KR20010081957A - Grid placement in lithium ion bi-cell counter electrodes - Google Patents

Abstract

Disclosed herein is a battery design for use in a bi-cell polymer matrix battery. Each bi-cell sequentially includes a first counter electrode 514a, a first thin film separation element 512a, a centrally located electrode 510, a second thin film separation element 512b, and a second counter electrode 514b. do. The current collector of each counter electrode is disposed at a place other than the middle in the counter electrode. In general, the current collector of the counter electrode is disposed in the outer half of the counter electrode. When the current collector is disposed at the outermost edge of the counter electrode, the cover thin film of the polymer matrix thin film passes over the current collector through the current collector and is stacked on the counter electrode material.

Description

GRID PLACEMENT IN LITHIUM ION BI-CELL COUNTER ELECTRODES}

Lithium ion electrolytic cells, such as, for example, rechargeable lithium ion batteries, are generally constructed by stacking electrodes and individually fabricated thin film separator cell elements. Each electrode and thin film separation element is each formed, for example, by coating, molding injection or other methods from a synthetic material comprising a bonding material and a plasticizer.

As shown in FIG. 1, the lithium ion electrolytic cell 101 is manufactured in a conventional manner in which the cathode 110, the separating element 112, and the anode 114 are arranged together in a sandwich shape.

The separating element is located between the positive electrode and the negative electrode. The anode, isolation element and cathode structures are stacked to form a standard single elastic electrolytic cell precursor structure. The precursor is extracted and activated by the electrolyte to form a functional battery. Lithium ion batteries typically include ancillary electrolytic cells in which currents from each cell are accumulated by some solid and conventional current collectors, with all currents generated by the battery being largely individual individual electrolytic cells used in the battery. It is equal to the sum of the currents generated from It is common to produce batteries by stacking individual electrolytic cells in lithium ion batteries.

Commercially, a single center electrode has two counter electrodes, and one electrode has evolved into a "bi-cell" placed on either side of the center electrode. The central electrode was the anode and the counter electrode was the cathode. By-cells are much more complex than standard cells and require successful stacking of more layers.

For example, the bi-cell 201 illustrated in FIG. 2A may include a first counter electrode 214a having a first current collector 215a sequentially disposed therein, a first separation element 212a, and a first center disposed at the center thereof. A center electrode 210 having a current collector 215a, a second separation element 212b, and a second counter electrode 214b having a second current collector 215b disposed therebetween. An electrode tab (not shown) connects the central electrode element with the outside of the package. Similar counter electrode tabs (not shown) connect the counter electrode elements to the outside of the package. Typically, the counter electrodes 214a and 214b are cathodes (positive electrodes), and the center electrode 210 is an anode (negative electrode).

Lamination methods are problematic in and will continue to produce polymer batteries. 2B is an enlarged view of an interface between current collectors. The current collector used may be a lattice or a pierced film 255, which applies a direct junction interface region 248 between two thin films 253a and 253b of the polymer electrode. This electrode-electrode junction, which spans the perforated current collector, proved important to produce bicells that prevent delamination during use.

It is desirable for the battery to achieve maximum energy potential and life cycle. Thus, current collectors at the anode and cathode electrodes are arranged to provide optimal battery performance.

The present invention generally relates to batteries comprising one or an integrated series of polymer matrix bi-cell batteries. Each bi-cell sequentially comprises a first counter electrode, a thin film separation element, a central electrode, a thin film separation element and a second counter electrode.

1 is a cross-sectional view showing a cross section of an electrolytic cell having an electrode, a separator, and a counter electrode.

FIG. 2A is a cross sectional view of a bi-cell having first and second counter electrodes, first and second separation elements, and a central electrode; FIG.

2B is an enlarged view showing an enlarged view of an interface between two thin films of counter electrode material bonded through a gap of a current collector grating;

3A through 3E are cross-sectional views of an anode outer bicell having first and second anodes, first and second separation elements, and a center electrode;

4 is a cross-sectional view of a cross-section of a bicell with improved current collector arrangement in accordance with the present invention.

5 is a schematic representation of a test embodiment of a bicell in which the counter electrode of the prior art and the improved counter electrode of the present invention have been tested simultaneously and relative to charge and discharge.

6 and 7 show the results obtained when the counter electrode is cathodeed during each charge and discharge period.

8 and 9 show the results obtained when the counter electrode is anodized during each charge and discharge period.

The drawings are shown for clarity and are not drawn to scale. Identical numbers represent the same structure.

It has been found by chance that disposing the current collector within the counter electrode can affect the electrochemical properties of the electrolytic cell. Placing the current collector in the counter electrode is preferably such that the counter electrode is changed within the outer half. As in the prior art, when the current collector of the counter electrode is not disposed in the middle or inside the electrode, however, when the current collector is disposed toward the outside of the counter electrode, that is, the current collector from the center electrode is removed. When removed, improved battery performance can be achieved in bi-cell batteries. The current collector is most preferably disposed at the outermost edges of the two counter electrodes.

The counter electrode material is preferably attached to another thin film of similar material through a penetrating current collector. When several percent of the counter electrode material is disposed external to the current collector, the counter electrode is coupled with itself through the current collector grid. The optimal placement of the current collector within the counter electrode is to place it at the outermost edge of the counter electrode with 100% electrode material between the current collector and the central electrode. However, if all the counter electrodes are only on one side of the current collector without any material to be joined to the opposite side of the current collector during the lamination process, the counter electrodes peel off relatively quickly to shorten the battery life.

An inert polymer matrix thin film composed of a material similar to the electrode material termination of the current collector to which the counter electrode material can be electrochemically bonded has been developed to position the current collector at an optimal location within the counter electrode, Minimize peeling. This polymer matrix is a termination thin film that provides an improved lamination process and battery life, but this termination thin film does not provide bichemical electrochemical activity. The thin film is a polymer matrix similar to the electrode thin film, but preferably does not contain an electrode active material. When selecting a material to be used for the terminal thin film, it is preferable to select a polymer matrix thin film separation.

Conventional polymer matrix electrochemical cells include a negative electrode, a positive electrode and a separating element (typically a polymer electrolyte thin film) between the negative electrode and the positive electrode. The ion conducting electrolyte transfers ions from a predetermined electrode to another electrode to infiltrate the porous structure of each electrode and the separating element in common.

The bi-cell includes a center electrode (either cathode or anode), the counter electrode is located opposite each side of the center electrode, and each counter electrode is separated from the center electrode by a thin film separation or separation element layer. Bi-cells are stacked under temperature and pressure to provide good contact between battery layers.

As described herein, the term “center electrode” refers to the electrode of one of the anode or the cathode disposed centrally in a separate bi-cell. The term "counter electrode" is expressed as an electrode with an electrochemical couple with a center electrode. There is one center electrode and two counter electrodes in the bi-cell. If the center electrode is an anode, the counter electrode is a cathode. If the center electrode is a cathode, the counter electrode is an anode.

Each stacked element of a lithium ion polymer battery herein is generally planar in structure. Polymer matrix electrodes herein generally comprise a planar grating or perforated current collector as part of the electrode structure. The general plane of the current collector is parallel to the general plane of the polymer matrix thin film portion of the electrode. Similarly the thin film separation is generally horizontal with the direction of orientation towards the electrode. Thus, when batteries are stacked, a series of general purpose planar stacked elements is created. These structures disposed in the center of the separate battery element are expressed as being "middle" or "middle disposed" within the battery element. In contrast, these structures, generally disposed in the center of the bi-cell, are expressed as being "centered" or "centered". For example, the current collector 211 of the center electrode 210 is disposed in the middle of the center electrode, and is also placed in the center of the bicell. The current collectors 215a and 215b of the counter electrodes 214a and 214b are respectively disposed in the middle in their respective counter electrodes, but are respectively disposed toward the outer edge of the bicell 201.

These devices are further away from the center of the bi-cell, especially those that form the outermost plane are represented by the "outside" device, and the structure is said to be "outward" of the stacked bi-cell structure. . For example, in the embodiment shown in FIG. 2A, the top and bottom surfaces can be "outer" surfaces. Each separate functional layer in the bicell is similarly a "inner" region (facing the center of the bicell) and "outward" (facing the bicell) horizontal to the general plane of the particular separation element and bicell structure. It can include an area. In each counter electrode, the inner half will be placed adjacent to the center electrode and the outer half will be placed at the end of the center electrode. "Half" will represent approximately 50% by weight of the counter electrode active material.

In making polymer matrix batteries, one of the more difficult parameters is the lamination rate of multiple battery elements for making a finished battery. Materials with similar polymer matrix structures can be stacked together more easily than stacking dissimilar materials. It has been proved that there is a particular problem in laminating polymer matrix materials on current collector gratings. Many bonding promoters and lamination techniques have been tried for a long time with varying results. Centrally located current collectors within the electrodes provide consistent lamination results in the polymer matrix for polymer matrix bonding through the current collection grating.

As further mentioned in the eighth to eleventh embodiments, a series of controlled tests are performed to determine the optimal grating batty at the counter electrode. It was determined that grid placement affects battery performance.

Each of FIGS. 3A-3E is labeled with an arrow to indicate the outside, ie direction, of the bi-cell.

As shown in FIG. 3A, the grating 315 disposed on the inner surface 314i of the counter electrode is capable of sandwiching the grating between the counter electrode 314 and the thin film separator 312. However, this arrangement provides poor battery performance.

3B shows an arrangement similar to the arrangement in which approximately 25% of the counter electrodes 314 are disposed with respect to the current collector 315 and sandwiched between the current collector 315 and the thin film separator 312. The remaining 75% of the counter electrodes are arranged outside the current collector. This example does not show improved efficacy compared to the conventional example.

FIG. 3C illustrates an embodiment opposite to the embodiment of FIG. 3B. In particular, approximately 75% of the counter electrodes are disposed midway with respect to the current collector, and are sandwiched between the current collector and the thin film separator 312. The remaining 25% of the counter electrodes are disposed outside the current collector. This example showed improved efficiency compared to the conventional example. In addition, there is a polymer matrix on both sides of the current collector, and the stack of battery assemblies is not damaged by the lattice arrangement.

3D illustrates an embodiment in which the current collector 315 is disposed on the outermost surface 314o of the counter electrode 314. The thin film separator 312 is disposed opposite the current collector grating 315. This embodiment provides optimized electrical performance compared to the embodiment shown in FIGS. 3A-3C. However, by laminating the electrode polymer matrix on a single side of the current collector, the bi-cells are difficult to stack and tend to delaminate relatively quickly. Peeling destroys the function of the battery. Thus, this embodiment optimizes battery efficiency but decreases battery life.

Embodiments such as the one shown diagrammatically in FIG. 3E have been determined to provide the advantage of an optimized current collector grid arrangement and at the same time provide a battery structure that does not peel off quickly.

As shown in FIG. 3E, a preferred embodiment includes a thin film separator 312 disposed centrally adjacent to the counter electrode 314. Current collector 315 is disposed on outer surface 314o of counter electrode 314. The polymer matrix thin film 313 is disposed outside the current collector 315 and laminated in place. The polymer matrix material is bonded to the counter electrode material through the current collector grating during the lamination process. This example optimizes for better efficiency and lifetime, but shows a somewhat thicker bi-cell structure. Most preferably, the counter electrode 314 is an anode in the preferred "anode-out" arrangement.

It is preferred that a predetermined amount of polymer matrix is present outside the current collector in the counter electrode. When the polymer matrix is an electrode material, it is generally preferred that the predetermined amount outside the current collector be minimized within the manufacturing parameters. For example, if the electrode material is formed in a film having a predetermined thickness, one film will exist outside of the current collector, and a plurality of films are disposed inside the current collector to form a counter electrode. When one film in the electrode thin film is laminated to the outside of the current collector and two films in the electrode thin film are stacked at the center of the current collector, a ratio of 1: 2 occurs. 3c shows a ratio of 1: 3. This ratio can range from 1: 1 to 1: 4 or higher, which varies with battery design and functional parameters. As long as battery performance and persistence are met, the thickness of the electrode portion outside of the current collector is not critical.

When the polymer matrix thin film is used outside the current collector of the counter electrode, the specific thickness of the polymer matrix thin film is not so important as long as a good laminated junction is formed. The same thin film used for thin film separation can be used as the polymer matrix thin film to simplify the manufacture. This has the advantage of using materials already produced for the batteries used in the new features. In addition, the lamination process required for thin film separation is well known and has an advantage because it can be applied as is known in the art.

In the structure of a lithium ion bi-cell battery, as shown in the cross-sectional view of FIG. 2A, the bonding material provides a polymer matrix to each center electrode, separation element film and counter electrode.

Each anode and cathode electrode is formed by a similar process but includes a particular anode active or cathode active material within the polymer junction. That is, the solid polymer matrix provides a portion of the electrode structure. Preferred separating element materials are polymer matrix thin films that do not comprise an electrode active material. Similarly, the polymer matrix thin film for use when the current collector is located at the outermost edge of the counter electrode is preferably a polymer matrix thin film, for example forming a separating element.

Composite polymers of polyvinylated difluoride (PVdF) and hexafluoropropylene (HFP) are common bonding materials and are commonly used bonding materials in the present invention. In general, the composite polymer comprises approximately 75% to 92% (in weight units) of PVdF, and approximately 8% to 25% of HFP. The composite polymer preferably comprises approximately 85% to 90% (weight units) of PVdF and approximately 10% to 15% of HFP. As one particular preferred embodiment, the commercially used composite polymer, KYNAR (R) Flax 2081 (Elven Athosham, Philadelphia, PA) provides a ratio of 88:12 of PVdF: HFP. Inorganic filter adducts, such as evaporated alumina or evaporated silica, for example, provide structural stability to the bonding material and are preferably added to provide the desired thin film.

Thin film separation is commercially available for separating elements made of optical fibers, porous polypropylene or porous polyethylene. Such isolation elements include A / E optical fiber filters (Gelman Science, Ann Arbor, Minnesota) and Celgard (Hostest-Celanis, NY). However, the separating element is, for example, a solid polymer matrix such as the polymer thin film described above. Such thin film separation is well known in the art. Preferred polymer electrolyte membranes are produced using a casting process in which the carrier liquid is removed to form an elastic thin film. Another preferred method is to produce a polymer electrolyte membrane by an extrusion process. Suitable polymer electrolyte membranes provide a polymeric matrix structure in which the porous plasticizer is impregnated onto the casting or cured product.

Plasticizers help form the porous polymer structure as an organic solvent. Suitable plasticizers have a high boiling point and typically have a boiling point in the range of 150 ° C to 350 ° C. The plasticizer or plasticizer system must be compatible with the device of the electrochemical cell precursor, processable within the design parameters, and exhibit low polymer solubility. The plasticizer may be removed continuously (eg by extraction) prior to formation of the activated electrolytic cell.

Many plasticizers for use in treating or activating battery precursors are well known in the art. Such materials include, for example, ethylene carbonate (EC); Ethyl propionate (EP); Propylene carbonate (PC); Butylene carbonate (BC); Vinyl carbonate (VC); Dimethyl adipate (DMA); Diethyl carbonate (DEC); Dipropylene carbonate (DPC); Dibutyl carbonate (DBC); acetate; Diesters; Oxalates, such as dimethyl, succinate, adipate, sub-ate and surbacate oxalate; Glymes; And small molecular weight polymeric materials such as, for example, polycarbonates, polyarlates, polyesters or polysiloxanes. Other plasticizers can include dimethyl, diethyl, dipropyl, dibutyl and dioctyl artiate, and the like. In recent years, it is preferable to use dibutyl petalate (DBP) as a plasticizer. The plasticizers may be mixed and used.

The electrode thin film forming material includes a bonding material, a suitable electrode active (anode or cathode active) material, a plasticizer solvent and, if appropriate, a cotton casting solvent. The electrode thin film is formed immediately after removing the address solvent from the electrode thin film forming material. Suitable electrode thin films provide an elastic membrane having a porous electrode active structure in which plastic material has penetrated after solvent casting.

The negative electrode is the anode during discharge. Typically anode active materials are well known in the art and may include an insertion layer based on an anode, such as carbon or tungsten oxide, for example. Suitable anode active materials for use in the process of the invention include lithium intercalating anodes using materials such as graphite, cork, mesocarbon, and the like. The anode may comprise an electrode conductive material such as carbon black.

The anode includes a current collector stacked with a negative electrode material. Suitable materials for anode current collectors are well known in the art, for example, these materials are generally included in electronic conductive materials such as metals or alloys. Typical materials include nickel, iron, stainless metals or copper. Copper thin films, aperture meshes and expanded metals, woven or non-woven or knitted wire structures or lattice structures are preferably used. Each current collector is also connected to a current collector tab that extends from the edge of the current collector. In a battery comprising a plurality of electrochemical cells, it is preferred that the anode tabs are electrically connected together and the tabs are connected to a copper or nickel lead wire. The external load can be electrically connected to these leads. Current collectors and tabs are described in US Pat. Nos. 4,925,752, 5,011,501 and 5,326,653, each of which is incorporated herein by reference. Bonding promoters can be used to assist bonding between the anode material and the anode current collector.

The positive electrode is the cathode during discharge. Many cathode active materials are known in the art and include intercalating compounds, i.e., certain materials that function as positive electrodes in solid electrolyte cells. For use in lithium ion devices these materials are generally characterized as containing all lithium for the cell. The cathode material extracts lithium at high voltage when it collides with lithium and makes it stable in air. Typical cathode materials include, for example, transition metal oxides, sulfides and selenides. Such materials include oxides of cobalt, manganese, molybdium and vanadium; Sulfides of titanium, molybdium and niobium; Multiple chromium oxides; Copper oxide; Cobalt, manganese, nickel oxide lithium oxide, and the like. The cathode material may include LixMn204, LiCoO2, LiNiO2, LiCo0.5Ni0.5O2, and the like.

In a preferred embodiment, the cathode material is mixed with an electron conducting material such as, for example, graphite, powdered carbon, powdered nickel, metal particles, conductive polymers and the like. This cathode is preferably produced using a polymer binder to form a positive electrode cathode film, ie the solid polymer matrix provides a portion of the cathode structure. Like the polymer electrolyte membrane / separation element, the polymer binder is formed using both a solid polymer forming material and a plasticizer composite.

The cathode includes a current collector stacked together with a positive electrode active thin film material. Suitable materials for use in the cathode current collector are well known in the art and are typically included in electrode conductive materials such as metals or alloys, for example. Typically, the cathode current collector is, for example, a metal such as aluminum stainless metal and foils with protective conductive coating foil. The cathode electrode collector is an aluminum foil membrane, aperturemash, knitted metal, woven or unwoven or knitted wire configuration or grating. Each current collector is also connected to a current collector tab that extends from the edge of the current collector. In batteries comprising a plurality of electrochemical cells, the cathode tabs are preferably joined together and connected to the lead wires. The external load can be electrically connected to the lead wires. Bonding promoters can be used to assist bonding between the anode material and the anode current collector.

An improved structure for use in a stacked bi-cell battery is shown in FIG. The stacked bi-cells sequentially include a first counter electrode 414a having a current collector 415a on its outermost surface; First isolation element component 412b; A central electrode 410 having a current collector 411 disposed in the middle; Second isolation element component 412a; And a second counter electrode 414b having a current collector 415b on its outermost surface.

The current distribution changes as the position of the current collector in the counter electrodes changes. It is desirable for the current distribution to be positionable within the inner half of the counter electrode. However, the position of the current collector is more preferably disposed in the outer half of the counter electrode. The preferred embodiment includes a current collector at the outermost edge of the counter electrode. Although not necessary, it is preferable that the current collector of the counter electrode is symmetrical, so that the electrochemical treatment is balanced in the bi-cell.

4 does not show a polymer matrix thin film outside of the current collector. The polymer matrix thin film adjacent to the current collector does not require initial bicell function and capacity. However, it is desirable to use such thin films to delay or eliminate delamination and extend battery life. The polymer matrix thin film located external to the current collector needs to be a function of the lamination parameters and the designed battery life.

The specific embodiment of the bi-cell does not depend on both the anode or the cathode being the center electrode. For example, if the center electrode is an anode, the counter electrode is a cathode. Similarly, if the center electrode is a cathode, the counter electrode is an anode.

A "dry" electrolytic cell precursor is formed by combining the anode, thin film separation and cathode and extracting the plasticizer from each layer. Each electrode and separation element can be extracted separately, but it is more convenient to stack and combine the appropriate layers with plasticizer intact to extract the plasticizer from the battery precursor as a device. Methods of forming and extracting battery precursors are described in US Pat. No. 5,456,000, which is incorporated herein by reference.

The extracted battery precursor is activated by adding a solvent / electrolyte salt solution. The electrolyte solvent is a solvent included in the electrolyte solvent for the purpose of dissolving the aliphatic salts during the operation of the electrolytic cell. Electrolyte solvents are compatible, electrochemically stable, relatively nonvolatile, aprotic, and relatively polar solvents. These materials preferably have a boiling point above 85 ° C. to simplify the manufacturing process and increase the operating range and shelf life of the battery. Typically, dimethyl carbonate (DMC), diethyl carbonate (DEC), propylene carbonate (PC), ethylene carbonate (EC), methyl carbonate (MEC), gamma-butyrolactone, triglyme, tetraglyme, dimethylsul Foursides, dioxolenes, sulfolenes and the like and mixtures of these materials may be examples of solvents.

Electrolyte salts are inorganic salts suitable for use in nasal liquid electrolytes. Particularly alkaline salts are used, where the cation of the salt is preferably an alkali selected from the group consisting of lithium, sodium, potassium, rudidium, silver, and cesium suitable for use in the solvent containing electrolyte and the opposite electrode of the electrolytic cell. .

Various electrolyte salts are well known in the art. For example, compounds such as LiPF ₆ , LiSCN, LIAsF ₆ , LiClO ₄ , LiN (CF ₃ SO ₂ ) ₂ , LiBF ₄ , LiCF ₃ SO ₃ , LiSbF ₆ , NaSCN, and the like may be electrolyte salts. Typically electrolyte salts comprise approximately 5 to 25 weight percent of inorganic ionic salts based on the total weight of the electrolyte. This salt is included in the electrolyte solvent and is preferably about 10 to 20 weight percent. As is well known in the art, the weight percentage of salt will vary depending on the type of salt and the particular electrolyte solvent used.

In general, the stacked battery precursors are located in a package that cannot penetrate moisture before they are activated by the electrolyte solvent and are electrically connected to the electrode tabs. Since many electrolyte salts are sensitive to moisture or other chemical compounds, upon activation of the electrolytic cell precursor, it is desirable to place them in an inert, moisture free environment that is, for example, an argon environment.

The following examples are provided for the purpose of illustration and the present invention should not be limited by these examples. In each battery produced by the following example, a separator element film was used as the insulating member. This is to facilitate the comparison in the laboratory and should not limit the material suitable as the insulator.

(Example 1)

Cathode current collector

As for the aluminum lattice used in the anode current collector, an unwrapped aluminum metal film of about 2.5 g / m ² is used (Smet, Nagut, CT).

The surface of the aluminum lattice is formed by etching the lattice in a series of solutions. In particular, the aluminum lattice is placed in an acetone solution for 5 minutes. The aluminum lattice is then washed for 1 to 2 minutes in distilled water. The aluminum lattice is immersed in a solution of an etching solution comprising 56 g of potassium potassium pellets dissolved in 1 L of methanol. The aluminum lattice is removed from the etching solution after 8 minutes and soaked in fresh distilled water solution for 8 minutes and then soaked in acetone solution for 3 minutes.

An adhesion promoter layer is formed as a diffuse colloidal solution. The lattice coating is formed by adding to a ball mixing jar at a ratio of 100 (per weight) ethanol 100, Morton Edcoat (50C12) 100, Super-P® (MMM carbon, Willeblock, Belgium) 5 and mixing for 1 hour. . The diffused colloidal solution is diluted with a proportion of ethanol 100 and spray coated onto the etched aluminum lattice.

(Example 2)

Control cathode structure

The cathode structure in which the current collector is located in the middle is formed.

The polymer / cathode mixture was KYNAR Flex 2801 ™ by weight (mixed polymer of PVdF and HFP) (Elf Atochem, Philadelphia, Pennsylvania) 10, 025 C (LiXMn2O4) (Ker-Megi) 65 per weight, and super- It is formed by mixing in the ratio of P (trade name) carbon black 5. The polymer / cathode mixture is mixed for 24 hours in a ball milling jar.

To dry, dibutyl phthalate (DBP) was mixed in a proportion of 20 to the powdered cathode active mixture. The wet material is mixed for 10-30 minutes under high shear stress until a homogeneous mixture is formed. The mixer is maintained at a temperature of 130 ° C., which is a temperature suitable for mixing.

Two cathode films, each having a thickness of 125 μm, are formed by applying high pressure on a suitable substrate at 130 ° C. for 30 seconds. The current collector of Example 1 is disposed on the upper surface of the first cathode film. The second cathode film is disposed on the upper surface of the current collector. Pressure is applied to the resulting three-layer structure to provide good contact between the layers, which are compressed at high pressure at 130 ° C. for 15 to 30 seconds to form a cathode structure.

(Example 3)

Enhanced cathode structure

A cathode structure having a current collector at a predetermined edge is formed.

The process of Example 2 is repeated to form two cathode films. These cathode films are formed together in layers so that the current collector of FIG. 1 is located on top of the two cathode films. Pressure is applied to the resulting three-layer structure to provide good contact between the layers, which are compressed at high pressure at 130 ° C. for 15 to 30 seconds to form a cathode structure. The cathode structure has twice the thickness of the cathode film having the current collector at a predetermined edge.

(Example 4)

Anode current collector

The copper grating used for the anode current collector is a film of copper metal spread to a thickness of approximately 50 μm. This copper grating is used in the designated (2Cu5-155) (flattened and annealed) state (Connecticut, Brandford, Delcker).

The surface of the copper grating is formed by etching in a series of solutions. In particular, the copper lattice is placed in the acetone solution for 5 minutes. The copper lattice is then washed for 1 to 2 minutes in distilled water. The copper lattice is immersed in a solution of an etching solution containing 1 mole of nitric acid (70 ml 70% nitric acid and 1 L distilled water). The copper lattice is removed from the etching solution after 5 minutes and soaked in fresh distilled water solution for 8 minutes and then for 3 minutes in acetone solution.

The adhesion promotion layer is formed by spray coating on the etched copper grating as described above.

Example 5

Control anode structure

An anode structure with a current collector located in the middle is formed.

The polymer mixture is formed by mixing a mixed polymer of PVdF: HFP (KYNAR Flex 2801 ™) with BG34 (Illinois, Bloomingdale, Superior Grepate) at a ratio of 12 in a ball milling jar for 24 hours. do. This produces a dry powder mixture, in which the small sized particulates are well mixed.

Dibutyl phthalate (DBP) is added to the flour mixture at a rate of 30 to dry. The wet material is mixed for 10-30 minutes or more under high temperature (130 ° C.) and high shear stress conditions until a homogeneous mixture is formed.

The anode film is formed by compressing the anode material at a high temperature for 30 seconds at 130 ° C. on a suitable substrate. The current collector of FIG. 3 is located on the top surface of the single anode film. The second anode film is used to cover the current collector and pressure is applied to the resulting structure. In order to provide good contact between the layers, these layers are hot rolled laminated or laminated at high pressure to form an anode structure.

(Example 6)

Enhanced anode structure

An anode structure having a current collector at a predetermined edge is formed.

The anode film is formed by compressing the anode material at a high temperature for 30 seconds at 130 ° C. on a suitable substrate. The two anode films are stacked together and the current collector of FIG. 3 is disposed on the surface thereon. Pressure is applied to the resulting structure. To provide good contact between the layers, these layers are roll laminated or hot press laminated at 120 ° C. to form the anode structure.

(Example 7)

Isolation element

Distilled silica 20 and KYNAR Flex 2801 ™ are placed in the ball mill jar at a rate of 30 and mixed for 24 hours. This produces a dry powder mixture, in which the small sized particulates are well mixed.

Dibutyl phthalate (DBP) is added to the flour mixture at a ratio of 55 to dry. The wet material is mixed for 5-10 minutes under low shear stress until a homogeneous mixture is formed.

The resulting mixture was subjected to high pressure at a temperature of 130 ° C. for 30 seconds to form a clean, high strength thin film having a thickness of approximately 2 mm.

(Example 8)

Formation of Mixed Cathode Bicell Precursors

The solid electrochemical cell precursor allows the first cathode counter electrode (prior art control cathode) of Example 2 to be laminated adjacent to the polymer thin film separation of the seventh embodiment, and the second cathode counter electrode of Example 3 (prior art Control cathodes) are formed so as to be adjacent to the polymer thin film separation of the seventh embodiment so that the current collector is directed outward. These two cathode counter electrodes are closely matched to each other by weight. The center anode electrode of Example 5 is disposed between two polymer thin film separations of two counter electrode structures and this unit is also stacked together.

The layers form a bi-cell precursor 501, as shown in FIG. These layers then comprise a first (control) cathode counter electrode 514a having a current collector 515a disposed therebetween; First isolation element 512a; A center anode electrode 510; Second separation element 512b; And an (enhanced) second cathode counter electrode 514b having a current collector 515b at the outermost edge of the bi-cell. These layers are heated under pressure to form a bi-cell precursor. The weight to weight ratio of cathode to anode in the formed bi-cell is 2.5: 1.

Bi-cells are extracted, activated and packaged as follows. That is, the bi-cell precursor is immersed in methanol or diethyl ether or continuously methanol or ether in the container to remove the plasticizer. The methanol or ether vessel (s) is preferably in contact with excess methanol or ether for at least 30 minutes.

The extracted battery precursor is vacuum dried overnight at 40 ° C. The electrolyte solvent is prepared by mixing ethylene carbonite and dimethyl carbonite in a ratio of 267 to 133. LiPF ₆ is mixed with this electrolyte solvent at a ratio of 60 to produce a predetermined electrolyte solvent solution. This electrolyte solvent solution is added to the bi cell precursor. The activated electrolytic cell is packaged in a vacuum in a rigid housing. The positive electrode and negative electrode chambers extend from the packaging. The battery is charged to 4.2V.

(Example 9)

Experiment and result

The two cathode counter electrodes are each branched so that the current distribution is monitored at each electrode. The current distribution is measured during the steady state current cycle of the cell.

6 shows a graph comparing the cathode counter electrode while the bi-cell is charging.

7 shows a graph comparing the cathode counter electrode while the bi-cell is discharging.

Data is shown as a function of cell capacity for both charge and discharge. The cell in between 23 ℃ 3 to 4.2V 0.5mA / cm ₂ (i.e., total 24mA / cm ₂₎ is circulated at a current density of.

Improved cathodes (external current collectors) operate more efficiently during charging and discharging. That is, the enhanced cathode draws relatively much current compared to the intermediate current collector cathode.

During initial cell charging (FIG. 6) this current is preferentially drawn from the conventional cathode counter electrode. It is only with respect to the terminal cell charging (current collectors outside the cathode counter electrode to approximate lithium depletion) that conventional cathode counter electrodes have started to have superior performance following the enhanced cathode electrode.

A similar pattern appears with an improved design cathode counter electrode that re-runs more effectively during cell discharge (FIG. 7). Note that in this feature, the current exhibits a negative value representing the discharge reaction.

(Example 10)

Preparation of Mixed Anode Bicell Precursors

The solid electrochemical cell precursor is laminated with the first anode counter electrode of FIG. 5 (prior art prior art control anode) adjacent to the first polymer separator of FIG. 7 with the current collector directed outward, and onto the second polymer separator of FIG. It is formed by stacking the second anode counter electrode in Fig. 6 (current collector outside the anode). Two anode counter electrodes match close to weight. The central cathode electrode of FIG. 2 is disposed between two polymer separators of two electrode structures and stacked together.

These layers are arranged to form the bi cell precursor 501 as shown in FIG. 5. These layers are sequentially arranged with a first (control) anode counter electrode 514a having a current collector 515a disposed in the center; A first separator 512a; A center cathode electrode 510; A second separator 512b; The second (enhanced) anode counter electrode 514b with current collector 515b at the outermost edge is arranged. These layers are heated under pressure to form a bi-cell precursor. In the finished bicell, the weight ratio of cathode to anode is 2.5: 1.

The bi-cells are extracted, activated and packaged as shown in FIG.

(Example 11)

Experiment and result

The two anode counter electrodes are each branched to allow the current distribution to be monitored within each electrode. The current distribution is measured during the steady state current cycle of the cell.

8 shows a graph comparing the anode counter electrode while the bi-cell is charging.

7 shows a graph comparing the anode counter electrode while the bi-cell is discharging.

Data is shown as a function of cell capacity for both charge and discharge. The cells in voltage in the range 3 to 23 ℃ 4.2V 0.5mA / cm ₂ (i.e., total 24mA / cm ₂₎ is circulated at a current density of.

Improved cathodes (external current collectors) operate more efficiently during charging and discharging. That is, the enhanced cathode draws relatively much current compared to the intermediate current collector cathode. An improved anode through the cell charging process clearly draws more current (so when the cell is fully charged, ultimately a higher level of lithium ion density is obtained). During the subsequent cell discharge process (FIG. 9), this shows a higher initial characteristic capacity at this anode counter electrode obtained during the charging process, but the improved anode counter electrode appears more effectively.

During initial cell charging (FIG. 8) this current is preferentially extracted from a conventional cathode counter electrode. Conventional cathode counter electrodes began to follow superior cathode electrodes and began to have superior performance only for terminal cell charging (current collectors outside the cathode counter electrodes would approach approximately lithium depletion).

A similar pattern appears with an improved design cathode counter electrode during cell discharge (FIG. 9). Note that in this feature, the current exhibits a discharge response and a negative value.

(Example 12)

Alternative Mixed Cathode Bicell Precursors

The solid electrochemical cell precursor is formed as described in Example 8, and the cathode counter electrode replacing the second counter electrode includes a current collector at the outermost edge of the cathode material and a polymer matrix thin film next to the current collector. Has These layers are heated under pressure to form a bi-cell precursor. Bi-cells are extracted, activated and packaged as described in Example 8.

These two cathode counter electrodes are each branched to allow the current distribution to be monitored at each electrode. The current distribution is measured during the steady state current cycle of the cell. The cells in voltage in the range 3 to 23 ℃ 4.2V 0.5mA / cm ₂ (i.e., total 24mA / cm ₂₎ is circulated at a current density of.

Current charging cathodes with cathode material-current collector-polymer matrix thin films during charging and discharging operate more efficiently than current collector intermediate cathodes.

(Example 13)

Alternative Mixed Cathode Bicell Precursors

The solid electrochemical cell precursor is formed as described in Example 8, and the cathode counter electrode replacing the second counter electrode has a current collector at the innermost edge of the cathode material. These layers are heated under pressure to form a bi-cell precursor. Bi-cells are extracted, activated and packaged as described in Example 8.

The two cathode counter electrodes are each branched to allow the current distribution to be monitored at each electrode. The current distribution is measured during the steady state current period of the cell as shown in Example 11. The cells in voltage in the range 3 to 23 ℃ 4.2V 0.5mA / cm ₂ (i.e., total 24mA / cm ₂₎ is circulated at a current density of.

During charging and discharging, the current collector center cathode operates somewhat inefficiently than the current collector intermediate cathode.

(Example 14)

Alternative Mixed Cathode Bicell Precursors

The solid electrochemical cell precursor is formed as described in Example 10, and the anode counter electrode, which replaces the second counter electrode, comprises a current collector at the outermost edge of the anode material and a polymer matrix thin film next to the current collector. Have These layers are heated under pressure to form a bi-cell precursor. Bi-cells are extracted, activated and packaged as described in Example 10.

These two anode counter electrodes are each branched to allow the current distribution to be monitored at each electrode. The current distribution is measured during the steady state current period of the cell as shown in Example 11. Improved anodes (external current collectors) operate more efficiently than current collector intermediate anodes during charging and discharging.

(Example 15)

Alternative Mixed Cathode Bicell Precursors

A solid electrochemical cell precursor is formed as described in Example 10, and the anode counter electrode replacing the second counter electrode has a current collector at the innermost edge of the anode material. These layers are heated under pressure to form a bi-cell precursor. Bi-cells are extracted, activated and packaged as described in Example 10.

These two anode counter electrodes are each branched to be tested as shown in Example 11. Current collector-center anodes operate less efficiently than current collector-middle anodes during charging and discharging.

As mentioned above, Figure 3 is suitable for the preferred "anode outside" bicell. This arrangement is preferable to "outside the cathode". The cathode outer arrangement is illustrated by FIG. 2, in which counter electrodes 214a and 214b are positive electrodes (cathodes) and center electrode 210 is negative electrodes (anodes). In the present invention according to FIG. 3, a preferred anode outer arrangement is shown and, on the contrary, referring back to FIG. 2 with the electrode formed, it will be easier to understand. In the present invention, the electrodes 214a and 214b are anode electrodes, and the center electrode 210 is a cathode electrode.

The anode outside design was compared with the cathode outside design. The anode outer battery increased the cell capacity from 2% to 5%. In addition, the battery life cycle (one cycle means charging to 4.2V after discharging up to 3V) in the anode outside design showed up to 600 cycles at 80% remaining capacity and 1200 cycles at 60% remaining capacity. Has been improved. The improved anode outer arrangement consists of the layers of the first anode, the first separating element, the cathode, the second separating element and the second anode. The cathode current collector, the anode current collector and the isolation element are formed according to the prior art as described for each of the above-described Examples 1, 4 and 7 above, and the cathode structure is formed according to the method according to Example 2 The anode is formed according to the method according to Example 5.

Further testing shows an anode outer design as an inherently and naturally improved advantage. The anode outside design works better than the cathode outside design. It is clear that the anode outer design provides significant advantages when connected with a current collector that is not disposed in the middle.

Unless otherwise noted, all percentages are in weight / weight percentages. Given a range of values that are "approximately" at a predetermined rate, each of these upper and lower ranges may vary in units of 5% to 10%, unless such fluctuations have a significant effect on this battery system.

Although the present invention has been described in connection with some exemplary embodiments, many modified embodiments will be apparent to those skilled in the art in the foregoing disclosure which we have illuminated. The scope of the claimed invention should be determined with reference to the following claims.

Claims (20)

In the structure of the laminate bi-cell (laminate bi-cell), The stacked bi-cell, (Iii) a first counter electrode; (Ii) a first separating element; (Iii) a central electrode; (Iii) a second separation element; (Iii) sequentially including second counter electrodes. At least one counter electrode of the first and second counter electrode structure of a stacked bi-cell battery, characterized in that it comprises a current collector not disposed in the middle. The structure of claim 1, wherein at least one counter electrode of the first and second counter electrodes comprises a current collector disposed within a position of an outer half of the counter electrode. The counter electrode of claim 1, wherein the first counter electrode and the second counter electrode each include an inner surface and an outer surface, and at least one counter electrode of the first counter electrode and the second counter electrode is an outer surface of the counter electrode. The structure of a stacked bi-cell battery comprising a current collector disposed in. The structure of claim 3, wherein each of the first counter electrode and the second counter electrode includes a current collector disposed on an outer surface of the counter electrode. 5. The structure of a stacked bi-cell battery as claimed in claim 4, further comprising an electrochemically incompatible polymer matrix thin film adjacent to the current collector outside. The structure of a stacked bi-cell battery according to claim 5, wherein the electrochemically incompatible polymer matrix thin film (insulator element) is a synthetic polymer of PVdF: HFP. The structure of claim 1, further comprising at least two bi-cells electrically connected to form a battery. The structure of claim 1, wherein the first counter electrode and the second counter electrode are an anode and the center electrode is a cathode. The structure of claim 1, wherein the first counter electrode and the second counter electrode are a cathode and the center electrode is an anode. In the structure of the stacked bi-cell battery, The stacked bi-cell is, (Iii) a first counter electrode having an inner half disposed proximate to the center electrode and an outer half disposed at an end of the central electrode; (Ii) a first separating element; (Iii) a central electrode; (Iii) a second separation element; (Iii) sequentially comprising a second counter electrode having an inner half disposed proximate to the center electrode and an outer half disposed at the end of the central electrode, At least one counter electrode of the first and second counter electrode structure of a stacked bi-cell battery, characterized in that it comprises a current collector disposed on the outer half of the at least one counter electrode. The structure of claim 10, wherein each of the first counter electrode and the second counter electrode includes a current collector disposed in a position of an outer half of the counter electrode. 11. The method of claim 10, wherein the first and second counter electrodes each comprise an inner surface and an outer surface, wherein at least one counter electrode of the first and second counter electrodes is disposed on an outer surface of the counter electrode. A structure of a stacked bi-cell battery comprising a disposed current collector. The structure of claim 12, wherein each of the first counter electrode and the second counter electrode includes a current collector disposed on an outer surface of the counter electrode. 15. The structure of claim 13, further comprising an electrochemically incompatible polymer matrix thin film deposited adjacent to the current collector. 15. The structure of a stacked bi-cell battery of claim 14 wherein the electrochemically incompatible polymer matrix thin film is a synthetic polymer of PVdF: HFP. The structure of a stacked bi-cell battery of claim 10, further comprising at least two bi-cells electrically connected to form a battery. The structure of claim 10, wherein the first counter electrode and the second counter electrode are an anode and the center electrode is a cathode. The structure of claim 10, wherein the first counter electrode and the second counter electrode are cathodes, and the central electrode is an anode. In the structure of the bi-cell battery, (Iii) a first anode; (Ii) a first separating element; (Iii) a cathode; (Iii) a second separation element; (Iii) includes a second anode, (Iii) each of the first anode and the second anode sequentially includes a first anode film, an anode current collector, and a second anode film; (Iii) the cathode comprises a first cathode film, a cathode current collector and a second cathode film in sequence. 20. The structure of claim 19, wherein said cathode current collector and said anode current collector are each capable of penetrating an electrolyte.