JP2010521053A - Battery electrode and battery including such electrode - Google Patents

Abstract

  The battery can include a housing, a cathode in the housing, and an anode in the housing. The cathode can include a lithium ion cathode active material and a network of conductive metal material within the cathode active material. The cathode can have a thickness of at least 1 mm.

Description

  In general, Li (lithium) and Li-ion (lithium ion) batteries are fabricated using relatively thin electrodes deposited on a metal foil or expanded metal grid. These electrodes typically are about 0.1 to 0.25 mm thick and are wrapped with a separator film in a cylindrical or square assembly called a “jelly roll”.

  This wound battery structure is more complex and expensive than a comparable size alkaline battery made using a bobbin structure. Batteries containing these thin electrodes also tend to have relatively low energy density due to the proportionally large inert capacity occupied by current collectors, separators and other inert components. Nevertheless, thin electrodes are used for the jelly roll structure because the electrodes and electrolytes are limited in electrical and ionic conduction.

  The electrode formulation used to deposit on a metal foil or expanded metal grid is typically based on a solvent phase, an active material, a conductive additive and an organic polymer binder. After evaporation of the solvent, the binder combines with the particulate material to provide mechanical strength and adhesion. However, due to the insulating properties of the polymer, it can be used in limited quantities without affecting the electrochemical performance of the electrode, ie without limiting the resulting electrode strength. As a result, the electrode thickness is generally less than about 0.25 mm to prevent cracking and / or delamination.

  Conventional wound arrangements, such as “jelly roll” arrangements, typically include a large volume of current collector and separator material, which occupies a significant capacity of the cell. By reducing the amount of current collector and separator material used, additional active materials can be added to the cell. Replacing the conventional arrangement with a bobbin cell structure allows up to 25 percent of the active material to be used in AA batteries or AAA batteries, resulting in a significant increase in energy density. By using the thick electrodes described herein, it is possible to produce a simple and low cost bobbin lithium cell with adequate rate capability under both charging and discharging conditions. In addition, other types of high-density cell structures such as a square structure are possible. The thick electrodes described herein allow for a variety of new cell arrangements that utilize lithium-based high energy densities.

  In one aspect, a battery is disclosed that includes a housing, a cathode in the housing, and an anode in the housing. The cathode includes a lithium ion cathode active material and a network of conductive metal material within the cathode active material. In some embodiments, the cathode has a thickness of at least 1 mm.

  In some embodiments, the network of conductive metal material comprises an open cell foam metal. The conductive metal material can include aluminum.

  In some embodiments, the network of conductive metal material includes a metal filler. Metal fillers include powders, flakes, fibrils, fibers or combinations thereof. The metal filler can be compressed or sintered in place to form a continuous network throughout the cathode active material.

  In some embodiments, the network of conductive metal material includes a metal alloy that expands or contracts during charge and discharge.

In some embodiments, the anode includes an anode active material and an anode network of conductive material within the anode active material. Examples of the anode active material include mesocarbon microbeads (MCMB), Li ₄ Ti ₅ O ₁₂ or a combination thereof. The anode network of conductive material can include an open cell foam metal. The anode network of conductive material can include copper. In some embodiments, the anode network of conductive material can include a metal filler. Metal fillers include powders, flakes, fibrils, fibers or combinations thereof. The metal filler can be compressed or sintered in place to form a continuous network throughout the anode active material.

  In some embodiments, the battery also includes a separator between the cathode and the anode. The separator can include a porous polyolefin. In some embodiments, the separator can include ceramic or glass.

  In some embodiments, the network of conductive metal material includes a surface layer of pores that does not include a cathode active material. In some embodiments, the surface layer of the pores that do not include the cathode active material may be oxidized. In some embodiments, the surface layer of pores free of cathode active material can be thick enough to function as a separator between the cathode and anode.

In some embodiments, the cathode active material includes Li [Ni _0.33 Co _0.33 Mn _0.33 ] O ₂ , LiFePO ₄ , LiCoO ₂ , LiMn ₂ O ₄ or a combination thereof. In some embodiments, the cathode thickness can be from about 2 mm to about 10 mm. In some embodiments, the cathode includes about 5 to about 15 weight percent conductive material.

  In some embodiments, the battery can be a secondary battery.

  In some embodiments, the battery can be made as a stacked square structure. In other embodiments, the battery can have a bobbin cell structure. In some embodiments, the battery includes a plurality of stacked disks each having at least one cathode region and at least one anode region.

In some embodiments, the rated capacity of the battery is at least about 1.5 mA / cm ² .

In another aspect, the secondary battery includes a housing and at least one cell having a bobbin type cell structure in the housing. The cell can include at least two electrodes including a cathode and an anode. Each electrode can include an electrode active material. The cathode can include a lithium ion cathode active material, and the anode can include an anode active material. The at least one electrode can include a network of conductive material within the electrode active material. In some embodiments, the cathode can include a network of conductive material, and the network of conductive material can include an open cell foam metal of aluminum. In some embodiments, the anode can include a network of conductive material. In some embodiments, the network of conductive material can include an open cell foam metal of copper. In some embodiments, the cathode active material includes Li [Ni _0.33 Co _0.33 Mn _0.33 ] O ₂ , LiFePO ₄ , LiCoO ₂ , LiMn ₂ O ₄ or a combination thereof. In some embodiments, the anode active material includes mesocarbon microbeads (MCMB), Li ₄ Ti ₅ O ₁₂ or combinations thereof.

In some embodiments, the secondary battery can include a separator between the cathode and the anode. In some embodiments, the battery can include a plurality of stacked disks, each including at least one cathode region and at least one anode region. In some embodiments, the secondary battery can have a rated capacity of at least about 1.5 mA / cm ² .

In another aspect, the primary battery includes a housing and at least one cell having a bobbin type cell structure in the housing. The cell can include at least two electrodes including a cathode and an anode, and each electrode can include an electrode active material. The cathode can include a cathode active material, and the anode can include an anode active material. The at least one electrode can include a network of conductive material within the electrode active material. In some embodiments, the cathode can include a network of conductive material. In some embodiments, the anode can include a network of conductive material. In some embodiments, the network of conductive material can include an open cell foam metal of aluminum. In some embodiments, the network of conductive material can include an open cell foam metal of copper. In some embodiments, the anode active _{material, MnO 2, FeS 2, NiS} 2, MnS 2, CuS, CuO, V 2 O 5, AgV 4 O 11 or combinations thereof. In some embodiments, the anode active material includes metallic lithium foil, metallic lithium powder, or combinations thereof.

  In some embodiments, the primary battery can include a separator between the cathode and the anode. In some embodiments, the primary battery can include a plurality of stacked disks, each including at least one cathode region and at least one anode region.

  The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the various embodiments will be apparent from the description and the accompanying drawings and claims.

1 is a schematic plan view of a cylindrical laminated disc (or pellet) in a bobbin cell structure according to one embodiment. FIG. The schematic plan view of the cylindrical lamination | stacking disk (or pellet) in the bobbin cell structure which shows the network structure of the electroconductive metal material in a cathode active material roughly. FIG. 3 is a schematic plan view showing a cylindrical stack of such a cylindrical laminated disk. FIG. 6 is a schematic plan view of a cylindrical laminated disc (or pellet) in a bobbin cell structure according to an additional embodiment. FIG. 6 is a schematic plan view of a cylindrical laminated disc (or pellet) in a bobbin cell structure according to an additional embodiment. FIG. 6 is a schematic plan view of a cylindrical laminated disc (or pellet) in a bobbin cell structure according to an additional embodiment. FIG. 6 is a schematic plan view of a cylindrical laminated disc (or pellet) in a bobbin cell structure according to an additional embodiment. FIG. 6 is a schematic plan view of a cylindrical laminated disc (or pellet) in a bobbin cell structure according to an additional embodiment. FIG. 6 is a schematic plan view of a cylindrical laminated disc (or pellet) in a bobbin cell structure according to an additional embodiment. FIG. 6 is a schematic plan view of a cylindrical laminated disc (or pellet) in a bobbin cell structure according to an additional embodiment. The schematic perspective view of the stacked square cell. The graph which shows the porosity of Al foam material investigated when rolling from (a) 3.2 mm and (b) 6.4 mm. The graph which shows the porosity of Al foam material investigated when rolling from (a) 3.2 mm and (b) 6.4 mm. The graph which shows the performance of the bag cell using an aluminum foil type cathode. The graph which shows the performance of the bag cell using a 1 mm aluminum foil LFP type | system | group cathode. The graph which shows the discharge performance of the bag cell using a 2 mm aluminum foil LFP type | system | group cathode. The graph which shows the discharge performance of the bag cell using a 2 mm aluminum foil LFP type | system | group cathode. The graph which shows the performance of the bag cell using copper foil MCMB type | system | group anode.

  The electrochemical cell can be a primary cell or a secondary cell. A primary electrochemical cell means that it is discharged only once, for example until it is completely consumed, and then discarded. The primary cell is not intended for recharging. Primary cells are described, for example, in David Linden, “Handbook of Batteries” (McGraw-Hill, 1995, 2nd edition). The secondary electrochemical cell can be recharged many times, for example, more than 50 times, more than 100 times or more. In some cases, secondary batteries can include relatively robust separators, such as separators with many layers and / or separators that are relatively thick. The secondary cell can also be designed to accommodate changes such as expansion that can occur in the cell. Secondary cells are, for example, Falk & Salkind's “Alkaline Storage Batteries” (John Wiley & Sons, Inc., 1969), U.S. Pat. No. 345,124 and French Patent 164,681, all of which are incorporated herein by reference. Both the primary cell and the secondary cell can have a bobbin cell array or a square array.

Bobbin Cell Array The bobbin cell array can include annular and rod-shaped electrodes. For example, a bobbin cell arrangement can include a ring or rod of cathode material and a ring of anode material surrounding it in the center. In other bobbin arrangements, additional rings or rods of the anode or cathode may also be present. The bobbin cell array can also have a non-circular cross-sectional shape.

  1A and 1B show two types of cylindrical laminated discs (or pellets) that can be used in a bobbin cell structure. Each illustrated laminated disc includes a cathode 22, an anode 24, and a separator 26 between the cathode 22 and the anode 24. As shown in FIG. 1B, the cathode 22 can include a network 27 of conductive metal material within the cathode active material of the cathode 22. In some embodiments (not shown), the anode 24 can also include a network of conductive material within the anode active material of the anode 24.

  FIG. 1C shows a perspective view showing a cylindrical stack of cylindrical laminated disks, such as those described above and shown in FIGS. 1A and 1B. Such a cylindrical stack of cylindrical laminated discs can be used to make a bobbin cell structure. In the illustrated embodiment, the grid 28 is located between adjacent cylindrical laminated disks. The grid 28 can collect current between adjacent cylindrical laminated disks. Any continuous metal structure can function as a grid 28, such as, for example, perforated metal foil, woven or welded wire mesh, or expanded metal (slit metal and stretched metal). For this purpose, expanded metal grids are commercially available, for example, from Dexmet Corporation, Naugatuck, Connecticut. Typically, their thickness varies from 25 to 127 micrometers (1 to 5 mils). By placing such a grid between the stacked electrode disks, a high conductive path is provided to the external battery housing, thus reducing the internal resistance. In other embodiments, not shown, the cylindrical laminated disk can be arranged without the intermediate grid 28. The cylindrical stack may be disposed within the battery housing 20. In some embodiments, the battery can include a current collector 32. The current collector 32 can collect current from, for example, the anode 24 or the cathode 22 as shown, depending on the arrangement of the cathode and anode in the cell.

  2A-2B illustrate various other cylindrical laminated disk embodiments. Each of these various other cylindrical laminated disk embodiments can be used to create a bobbin cell array. The arrangement can be selected to provide the desired amount of shared surface area between the anode 24 and the cathode 22. The number of electrodes used in the cell can also be varied depending on the required cell performance.

  The bobbin cell array is shown as a bobbin array with stacked disks, but other bobbin cell arrays are possible. For example, the battery can include separately formed anode region 24 and cathode region 22 that are separately disposed within the battery housing.

Square Array FIG. 3 shows a stacked square structure. The laminated square structure includes a cathode 22 layer and an anode 24 layer. The thickness of each layer of cathode 22 or anode 24 can be at least 1 mm. In some embodiments, the thickness of each layer of cathode 22 and / or anode 24 can be at least 1.5 mm (eg, 2 mm to 100 mm thick). In some embodiments, as illustrated, the square structure includes a layer of separator 26 between layers of alternating cathode and anode materials.

  In the case of a conventional lithium ion prismatic battery, a flat, spirally wound electrode stack assembly, such as the NP-60 design, can be replaced with a simple stacked electrode assembly as shown in FIG. Is possible. The stacked electrodes 22, 24 are compressed to form a pellet, penetrated into a preformed conductive metal material network 27, or to form an in situ conductive metal network 27. The electrode active material produced by shape | molding / compressing a substance and a metal powder can be included.

Electrode Structure The cathode 22 can include a lithium ion cathode active material. For example, the cathode can include Li [Ni _0.33 Co _0.33 Mn _0.33 ] O ₂ , LiFePO ₄ , LiCoO ₂ , LiMn ₂ O ₄ or a combination thereof as the cathode active material. In some embodiments, the thickness of the cathode can be at least 1 mm (eg, at least 1.5 mm or 2 mm to 100 mm). In some embodiments, the conductive metal network can include aluminum. In some embodiments, the cathode 22 can be part of a secondary cell.

As described above, the anode 24 can include an anode active material (eg, mesocarbon microbeads or Li ₄ Ti ₅ O ₁₂ ) and an anode network of conductive material within the anode active material. Anode active materials also include graphite, amorphous carbon, alloy anodes, metal compounds (oxides, chalcogenides and other compounds) or mixtures thereof. In some embodiments, the anode network of conductive material can include copper. In some embodiments, the cathode 24 can be part of a secondary cell.

  The network of conductive metal material can function as a current collector that is incorporated into the electrodes (cathode 22 and / or anode 24), thereby providing good electrical conductivity. A composite of active material (anode and / or cathode) and a network of conductive material is applied to the network 27 (eg, foam metal) preformed using various coating and / or infiltration procedures. It can be fabricated using a variety of methods, including depositing material. For example, a curtain coating procedure can be used to form the composite.

  In some embodiments, the network of conductive material can include an open cell foam metal. The open-celled foam metal can be machined or shaped into a shape such as an annular electrode in a battery design such as a bobbin cell before and after deposition of the electrode active material. The foam can be treated prior to deposition of the electrode active material, for example, to remove the coating with oxide and / or primary material to increase conductivity and adhesion.

  Various slurry formulations with different binders and / or solvents can be used to infiltrate the foam or other network of conductive metal material with electrode active material. In some embodiments, aqueous binders (eg, latex binders and rheology modifiers) may be used to coat the active material on the foam.

  The foam matrix allows for better thermal diffusion than conventional “jelly roll” arrangements, for example in cells that charge and discharge at rates that lead to heat generation. The electrode (cathode or anode) has two or more foams with different metal contents (ie different relative densities) or different pore sizes and sandwiched together (before or after active material infiltration or coating) Can do.

  Alternatively, the network of conductive metal material can include a metal filler. Metal fillers include powders, flakes, fibrils, fibers or combinations thereof. The metal filler can be compressed or sintered in place to form a continuous network throughout the active material.

  In some embodiments, the network of conductive material can include a metal alloy that expands or contracts during charge and discharge. In some embodiments, the cathode active material and / or anode active material can expand or contract during charge and discharge. Depending on the expansion characteristics, the electrode active material and the network material can be selected to prevent the electrodes from separating or delamination in the battery in use.

In some cases, two different types of active materials may be coated on both sides of the network 27 in certain applications, for example, to regulate the discharge / charge of the active materials in the desired order. For example, the side of the cathode 22 facing the anode 24 can directly have a coating of cathode active material, such as LiFePO ₄ , that is more useful in regulating overcharge, while the opposite side of the network 27 is LiOO. ₂ and can be coated with a high capacity material that is less resistant to overcharging.

  In some embodiments, the electrode can be highly porous. For example, the foam network 27 of conductive material can improve the level of porosity in the electrode active material (cathode 22 or anode 24) and improve the discharge / charge efficiency of the active material. For example, the pore-forming additive can be incorporated into the coating and / or infiltration slurry to help form the desired porous structure within the electrode active material. The pore forming agent can include any material that can be removed from the prepared electrode after formation of the pores. Such materials can be removed by a number of methods including a heating step (which can be performed under vacuum) and a solvent washing step, where the electrode components are insoluble but the pore former is It is soluble. Examples of materials that can be used as pore formers include sulfolane and ethylene carbonate. Various Li salts are soluble and can also be used as pore formers that are compatible with the electrolyte. Incorporating pores is beneficial in the electrode and improves the electrode reaction rate, ie the rate capability of the cell.

In some embodiments, the battery can be a primary lithium battery that uses metallic Li foil or powder as the anode. In such a primary lithium battery, the cathode active material may include materials such as MnO ₂ , FeS ₂ , NiS ₂ , MnS ₂ , CuS, CuO, V ₂ O ₅ and / or AgV ₄ O _11. . In some embodiments, a primary lithium battery fabricated with a bobbin cell structure is comparable to a conventional lithium ion cell, eg, two NiS ₂ cells connected in series to provide a 3.6V battery. It can be connected in series to provide a voltage.

Separator In some embodiments, the battery can include a separator 26 between the cathode 22 and the anode 24. Separator 26 is disposed between independent anodes and cathodes in other bobbin cell arrangements (not shown) disposed within a cylindrical laminated disk, as shown in FIGS. 1A and 1B, or FIG. As shown in FIG. 3, it can be disposed between layers of cathode and anode materials in a square structure.

  In some embodiments, the separator can include a porous polyolefin. In some embodiments, the separator can include ceramic or glass. In some embodiments, the insulating porous coating can be deposited on the electrode to function as a separator.

  In some embodiments, the network of conductive metal material can include a surface having pores that are free of active material. For example, this can be accomplished by selectively coating and / or infiltrating a preformed network 27 such as foam metal. The surface with pores free of active material can be oxidized and can be thick enough to function as a separator between cathode 22 and anode 24. This procedure can be used to make a separator between the anode and cathode by making a separator on either the anode or cathode surface.

Electrolyte In some embodiments, the battery can include an electrolyte. In Li-ion technology, the electrolyte is not consumed during charging and discharging. The electrolytic mass in the cell can be based on the porous capacity available in the cell.

Example 1: Fabrication of a network for use with thick electrodes Open cell aluminum foam was purchased from Goodfellow Corporation of Devon, PA. The foam contained aluminum 6101 and had the following characteristics.
Thickness: 3.2mm and 6.4mm
Bulk density: 0.2 g / cm ³
Hole / cm: 16
Porosity: 93%

As a reference, a typical aluminum 6101 composition is as follows.

Aluminum 6101 is an aluminum alloy with high electrical conductivity and good mechanical (strength) characteristics. The electrical conductivity of copper is 56% and the density of the alloy is 2.685 g / cm ³ . Prior to fabrication of the electrodes, untreated 3.2 mm and 6.4 mm foams were subsequently rolled on a gem processing mill to prepare thinner foams. The effect of thickness reduction on the porosity of the material is shown in FIGS. 4A and 4B. FIG. 4A shows the effect on porosity in foams rolled from 3.2 mm. FIG. 4B shows the effect on porosity in foams rolled from 6.4 mm.

Example 2 Fabrication of 1 mm Li [Ni _0.33 Co _0.33 Mn _0.33 ] O ₂ Cathode The original 3.2 mm foam was cut into 5 cm wide strips followed by rolling for gem processing. Rolled on a machine to produce a material with a thickness of about 1 mm. A 1 mm foam was cut into 7 cm × 13.5 cm rectangular blocks. The edge of the long side (2 mm) was covered with tape. The foam was placed on a release liner coated with silicone and the N-methylpyrrolidinone cathode slurry was poured and spread on the foam. This process was repeated twice to completely infiltrate the foam. The composition (wt%) of the cathode slurry is as follows.
88% Li [Ni _0.33 Co _0.33 Mn _0.33 ] O ₂
2% KS-6 Graphite 4% SAB Carbon Black 6% Atofina 761A PVDF

After infiltration, the foam was dried at 80 ° C. and passed through a rolling mill for gem processing with a gap of 1 mm. The material was further dried under vacuum at 80 ° C. and cut to have an electrode coverage of 135 mg / cm ² and a 0.2 cm uncoated area on the top surface of the electrode (active area = 15.75 cm ² and All regions = 16.45 cm ² ), 4.7 cm × 3.5 cm electrodes were obtained. This is equal to 1350 mg / cm ³ . This coating amount is the same as that of an electrode coated with a conventional aluminum foil. At 135 mAh / g, this electrode has a theoretical capacity of about 253 mAh. At 1 cm ³ of such an electrode, the Al foam current collector accounts for up to 24% of the total capacity.

For comparison, the same slurry was coated on both sides of a 17.8 micrometer (0.7 mil) aluminum foil to give a coating amount of 22.2 mg / cm ² . After calendering to a total thickness of 165 micrometers (6.5 mils), the electrode coating was 1345 mg / cm ³ . At 1 cm ³ of such an electrode, the Al foil current collector occupies up to 10.8% of the total capacity.

A nickel tab is spot welded to the covered area of the foam, Celgard ™ 2325 separator, 1M LiPF ₆ and 88.9 micrometer (3.5 mil) lithium foil in EC / DMC electrolyte. Was used to make a bag cell. Increasing rate: The cells were cycled from 4.2 V to 2.8 V at 25, 100, 250 mA. The performance of the bag cell is shown in FIG.

The data is also shown in Table I below.

These results show that acceptable rate capability can be obtained from a 1 mm cathode using an aluminum foam support / current collector. For example, the total theoretical capacity can be obtained at a rate of 1.6 mA / cm ² . In comparison, the rate capability of commercially available high energy Li-ion rechargeable batteries (1.8 Ah, 18650 cells) utilizing much thinner electrodes (cathode surface area up to about 0.18 mm: 503 cm ² ) is C / 2 The rate is up to 1.8 mA / cm ² .

Example 3 Fabrication of 1 mm LiFePO ₄ Cathode As described in Example 1, a 1 mm foam was prepared from the original 3.2 mm foam and cut into 5 cm wide strips followed by gem processing The material was 1 mm thick by rolling with a rolling mill. The covered area of foam (1 cm × 2 cm in 5 cm × 2 cm) was infiltrated into the N-methylpyrrolidinone cathode slurry to remove excess material. This process was repeated twice to completely infiltrate the foam.

The composition (wt%) of the cathode slurry is as follows.
86% LiFePO ₄ with carbon coating in situ
2.7% KS-6 graphite 5.3% SAB carbon black 6% Atofina 761A PVDF

  Using such a formulation and an aluminum foam substrate, it was possible to easily prepare an electrode. In contrast, attempts to coat this formulation on conventional aluminum foils at any suitable application level resulted in enormous cracking and loss of electrode adhesion.

After infiltration, the foam was dried at 80 ° C. and again passed through a rolling mill for gem processing with a gap setting of 1 mm. The material was further dried under vacuum at 80 ° C. and arranged to provide an electrode with an active area of 4 cm × 2 cm and an electrode coverage of 106 mg / cm ² .

A nickel tab is spot welded to the covered area of the foam, Celgard ™ 2325 separator, 1M LiPF ₆ and 88.9 micrometer (3.5 mil) lithium foil in EC / DMC electrolyte. Was used to make a bag cell. The cells were cycled from 4.2V to 2.8V at an increasing rate. The performance of the bag cell is shown in FIG. 6 below by the active LiFePO ₄ mAh / g. Good rate characteristics were observed at ² mA / cm ² .

Example 4: In the same manner as described in LiFePO ₄ cathode fabrication Example 2 of 2mm, using Al foam 2mm which is rolled from the original 6.4mm aluminum foam, 2mm LiFePO ₄ cathode of Was prepared. The electrode performance in the bag cell is shown in FIG. 7 below. As shown in FIG. 7, about 80% of the theoretical capacity of the electrode is delivered at a rate from 2 mm electrode to C / 10, and it is possible to obtain sufficient performance from a cathode of such thickness Is shown.

Example 5: Fabrication of Thick Mesocarbon Microbead (MCMB) Anode In the same manner as described in Examples 1-4, a copper foam substrate can be used to prepare a thick carbon-based anode. is there. Open cell copper foam was obtained from EFoam (Circuit Foil Luxembourg Trading). The foam had the following characteristics:
Thickness: 2.0mm
Bulk density: 0.2 g / cm ³
Hole / cm: 18
Porosity: 98%

The original 2 mm foam was cut into 5 cm wide strips and subsequently rolled on a gem processing mill to produce a 1 mm thick material. Measuring the apparent density showed that a 1 mm foam had a porosity of up to 95%. A 1 mm foam was cut into 7 cm × 13.5 cm rectangular blocks. The edge of one of the long sides was covered with tape (5 mm). The foam was placed on a release liner coated with silicone and N-methylpyrrolidinone anode slurry was poured and spread on the foam. This process was repeated twice to completely infiltrate the foam. The composition (% by weight) of the anode slurry is as follows.
88% MCMB 28-10
6% SAB carbon black 6% Atofina 761A PVDF

The slurry also contained a small amount of oxalic acid: 3 × 10 ⁻³ g of oxalic acid per gram of MCMB.

After infiltration, the foam was dried at 80 ° C. and passed through a rolling mill for gem processing with a gap of 1 mm. The material was dried under vacuum at 80 ° C. and cut to have an electrode coverage of 43 mg / cm ² and 0.5 cm uncoated area on the top surface of the electrode (active area = 15.75 cm ² and total Region = 17.5 cm ² ), 5 × 3.5 cm electrodes were obtained. At 300 mAh / g, this electrode has a theoretical capacity up to 179 mAh. A nickel tab is spot welded to the covered area of the foam, Celgard ™ 2325 separator, 1M LiPF ₆ and 88.9 micrometer (3.5 mil) lithium foil in EC / DMC electrolyte. Was used to make a bag cell. Cu foam-based MMB anodes have performed well in foil bag tests and the results show in FIG. 8 satisfactory rate capability and properties from thick foam-based anodes.

  A number of embodiments have been described. However, it will be understood that various other modifications can be made without departing from the spirit and scope of the invention.

Claims (10)

A housing;
A cathode in the housing, the cathode comprising a lithium ion cathode active material and a network of conductive metal material in the cathode active material and having a thickness of at least 1 mm;
A battery including an anode in the housing.   The battery according to claim 1, wherein the network of the conductive metal material includes an open-cell foam metal, aluminum, a metal filler, or a metal alloy that expands or contracts during charge and discharge.   The battery of claim 1, wherein the anode comprises an anode active material and an anode network of conductive material within the anode active material. The battery of claim 3, wherein the anode active material comprises mesocarbon microbeads (MCMB), Li ₄ Ti ₅ O ₁₂ or a combination thereof.   The battery of claim 3, wherein the anode network of conductive material comprises open cell foam metal, copper, or a metal filler.   The battery of claim 1, further comprising a separator between the cathode and the anode.   The battery according to claim 1, wherein the network of the conductive metal material includes a surface layer of pores not including a cathode active material.   The battery according to claim 1, wherein the battery is a secondary battery.   The battery of claim 1, wherein the battery includes a laminated square structure.   The battery of claim 1, wherein the battery comprises a plurality of stacked discs each including at least one cathode region and at least one anode region.

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