness of the said ceramic layer is 0.1 micrometer or more and 50 micrometers or less.
The separator according to any one of claims 1 to 9,
A separator in which the separator is a lithium ion secondary battery separator.
A bag-shaped separator obtained by heat-sealing the heat-fusion intended portion of the separator according to any one of claims 1 to 10.
A packaged electrode comprising the pouch-shaped separator according to claim 11 and an electrode accommodated in the pouch-shaped separator.
A lithium ion secondary battery in which a positive electrode that absorbs and releases lithium, a negative electrode that inserts and discharges lithium, a non-aqueous electrolyte containing a lithium salt, and a separator sandwiched between the positive electrode and the negative electrode are accommodated in a container The next battery,
A lithium ion secondary battery, wherein the separator comprises the bag-like separator according to claim 11.