CN112271299A - Laminated battery core and lithium ion battery - Google Patents
Laminated battery core and lithium ion battery Download PDFInfo
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- CN112271299A CN112271299A CN202011154306.4A CN202011154306A CN112271299A CN 112271299 A CN112271299 A CN 112271299A CN 202011154306 A CN202011154306 A CN 202011154306A CN 112271299 A CN112271299 A CN 112271299A
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/058—Construction or manufacture
- H01M10/0583—Construction or manufacture of accumulators with folded construction elements except wound ones, i.e. folded positive or negative electrodes or separators, e.g. with "Z"-shaped electrodes or separators
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- A—HUMAN NECESSITIES
- A62—LIFE-SAVING; FIRE-FIGHTING
- A62C—FIRE-FIGHTING
- A62C3/00—Fire prevention, containment or extinguishing specially adapted for particular objects or places
- A62C3/16—Fire prevention, containment or extinguishing specially adapted for particular objects or places in electrical installations, e.g. cableways
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/60—Heating or cooling; Temperature control
- H01M10/61—Types of temperature control
- H01M10/613—Cooling or keeping cold
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/60—Heating or cooling; Temperature control
- H01M10/65—Means for temperature control structurally associated with the cells
- H01M10/653—Means for temperature control structurally associated with the cells characterised by electrically insulating or thermally conductive materials
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/64—Carriers or collectors
- H01M4/66—Selection of materials
- H01M4/665—Composites
- H01M4/667—Composites in the form of layers, e.g. coatings
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
Abstract
The invention provides a laminated battery cell and a lithium ion battery. The laminated cell of the present invention comprises: the positive pole pieces and the negative pole pieces are alternately stacked, and a diaphragm is arranged between every two adjacent pole pieces; each pole piece located on the outermost side comprises a current collector, an active layer and a coating, wherein the active layer is located on one side, close to the inside of the battery core, of the current collector, the coating is located on one side, far away from the inside of the battery core, of the current collector, and heat conduction materials and/or flame retardant materials are/is arranged in the coating. The invention solves the problems of active lithium consumption at the outermost layer of the lamination structure and first effect and capacity reduction, and also solves the problem of roll breakage and resistance of the single-side coating pole piece caused by rolling stress, more importantly, the heat conduction material and/or the flame retardant material can improve the safety performance of heat dissipation, flame retardance and the like of the laminated core, and greatly improves the safety and the practicability of the electric core.
Description
Technical Field
The invention relates to the technical field of batteries, in particular to a laminated battery cell and a lithium ion battery.
Background
In consideration of safety and practicability, the current lithium ion battery with a laminated structure has the following advantages that one more layer of negative electrode is needed than the positive electrode, and the extra layer of negative electrode sheet is provided with negative active materials, such as graphite or silicon materials, on both sides of a copper foil current collector, but the negative active material on the outermost negative electrode side has no practical application, but has some negative effects: on one hand, the weight of the battery cell is increased, the energy density of the battery cell is reduced, and on the other hand, more lithium ions are consumed due to the fact that the SEI film is generated on the outermost negative electrode layer, so that the first effect of the battery cell is reduced, and the capacity of the battery cell is reduced. If the positive and negative current collectors are only coated on one side, the pole pieces are rolled and damaged during subsequent rolling process, and the assembly efficiency of the battery is affected. For the above-mentioned pole piece rolling problem, the existing battery cell manufacturing process has to coat the same formula, the same weight and the same thickness of material on the two sides of the pole piece, and when rolling, the stress generated by the extension of the two sides is offset, and the rolling phenomenon will not occur. However, this method causes the following problems: the active material on the other side is wasted, the cost and the quality of the battery cell are increased, the first effect and the capacity of the battery cell are reduced, and the energy density is reduced.
In addition, the lithium battery may undergo a chemical reaction inside the battery during discharge, generating a large amount of heat energy, resulting in an increase in the temperature of the battery. When the heat generated in the battery can not be discharged in time, the thermal runaway of the battery is easily caused, and accidents such as fire and explosion of the battery can happen in serious cases.
Disclosure of Invention
In view of the above, the present invention provides a laminated battery cell and a lithium ion battery, so as to solve the following problems of the current lithium ion battery: the battery is easy to cause the safety problem of combustion due to thermal runaway.
In order to solve the technical problems, the invention has the following technical scheme:
in a first aspect, a laminated battery according to an embodiment of the present invention includes:
the positive pole pieces and the negative pole pieces are alternately stacked, and a diaphragm is arranged between every two adjacent pole pieces;
each pole piece located on the outermost side comprises a current collector, an active layer and a coating, wherein the active layer is located on one side, close to the inside of the battery core, of the current collector, the coating is located on one side, far away from the inside of the battery core, of the current collector, and heat conduction materials and/or flame retardant materials are/is arranged in the coating.
Wherein, the two pole pieces positioned at the outermost side are the positive pole pieces or the negative pole pieces at the same time; or one sheet is the positive plate and the other sheet is the negative plate.
Wherein the coating layer is provided with a hot melt adhesive, and the heat conduction material and/or the flame retardant material are dispersed in the hot melt adhesive.
Wherein the coating comprises 40-70 parts by weight of hot melt adhesive, 30-50 parts by weight of heat conducting material and 5-10 parts by weight of flame retardant material.
The hot melt adhesive comprises any one or the combination of more than two of ethylene copolymer, polyurethane, polyamide, polyester, amorphous olefin copolymer, polyolefin and styrene copolymer.
Wherein the coating is provided with a heat conducting material, and the heat conducting material comprises any one or a combination of more than two of high heat conducting polymer, oxide, nitride and carbon-based material;
wherein: the high heat-conducting polymer comprises one or more of polyacetylene and polypyrrole;
the oxide comprises one or more of silicon oxide, titanium oxide, aluminum oxide and magnesium oxide;
the nitride comprises one or more of aluminum nitride, boron nitride, carbon nitride, magnesium nitride, titanium nitride and tantalum nitride;
the carbon-based material comprises one or more of silicon carbide, graphite, carbon nanotubes and graphene.
The coating is provided with a flame-retardant material, and the flame-retardant material comprises any one or a combination of more than two of zinc borate, decabromodiphenylethane, microencapsulated red phosphorus, polyester fiber, silicon oxide, titanium oxide, aluminum oxide, magnesium oxide, aluminum nitride, boron nitride, carbon nitride, magnesium nitride, titanium nitride, tantalum nitride, silicon carbide, graphite, carbon nano tubes and graphene.
Wherein the thickness of the coating is 5-100 μm.
In a second aspect, a lithium ion battery according to an embodiment of the present invention includes:
laminated cells as described in the above embodiments.
The battery further comprises a shell, the laminated battery core is arranged in the shell, a hot melt adhesive is arranged in the coating, and the hot melt adhesive in the coating is bonded with the inner side wall of the shell.
The technical scheme of the invention has the following beneficial effects:
the laminated cell according to the embodiment of the invention comprises: the positive pole pieces and the negative pole pieces are alternately stacked, and a diaphragm is arranged between every two adjacent pole pieces; each pole piece located on the outermost side comprises a current collector, an active layer and a coating, wherein the active layer is located on one side, close to the inside of the battery core, of the current collector, the coating is located on one side, far away from the inside of the battery core, of the current collector, and heat conduction materials and/or flame retardant materials are/is arranged in the coating. Through so setting up the lamination battery, the technical effect that can realize includes:
(1) the outermost heat-dissipation flame-retardant material coating of the laminated structure is low in density and easy to coat, stress can be offset, the problem that a single-side active material coating is curled and damaged during rolling is solved, the weight of a battery cell can be reduced, and the energy density of the battery cell is improved.
(2) The outermost heat-dissipation flame-retardant material coating of the laminated structure is beneficial to heat dissipation of the battery core, can reduce the internal temperature of the battery core, and can cut off the combustion connection between the laminated core and the aluminum plastic film to ensure the safety of the battery.
Drawings
Fig. 1 is a schematic structural diagram of a laminated cell according to an embodiment of the present invention;
fig. 2 is another schematic structural diagram of a laminated cell according to an embodiment of the present invention.
Reference numerals
A negative plate 1; a negative active layer 11; a negative current collector 12;
a diaphragm 2;
a positive plate 3; a positive active layer 31; a positive current collector 32;
and (4) coating.
Detailed Description
A laminated cell according to an embodiment of the present invention is described in detail below with reference to the accompanying drawings.
The laminated cell according to the embodiment of the invention comprises: the cathode plate comprises a cathode plate 3 and an anode plate 1, wherein the cathode plate 3 and the anode plate 1 are alternately stacked, and a diaphragm 2 is arranged between two adjacent cathode plates; each pole piece located on the outermost side comprises a current collector, an active layer and a coating, wherein the active layer is located on one side, close to the inside of the battery core, of the current collector, the coating is located on one side, far away from the inside of the battery core, of the current collector, and heat conduction materials and/or flame retardant materials are/is arranged in the coating.
As shown in fig. 1, a laminated cell according to an embodiment of the present invention includes: the cathode plate comprises a cathode plate 1 and an anode plate 3, wherein the cathode plate 1 and the anode plate 3 are alternately stacked, and a diaphragm 2 is arranged between the two adjacent electrode plates; the negative plate 1 positioned on the outermost side comprises a negative current collector 12, a negative active layer 11 and a coating 4 respectively, wherein the negative active layer 11 is positioned on the negative current collector 12 and close to one side inside the battery core, the coating 4 is positioned on the negative current collector 12 and far away from one side inside the battery core, and the coating 4 is provided with a heat conduction material and/or a flame retardant material. The other negative electrode sheets 1 may be coated with negative active layers 11 on both sides of the negative electrode collector 12.
As shown in fig. 2, a laminated cell according to an embodiment of the present invention includes: the cathode plate comprises a cathode plate 1 and an anode plate 3, wherein the cathode plate 1 and the anode plate 3 are alternately stacked, and a diaphragm 2 is arranged between the two adjacent electrode plates; the positive plate 3 positioned on the outermost side comprises a positive current collector 32, a positive active layer 31 and a coating 4 respectively, the positive active layer 31 is positioned on one side, close to the inside of the battery core, of the positive current collector 32, the coating 4 is positioned on one side, far away from the inside of the battery core, of the positive current collector 32, and the coating 4 is provided with a heat conduction material and/or a flame retardant material. The other positive electrode sheets 3 may be coated with the positive active layers 31 on both sides of the positive electrode collector 32.
That is to say, the structure of the laminated battery cell is composed of a negative electrode plate 1, a diaphragm 2 and a positive electrode plate 3 which are sequentially stacked, and the diaphragm 2 is arranged between two adjacent electrode plates. The surface of the outermost pole piece is coated with a coating 4, the coating 4 is located on one side, far away from the interior of the battery core, of the current collector, and the coating 4 is provided with a heat conduction material and/or a flame retardant material. According to the invention, the heat conduction material and/or the flame retardant material is coated outside the positive or negative current collector in the pole piece positioned on the outermost layer of the laminated battery cell, and the other surface is normally coated with the conventional active substance layer, so that the problems of active lithium consumption and first effect and capacity reduction of the outermost layer of the laminated structure are solved, the problem of roll breakage and resistance caused by rolling stress of the pole piece with the single-surface coating is also solved, more importantly, the heat conduction material and/or the flame retardant material can improve the safety performances of heat dissipation, flame retardance and the like of the laminated core, and the safety and the practicability of the battery cell are greatly improved.
It should be understood that fig. 1 and 2 are merely illustrative of the structure of two laminated cells and are not intended to limit the structure of the laminated cell in the present invention. In other embodiments of the present invention, two outermost pole pieces may be the positive pole piece 3 and the negative pole piece 1, instead of the negative pole piece 1 (fig. 1) or the positive pole piece 3 (fig. 2). The specific setting can be selected according to actual conditions.
In some embodiments of the present invention, the coating 4 has a hot melt adhesive therein, and the thermally conductive material and/or the flame retardant material is dispersed in the hot melt adhesive. In the process of manufacturing the lithium ion soft package battery, the laminated core and the aluminum plastic film are connected only through the tab glue, so that the laminated core of the lithium ion battery is easy to slide, and particularly, the laminated core moves under the condition of uneven stress in the formation process, so that the aluminum plastic film is wrinkled, the tab is damaged, and safety accidents can be caused when the tab is serious. And a gap is reserved between the laminated core and the aluminum-plastic film and is separated by the diaphragm, so that heat cannot be dissipated, the laminated core cannot be flame-retardant when being ignited, and the aluminum-plastic film can be driven to be ignited and combusted. And then make whole battery package catch fire, cause bigger incident. The hot melt adhesive is a plastic adhesive, the physical state of which changes with the temperature within a certain temperature range, and the chemical property of which is unchanged, and the hot melt adhesive is nontoxic and tasteless, and has the advantages of low density, light weight, high adhesive strength and high speed. According to the invention, the hot melt adhesive material is coated on the outer layer of the anode or cathode current collector on the outermost layer of the laminated cell structure, and the heat conduction material and/or the flame retardant material is dispersed in the hot melt adhesive, so that various beneficial effects can be realized: (1) the coating on the outermost layer of the laminated battery can offset stress, and the problem of curling and breakage of the single-sided active material coating during rolling is solved; (2) the coating material is low in density and easy to coat, the weight of the battery cell can be reduced, and the energy density of the battery cell is improved; (3) the laminated core and the aluminum plastic film are glued together by the coating to fix the laminated core, so that the laminated core is prevented from sliding, the aluminum plastic film produced in the subsequent process of the battery cell is prevented from being wrinkled, the battery cell is prevented from shifting during use, and the safety performance of the battery cell is improved; (4) the heat conduction material in the coating and/or the flame retardant material are beneficial to heat dissipation of the battery cell, the internal temperature of the battery cell is reduced, the combustion connection between the laminated core and the aluminum-plastic film can be cut off, and the safety of the battery is ensured.
In some embodiments of the present invention, the coating 4 comprises 40-70 parts by weight of hot melt adhesive, 30-50 parts by weight of thermally conductive material, and 5-10 parts by weight of flame retardant material. For example, the coating 4 includes 40 parts by weight of a hot melt adhesive, 30 parts by weight of a heat conductive material, and 5 parts by weight of a flame retardant material, the hot melt adhesive may be polyethylene, the heat conductive material may be aluminum nitride, the flame retardant material may be silicon carbide, and the specific component content and kind may be selected as required.
Wherein, the hot melt adhesive can be at least one of ethylene copolymer, polyurethane (such as pressure sensitive adhesive and 1653PUR waterborne adhesive), Polyamide (PA), Polyester (PES), amorphous olefin copolymer (APAO), polyolefin and styrene copolymer. Wherein the ethylene copolymer may include one or more of ethylene-vinyl acetate copolymer (EVA), ethylene-ethyl acrylate resin (EEA), ethylene acrylic acid copolymer (EAA), and saponified or partially saponified ethylene-vinyl acetate copolymer (EVAL); the polyolefin may include one or more of Polyethylene (PE) and polypropylene (PP); the styrene copolymer may include one or more of styrene-butadiene-styrene block copolymer (SBS) and styrene-isoprene-styrene block copolymer (SIS); for example, the hot melt adhesive may be EVA or polyester.
The heat conducting material can be at least one of a high heat conducting polymer, an oxide, a nitride and a carbon-based material, and the high heat conducting polymer can be one or more of polyacetylene and polypyrrole; the oxide can be one or more of silicon oxide, titanium oxide, aluminum oxide and magnesium oxide; the nitride can be one or more of aluminum nitride, boron nitride, carbon nitride, magnesium nitride, titanium nitride and tantalum nitride; the carbon-based material comprises one or more of silicon carbide, graphite, carbon nanotubes and graphene. For example, the thermally conductive material may be alumina or polyacetylene.
The flame-retardant material can be at least one of zinc borate, decabromodiphenylethane, microencapsulated red phosphorus, polyester fiber, silicon oxide, titanium oxide, aluminum oxide, magnesium oxide, aluminum nitride, boron nitride, carbon nitride, magnesium nitride, titanium nitride, tantalum nitride, silicon carbide, graphite, carbon nano tube and graphene. For example, the flame retardant material may be zinc borate or polyester fiber.
According to some embodiments of the invention, the thickness of the coating 4 is 5-100 μm.
According to some embodiments of the present invention, the morphology structure of the coating 4 is particles, fibers or microspheres, the particle size of the particles and the microspheres is 5nm to 100 μm, and the aspect ratio of the fibers is 10 to 1000.
The preparation method of the coating 4 comprises the following steps: mixing the hot melt adhesive material, the heat dissipation material, the flame retardant material and the adhesive, and stirring at a high speed to obtain a uniformly dispersed mixture. The mixture is made into heat-dissipation flame-retardant hot melt adhesive material slurry by using a solvent, the slurry is uniformly coated on one surface of the positive current collector or the negative current collector, and the coating 4 is obtained after drying. The solvent may be at least one of N-methylpyrrolidone (NMP), N-Dimethylformamide (DMF), Dimethylsulfoxide (DMSO), or water, for example the solvent may be N-methylpyrrolidone (NMP). The binder can be at least one of polyvinylidene fluoride, polytetrafluoroethylene, styrene butadiene rubber and sodium carboxymethyl cellulose, for example, the binder can be polyvinylidene fluoride.
According to an embodiment of the present invention, the negative active layer 11 in the negative electrode sheet 1 in the laminated cell may include a negative active material, and/or a binder, and/or a conductive agent. The negative active material comprises at least one of graphite, lithium titanate, a silicon-based material, hard carbon, a tin-based material, graphene and carbon nano. For example, the negative active material may include graphite, or the negative active material may include graphite and hard carbon; the binder may include: at least one of polyvinylidene fluoride, polytetrafluoroethylene, styrene butadiene rubber and sodium carboxymethylcellulose. For example, the binder can be polyvinylidene fluoride and can be styrene butadiene rubber; the conductive agent may include at least one of conductive carbon black (SP), Ketjen black, acetylene black, graphite conductive agent (KS-6, KS-15, S-O, SEG-6), carbon fiber (VGCG), Carbon Nanotube (CNT), and graphene, for example, the conductive agent may include conductive carbon black or carbon nanotube.
The positive active layer 31 in the positive electrode sheet 3 in the laminated cell may include a positive active material, and/or a binder, and/or a conductive agent. The positive active substance comprises at least one of a nickel-cobalt-manganese ternary material, a lithium iron phosphate material, a lithium cobaltate material, a lithium manganate material, a lithium nickelate material, a lithium-rich manganese-based material and active carbon. For example, the positive active material may include a nickel cobalt manganese ternary material; the binder may include: at least one of polyvinylidene fluoride, polytetrafluoroethylene, styrene butadiene rubber and sodium carboxymethylcellulose. For example, the binder can be polyvinylidene fluoride and can be styrene butadiene rubber; the conductive agent may include at least one of conductive carbon black (SP), Ketjen black, acetylene black, graphite conductive agent (KS-6, KS-15, S-O, SEG-6), carbon fiber (VGCG), Carbon Nanotube (CNT), and graphene, for example, the conductive agent may include conductive carbon black or carbon nanotube.
The invention provides a lithium ion battery, which comprises a laminated battery cell in the embodiment. The lithium ion battery with the laminated battery cell is beneficial to preventing safety problems such as combustion caused by thermal runaway of the battery cell, and meanwhile, the weight of the battery cell can be reduced, the energy density of the battery cell is improved, and the safety of the battery is ensured.
According to the embodiment of the invention, the lithium ion battery further comprises a shell, the laminated battery cell is arranged in the shell, the coating 4 is provided with the hot melt adhesive, and the hot melt adhesive in the coating 4 is bonded with the inner side wall of the shell. The lithium ion battery with the coating 4 can not only reduce the internal temperature of the battery core, but also cut off the combustion connection between the laminated core and the aluminum-plastic film; meanwhile, the laminated core and the aluminum plastic film are connected together by the coating in a gluing mode, the laminated core is fixed, sliding is prevented, buckling of the aluminum plastic film produced in the subsequent process of the battery cell is avoided, the battery cell is prevented from shifting during use, and the safety performance of the battery cell is improved in two aspects; in addition, in the process of manufacturing the lithium ion battery with the laminated battery core in the structure, the outermost coating of the laminated battery can offset stress, so that the problem of curling and damage when a single-sided active material coating is rolled is solved; and the coating material has low density, is easy to coat, can reduce the weight of the battery cell and improve the energy density of the battery cell.
The invention is further illustrated by the following specific examples.
Example 1
(1) Preparing positive plate P0 with single side coated with active substance and single side coated with heat-dissipating flame-retardant hot melt adhesive coating
Mixing a ternary nickel-cobalt-manganese (NCM) serving as a positive electrode active substance, a PVDF (polyvinylidene fluoride) binder and conductive carbon black, and stirring at a high speed to obtain a uniformly dispersed mixture. In the mixture, the solid component contained 95% by weight of NCM, 2% by weight of PVDF as binder and 3% by weight of conductive carbon black. The mixture was made into positive electrode active material slurry using N-methylpyrrolidone as a solvent, and the solid content in the slurry was 70 wt%. The slurry is uniformly coated on the single surface of the aluminum foil of the positive current collector, and the single-surface coating of the active material of the aluminum foil positive current collector, namely the positive active layer, is obtained after drying, wherein the thickness of the coating is 120 mu m.
Mixing 60 wt% of EVA hot melt adhesive material, 35 wt% of alumina heat dissipation material, 3 wt% of polyester fiber flame retardant material and 2 wt% of adhesive PVDF, and stirring at high speed to obtain a uniformly dispersed mixture. The mixture is prepared into heat-dissipation flame-retardant hot melt adhesive material slurry by using N-methyl pyrrolidone as a solvent, wherein the solid content in the slurry is 70 wt%. And uniformly coating the slurry on the other side of the aluminum foil current collector with the positive active layer coated on one side, wherein the thickness of the coating is 20 microns, and drying and rolling to obtain a positive plate P0 with an active substance coated on one side and a heat-dissipation flame-retardant hot melt adhesive coating coated on the other side.
(2) Preparation of Positive electrode sheet P1 coated with active Material on both sides
Mixing the ternary nickel-cobalt-manganese NCM serving as the positive electrode active substance, the PVDF serving as the binder and the conductive carbon black, and stirring at a high speed to obtain a uniformly dispersed mixture. In the mixture, the solid component contained 95% by weight of NCM, 2% by weight of PVDF as binder and 3% by weight of conductive carbon black. The mixture was made into positive electrode active material slurry using N-methylpyrrolidone as a solvent, and the solid content in the slurry was 70 wt%. The slurry is evenly coated on both sides of an aluminum foil, and the positive plate P1 with active substances coated on both sides is obtained after drying and compacting by a roller press, wherein the thickness of the coating is 120 mu m.
(3) Preparation of negative plate N1 coated with active material on both sides
Mixing the negative active material graphite, SBR binder, thickener carboxymethylcellulose sodium and conductive carbon black as a conductive agent, and stirring at a high speed to obtain a mixture containing the negative active material, wherein the mixture is uniformly dispersed. In the mixture, the solid component contained 95 wt% of graphite, 1.5 wt% of sodium carboxymethyl cellulose, 1.5 wt% of conductive carbon black, and 2 wt% of a binder. Deionized water is used as a solvent to prepare cathode active substance slurry, and the solid content of the slurry is 50 wt%. The slurry is uniformly coated on two sides of a copper foil of a negative current collector, and the negative plate N1 with active substances coated on two sides is obtained through drying and compacting by a roll squeezer, wherein the thickness of the coating is 130 mu m.
(4) Assembled Battery C1
The positive plate P0,Punching a positive plate P1 and a negative plate N1, placing the two positive plates P0 on the outermost layer, adopting Z-shaped lamination to form a bare cell after punching, and respectively rolling out an aluminum tab and a copper nickel-plated tab. Clamping the bare cell by a glass clamp with a force of 100MPa/m2And vacuum baking at 85 deg.C for 24 hr, and packaging with aluminum plastic film. The electrolyte adopts 1M lithium hexafluorophosphate electrolyte, and the solvent is a mixed solvent of ethylene carbonate/dimethyl carbonate/1, 2 propylene carbonate-1: 1:1 (volume ratio). After packaging, the cells were fully electrochemical grown (pre-lithiated) and aged to give a rectangular flexibly packaged cell having a length, width and thickness of 160mm × 60mm × 10mm, and was designated as C1.
Example 2
(1) Preparing negative pole piece N0 with single-side coated with active substance and single-side coated with heat-dissipation flame-retardant hot melt adhesive coating
Mixing the negative active material graphite, SBR binder, thickener carboxymethylcellulose sodium and conductive carbon black as a conductive agent, and stirring at a high speed to obtain a mixture containing the negative active material, wherein the mixture is uniformly dispersed. In the mixture, the solid component contained 95 wt% of graphite, 1.5 wt% of sodium carboxymethyl cellulose, 1.5 wt% of conductive carbon black, and 2 wt% of a binder. Deionized water is used as a solvent to prepare cathode active substance slurry, and the solid content of the slurry is 50 wt%. The slurry is uniformly coated on one side of a copper foil, and the active material single-side coating negative plate is obtained after drying, wherein the thickness of the coating is 130 mu m.
Mixing 60 wt% of EVA hot melt adhesive material, 35 wt% of alumina heat dissipation material, 3 wt% of polyester fiber flame retardant material and 2 wt% of adhesive PVDF, and stirring at high speed to obtain a uniformly dispersed mixture. The mixture is prepared into heat-dissipation flame-retardant hot melt adhesive material slurry by using N-methyl pyrrolidone as a solvent, wherein the solid content in the slurry is 70 wt%. And uniformly coating the slurry on the other side of the aluminum foil current collector with the negative active layer coated on one side, wherein the thickness of the coating is 20 microns, and drying and rolling to obtain a negative plate N0 with an active substance coated on one side and a heat-dissipation flame-retardant hot melt adhesive coating coated on the other side.
(2) Preparing a positive plate P1 with two sides coated with active substances: same as in step (2) of example 1.
(2) Preparing a negative plate N1 with active material coated on both sides: same as in step (3) of example 1.
(3) Assembled battery C2:
the only difference from step (4) of example 1 is that: the negative electrode sheet N0, the positive electrode sheet P1, and the negative electrode sheet N1 were punched, and the two negative electrode sheets N0 were placed on the outermost layer. The remaining procedure was the same as in example 1, and the assembled cell was designated as C2.
Example 3
Example 3 differs from example 1 only in that: replacing the hot-melt adhesive material EVA in the step (1) with a polyurethane hot-melt adhesive material. The remaining steps and operating method were the same as in example 1, and the assembled cell was designated as C3.
Example 4
Example 4 differs from example 2 only in that: replacing the hot-melt adhesive material EVA in the step (1) with a polyurethane hot-melt adhesive material. The remaining steps and operating procedure were the same as in example 2, and the assembled cell was designated C4.
Example 5
Example 5 differs from example 1 only in that: and (2) changing the thickness of the heat-dissipation flame-retardant hot melt adhesive coating in the step (1) from 20 micrometers to 5 micrometers. The remaining steps and operating method were the same as in example 1, and the assembled cell was designated as C5.
Example 6
Example 6 differs from example 1 only in that: and (2) changing the thickness of the heat-dissipation flame-retardant hot melt adhesive coating in the step (1) from 20 micrometers to 10 micrometers. The remaining steps and operating method were the same as in example 1, and the assembled cell was designated as C6.
Example 7
Example 7 differs from example 1 only in that: and (2) changing the thickness of the heat-dissipation flame-retardant hot melt adhesive coating in the step (1) from 20 micrometers to 100 micrometers. The remaining steps and operating method were the same as in example 1, and the assembled cell was designated as C7.
Comparative example
(1) Preparing a positive plate P1 with two sides coated with active substances: same as in step (2) of example 1.
(2) Preparing a negative plate N1 with active material coated on both sides: same as in step (3) of example 1.
(3) Assembled Battery C8
The only difference from step (4) of example 1 is that: the positive electrode sheet P1 and the negative electrode sheet N1 were punched, and the two negative electrode sheets N1 were placed on the outermost layers. The remaining procedure was the same as in example 1, and the assembled cell was designated as C8.
The lithium ion batteries C1 to C8 prepared in the comparative example and examples 1 to 7 were used to test the rolling and coiling conditions of the outermost pole pieces of the lithium ion batteries C1 to C8, as well as the weight, first effect, gram capacity and energy density of the cells, respectively. The test data are shown in table 1.
Tables 1C1, C2, C3, C4, C5, C6, C7 and C8 cell and outermost pole piece data
As can be seen from the data in table 1: the lithium ion battery C1 prepared in example 1 has no rolling or damage during the rolling of the pole piece, which indicates that when the thickness of the coating is 20 μm for the heat-dissipating flame-retardant hot-melt adhesive material, the stresses on the two sides of the positive or negative foil almost cancel each other out, so the rolling and damage of the pole piece cannot occur. Comparing lithium ion batteries C1-C7 and C8, when the porous polymer coating replaces the traditional graphite coating, the consumption of the SEI film of the outermost graphite to active lithium can be reduced, the first effect of the battery cell is improved by about 1%, and the gram capacity of the positive active material is improved by 2-3 mAh/g. The 20-micron heat-dissipation flame-retardant hot-melt adhesive material coating enables the weight of the battery cell to be reduced by about 4%, and therefore the weight energy density of the battery is improved by 4-5%.
Table 2 is a comparison table of the wrinkles of the aluminum plastic films at the tabs when the cells C1, C2, C3, C4, C5, C6, C7 and C8 are subjected to unbalanced compression formation. The formation of the battery cell under the unbalanced pressure means that the pressure difference between two sections of the battery cell is larger than 5 MPa.
Table 2 comparison table of crumpling of aluminum plastic film at tab during unbalanced pressure formation of C1, C2, C3, C4, C5, C6, C7 and C8 cells
| C1 | C2 | C3 | C4 | C5 | | C7 | C8 | ||
| 1# | Without crumpling | Without crumpling | Without crumpling | Without crumpling | Without crumpling | Without crumpling | Without crumpling | Severe crumpling | |
| 2# | Without crumpling | Without crumpling | Without crumpling | Without crumpling | Without crumpling | Without crumpling | Without crumpling | Severe crumpling |
As can be seen from the data in table 2: when the outermost heat-dissipation flame-retardant hot melt adhesive material coating of the laminated core exists, the aluminum plastic film and the laminated core are adhered together through the hot melt adhesive, and even if the stress of the battery cell is unbalanced during formation, the aluminum plastic film at the tab position cannot be wrinkled, as shown in a C1-C7 battery cell. When the outermost layer of the laminated core does not have the heat-dissipation flame-retardant hot-melt adhesive material coating, as shown in the battery cell C8, because the aluminum-plastic film is not bonded with the laminated core, and the tab is fixed with the aluminum-plastic film, the aluminum-plastic film at the tab is seriously wrinkled, and the potential safety hazard occurs in the battery cell. The result shows that the existence of the heat-dissipation flame-retardant hot melt adhesive material coating on the outermost layer of the laminated core enables the aluminum plastic film and the laminated core to be bonded and fixed together, and the safety performance of the battery cell in the formation and use processes is improved.
Unless defined otherwise, technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention belongs. The use of "first," "second," and similar terms in the present application do not denote any order, quantity, or importance, but rather the terms are used to distinguish one element from another. The terms "connected" or "coupled" and the like are not restricted to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "upper", "lower", "left", "right", and the like are used merely to indicate relative positional relationships, and when the absolute position of the object being described is changed, the relative positional relationships are changed accordingly.
While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims.
Claims (10)
1. A laminated cell, comprising:
the positive pole pieces and the negative pole pieces are alternately stacked, and a diaphragm is arranged between every two adjacent pole pieces;
each pole piece located on the outermost side comprises a current collector, an active layer and a coating, wherein the active layer is located on one side, close to the inside of the battery core, of the current collector, the coating is located on one side, far away from the inside of the battery core, of the current collector, and heat conduction materials and/or flame retardant materials are/is arranged in the coating.
2. The laminated cell of claim 1, wherein the two outermost pole pieces are the positive pole piece or the negative pole piece at the same time; or one sheet is the positive plate and the other sheet is the negative plate.
3. The laminated cell of claim 1, wherein the coating has a hot melt adhesive therein, and the thermally conductive material and/or the flame retardant material is dispersed in the hot melt adhesive.
4. The laminated cell of claim 3, wherein the coating comprises 40 to 70 parts by weight of the hot melt adhesive, 30 to 50 parts by weight of the thermally conductive material, and 5 to 10 parts by weight of the flame retardant material.
5. The laminated cell of claim 3, wherein the hot melt adhesive comprises any one or a combination of two or more of ethylene copolymers, polyurethanes, polyamides, polyesters, amorphous olefin copolymers, polyolefins, and styrene copolymers.
6. The laminated cell of claim 1, wherein the coating has a thermally conductive material therein, the thermally conductive material comprising any one or a combination of two or more of a highly thermally conductive polymer, an oxide, a nitride, and a carbon-based material;
wherein: the high heat-conducting polymer comprises one or more of polyacetylene and polypyrrole;
the oxide comprises one or more of silicon oxide, titanium oxide, aluminum oxide and magnesium oxide;
the nitride comprises one or more of aluminum nitride, boron nitride, carbon nitride, magnesium nitride, titanium nitride and tantalum nitride;
the carbon-based material comprises one or more of silicon carbide, graphite, carbon nanotubes and graphene.
7. The laminated cell of claim 1, wherein the coating has a flame retardant material therein, the flame retardant material comprising any one or a combination of two or more of zinc borate, decabromodiphenylethane, microencapsulated red phosphorus, polyester fiber, silicon oxide, titanium oxide, aluminum oxide, magnesium oxide, aluminum nitride, boron nitride, carbon nitride, magnesium nitride, titanium nitride, tantalum nitride, silicon carbide, graphite, carbon nanotubes, and graphene.
8. The laminated cell of claim 1, wherein the coating has a thickness of 5-100 μ ι η.
9. A lithium ion battery comprising a laminated cell according to any of claims 1 to 8.
10. The lithium ion battery of claim 9, further comprising:
the laminated battery cell is arranged in the shell, a hot melt adhesive is arranged in the coating, and the hot melt adhesive in the coating is bonded with the inner side wall of the shell.
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| CN113036078A (en) * | 2021-03-08 | 2021-06-25 | 珠海冠宇动力电池有限公司 | End pole piece of laminated battery cell, laminated battery cell and corresponding preparation method |
| CN113258037A (en) * | 2021-05-28 | 2021-08-13 | 陕西煤业化工技术研究院有限责任公司 | Overcharge-prevention low-temperature-rate negative pole piece, manufacturing method thereof and lithium ion battery based on overcharge-prevention low-temperature-rate negative pole piece |
| CN114388809A (en) * | 2022-01-17 | 2022-04-22 | 惠州锂威新能源科技有限公司 | Laminated high-thermal-safety lithium ion battery |
| CN114597475A (en) * | 2022-03-23 | 2022-06-07 | 珠海冠宇动力电池有限公司 | Battery with a battery cell |
| CN114695841A (en) * | 2022-04-25 | 2022-07-01 | 芜湖天弋能源科技有限公司 | Lithium ion battery positive pole piece, lithium ion battery and preparation method thereof |
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Application publication date: 20210126 |