CN102420312A - High-voltage lithium ion battery, composite electrode couple and preparation methods of high-voltage lithium ion battery and composite electrode couple - Google Patents

Abstract

The invention discloses a high-voltage lithium ion battery, a composite electrode pair and a preparation method, and belongs to the technical field of lithium ion batteries. The composite electrode pair of the present invention comprises a porous diaphragm, a positive electrode mixture and a negative electrode mixture, one side of the porous diaphragm is coated with a positive electrode mixture comprising a positive electrode active material, a conductive agent and an adhesive, and the other side is coated with a negative electrode active material, a conductive agent and an adhesive. negative electrode mixture. The high-voltage lithium-ion battery of the present invention includes a composite electrode pair, a composite current collector and an electrolyte, wherein a plurality of composite electrode pairs and composite current collectors are alternately stacked to form a block, and the composite electrode pairs in the block are soaked in the electrolyte. There is an electronically conductive adhesive layer with a thickness of less than 10 microns between the composite electrode pair and the composite current collector, and the upper and lower surfaces of the block are composite current collectors. The high-voltage lithium ion battery of the invention has the advantages of high voltage, good safety, good consistency and the like.

Description

A kind of high-voltage lithium ion battery, composite electrode pair and preparation method

technical field

The invention belongs to the technical field of lithium ion batteries, and in particular relates to a high-voltage lithium ion battery for electric vehicles, a composite electrode pair and a preparation method thereof.

Background technique

As an important aspect of future new energy development, the large-scale development of electric vehicles is an inevitable trend. Lithium-ion batteries have attracted much attention as power batteries for electric vehicles, because lithium-ion batteries have the advantages of high specific energy, high operating voltage, long cycle life, low self-discharge, and no memory effect. However, at present, the safety and consistency of power batteries for electric vehicles have become a technical bottleneck in the scale development of the electric vehicle industry.

Internal stacking of electrodes in series to prepare high-voltage lithium-ion batteries is a better solution to the above problems. However, in the existing manufacturing process of lithium-ion batteries, the electrode active material is coated on the current collector, and then dried and pressed into tablets. The pressure of the tableting is generally 6-20 MPa. The current collector of the internal series high-voltage lithium-ion battery is generally made of copper-aluminum composite foil film, and the thickness of the foil film is less than 100 microns. Once the current collector is crushed and cracks appear, a short circuit will occur between adjacent battery cells inside the high-voltage lithium-ion battery. Therefore, it is necessary to find a new high-voltage lithium-ion battery structure and a new manufacturing method that can avoid direct compression of the composite current collector.

Contents of the invention

In order to solve the above-mentioned problems existing in high-voltage lithium-ion batteries, the present invention provides a technology of directly coating electrode active materials on porous diaphragms to prepare composite electrode pairs, which is applied to the manufacture of new high-voltage lithium-ion batteries.

The present invention adopts following technical scheme:

The high-voltage lithium-ion battery of the present invention is composed of a composite electrode pair 4, an electronically conductive adhesive layer 6, a composite current collector 5, tabs, an electrolyte, and a casing. The composite electrode pair 4 includes a porous diaphragm 1, a positive electrode mixture 2 and a negative electrode mixture 3, one side of the porous diaphragm 1 is coated with the positive electrode mixture 2 including positive electrode active material, conductive agent and adhesive, and the other side is coated with the positive electrode mixture 2 including the negative electrode The negative electrode mixture 3 of the active material, the conductive agent and the binder together constitute the composite electrode pair 4 . There is a blank area with a width greater than 5mm that is not coated with active material on the periphery of the composite electrode pair 4 . There is an electronically conductive adhesive layer 6 between the composite electrode pairs 4 and the composite current collector 5 , so that multiple composite electrode pairs 4 and composite current collectors 5 are bonded alternately to form a block. The composite current collector 5 is a piece of composite metal foil film. The composite metal foil film is composed of aluminum foil with a thickness of less than 50 microns and copper foil with a thickness of less than 50 microns. The composite methods include but are not limited to electroplating, electrochemical plating, evaporation, glue Sticky and pressure rolled.

The material of the porous diaphragm 1 is polyethylene, polypropylene, polyvinylidene fluoride or other electronically non-conductive porous polymer materials, or the material of the porous diaphragm 1 is glass fiber non-woven fabric, synthetic fiber non-woven fabric, Composite porous material of ceramic fiber paper or other electronically non-conductive inorganic non-metallic materials and organic polymers.

The positive electrode active material is lithium-containing lithium ferrous phosphate (LiFePO ₄ ), doped lithium manganese oxide (Li _0.9-1.2 M _0-0.2 Mn ₂ O ₄ , M is Na, Mg, Ca, Ni, Co One or several elements in), lithium cobalt oxide (LiCoO ₂ ), lithium nickel cobalt oxide (LiNi _0.8 Co _0.2 O ₂ ), lithium nickel manganese cobalt oxide (LiNi _1/3 Mn _1/3 Co _{1 /3} O ₂ or LiNi _2/5 Mn _2/5 Co _1/5 O ₂ ) and one or more mixtures of other lithium-containing metal oxides; the negative electrode active material is an aluminum-based alloy capable of reversibly intercalating lithium , silicon-based alloy, tin-based alloy, lithium titanium oxide (Li ₄ Ti ₅ O ₁₂ ), one or more mixtures of carbon materials; the conductive agent is one or more of carbon black, carbon fiber, metal particles Several mixtures. The adhesive is polyvinylidene fluoride, polyvinyl alcohol, sodium carboxymethyl cellulose, starch, hydroxymethyl cellulose, regenerated cellulose, polyethylene oxide, polyvinyl pyrrolidone, polytetrafluoroethylene, polyethylene, polyvinyl One or several mixtures of propylene EPDM rubber, styrene-butadiene rubber, fluororubber, epoxy resin, phenolic resin and various synthetic adhesive materials.

The preparation method of the composite electrode pair 4 is characterized in that: firstly, the positive electrode slurry is obtained by mixing the positive electrode active material, the conductive agent, and the adhesive in a solvent, and is coated on one side of the porous diaphragm 1 at a temperature of 60 to 110 ℃; then mix the negative electrode active material, conductive agent, and adhesive in the solvent to obtain the negative electrode slurry, which is coated on the other side of the porous diaphragm 1, dried at a temperature of 60-110°C, and then dried at a pressure of 6 Tablets within ~20MPa, and cut to make a composite electrode pair 4; or, first mix the negative electrode active material, conductive agent, and adhesive in the solvent to obtain the negative electrode slurry, and apply it on one side of the porous separator 1. Drying within the range of 60-110°C; then mixing the positive electrode active material, conductive agent, and adhesive in a solvent to obtain positive electrode slurry, coating on the other side of the porous separator 1, drying at a temperature within the range of 60-110°C, and then The composite electrode pair 4 is obtained after pressing into a tablet under a pressure range of 6-20 MPa and cutting.

The preparation method of the high-voltage lithium-ion battery includes the following steps: a. preparing a composite electrode pair 4; b. mixing a conductive agent and an adhesive in a solvent to make a slurry, and coating on both sides of the composite electrode pair 4 to form a thick An electronically conductive adhesive layer 6 less than 10 microns; c. Alternately superimposing multiple composite electrode pairs 4 and composite current collectors 5 coated with electronically conductive adhesive layers 6 on both sides, and coating the composite electrode pairs 4 with positive electrodes respectively The surface of the active material 2 is bonded to the aluminum foil of the composite current collector 5, and the surface of the composite electrode pair 4 coated with the negative electrode active material 3 is bonded to the copper foil of the composite current collector 5 to form a block, the upper and lower surfaces of the block It is a composite current collector 5; d. After the above-mentioned block is vacuum-dried, apply a pressure of less than 6 MPa on the upper and lower surfaces of the block and inject electrolyte, and then use an insulating adhesive 7 to bond and seal the edge of the composite current collector 5 and Insulate each other, and connect the surface positive electrode 8 of the block (the aluminum foil side of the surface composite current collector) to the positive electrode tab 9, and the surface negative electrode 10 of the block (the copper foil side of the surface composite current collector) to connect the negative electrode tab 11, After cleaning and encapsulation, the casing is wrapped to form a high-voltage lithium-ion battery.

The insulating adhesive in the step d is: epoxy acrylate, polyurethane acrylic resin, polyester acrylic resin, aminoacrylic resin, epoxy resin, phenolic resin, furan resin, polybutadiene resin, silicone resin or rubber-based One or more of the resins. The solvent is: deionized water, isopropanol, N-methylpyrrolidone, dimethylamide and dimethylacetamide or one or more of the derivatives of the above materials.

The technical advantages of the present invention are reflected in:

1. The electrode active material is directly coated on the porous separator and then dried and pressed to form a composite electrode pair, which can avoid local damage and asymmetric bending of the current collector after the electrode active material is coated on the composite current collector. problems, thereby avoiding the potential safety hazard of internal short circuit of high-voltage lithium-ion batteries caused by damage to current collectors;

2. The electronic conductive adhesive layer is used to bond the composite electrode pair and the composite current collector as a whole, which improves the dynamic consistency and safety of the power battery during use.

Description of drawings

Figure 1 is a schematic diagram of the structure of a composite electrode pair, in which: 1 - porous diaphragm; 2 - positive electrode mixture; 3 - negative electrode mixture.

Figure 2 is a schematic diagram of the structure of a high-voltage lithium-ion battery, in which Figure 2a is an internal structure diagram, Figure 2b is a side view of the external structure, in the figure: 4--composite electrode pair, 5--composite current collector, 6--electronic conductive glue Adhesive layer, 7--insulating adhesive, 8--surface positive pole, 9--positive pole tab, 10--surface negative pole, 11--negative pole tab.

Detailed ways

Embodiment one:

Preparation of composite electrode pair: Polyethylene oxide, LiFePO ₄ /C and carbon black are composed of adhesive by weight percentage: carbon black: LiFePO ₄ /C=8:7:85 are mixed in deionized water to obtain positive electrode slurry, and the The slurry is evenly coated on one side of the non-woven porous diaphragm coated with a layer of inorganic nanoparticles (thickness is less than 5 microns, and the inorganic nanoparticles are SiO ₂ , Al ₂ O ₃ , TiO _{2 ,} etc.), and baked at 80°C. dry; then sodium carboxymethyl cellulose, carbon black, Li ₄ Ti ₅ O ₁₂ (lithium titanate) by weight percentage composition Li ₄ Ti ₅ O ₁₂ : carbon black: adhesive = 90: 3: 7 mixed in the Negative electrode slurry is obtained in deionized water, and the slurry is evenly coated on a non-woven porous non-woven fabric coated with a layer of inorganic nanoparticles (thickness is less than 5 microns, inorganic nanoparticles are SiO ₂ , Al ₂ O ₃ , TiO _{2 ,} etc.) The other side of the diaphragm is dried at 80°C, and then pressed into a sheet under a pressure of 6-20 MPa, and then cut to obtain a composite electrode pair.

Preparation of the electronically conductive adhesive layer: carbon black and polyethylene oxide are mixed in deionized water as carbon black: polyethylene oxide = 7: 3 by weight percentage to make a slurry, which is coated on both sides of the composite electrode pair to form a thickness Electronically conductive adhesive layers smaller than 10 microns.

10 composite electrode pairs coated with electronically conductive adhesive layers on both sides and 11 composite current collectors are alternately stacked, and the surfaces of the composite electrode pairs coated with positive active materials are bonded to the aluminum foil of the composite current collector respectively. Adhere the surface coated with the negative electrode active material and the copper foil of the composite current collector to form a block. The upper and lower surfaces of the block are composite current collectors. After vacuum drying, the pressure applied to the upper and lower surfaces of the block is less than 6MPa The pressure and inject the electrolyte, and then use the insulating adhesive to bond and close the edge of the composite current collector and insulate each other, and connect the positive electrode on the surface of the block (the aluminum foil side of the composite current collector) to the positive electrode tab, The negative electrode (the copper foil side of the composite current collector) is connected to the negative electrode lug, and the casing is wrapped after cleaning and packaging to obtain a high-voltage lithium-ion battery with a working voltage of about 20V.

Embodiment two:

Preparation of composite electrode pair: PVDF (polyvinylidene fluoride), modified lithium manganate and carbon black are composed of adhesive by weight percentage: carbon black: lithium manganate=8: 7: 85 mixed with NMP (N-methyl pyrrolidone), fully mixed to make positive electrode slurry. Apply the slurry evenly on one side of the polyolefin porous diaphragm, and dry at 60-110°C; PVDF, lithium titanate and carbon black are composed of lithium titanate: carbon black: adhesive = 90:3 :7 mixed in NMP, fully mixed to make negative electrode slurry, and then evenly coated the slurry on the other side of the polyolefin porous diaphragm, dried at 60 ~ 110 ° C, and then pressed in the range of 6 ~ 20MPa The sheet was cut to make a composite electrode pair.

Preparation of electronically conductive adhesive layer: PVDF and carbon black weight percentages are composed of carbon black: PVDF=7:3 dissolved in NMP to make a slurry, coated on both sides of the composite electrode pair to form an electronic layer with a thickness of less than 10 microns. Conductive adhesive layer.

50 composite electrode pairs coated with electronically conductive adhesive layers on both sides and 51 composite current collectors are alternately superimposed, and the surfaces of the composite electrode pairs coated with positive active materials are bonded to the aluminum foil of the composite current collector respectively. Adhere the surface coated with the negative electrode active material and the copper foil of the composite current collector to form a block. The upper and lower surfaces of the block are composite current collectors. After vacuum drying, the pressure applied to the upper and lower surfaces of the block is less than 6MPa The pressure and inject the electrolyte, and then use the insulating adhesive to bond and close the edge of the composite current collector and insulate each other, and connect the positive electrode on the surface of the block (the aluminum foil side of the composite current collector) to the positive electrode tab, The negative electrode (the copper foil side of the composite current collector) is connected to the negative electrode lug, and the casing is wrapped after cleaning and packaging to obtain a high-voltage lithium-ion battery with a working voltage platform of about 125V.

The specific embodiments of the present invention are not intended to limit the present invention. Any person familiar with the art, without departing from the scope of the technical solution of the present invention, can use the methods and technical content disclosed above to make many possible changes and modifications to the technical solution of the present invention, or modify it into an equivalent implementation of equivalent changes example. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention, which do not deviate from the technical solution of the present invention, still fall within the protection scope of the technical solution of the present invention.

Claims (10)

1. A composite electrode pair of a high-voltage lithium-ion battery, characterized in that: comprise a porous separator, a positive electrode mixture and a negative electrode mixture, and one side of the porous separator is coated with a positive electrode mixture comprising a positive electrode active material, a conductive agent and an adhesive, The other side is coated with a negative electrode mixture including a negative electrode active material, a conductive agent and a binder, and an uncoated blank area with a width greater than 5mm is left around the edge of the porous separator. 2. The composite electrode pair as claimed in claim 1, characterized in that: the porous diaphragm material is polyethylene, polypropylene, polyvinylidene fluoride or other electronically non-conductive porous polymer materials, or, the porous diaphragm The material is a composite porous material of glass fiber non-woven fabric, synthetic fiber non-woven fabric, ceramic fiber paper or other electronically non-conductive inorganic non-metallic materials and organic polymers. 3. The composite electrode pair according to claim 1, wherein the positive electrode active material is lithium-containing lithium ferrous phosphate, doped lithium manganese oxide, lithium cobalt oxide, lithium nickel cobalt oxide, One or more mixtures of lithium nickel manganese cobalt oxide and other lithium-containing metal oxides; the negative electrode active material is an aluminum-based alloy capable of reversibly intercalating lithium, a silicon-based alloy, a tin-based alloy, lithium titanium oxide, carbon One or several mixtures of materials; the conductive agent is one or several mixtures of carbon black, carbon fiber and metal particles. 4. A high-voltage lithium-ion battery, characterized in that, comprises a composite electrode pair, a composite current collector and an electrolyte as claimed in claim 1, and the composite current collector is a piece of aluminum foil with a thickness less than 50 microns and a thickness of less than 50 microns. A composite metal foil film composed of 50 micron copper foil, multiple composite electrode pairs and composite current collectors are alternately stacked to form a body, and there is a layer of electronically conductive adhesive with a thickness of less than 10 microns between the composite electrode pairs and the composite current collector layer, the upper and lower surfaces of the block are composite current collectors, and the composite electrode pairs inside the block are soaked in the electrolyte. 5. The high-voltage lithium-ion battery as claimed in claim 4, characterized in that: the electronically conductive adhesive layer is a mixture of an adhesive and a metal or carbon material conductive agent, and the mass percentage of the conductive agent is greater than 60%. The thickness of the electronically conductive adhesive layer is less than 10 microns. 6. The high-voltage lithium-ion battery as claimed in claim 4, characterized in that: the adhesive is polyvinylidene fluoride, polyvinyl alcohol, sodium carboxymethyl cellulose, starch, hydroxymethyl cellulose, regenerated cellulose, One or more of polyethylene oxide, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene EPDM rubber, styrene-butadiene rubber, fluororubber, epoxy resin, phenolic resin and various synthetic insulating adhesive materials mixture. 7. A method for preparing a composite electrode pair, characterized in that: a. Mix the positive electrode active material, conductive agent, and adhesive in a solvent to obtain positive electrode slurry, apply it on one side of the porous diaphragm, and dry it at a temperature of 60 to 110°C; at the same time, mix the negative electrode active material, conductive agent 1. The adhesive is mixed in a solvent to obtain a negative electrode slurry, which is coated on the other side of the porous diaphragm and dried at a temperature ranging from 60 to 110°C; b. Press into tablets at a pressure of 6-20 MPa, and cut to obtain a composite electrode pair. 8. A preparation method for a high-voltage lithium-ion battery, characterized in that: the method comprises the following steps: A, prepare composite electrode pair as described in the method for claim 7; b. Mix the conductive agent and the adhesive in a solvent to make a slurry, and coat the two sides of the composite electrode pair to form an electronically conductive adhesive layer with a thickness of less than 10 microns; c, a plurality of composite electrode pairs coated with electronically conductive adhesive layers on both sides and multiple composite current collectors are alternately stacked, and the composite electrode pairs are respectively bonded to the aluminum foil of the composite current collector on the surface coated with the positive electrode active material, The composite electrode is bonded to the surface coated with the negative electrode active material and the copper foil of the composite current collector to form a block, and the upper and lower surfaces of the block are composite current collectors; d. After the above block is vacuum-dried, apply a pressure of less than 6 MPa on the upper and lower surfaces of the block and inject electrolyte, then use an insulating adhesive to bond and seal the edges of the composite current collector and insulate them from each other, and place the positive electrode on the surface of the block It is connected to the positive pole lug, and the negative pole on the surface of the block is connected to the negative pole lug. After cleaning and packaging, the shell is wrapped to form a high-voltage lithium-ion battery. 9. The preparation method as claimed in claim 8, characterized in that: the insulating adhesive in the step d is: epoxy acrylate, polyurethane acrylic resin, polyester acrylic resin, aminoacrylic resin, epoxy resin, phenolic resin One or more of resin, furan resin, polybutadiene resin, silicone resin or rubber-based resin. 10. as claimed in claim 7 and the preparation method described in claim 8, it is characterized in that: described solvent is: deionized water, Virahol, N-methylpyrrolidone, dimethylamide and dimethyl ethyl alcohol One or more of amides or derivatives of the aforementioned materials.

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