CN116454199A - Bipolar pole piece, preparation method thereof and battery - Google Patents
Bipolar pole piece, preparation method thereof and battery Download PDFInfo
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- CN116454199A CN116454199A CN202210023495.4A CN202210023495A CN116454199A CN 116454199 A CN116454199 A CN 116454199A CN 202210023495 A CN202210023495 A CN 202210023495A CN 116454199 A CN116454199 A CN 116454199A
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- layer
- bipolar
- electrode active
- positive electrode
- foam
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- 238000002360 preparation method Methods 0.000 title claims abstract description 15
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims abstract description 110
- 229910052802 copper Inorganic materials 0.000 claims abstract description 110
- 239000010949 copper Substances 0.000 claims abstract description 110
- 239000006260 foam Substances 0.000 claims abstract description 91
- 239000000463 material Substances 0.000 claims abstract description 32
- 229910052751 metal Inorganic materials 0.000 claims abstract description 8
- 239000002184 metal Substances 0.000 claims abstract description 8
- 239000011267 electrode slurry Substances 0.000 claims description 77
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 56
- 239000011230 binding agent Substances 0.000 claims description 45
- 239000006258 conductive agent Substances 0.000 claims description 45
- 239000007784 solid electrolyte Substances 0.000 claims description 37
- 238000000576 coating method Methods 0.000 claims description 29
- 239000011248 coating agent Substances 0.000 claims description 28
- 239000011148 porous material Substances 0.000 claims description 27
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 26
- 239000012528 membrane Substances 0.000 claims description 26
- 239000002904 solvent Substances 0.000 claims description 25
- 239000007773 negative electrode material Substances 0.000 claims description 24
- 239000007774 positive electrode material Substances 0.000 claims description 22
- -1 polytetrafluoroethylene Polymers 0.000 claims description 18
- 238000003756 stirring Methods 0.000 claims description 17
- 238000001035 drying Methods 0.000 claims description 15
- 238000011049 filling Methods 0.000 claims description 12
- 239000004810 polytetrafluoroethylene Substances 0.000 claims description 12
- 229920001343 polytetrafluoroethylene Polymers 0.000 claims description 12
- 229920000058 polyacrylate Polymers 0.000 claims description 10
- 239000006183 anode active material Substances 0.000 claims description 9
- 229910002804 graphite Inorganic materials 0.000 claims description 9
- 239000010439 graphite Substances 0.000 claims description 9
- 238000002156 mixing Methods 0.000 claims description 9
- 239000003960 organic solvent Substances 0.000 claims description 9
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims description 8
- 229910052744 lithium Inorganic materials 0.000 claims description 8
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims description 8
- 239000002033 PVDF binder Substances 0.000 claims description 7
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 7
- 229910021393 carbon nanotube Inorganic materials 0.000 claims description 7
- 239000002041 carbon nanotube Substances 0.000 claims description 7
- 229920002981 polyvinylidene fluoride Polymers 0.000 claims description 7
- 229910052814 silicon oxide Inorganic materials 0.000 claims description 7
- 239000002210 silicon-based material Substances 0.000 claims description 7
- DPXJVFZANSGRMM-UHFFFAOYSA-N acetic acid;2,3,4,5,6-pentahydroxyhexanal;sodium Chemical compound [Na].CC(O)=O.OCC(O)C(O)C(O)C(O)C=O DPXJVFZANSGRMM-UHFFFAOYSA-N 0.000 claims description 6
- 239000001768 carboxy methyl cellulose Substances 0.000 claims description 6
- 239000002245 particle Substances 0.000 claims description 6
- 235000019812 sodium carboxymethyl cellulose Nutrition 0.000 claims description 6
- 229920001027 sodium carboxymethylcellulose Polymers 0.000 claims description 6
- 229920003048 styrene butadiene rubber Polymers 0.000 claims description 6
- 238000007738 vacuum evaporation Methods 0.000 claims description 6
- 229920000049 Carbon (fiber) Polymers 0.000 claims description 5
- 239000004952 Polyamide Substances 0.000 claims description 5
- 229920002125 Sokalan® Polymers 0.000 claims description 5
- 239000006230 acetylene black Substances 0.000 claims description 5
- 239000004917 carbon fiber Substances 0.000 claims description 5
- 229910021389 graphene Inorganic materials 0.000 claims description 5
- 239000003049 inorganic solvent Substances 0.000 claims description 5
- 229910001867 inorganic solvent Inorganic materials 0.000 claims description 5
- 229920000620 organic polymer Polymers 0.000 claims description 5
- 229920003229 poly(methyl methacrylate) Polymers 0.000 claims description 5
- 239000004584 polyacrylic acid Substances 0.000 claims description 5
- 229920002239 polyacrylonitrile Polymers 0.000 claims description 5
- 229920002647 polyamide Polymers 0.000 claims description 5
- 239000004926 polymethyl methacrylate Substances 0.000 claims description 5
- 229920001289 polyvinyl ether Polymers 0.000 claims description 5
- HFCVPDYCRZVZDF-UHFFFAOYSA-N [Li+].[Co+2].[Ni+2].[O-][Mn]([O-])(=O)=O Chemical compound [Li+].[Co+2].[Ni+2].[O-][Mn]([O-])(=O)=O HFCVPDYCRZVZDF-UHFFFAOYSA-N 0.000 claims description 4
- QHGJSLXSVXVKHZ-UHFFFAOYSA-N dilithium;dioxido(dioxo)manganese Chemical compound [Li+].[Li+].[O-][Mn]([O-])(=O)=O QHGJSLXSVXVKHZ-UHFFFAOYSA-N 0.000 claims description 4
- 239000002003 electrode paste Substances 0.000 claims description 4
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 claims description 4
- 229910052782 aluminium Inorganic materials 0.000 claims description 3
- 238000004140 cleaning Methods 0.000 claims description 3
- 238000001816 cooling Methods 0.000 claims description 3
- 238000000151 deposition Methods 0.000 claims description 3
- 238000004519 manufacturing process Methods 0.000 claims description 3
- 239000004411 aluminium Substances 0.000 claims 1
- 239000007787 solid Substances 0.000 description 18
- 238000000034 method Methods 0.000 description 14
- 230000002035 prolonged effect Effects 0.000 description 14
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 10
- 229910001416 lithium ion Inorganic materials 0.000 description 10
- 239000006261 foam material Substances 0.000 description 5
- WYURNTSHIVDZCO-UHFFFAOYSA-N Tetrahydrofuran Chemical compound C1CCOC1 WYURNTSHIVDZCO-UHFFFAOYSA-N 0.000 description 4
- 239000013543 active substance Substances 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 4
- 239000006185 dispersion Substances 0.000 description 4
- 230000007547 defect Effects 0.000 description 3
- 239000011532 electronic conductor Substances 0.000 description 3
- 230000007774 longterm Effects 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 239000002002 slurry Substances 0.000 description 3
- 238000003466 welding Methods 0.000 description 3
- 229910001228 Li[Ni1/3Co1/3Mn1/3]O2 (NCM 111) Inorganic materials 0.000 description 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000007731 hot pressing Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 238000011056 performance test Methods 0.000 description 2
- 239000002985 plastic film Substances 0.000 description 2
- 229920006255 plastic film Polymers 0.000 description 2
- 238000010008 shearing Methods 0.000 description 2
- 239000010703 silicon Substances 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- YLQBMQCUIZJEEH-UHFFFAOYSA-N tetrahydrofuran Natural products C=1C=COC=1 YLQBMQCUIZJEEH-UHFFFAOYSA-N 0.000 description 2
- 239000005279 LLTO - Lithium Lanthanum Titanium Oxide Substances 0.000 description 1
- WPPDFTBPZNZZRP-UHFFFAOYSA-N aluminum copper Chemical compound [Al].[Cu] WPPDFTBPZNZZRP-UHFFFAOYSA-N 0.000 description 1
- 229910021383 artificial graphite Inorganic materials 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000006229 carbon black Substances 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 239000011889 copper foil Substances 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 229910000664 lithium aluminum titanium phosphates (LATP) Inorganic materials 0.000 description 1
- 229910003473 lithium bis(trifluoromethanesulfonyl)imide Inorganic materials 0.000 description 1
- QSZMZKBZAYQGRS-UHFFFAOYSA-N lithium;bis(trifluoromethylsulfonyl)azanide Chemical compound [Li+].FC(F)(F)S(=O)(=O)[N-]S(=O)(=O)C(F)(F)F QSZMZKBZAYQGRS-UHFFFAOYSA-N 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
Classifications
-
- 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
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
-
- 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
-
- 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
- H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
- H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
- H01M10/0565—Polymeric materials, e.g. gel-type or solid-type
-
- 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
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/139—Processes of manufacture
-
- 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
- H01M4/661—Metal or alloys, e.g. alloy coatings
-
- 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
-
- 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
- H01M4/70—Carriers or collectors characterised by shape or form
- H01M4/80—Porous plates, e.g. sintered carriers
- H01M4/808—Foamed, spongy materials
-
- 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
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Materials Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- Dispersion Chemistry (AREA)
- General Physics & Mathematics (AREA)
- Inorganic Chemistry (AREA)
- Composite Materials (AREA)
- Cell Electrode Carriers And Collectors (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
The embodiment of the invention discloses a bipolar pole piece, a preparation method thereof and a battery. The foam copper material has higher porosity and mass density far lower than copper metal, so that the weight of the bipolar current collector and the bipolar pole piece in the battery is smaller, and the energy density and the cycle life of the battery are improved.
Description
Technical Field
The invention relates to the technical field of lithium ion batteries, in particular to a bipolar pole piece, a preparation method thereof and a battery.
Background
The lithium ion battery has the advantages of high energy density, long cycle life, low self-discharge rate, green environmental protection and the like, and is widely applied to the field of new energy automobiles. In a new energy automobile, lithium ion single batteries are used as a power source to output energy through a battery pack formed by a serial/parallel connection mode. The structural connecting piece used for serial/parallel connection of the lithium ion single batteries occupies a certain space of the battery pack, increases the weight of the battery pack, and reduces the overall energy density of the battery pack. Meanwhile, the electrical impedance of the structural connecting piece can also reduce the external output current, and the output power of the battery pack is reduced.
Disclosure of Invention
In view of the above, the embodiment of the invention provides a bipolar pole piece, a preparation method thereof and a battery, wherein a foam copper material has higher porosity and mass density far lower than copper metal, so that the weight of the bipolar current collector and the bipolar pole piece in the battery is smaller, and the energy density and the cycle life of the battery are improved.
In a first aspect, an embodiment of the present invention provides a bipolar pole piece, where the bipolar pole piece includes a bipolar current collector and an electrode layer disposed on at least one side of the bipolar current collector, and the bipolar current collector includes a copper foam layer formed from a copper foam material and an aluminum metal layer formed on a surface of the copper foam layer.
Further, the electrode layer is a negative electrode active layer filled inside the pores of the copper foam layer and attached to the other surface thereof.
Further, the electrode layer is a positive electrode active layer formed on the surface of the aluminum metal layer.
Further, the bipolar pole piece comprises the bipolar current collector and electrode layers arranged on two sides of the bipolar current collector, wherein the electrode layers comprise a negative electrode active layer filled in pores of the foam copper layer and attached to the other surface of the foam copper layer and a positive electrode active layer formed on the surface of the aluminum metal layer.
Further, the positive electrode active layer is formed by coating positive electrode slurry on the surface of the aluminum metal layer, and the positive electrode slurry is formed by dispersing and stirring a positive electrode active substance, a conductive agent, a binder and a solvent;
the negative electrode active layer is formed by filling a negative electrode slurry in the pores of the foam copper layer and adhering the other surface of the foam copper layer, and the negative electrode slurry is formed by dispersing and stirring a negative electrode active substance, a conductive agent, a binder and a solvent.
Further, in the positive electrode slurry, the mass ratio of the positive electrode active material, the conductive agent and the binder is as follows: 90% -97%:1% -5%:1% -5% of the total mass of the positive electrode active material, the conductive agent and the binder accounts for 65% -75% of the total mass of the positive electrode slurry;
the mass ratio of the negative electrode active material, the conductive agent and the binder in the negative electrode slurry is as follows: 90% -97%:1% -5%:1% -5% of the total mass of the anode active material, the conductive agent and the binder accounts for 40% -50% of the total mass of the anode electrode slurry.
Further, the positive electrode active material includes lithium cobaltate, lithium manganate, lithium iron phosphate, lithium nickelate, lithium nickel cobalt manganate, the negative electrode active material includes silicon material, silicon oxide material, silicon/silicon oxide and graphite mixture, the conductive agent includes conductive carbon black, acetylene black, carbon nano tube, graphene, carbon fiber, small particle size graphite, the binder includes polyvinylidene fluoride, polytetrafluoroethylene, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, sodium carboxymethyl cellulose, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene, polyhexafluoropropylene, styrene butadiene rubber, and the solvent includes organic solvent NMP and inorganic solvent.
Further, the thickness of the foam copper layer is 0.2-10mm, the average pore diameter of the foam copper layer is 0.2-4mm, the porosity of the foam copper layer is 50% -90%, and the mass density of the foam copper layer is 0.5-5.0g/cm 3 The thickness of the aluminum metal layer is 1um-5um.
In a second aspect, an embodiment of the present invention provides a method for preparing a bipolar pole piece, where the method includes:
extending and cleaning the surface of the foam copper material to form a foam copper layer;
depositing and cooling aluminum metal on the surface of the foam copper layer through vacuum evaporation to form an aluminum metal layer;
and filling the electrode slurry into the pores of the foam copper layer, attaching the other surface of the foam copper layer and/or coating the surface of the aluminum metal layer to form an electrode layer.
Further, the forming the electrode layer by filling the electrode paste inside the pores of the copper foam layer and attaching the other surface thereof and/or coating the surface of the aluminum metal layer comprises:
coating the anode electrode slurry on the surface of the aluminum metal layer, and drying to form an anode active layer;
and filling the anode electrode slurry into the pores of the foam copper layer, attaching the anode electrode slurry to the other surface of the foam copper layer, and drying the anode electrode slurry to form an anode active layer.
Further, the preparation method further comprises the following steps:
dispersing and stirring the positive electrode active material, the conductive agent, the binder and the solvent to form positive electrode slurry;
the negative electrode active material, the conductive agent, the binder and the solvent are dispersed and stirred to form a negative electrode slurry.
In a third aspect, an embodiment of the present invention provides a battery including:
the bipolar pole pieces according to the first aspect are sequentially stacked;
a plurality of solid electrolyte membranes, one solid electrolyte membrane is arranged between two adjacent bipolar pole pieces, and two sides of the solid electrolyte membranes are respectively provided with electrode layers with different polarities;
the bipolar pole pieces positioned at the two sides respectively comprise an electrode layer, the polarities of the electrode layers of the bipolar pole pieces positioned at the two sides are different, and the bipolar pole piece positioned in the middle comprises two electrode layers with different polarities.
Further, the electrode layer includes a negative electrode active layer filled inside the pores of the copper foam layer and attached to the other surface thereof and/or a positive electrode active layer formed on the surface of the aluminum metal layer.
Further, the solid electrolyte membrane is formed by mixing an oxide solid electrolyte and an organic polymer solid electrolyte.
The embodiment of the invention provides a bipolar pole piece, a preparation method thereof and a battery. The foam copper material has higher porosity and mass density far lower than copper metal, so that the weight of the bipolar current collector and the bipolar pole piece in the battery is smaller, and the energy density and the cycle life of the battery are improved.
Drawings
The above and other objects, features and advantages of the present invention will become more apparent from the following description of embodiments of the present invention with reference to the accompanying drawings, in which:
FIG. 1 is a schematic view of a bipolar current collector according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a bipolar pole piece of an embodiment of the present invention;
fig. 3 is a schematic view of a structure in which a negative electrode active layer is formed on the surface of a bipolar current collector according to an embodiment of the present invention;
fig. 4 is a schematic view of a bipolar current collector according to an embodiment of the present invention, in which a positive electrode active layer is formed on a surface thereof;
FIG. 5 is a schematic view of a bipolar battery according to an embodiment of the present invention;
FIG. 6 is a flow chart of a method for preparing a bipolar pole piece in accordance with an embodiment of the present invention;
FIG. 7 is a flow chart of a method of preparing positive and negative active layers according to an embodiment of the present invention;
fig. 8 is a graph showing cycle performance of the bipolar battery of the embodiment of the invention and the comparative battery.
The reference numerals:
1-bipolar current collector; 11-a layer of copper foam; 12-an aluminum metal layer; 2-a negative electrode active layer; 3-a positive electrode active layer; 4-solid electrolyte membrane.
Detailed Description
The present invention is described below based on examples, but the present invention is not limited to only these examples. In the following detailed description of the present invention, certain specific details are set forth in detail. The present invention will be fully understood by those skilled in the art without the details described herein. Well-known methods, procedures, flows, components and circuits have not been described in detail so as not to obscure the nature of the invention.
Moreover, those of ordinary skill in the art will appreciate that the drawings are provided herein for illustrative purposes and that the drawings are not necessarily drawn to scale.
Unless the context clearly requires otherwise, the words "comprise," "comprising," and the like in the description are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is, it is the meaning of "including but not limited to".
In the description of the present invention, it should be understood that the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. Furthermore, in the description of the present invention, unless otherwise indicated, the meaning of "a plurality" is two or more.
Unless specifically stated or limited otherwise, the terms "mounted," "connected," "secured" and the like should be construed broadly, as they may be fixed, removable, or integral, for example; can be mechanically or electrically connected; either directly or indirectly, through intermediaries, or both, may be in communication with each other or in interaction with each other, unless expressly defined otherwise. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.
Fig. 1 is a schematic structural view of a bipolar current collector of the present embodiment. As shown in fig. 1, the bipolar current collector 1 includes a copper foam layer 11 and an aluminum metal layer 12. Wherein the copper foam layer 11 is formed of a copper foam material. The foam copper material is of a three-dimensional net structure with higher porosity, and has good conductivity and ductility. The surface of the copper foam layer 11 is cleaned, and then aluminum metal is deposited and cooled on the surface of the copper foam layer 11 by means of vacuum evaporation to form an aluminum metal layer 12. The foam copper material has higher porosity and the mass density is far lower than that of copper metal, so that the weight of the bipolar current collector 1 in the battery is smaller, and the energy density of the battery is improved.
In the actual preparation process, the aluminum metal layer 12 is formed on the copper foam layer 11 by vacuum evaporation of aluminum metal powder, and the copper foam layer 11 is of a three-dimensional network structure with pores, so that part of aluminum metal powder is deposited and permeated into the copper foam layer 11, and the bipolar performance of the bipolar current collector 1 can be further improved.
In one embodiment, the thickness of the copper foam layer 11 is 0.2-10mm, the average pore diameter of the copper foam layer 11 is 0.2-4mm, the porosity of the copper foam layer 11 is 50-90%, and the mass density of the copper foam layer 11 is 0.5-5.0g/cm 3 The thickness of the aluminum metal layer 12 is 1um-5um, so that the energy density of the battery can be further improved, the expansion of the negative electrode active material is weakened, and the cycle life of the battery is prolonged on the premise of reducing the weight ratio of the bipolar current collector 1.
Further, the application also discloses a bipolar pole piece, as shown in fig. 2-4. The bipolar pole piece comprises a bipolar current collector 1 and an electrode layer arranged on at least one side of the bipolar current collector 1. The bipolar current collector 1 has the same structure and the same preparation method as those of the bipolar current collector 1 in the above embodiment, and will not be described herein. The electrode layer may be a negative active layer 2 filled inside the pores of the foamy copper layer 11 of the bipolar current collector 1 and attached to the other surface of the foamy copper layer 11 with respect to the aluminum metal layer 12. The electrode layer may also be a positive electrode active layer 3 formed on the surface of the aluminum metal layer 12.
In one embodiment, the bipolar electrode sheet includes only the bipolar current collector 1 and the negative electrode active layer 2, as shown in fig. 3. The anode active layer 2 is formed into a bipolar electrode sheet with a single-side anode coating after drying by filling anode electrode slurry into pores of the foamy copper layer 11 of the bipolar current collector 1 and attaching the anode electrode slurry to the surface of the foamy copper layer 11, which is far away from the aluminum metal layer 12. The foam copper layer 11 of the bipolar current collector 1 has a three-dimensional network structure, and the bipolar pole piece can bind the anode active material (for example, silicon material) in the three-dimensional network structure of the foam copper layer 11 when rolling, so that the expansion of the anode active material can be weakened in the long-term circulation process, and the cycle life of the battery is prolonged. Meanwhile, the foam copper material is a good electronic conductor material, and a three-dimensional conductive net can be constructed in the anode active layer 2 in a phase-changing manner, so that the conductive capacity of the anode active layer 2 is enhanced, the defect of breakage of the anode conductive net caused by expansion of anode active substances is overcome, and the cycle life of the battery is prolonged.
When the bipolar pole piece with the single-side negative electrode coating is assembled to form the battery, the bipolar current collector of the bipolar pole piece with the single-side negative electrode coating is extended a little (namely, the length of the bipolar current collector is longer than that of the negative electrode coating), and the external negative electrode lug of the battery is directly connected to the foam copper layer of the extension part for welding.
In one embodiment, the bipolar electrode sheet includes only the bipolar current collector 1 and the positive electrode active layer 3, as shown in fig. 4. The positive electrode active layer 3 is coated on the surface of the aluminum metal layer 12 of the bipolar current collector 1 by positive electrode slurry, and a bipolar pole piece with a single-side positive electrode coating is formed after drying. The positive electrode slurry is formed by dispersing and stirring a positive electrode active material, a conductive agent, a binder and a solvent. When the bipolar pole piece with the single-side positive electrode coating is assembled to form a battery, the bipolar current collector of the bipolar pole piece with the single-side positive electrode coating is positioned at the outer sides of the bipolar pole pieces, the bipolar current collector of the bipolar pole piece with the single-side positive electrode coating is prolonged a little (namely, the length of the bipolar current collector is longer than that of the positive electrode coating), and the external positive electrode lug of the battery is directly connected to an aluminum metal layer of the prolonged part for welding.
In one embodiment, the bipolar electrode sheet includes a bipolar current collector 1, a positive electrode active layer 3, and a negative electrode active layer 2, as shown in fig. 2. The positive electrode active layer 3 is coated on the surface of the aluminum metal layer 12 of the bipolar current collector 1 by the positive electrode slurry, and dried. The anode active layer 2 is formed into a bipolar pole piece with anode and cathode coatings on both sides respectively by filling anode electrode slurry into pores of the foamy copper layer 11 of the bipolar current collector 1 and attaching the anode electrode slurry to the surface of the foamy copper layer 11, which is far away from the aluminum metal layer 12, and drying the anode electrode slurry. The bipolar electrode plate is positioned between the bipolar electrode plate with the single-side positive electrode coating and the bipolar electrode plate with the single-side negative electrode coating when assembled to form the battery.
In the above three embodiments, the method, material, etc. for forming the anode active layer 2 on one side of the bipolar current collector are the same, and the method, material, etc. for forming the cathode active layer 3 on the other side of the bipolar current collector are the same. During charging, lithium ions released from the positive electrode active layer 3 pass through the solid electrolyte membrane 4 to reach the negative electrode active layer 2 of the other bipolar electrode plate, and electrons pass through the bipolar current collector (the aluminum metal layer 12 and the foam copper layer 11) to reach the negative electrode active layer 2; during discharge, lithium ions released from the negative electrode active layer 2 pass through the solid electrolyte membrane 4 to reach the positive electrode active layer 3 of the other bipolar electrode plate, and electrons pass through the bipolar current collector (the aluminum metal layer 12 and the foam copper layer 11) to reach the positive electrode active layer 3. Electrons can be transmitted through the bipolar current collector without passing through an external circuit, so that the path is shortened, the conductive efficiency is improved, and the internal resistance is reduced.
Wherein the anode active layer 2 is filled with anode electrode paste inside the pores of the foamy copper layer 11 of the bipolar current collector 1 and attached to the surface thereof on the side away from the aluminum metal layer 12, and is formed by drying. The negative electrode slurry is formed by dispersing and stirring a negative electrode active material, a conductive agent, a binder and a solvent, namely, homogenizing. The mass ratio of the negative electrode active material, the conductive agent and the binder in the negative electrode slurry is as follows: 90% -97%:1% -5%:1% -5%, and the sum of the three is 100%. The solid content in the cathode electrode slurry is 40% -50%. The solid content refers to the proportion of the weight of the solid component to the total weight of the anode electrode slurry. The solid components in the negative electrode slurry include a negative electrode active material, a conductive agent, and a binder. That is, the sum of the mass of the anode active material, the conductive agent, and the binder is 40% to 50% of the total mass of the anode electrode slurry.
The negative electrode active material includes, but is not limited to, at least one of graphite, a silicon material, and a silicon oxide material. The conductive agent includes, but is not limited to, at least one of conductive carbon black, acetylene black, carbon nanotubes, graphene, carbon fibers, and small particle size graphite. The binder includes, but is not limited to, at least one of polyvinylidene fluoride, polytetrafluoroethylene, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, sodium carboxymethyl cellulose, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene, polyhexafluoropropylene, styrene-butadiene rubber. The solvent includes, but is not limited to, at least one of an organic solvent NMP and an inorganic solvent. Preferably, the solvent is selected from an organic solvent NMP. Preferably, the negative electrode active material is made of a silicon material, so that the energy density of the battery can be further improved.
Wherein the positive electrode active layer 3 is coated on the surface of the aluminum metal layer 12 of the bipolar current collector 1 from a positive electrode slurry and formed by drying. The positive electrode slurry is formed by dispersing and stirring a positive electrode active material, a conductive agent, a binder and a solvent, namely, homogenizing. The mass ratio of the positive electrode active material, the conductive agent and the binder in the positive electrode slurry is as follows: 90% -97%:1% -5%:1% -5%, and the sum of the three is 100%. The solid content in the positive electrode slurry is 65% -75%. The solid content refers to the proportion of the weight of the solid component to the total weight of the positive electrode slurry. The solid components in the positive electrode slurry include a positive electrode active material, a conductive agent, and a binder. That is, the sum of the mass of the positive electrode active material, the conductive agent, and the binder accounts for 65% to 75% of the total mass of the positive electrode slurry.
The positive electrode active material includes, but is not limited to, at least one of lithium cobaltate, lithium manganate, lithium iron phosphate, lithium nickelate, lithium nickel cobalt manganate (NCM 111, NCM523, NCM622, NCM 811). The conductive agent includes, but is not limited to, at least one of conductive carbon black, acetylene black, carbon nanotubes, graphene, carbon fibers, and small particle size graphite. The binder includes, but is not limited to, at least one of polyvinylidene fluoride, polytetrafluoroethylene, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, sodium carboxymethyl cellulose, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene, polyhexafluoropropylene, styrene-butadiene rubber. The solvents include, but are not limited to, organic solvents NMP and inorganic solvents. Preferably, the solvent is selected from an organic solvent NMP.
The negative electrode slurry is formed by dispersing and stirring a negative electrode active material, a conductive agent, a binder and a solvent, and the positive electrode slurry is formed by dispersing and stirring a positive electrode active material, a conductive agent, a binder and a solvent. Wherein, the dispersion mainly refers to the rapid and uniform breaking and dispersing of materials, and the dispersion technology can be used for dissolving and mixing some soluble solids and liquid phases. The dispersion has shearing and crushing effects on materials, firstly, the materials are crushed, so that the materials are mutually fused in a smaller particle shape, and the stability of the mixed materials can be improved. The stirring relative dispersion is mild, the stirring has no shearing and breaking effects, and the materials are effectively mixed by the rotation of the stirrer.
In the three embodiments, the bipolar pole pieces are all formed on the basis of the bipolar current collector prepared by the method, so that the bipolar pole pieces are provided with the foam copper layers, the foam copper materials for forming the foam copper layers have higher porosity and the mass density is far lower than that of copper metal, the weight of the bipolar pole pieces in the battery is smaller, and the energy density of the battery is improved. Meanwhile, the three-dimensional network structure of the foam copper material can bind the negative electrode active material in the three-dimensional network structure when the bipolar pole piece is rolled, so that the expansion of the negative electrode active material is weakened in the long-term circulation process, and the cycle life of the battery is prolonged. Further, the foam copper material is a good electronic conductor, and the anode electrode slurry can be filled in the foam copper layer, so that a three-dimensional conductive net can be constructed in the anode active layer in a phase-changing manner, the conductivity of the anode active layer is enhanced, the defect of breakage of the anode conductive net caused by expansion of the anode active material is overcome, and the cycle life of the battery is prolonged.
Further, the application also provides a preparation method of the bipolar pole piece, as shown in fig. 6. The preparation method comprises the following steps:
and S100, stretching and surface cleaning the foam copper material to form a foam copper layer.
The copper foam material is correspondingly expanded to form a copper foam layer 11 having a predetermined thickness, a predetermined range of average pore sizes, and a predetermined range of porosities, a predetermined mass density. The low mass ratio of the copper foam material can improve the energy density of the subsequently formed battery. The copper foam material has good conductivity and ductility, can bind and weaken the expansion of the anode active material, and improves the cycle life of the battery. In a preferred embodiment, the thickness of the copper foam layer 11 is 0.2-10mm, the average pore diameter of the copper foam layer 11 is 0.2-4mm, the porosity of the copper foam layer 11 is 50% -90%, and the mass density of the copper foam layer 11 is 0.5-5.0g/cm 3 。
And step 200, depositing and cooling aluminum metal on the surface of the foam copper layer through vacuum evaporation to form an aluminum metal layer.
The surface of the copper foam layer 11 is cleaned, and then aluminum metal is deposited and cooled on the surface of the copper foam layer 11 by means of vacuum evaporation to form an aluminum metal layer 12. Preferably, the thickness of the aluminum metal layer 12 is 1um to 5um.
And step S300, filling the electrode slurry into the pores of the foam copper layer, attaching the other surface of the foam copper layer and/or coating the surface of the aluminum metal layer to form an electrode layer.
Firstly, selecting various materials with preset mass ratio, and homogenizing to form electrode slurry. The positive electrode slurry may be coated on the surface of the aluminum metal layer 12 described above to form the positive electrode active layer 3. The anode electrode paste may be filled inside the pores of the above-described copper foam layer 11 and attached on the outer surface away from the aluminum metal layer 12 to form the anode active layer 2. The specific formation method of the electrode layer is specifically described in the following examples.
As shown in fig. 7, the preparation method further includes:
and step S310, dispersing and stirring the positive electrode active material, the conductive agent, the binder and the solvent to form positive electrode slurry.
The mass ratio of the positive electrode active material, the conductive agent and the binder in the positive electrode slurry is as follows: 90% -97%:1% -5%:1% -5%, and the sum of the three is 100%. The solid content in the positive electrode slurry is 65% -75%. The solid content refers to the proportion of the weight of the solid component to the total weight of the positive electrode slurry. The solid components in the positive electrode slurry include a positive electrode active material, a conductive agent, and a binder. That is, the sum of the mass of the positive electrode active material, the conductive agent, and the binder accounts for 65% to 75% of the total mass of the positive electrode slurry.
The positive electrode active material includes, but is not limited to, at least one of lithium cobaltate, lithium manganate, lithium iron phosphate, lithium nickelate, lithium nickel cobalt manganate (such as NCM111, NCM523, NCM622, NCM 811). The conductive agent includes, but is not limited to, at least one of conductive carbon black, acetylene black, carbon nanotubes, graphene, carbon fibers, and small particle size graphite. The binder includes, but is not limited to, at least one of polyvinylidene fluoride, polytetrafluoroethylene, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, sodium carboxymethyl cellulose, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene, polyhexafluoropropylene, styrene-butadiene rubber. The solvents include, but are not limited to, organic solvents NMP and inorganic solvents. Preferably, the solvent is selected from an organic solvent NMP.
And step 320, coating the anode electrode slurry on the surface of the aluminum metal layer, and drying to form an anode active layer.
Step S330, dispersing and stirring the negative electrode active material, the conductive agent, the binder and the solvent to form a negative electrode slurry.
The mass ratio of the negative electrode active material, the conductive agent and the binder in the negative electrode slurry is as follows: 90% -97%:1% -5%:1% -5%, and the sum of the three is 100%. The solid content in the cathode electrode slurry is 40% -50%. The solid content refers to the proportion of the weight of the solid component to the total weight of the anode electrode slurry. The solid components in the negative electrode slurry include a negative electrode active material, a conductive agent, and a binder. That is, the sum of the mass of the anode active material, the conductive agent, and the binder is 40% to 50% of the total mass of the anode electrode slurry.
The negative electrode active material includes, but is not limited to, a silicon material, a silicon oxide material, a mixture of silicon/silicon oxide and graphite, and the like. The conductive agent, the binder, and the solvent are substantially the same as in forming the positive electrode slurry. Preferably, the solvent is selected from an organic solvent NMP. Preferably, the negative electrode active material is made of a silicon material, so that the energy density of the battery can be further improved.
And step S340, filling the anode electrode slurry into the pores of the foam copper layer and attaching the anode electrode slurry to the other surface of the foam copper layer, and drying the anode electrode slurry to form an anode active layer.
In the preparation process, the step S310 and the step S320 have a sequence, and the step S330 and the step S340 have a sequence; there is no order of preparing the positive electrode active layer and the negative electrode active layer on the bipolar current collector.
The application also provides a battery. As shown in fig. 5, the battery includes a plurality of bipolar electrode sheets and a plurality of solid electrolyte membranes 4. Wherein, a plurality of bipolar pole pieces are overlapped in turn, and a solid electrolyte membrane 4 is arranged between two adjacent bipolar pole pieces for separation. The electrode layers on both sides of the solid electrolyte membrane 4 are electrode layers with different polarities of the two bipolar electrode plates, as shown in fig. 5. Wherein the number of solid electrolyte membranes 4 is 1 less than the number of bipolar pole pieces.
The bipolar electrode plates positioned at the outer sides respectively comprise an electrode layer, the polarities of the electrode layers of the two bipolar electrode plates at the two sides are different, the bipolar electrode plate positioned in the middle comprises two electrode layers with different polarities, and finally, the outer sides of the bipolar electrode plates are packaged by an aluminum plastic film in a hot-pressing mode to prepare the battery. That is, among the plurality of bipolar plates forming the battery, one bipolar plate has only the positive electrode active layer 3 as the positive electrode plate of the battery, one bipolar plate has only the negative electrode active layer 2 as the negative electrode plate of the battery, and the remaining bipolar plates have both the positive electrode active layer 3 and the negative electrode active layer 2.
The length of the bipolar current collector of the bipolar pole pieces at the outer sides of the 2 batteries is prolonged, the extension part is not coated with slurry, and the extension part is welded with the external pole lugs, so that electron transmission is realized. The polarity of the outer tab is the same as the polarity of the coating of the bipolar pole pieces at the 2 outer sides, and the welding position is welded at the extension part of the bipolar current collector at the adjacent side of the coating. Specifically, the length of the bipolar current collector of the bipolar pole piece with the single-side positive electrode coating is prolonged, and the external positive electrode lug of the battery is welded with the aluminum metal layer of the bipolar current collector prolonged part; the bipolar current collector of the bipolar pole piece with the single-side negative electrode coating is prolonged in length, and the outer negative electrode lug of the battery is welded with the foam copper layer of the bipolar current collector prolonged part. In the present application, one positive electrode active layer 3, one negative electrode active layer 2, and one solid electrolyte membrane 4 constitute one basic unit, the number of basic units inside the battery is not less than 2, and the voltage of the battery is equal to the voltage of the basic unit. In this embodiment, the bipolar pole piece is the same as the bipolar pole piece in the above embodiment, and will not be described herein.
The electrode layers on both sides of the solid electrolyte membrane 4 are respectively a positive electrode active layer 3 of one bipolar electrode plate and a negative electrode active layer 2 of the other bipolar electrode plate. During charging, lithium ions released from the positive electrode active layer 3 pass through the solid electrolyte membrane 4 to reach the negative electrode active layer 2 of the other bipolar electrode plate, and electrons pass through the bipolar current collector (the aluminum metal layer 12 and the foam copper layer 11) to reach the negative electrode active layer 2; during discharge, lithium ions released from the negative electrode active layer 2 pass through the solid electrolyte membrane 4 to reach the positive electrode active layer 3 of the other bipolar electrode plate, and electrons pass through the bipolar current collector (the aluminum metal layer 12 and the foam copper layer 11) to reach the positive electrode active layer 3. Electrons can be transmitted through the bipolar current collector without passing through an external circuit, so that the path is shortened, the conductive efficiency is improved, and the internal resistance is reduced.
In the present application, the solid electrolyte membrane 4 is formed by mixing an oxide solid electrolyte and an organic polymer solid electrolyte. In one embodiment, the solid electrolyte membrane 4 is formed as follows: adding an oxide solid electrolyte into tetrahydrofuran solution in which PEO/LiTFSI organic polymer solid electrolyte is dissolved, mixing and stirring uniformly, wherein the stirring temperature is preferably 30-100 ℃; and then uniformly coating the slurry on a support carrier taking polytetrafluoroethylene as a substrate, drying the support carrier after airing, wherein the drying temperature is preferably 40-100 ℃, and stripping the support carrier to obtain the solid electrolyte membrane 4, wherein the oxide solid electrolyte can be LAGP, LATP, LLZO, LLTO and other materials.
The advantages of the battery in the present application include: (1) The foam copper material has higher porosity and mass density far lower than copper metal, so that the weight of the bipolar current collector in the battery is smaller, and the energy density of the battery is improved; (2) The three-dimensional network structure of the foam copper material can bind the negative electrode active material in the three-dimensional network structure when the pole piece is rolled, so that the expansion of the negative electrode active material is weakened in the long-term circulation process, and the cycle life of the battery is prolonged; (3) The foam copper material is a good electronic conductor, a three-dimensional conductive net is constructed in the anode active layer in a phase-changing manner, the conductive capacity of the anode active layer is enhanced, the defect of breakage of the anode conductive net caused by expansion of the anode active material is overcome, and the cycle life of the battery is prolonged.
The present application is further illustrated below in conjunction with examples and comparative examples. It should be understood that these examples are illustrative only of the present application and are not intended to limit the scope of the present application.
Example 1:
the bipolar current collector in the application is selected to manufacture the bipolar pole piece. NCM811 was selected as the positive electrode active material, polyvinylidene fluoride (PVDF) as the binder, carbon nanotubes and conductive carbon black as the conductive agent, NCM811: conductive agent: binder = 96.5:2:1.5, carbon nanotubes: conducting carbon black=0.5:1.5, homogenizing to form anode electrode slurry, and coating the anode electrode slurry on an aluminum metal layer of the bipolar current collector12, and drying to obtain the bipolar pole piece of the single-side positive electrode active layer 3. Mixing silicon oxide and artificial graphite according to a mass ratio of 2:8, uniformly mixing the sodium carboxymethyl cellulose and the styrene-butadiene rubber as negative electrode active substances according to the mass ratio of 1:1.8 uniformly mixing as a binder, conductive carbon black as a conductive agent, and mixing a negative electrode active material: and (2) a binder: and (3) homogenizing the conductive agent=96.2:1:2.8 to form negative electrode slurry, coating the negative electrode slurry on the surface of the foam copper layer 11 of the bipolar pole piece, and drying to obtain the bipolar pole piece. Wherein the surface density of the positive electrode active layer 3 was 15.2mg/cm 2 The areal density of the anode active layer 2 was 6.1mg/cm 2 . Meanwhile, preparing a bipolar pole piece with a single-side positive electrode active layer and a bipolar pole piece with a single-side negative electrode active layer respectively according to the same surface density.
Preparing a solid electrolyte membrane: 50g of LLZO powder is added into tetrahydrofuran solution of PEO/Li TFSI (5:1) organic polymer solid electrolyte dissolved with 30g, and the mixture is uniformly mixed and stirred for 24 hours at 50 ℃, then the slurry is uniformly coated on a support carrier taking polytetrafluoroethylene as a substrate, and the support carrier is dried for 8 hours at 40 ℃, and then the solid electrolyte film is obtained after stripping.
And sequentially superposing the bipolar electrode plate with the single-side positive electrode active layer, the solid electrolyte membrane, the bipolar electrode plate, the solid electrolyte membrane and the bipolar electrode plate with the single-side negative electrode active layer, assembling the bipolar solid battery, always keeping the positive electrode active layer adjacent to the negative electrode active layer, and inserting the solid electrolyte membrane in the middle. The two outermost layers of the battery are respectively a negative electrode plate of a single-side negative electrode active layer and a positive electrode plate of a single-side positive electrode active layer, a 2Ah flexible package bipolar solid-state lithium ion battery is prepared by adopting an aluminum plastic film for hot-pressing packaging, and then a 0.5C/0.5C cycle performance test is carried out, as shown in figure 8.
Comparative example:
commercial aluminum-copper foil composite current collector is selected as bipolar current collector, bipolar pole piece and bipolar solid-state lithium ion battery are prepared according to the same method, and 0.5C/0.5C cycle performance test is carried out, as shown in FIG. 8.
As can be seen from the comparison of the cycle performance of fig. 8, the battery prepared by the present application has improved cycle life and capacity retention compared to the battery prepared by the comparative example.
The embodiment of the invention provides a bipolar pole piece, a preparation method thereof and a battery. The foam copper material has higher porosity and mass density far lower than copper metal, so that the weight of the bipolar current collector and the bipolar pole piece in the battery is smaller, and the energy density and the cycle life of the battery are improved.
The above description is only of the preferred embodiments of the present invention and is not intended to limit the present invention, and various modifications and variations may be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (14)
1. A bipolar pole piece, characterized in that the bipolar pole piece comprises a bipolar current collector (1) and an electrode layer arranged on at least one side of the bipolar current collector (1), wherein the bipolar current collector (1) comprises a foam copper layer (11) formed by foam copper materials and an aluminum metal layer (12) formed on the surface of the foam copper layer (11).
2. Bipolar pole piece according to claim 1, characterized in that the electrode layer is a negative active layer (2) filled inside the pores of the copper foam layer (11) and attached to its other surface.
3. Bipolar pole piece according to claim 1, characterized in that the electrode layer is a positive active layer (3) formed on the surface of the aluminium metal layer (12).
4. The bipolar pole piece as claimed in claim 1, comprising the bipolar current collector (1) and electrode layers disposed on both sides of the bipolar current collector (1), the electrode layers comprising a negative electrode active layer (2) filled inside pores of the copper foam layer (11) and attached to the other surface thereof and a positive electrode active layer (3) formed on the surface of the aluminum metal layer (12).
5. The bipolar pole piece of claim 4, wherein the positive electrode active layer (3) is formed by coating positive electrode slurry on the surface of the aluminum metal layer (12), and the positive electrode slurry is formed by dispersing and stirring a positive electrode active material, a conductive agent, a binder and a solvent;
the negative electrode active layer (2) is formed by filling the inside of the pores of the foam copper layer (11) with a negative electrode slurry formed by dispersing and stirring a negative electrode active material, a conductive agent, a binder and a solvent, and adhering the other surface thereof.
6. The bipolar pole piece of claim 5 wherein the mass ratio of the positive electrode active material, the conductive agent, and the binder in the positive electrode slurry is: 90% -97%:1% -5%:1% -5% of the total mass of the positive electrode active material, the conductive agent and the binder accounts for 65% -75% of the total mass of the positive electrode slurry;
the mass ratio of the negative electrode active material, the conductive agent and the binder in the negative electrode slurry is as follows: 90% -97%:1% -5%:1% -5% of the total mass of the anode active material, the conductive agent and the binder accounts for 40% -50% of the total mass of the anode electrode slurry.
7. The bipolar pole piece of any of claims 5-6 wherein the positive electrode active material comprises at least one of lithium cobaltate, lithium manganate, lithium iron phosphate, lithium nickelate, lithium nickel cobalt manganate, the negative electrode active material comprises at least one of graphite, silicon material, and silicon oxide material, the conductive agent comprises at least one of conductive carbon black, acetylene black, carbon nanotubes, graphene, carbon fibers, and small particle size graphite, the binder comprises at least one of polyvinylidene fluoride, polytetrafluoroethylene, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, sodium carboxymethyl cellulose, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene, polyhexafluoropropylene, and styrene butadiene rubber, and the solvent comprises at least one of an organic solvent NMP and an inorganic solvent.
8. Bipolar pole piece as claimed in claim 1, characterized in that the thickness of the copper foam layer (11) is 0.2-10mm, the average pore diameter of the copper foam layer (11) is 0.2-4mm, the porosity of the copper foam layer (11) is 50% -90%, the mass density of the copper foam layer (11) is 0.5-5.0g/cm 3 The thickness of the aluminum metal layer (12) is 1um-5um.
9. The preparation method of the bipolar pole piece is characterized by comprising the following steps of:
extending and cleaning the surface of the foam copper material to form a foam copper layer;
depositing and cooling aluminum metal on the surface of the foam copper layer through vacuum evaporation to form an aluminum metal layer;
and filling the electrode slurry into the pores of the foam copper layer, attaching the other surface of the foam copper layer and/or coating the surface of the aluminum metal layer to form an electrode layer.
10. The method of manufacturing according to claim 9, wherein the filling the electrode paste inside the pores of the copper foam layer and adhering the other surface thereof and/or coating the surface of the aluminum metal layer to form an electrode layer comprises:
coating the anode electrode slurry on the surface of the aluminum metal layer, and drying to form an anode active layer;
and filling the anode electrode slurry into the pores of the foam copper layer, attaching the anode electrode slurry to the other surface of the foam copper layer, and drying the anode electrode slurry to form an anode active layer.
11. The method of manufacturing according to claim 10, further comprising:
dispersing and stirring the positive electrode active material, the conductive agent, the binder and the solvent to form positive electrode slurry;
the negative electrode active material, the conductive agent, the binder and the solvent are dispersed and stirred to form a negative electrode slurry.
12. A battery, the battery comprising:
a plurality of bipolar pole pieces according to any one of claims 1-8, stacked in sequence;
a plurality of solid electrolyte membranes (4), one solid electrolyte membrane (4) is arranged between two adjacent bipolar pole pieces, and two sides of the solid electrolyte membranes (4) are respectively provided with electrode layers with different polarities;
the bipolar pole pieces positioned at the two sides respectively comprise an electrode layer, the polarities of the electrode layers of the bipolar pole pieces positioned at the two sides are different, and the bipolar pole piece positioned in the middle comprises two electrode layers with different polarities.
13. The battery according to claim 12, characterized in that the electrode layer includes a negative electrode active layer (2) filled inside the pores of the copper foam layer (11) and attached to the other surface thereof and/or a positive electrode active layer (3) formed on the surface of the aluminum metal layer (12).
14. The battery according to claim 12, wherein the solid electrolyte membrane (4) is formed by mixing an oxide solid electrolyte and an organic polymer solid electrolyte.
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