CN114094039A - Electrode plate and lithium ion battery comprising same - Google Patents

Electrode plate and lithium ion battery comprising same Download PDF

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Publication number
CN114094039A
CN114094039A CN202111288589.6A CN202111288589A CN114094039A CN 114094039 A CN114094039 A CN 114094039A CN 202111288589 A CN202111288589 A CN 202111288589A CN 114094039 A CN114094039 A CN 114094039A
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electrolyte
active material
material layer
positive
electrode sheet
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CN114094039B (en
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赵伟
李素丽
张赵帅
唐伟超
董德锐
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Zhuhai Cosmx Battery Co Ltd
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Zhuhai Cosmx Battery Co Ltd
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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
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • H—ELECTRICITY
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    • 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
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    • 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
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    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
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    • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
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    • H—ELECTRICITY
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    • 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
    • H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H—ELECTRICITY
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    • 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
    • H01M4/134—Electrodes based on metals, Si or alloys
    • 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
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H01M4/1391—Processes of manufacture of electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
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    • 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
    • H01M4/1393—Processes of manufacture of electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H—ELECTRICITY
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    • 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
    • H01M4/1395—Processes of manufacture of electrodes based on metals, Si or alloys
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    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/572—Means for preventing undesired use or discharge
    • H01M50/584—Means for preventing undesired use or discharge for preventing incorrect connections inside or outside the batteries
    • H01M50/586—Means for preventing undesired use or discharge for preventing incorrect connections inside or outside the batteries inside the batteries, e.g. incorrect connections of electrodes
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    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/572—Means for preventing undesired use or discharge
    • H01M50/584—Means for preventing undesired use or discharge for preventing incorrect connections inside or outside the batteries
    • H01M50/59—Means for preventing undesired use or discharge for preventing incorrect connections inside or outside the batteries characterised by the protection means
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    • H01M2300/0091—Composites in the form of mixtures
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Abstract

The invention provides an electrode plate and a lithium ion battery comprising the same. The electrode sheet of the present invention includes: a current collector, an active material layer, an electrolyte and a functional coating; wherein the current collector has two opposing surfaces; the active material layer is disposed on at least one surface of the current collector; the electrolyte is arranged inside and/or on the surface of the active material layer; the functional coating is disposed on the active material layer including an electrolyte. According to the invention, through constructing the in-situ solidified electrolyte and the functional coating, the needling and heating safety of the battery is improved, meanwhile, the influence of a single functional coating mode on the increase of the internal resistance of the battery can be reduced, and the electrical property of the battery is ensured.

Description

Electrode plate and lithium ion battery comprising same
Technical Field
The invention belongs to the technical field of lithium ion batteries, and particularly relates to an electrode plate and a lithium ion battery prepared by the electrode plate.
Background
At present, the development of lithium ion batteries mainly advances towards high energy density and ultra-fast charge technology, such as application of materials such as high nickel ternary and silicon carbon negative electrodes, so that intrinsic safety of the batteries is greatly deteriorated, and additionally, external uncontrollable factors such as overcharge, overheating and impact under various conditions frequently cause battery safety accidents, so that improvement of battery safety is very necessary.
There are many ways to improve the safety of the battery, such as modifying the coating of the diaphragm, using the high temperature resistant diaphragm, polymer composite current collector, electrolyte flame retardant additive, coating the positive electrode material, etc. Although these methods have improved safety to some extent, there are many problems, such as limited degree of improvement, difficulty in manufacturing, high cost, and deterioration of battery performance.
Therefore, more and more new technologies for improving safety are being developed, and as the prior art discloses that the surface of the electrode plates of the positive and negative electrodes is coated, the coating has high elongation and electronic insulation characteristics, and when the battery is punctured by a foreign object, the area of the short circuit area of the positive and negative electrodes can be reduced or even avoided, thereby improving the safety of the battery. However, similar to the pole piece surface coating technology, the electrolyte still adopts a liquid system, and under the condition of battery overheating, the active material is directly contacted with the electrolyte, a series of side reactions can occur, and a large amount of heat is released to cause the battery to generate complete thermal runaway. Therefore, the safety problem under the conditions of battery needling and overheating is difficult to solve simultaneously by adopting a single technical means.
Disclosure of Invention
In view of the defects in the prior art, the invention provides an electrode plate containing an in-situ cured electrolyte and a functional coating and a lithium ion battery containing the electrode plate.
The present invention provides an electrode sheet, including: a current collector, an active material layer, an electrolyte and a functional coating; wherein the content of the first and second substances,
the current collector has two opposing surfaces;
the active material layer is disposed on at least one surface of the current collector;
the electrolyte is arranged inside and/or on the surface of the active material layer;
the functional coating is disposed on an active material layer of an electrolyte.
According to an embodiment of the invention, the electrolyte is a solid electrolyte. Specifically, the solid electrolyte includes a first polymer and an electrolyte dispersed therein.
According to an embodiment of the present invention, the first polymer is at least one of polymethyl methacrylate or a copolymer thereof, polyhydroxyethyl methacrylate or a copolymer thereof, polyethylene glycol polymethacrylate or a copolymer thereof, polyethylene glycol diacrylate or a copolymer thereof, polytrimethylolpropane triacrylate or a copolymer thereof, polybutyl acrylate or a copolymer thereof, polyvinyl n-butyl ether or a copolymer thereof, or polyethyl acetate or a copolymer thereof, for example. For example, the copolymer of the above homopolymer may be a copolymer of a monomer in the homopolymer and at least one monomer in other homopolymers, or may be a copolymer of a monomer in the homopolymer and another monomer suitable for copolymerization therewith.
According to an embodiment of the present invention, the content of the electrolytic solution in the electrolyte is 80 to 95 wt%.
According to the embodiment of the present invention, the electrolyte may be selected from those known in the art. Preferably, the electrolyte includes at least a lithium salt and a solvent. Illustratively, the lithium salt is selected from LiPF6、LiBF4、LiClO4、LiAsF6、LiSO2CF3、LiN(CF3SO2)2LiBOB, LiDFOB or LiN (C)2F5SO2)2At least one of (1). Illustratively, the solvent is selected from cyclic carbonates and/or chain carbonates. Illustratively, the cyclic carbonate is selected from at least one of ethylene carbonate, propylene carbonate, or γ -butyrolactone. Illustratively, the chain carbonate is selected from at least one of dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, propyl methyl carbonate, or propyl ethyl carbonate. For example, the electrolyte is lithium hexafluorophosphate (LiPF)6) Dissolved in a mixed solvent (for example, 1:1:1 mass ratio) composed of Ethylene Carbonate (EC), dimethyl carbonate (DEC) and Ethyl Methyl Carbonate (EMC). Specifically, lithium hexafluorophosphate (LiPF)6) The content of (b) is 0.1 to 3mol/L, for example 1mol/L, 2mol/L or 3 mol/L.
According to an embodiment of the present invention, a conductive polymer is further included in the electrolyte.
According to an embodiment of the present invention, the conductive polymer includes, but is not limited to, at least one of polyaryl oxadiazole, polythiophene, polypyrrole, polyaniline.
According to an embodiment of the present invention, the raw materials forming the electrolyte include at least a monomer, an initiator, and an electrolytic solution.
According to an embodiment of the present invention, the electrolyte is obtained by impregnating the raw material into the inside and/or surface of the active material layer by spraying or dipping, and then heating and curing. Preferably, the electrolyte part forms an electrolyte layer on the surface of the active material layer after heat curing.
According to an embodiment of the present invention, the raw material forming the electrolyte further includes the conductive polymer.
According to the embodiment of the invention, the raw materials for forming the electrolyte comprise the following components in mass fraction: 2-10 wt% of monomer, 0.2-1 wt% of initiator, 80-95 wt% of electrolyte and 0-10 wt% of conductive polymer.
According to an embodiment of the present invention, the electrolyte is obtained by impregnating the raw material into the inside and/or surface of the active material layer by spraying or dipping, and then heating and curing. Preferably, the electrolyte part forms an electrolyte layer on the surface of the active material layer after heat curing.
According to an embodiment of the present invention, the monomer includes, but is not limited to, at least one of methyl methacrylate, hydroxyethyl methacrylate, polyethylene glycol diacrylate, trimethylolpropane triacrylate, butyl acrylate, vinyl n-butyl ether, and ethyl acetate.
According to an embodiment of the present invention, the initiator includes, but is not limited to, at least one of cumene hydroperoxide, dicumyl peroxide, di-t-butyl peroxide, dibenzoyl peroxide, lauroyl peroxide, azobisisobutyronitrile, and azobisisoheptonitrile.
According to an embodiment of the present invention, the electrolyte and the conductive polymer in the raw material are as defined above.
According to an embodiment of the invention, the functional coating has a thickness of 0.1 μm to 20 μm.
According to an embodiment of the invention, the functional coating comprises at least a second polymer. Further preferably, the functional coating further comprises a plasticizer.
According to the embodiment of the invention, the functional coating comprises the following components in percentage by mass: 30-80 wt% of second polymer, 0-50 wt% of plasticizer and 0-50 wt% of lithium salt.
Preferably, the second polymer includes, but is not limited to, at least one of polyvinylidene fluoride, polyvinyl alcohol, polytetrafluoroethylene, polyvinylidene fluoride-hexafluoropropylene copolymer, and polymethyl methacrylate. The second polymer has the main function of swelling electrolyte to ensure normal conduction of lithium ions, and simultaneously needs to have high elongation at break after film formation, so that when a foreign object punctures, the functional coating wraps the active substance coating, and the safety is improved.
Preferably, the plasticizer comprises a small molecule material. Further preferably, the small molecule material includes, but is not limited to, at least one of poly (ethylene carbonate), ethylene carbonate, succinonitrile, methyl methacrylate, and polyethylene glycol methyl ether methacrylate. The plasticizer mainly has the effects of improving the swelling of the polymer in the electrolyte, so that the ionic conductivity of the functional coating is improved, and meanwhile, the addition of the plasticizer can reduce the crystallinity of the polymer and improve the fracture elongation of the functional coating.
Preferably, the lithium salt includes, but is not limited to, at least one of lithium bistrifluoromethylsulfonyl imide, lithium bisoxalato borate and lithium difluorooxalato borate. The main function of the lithium salt is to improve the lithium ion conductivity of the functional coating.
According to an embodiment of the present invention, an active material, a binder, and a conductive agent are included in an active material layer. The active material, binder and conductive agent may be any materials known in the art, as long as the performance requirements of the active material layer are met. Illustratively, the binder includes, but is not limited to, at least one of styrene-butadiene rubber (SBR) and polyvinylidene fluoride (PVDF). Illustratively, the conductive agent includes, but is not limited to, at least one of conductive materials such as natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber, and the like. In the present invention, the content of each substance in the active material layer is not particularly limited as long as the performance requirements of the electrode sheet can be satisfied.
Preferably, in the active material layer, the active material layer further comprises a thickener including, but not limited to, sodium carboxymethylcellulose (CMC).
According to an embodiment of the present invention, when the electrode sheet is used for a positive electrode, in the electrode sheet, a current collector is selected from positive electrode current collectors, and the active material layer includes a positive electrode active material.
Preferably, the positive electrode current collector includes, but is not limited to, aluminum material, aluminum/polymer, aluminum/carbon composite. Illustratively, the aluminum material, aluminum/polymer, aluminum/carbon composite may be selected from porous or non-porous aluminum materials, aluminum/polymers, aluminum/carbon composite foils.
Preferably, the positive electrode active material includes a composite oxide containing lithium and at least one element selected from cobalt, manganese and nickel, and preferably includes at least one of lithium cobaltate, a lithium nickel manganese cobalt ternary material, lithium manganate, lithium nickel manganate, and lithium iron phosphate.
According to an embodiment of the present invention, when the electrode sheet is used for an anode, in the electrode sheet, a current collector is selected from anode current collectors, and the active material layer includes an anode active material.
Preferably, the negative electrode current collector includes, but is not limited to, copper material, copper/polymer, copper/carbon composite. Illustratively, the copper material, copper/polymer, copper/carbon composite may be selected from a porous or non-porous copper material, copper/polymer, or copper/carbon composite foil.
Preferably, the negative active material is selected from natural graphite, artificial graphite, mesophase micro carbon spheres, hard carbon, soft carbon, silicon-carbon composite, Li-Sn alloy, Li-Sn-O alloy, Sn, SnO2Spinel-structured lithiated TiO2-Li4Ti5O12And Li-Al alloy.
The invention also provides a preparation method of the electrode plate, which comprises the following steps:
1) uniformly mixing an active substance, a conductive agent and a binder to prepare electrode slurry, coating the electrode slurry on at least one surface of a current collector, drying to form an active substance layer, and performing cold pressing to obtain an electrode plate of the active substance layer;
2) dissolving a monomer, an electrolyte and an initiator in a solvent to form an electrolyte precursor solution, completely soaking the electrode slice obtained in the step 1) in the electrolyte precursor solution in a spraying or dipping mode, and heating to initiate curing to obtain the electrode slice.
According to an embodiment of the present invention, the step 2) is specifically: dissolving a monomer, an electrolyte, a conductive polymer and an initiator in a solvent to form an electrolyte precursor solution, completely soaking the electrode plate obtained in the step 1) in the electrolyte precursor solution in a spraying or dipping mode, and heating to initiate curing to obtain the electrode plate.
According to the embodiment of the invention, a functional coating is further arranged on the electrode sheet, and the functional coating specifically comprises: dissolving a second polymer, a plasticizer and lithium salt in an organic solvent, uniformly mixing to prepare coating slurry, coating the second coating slurry on the surface of the electrode plate obtained in the step 2), and carrying out forced air drying at 50-100 ℃ to obtain the functional coating.
According to an embodiment of the present invention, the active material, the conductive agent, the binder, the second polymer, the plasticizer, and the lithium salt have the meanings as described above. In the present invention, the active material layer, the functional coating layer, and the electrolyte have the meanings as described above.
According to an embodiment of the present invention, the organic solvent is a solvent commonly used by those skilled in the art, including but not limited to at least one of N, N-dimethylformamide, N-dimethylacetamide and N-methylpyrrolidone.
The invention also provides the application of the electrode plate in an energy storage battery, preferably a lithium ion battery.
The invention also provides a lithium ion battery, which comprises a positive plate, a negative plate, a diaphragm and electrolyte, wherein the diaphragm is arranged between the positive electrode and the negative electrode, and the positive plate and the negative plate are independently selected from the electrode plates.
According to an embodiment of the present invention, the functional coating layer is included in the positive electrode tab and/or the negative electrode tab.
According to an exemplary aspect of the present invention, when the positive electrode tab includes a current collector, an active material layer, and an electrolyte, the negative electrode tab includes a current collector, an active material layer, an electrolyte, and a functional coating layer.
According to an exemplary aspect of the present invention, when the positive electrode tab includes a current collector, an active material layer, an electrolyte, and a functional coating layer, the negative electrode tab includes a current collector, an active material layer, and an electrolyte.
According to an exemplary aspect of the present invention, each of the positive electrode tab and the negative electrode tab includes a current collector, an active material layer, an electrolyte, and a functional coating layer.
The invention has the beneficial effects that:
the electrode plate of the lithium ion battery prepared by using the electrode plate comprises the functional coating, so that the electrode plate has high extension, electronic insulation property and ion conduction property, when the battery is punctured by a foreign object, the functional coating plays a role in wrapping active substances in the electrode plate, the area of a region where short circuit occurs between a positive electrode and a negative electrode can be greatly reduced, even avoided, and the needling safety of the battery is improved. Meanwhile, due to the existence of the in-situ solidified electrolyte, the lithium ion conduction in the pole piece depends on the solidified electrolyte, the active substance is not in direct contact with the liquid electrolyte, the occurrence of series side reactions of the active substance and the liquid electrolyte is greatly reduced, the solidified electrolyte and the active substance have higher thermal stability under an overheat condition, and the safety of the battery under the overheat condition is improved.
According to the electrode plate, the conductive polymer is added into the electrolyte, so that the electrode plate has electronic and ionic conductivity characteristics, the electrolyte is obtained in the inner part and/or the surface of the active material layer through infiltration and in-situ curing, and the problem that the functional coating slurry with the electronic insulation characteristic is directly coated on the surface of the electrode plate to wrap the active material, so that the electronic resistance in the electrode plate is increased. Therefore, the method can reduce the influence of a single-function coating mode on the increase of the internal resistance of the battery and ensure the electrical property of the battery by constructing the in-situ solidified electrolyte.
Drawings
Fig. 1 is a schematic structural view of an electrode sheet according to a preferred embodiment of the present invention;
fig. 2 is a schematic structural view of an electrode sheet according to another preferred embodiment of the present invention;
wherein, 1 is a current collector, 2 is an active material layer (containing solidified electrolyte inside), 3 is a solidified electrolyte layer, and 4 is a functional coating.
Detailed Description
The technical solution of the present invention will be further described in detail with reference to specific embodiments. It is to be understood that the following examples are only illustrative and explanatory of the present invention and should not be construed as limiting the scope of the present invention. All the technologies realized based on the above-mentioned contents of the present invention are covered in the protection scope of the present invention.
Unless otherwise indicated, the raw materials and reagents used in the following examples are all commercially available products or can be prepared by known methods.
The electrolyte used hereinafter refers to common commercial electrolyte, and specifically includes: lithium hexafluorophosphate (LiPF)6) Dissolving in a mixed solvent composed of Ethylene Carbonate (EC), dimethyl carbonate (DEC) and Ethyl Methyl Carbonate (EMC) (the mass ratio of the three is 1:1:1), and LiPF6The concentration is about 1 mol/L. The positive electrode active materials used hereinafter are all commercially available NCM high nickel 8-based positive electrodes.
Example 1
Firstly, preparing a positive plate containing an in-situ curing electrolyte and a functional coating:
1) uniformly mixing an NCM high-nickel 8-series positive electrode (positive active material), conductive agent superconducting carbon (Super-P) and a binder polyvinylidene fluoride (PVDF) according to a mass ratio of 97:1.5:1.5 to prepare positive slurry, coating the positive slurry on two surfaces of a current collector aluminum foil, drying at 100 ℃ to form a positive active material layer, and performing cold pressing to obtain a positive plate containing the active material layer;
2) uniformly mixing polyethylene glycol diacrylate, polyaryl oxadiazole, azodiisobutyronitrile and commercial electrolyte according to the mass ratio of 3:1:0.03:95.97 to obtain a uniform precursor solution, completely soaking the positive plate containing the active material layer prepared in the step 1) into the precursor solution in a spraying mode, heating at 60 ℃ to cure the precursor solution in situ, and controlling the thickness of a solidified electrolyte layer on the surface of the positive plate to be 1 mu m to obtain the positive plate containing solidified electrolyte;
3) dissolving polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene carbonate and lithium bis (trifluoromethyl) sulfonyl imide in an organic solvent N, N-Dimethylacetamide (DMAC) according to a mass ratio of 70:10:20, uniformly mixing to prepare coating slurry, coating the coating slurry on the surface of a positive plate containing a solidified electrolyte, and performing forced air drying at 80 ℃ to obtain a functional coating with the thickness of 10 mu m, so as to obtain the positive plate containing the in-situ solidified electrolyte and the functional coating;
4) and 3) carrying out edge cutting, sheet cutting and slitting on the positive plate obtained in the step 3), and taking the positive plate as a positive plate of the lithium ion battery after slitting.
Secondly, preparing the negative plate containing the in-situ solidified electrolyte:
1') preparing negative electrode slurry from negative electrode active material graphite, conductive agent superconducting carbon (Super-P), thickening agent carboxymethyl cellulose sodium (CMC) and binder Styrene Butadiene Rubber (SBR) according to the mass ratio of 96.5:1.0:1.0:1.5, coating the negative electrode slurry on a current collector copper foil, drying the current collector copper foil at 90 ℃ to form a negative electrode active material layer, and carrying out cold pressing to obtain a negative electrode sheet containing the negative electrode active material layer;
2 ') uniformly mixing polyethylene glycol diacrylate, polyaryl oxadiazole, azodiisobutyronitrile and commercial electrolyte according to the mass ratio of 3:1:0.03:95.97 to obtain a uniform precursor solution, then completely soaking the cathode sheet in the step 1 ') into the precursor solution in a spraying manner, and heating and curing at 80 ℃ on the surface of the cathode sheet in the step 1 ') to obtain a cured electrolyte layer with the thickness of 1 mu m;
3 ') cutting edges, cutting pieces and dividing strips of the negative pole pieces obtained in the step 2') to obtain the negative pole pieces of the lithium ion battery.
Thirdly, preparing electrolyte: prepared according to the above-mentioned general commercial electrolyte.
Fourthly, preparing the lithium ion battery: winding the positive plate, the negative plate and the diaphragm into a battery cell, wherein the design capacity of the battery cell is 5Ah, the diaphragm is positioned between the adjacent positive plate and negative plate, the positive plate is led out by aluminum tab spot welding, and the negative plate is led out by nickel tab spot welding; then the electric core is placed in an aluminum-plastic packaging bag, the electrolyte is injected after baking, and finally the lithium ion battery is prepared after the processes of packaging, formation, sorting and the like.
Example 2
Firstly, preparing a positive plate containing an in-situ solidified electrolyte and a functional coating:
1) uniformly mixing an NCM high-nickel 8-series positive electrode (positive active material), conductive agent superconducting carbon (Super-P) and a binder polyvinylidene fluoride (PVDF) according to a mass ratio of 97:1.5:1.5 to prepare positive slurry, coating the positive slurry on two surfaces of a current collector aluminum foil, drying at 100 ℃ to form a positive active material layer, and performing cold pressing to obtain a positive plate containing the active material layer;
2) uniformly mixing trimethylolpropane triacrylate, polyaryl oxadiazole and azodiisobutyronitrile with commercial electrolyte according to the mass ratio of 3:1:0.03:95.97 to obtain a uniform precursor solution, then completely soaking the positive plate containing the active material layer prepared in the step 1) into the precursor solution in a spraying mode, heating at 80 ℃ to cure the precursor solution in situ, and controlling the thickness of a solidified electrolyte layer on the surface of the positive plate to be 1 mu m to obtain the positive plate containing the solidified electrolyte;
3) dissolving polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene carbonate and lithium bis (trifluoromethyl) sulfonyl imide in an organic solvent DMAC (dimethylacetamide) according to a mass ratio of 70:10:20, uniformly mixing to prepare coating slurry, coating the coating slurry on the surface of a positive plate containing a precursor solution, and performing forced air drying at 80 ℃ to obtain a functional coating with the thickness of 5 mu m, so as to obtain the positive plate containing an in-situ curing electrolyte and the functional coating;
4) and 3) carrying out edge cutting, sheet cutting and slitting on the positive plate obtained in the step 3), and taking the positive plate as a positive plate of the lithium ion battery after slitting.
Secondly, preparing the negative plate containing the in-situ solidified electrolyte:
1') preparing negative electrode slurry from negative electrode active material graphite, conductive agent superconducting carbon (Super-P), thickening agent carboxymethyl cellulose sodium (CMC) and binder Styrene Butadiene Rubber (SBR) according to the mass ratio of 96.5:1.0:1.0:1.5, coating the negative electrode slurry on a current collector copper foil, drying the current collector copper foil at 90 ℃ to form a negative electrode active material layer, and carrying out cold pressing to obtain a negative electrode sheet containing the negative electrode active material layer;
2 ') uniformly mixing trimethylolpropane triacrylate, polyaryl oxadiazole, azodiisobutyronitrile and commercial electrolyte according to the mass ratio of 3:1:0.03:95.97 to obtain a uniform precursor solution, then completely soaking the cathode sheet into the precursor solution in a spraying mode, heating and curing at 80 ℃ to obtain the cathode sheet of the solidified electrolyte layer with the thickness of 1 mu m on the surface of the cathode sheet in the step 1');
3 ') cutting edges, cutting pieces and dividing strips of the negative pole pieces obtained in the step 2') to obtain the negative pole pieces of the lithium ion battery.
Preparing electrolyte and a lithium ion battery: same as in example 1.
Example 3
Firstly, preparing a positive plate containing an in-situ solidified electrolyte and a functional coating:
1) uniformly mixing an NCM8 series positive electrode (positive active material), conductive agent superconducting carbon (Super-P) and binder polyvinylidene fluoride (PVDF) according to the mass ratio of 97:1.5:1.5 to prepare positive slurry, coating the positive slurry on two surfaces of a current collector aluminum foil, drying at 100 ℃ to form a positive active material layer, and carrying out cold pressing to obtain a positive plate containing the active material layer;
2) uniformly mixing trimethylolpropane triacrylate, azobisisobutyronitrile and commercial electrolyte according to the mass ratio of 3:0.03:96.97 to obtain a uniform precursor solution, then completely soaking the positive plate containing the active material layer prepared in the step 1) into the precursor solution in a spraying manner, heating at 80 ℃ to cure the precursor solution in situ, and controlling the thickness of a cured electrolyte layer on the surface of the positive plate to be 1 mu m to obtain the positive plate containing the cured electrolyte;
3) dissolving polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene carbonate and lithium bis (trifluoromethyl) sulfonyl imide in an organic solvent DMAC (dimethylacetamide) according to a mass ratio of 70:10:20, uniformly mixing to prepare coating slurry, coating the coating slurry on the surface of a positive plate containing a precursor solution, and performing forced air drying at 80 ℃ to obtain a functional coating with the thickness of 5 mu m, so as to obtain the positive plate containing an in-situ curing electrolyte and the functional coating;
4) and 3) carrying out edge cutting, sheet cutting and slitting on the positive plate obtained in the step 3), and taking the positive plate as a positive plate of the lithium ion battery after slitting.
Secondly, preparing the negative plate containing the in-situ solidified electrolyte:
1') preparing graphite, conductive agent superconducting carbon (Super-P), thickening agent carboxymethyl cellulose sodium (CMC) and binder Styrene Butadiene Rubber (SBR) into negative electrode slurry according to the mass ratio of 96.5:1.0:1.0:1.5, coating the negative electrode slurry on a current collector copper foil, drying the current collector copper foil at 90 ℃ to form a negative electrode active substance layer, and then carrying out cold pressing to obtain a negative electrode sheet containing the negative electrode active substance layer;
2 ') uniformly mixing trimethylolpropane triacrylate, azobisisobutyronitrile and commercial electrolyte according to the mass ratio of 3:0.03:96.97 to obtain a uniform precursor solution, then completely soaking the cathode sheet obtained in the step 1') into the precursor solution in a spraying manner, and heating and curing at 80 ℃ to obtain the cathode sheet with the surface thickness of 1 mu m and a cured electrolyte layer;
3 ') cutting edges, cutting pieces and dividing into strips of the negative pole pieces obtained in the step 2'), and taking the negative pole pieces as the negative pole pieces of the lithium ion battery after the strips are divided.
Preparing electrolyte and a lithium ion battery: same as in example 1.
Example 4
Firstly, preparing a positive plate containing an in-situ solidified electrolyte and a functional coating:
1) uniformly mixing an NCM high-nickel 8-series positive electrode (positive active material), conductive agent superconducting carbon (Super-P) and a binder polyvinylidene fluoride (PVDF) according to a mass ratio of 97:1.5:1.5 to prepare positive slurry, coating the positive slurry on two surfaces of a current collector aluminum foil, drying at 100 ℃ to form a positive active material layer, and performing cold pressing to obtain a positive plate containing the active material layer;
2) uniformly mixing trimethylolpropane triacrylate, polyaniline, azodiisobutyronitrile and commercial electrolyte according to the mass ratio of 7:1:0.07:91.93 to obtain a uniform precursor solution, then completely soaking the positive plate containing the active material layer prepared in the step 1) into the precursor solution in a spraying mode, heating at 80 ℃ to solidify the precursor solution, and controlling the thickness of a solidified electrolyte layer on the surface of the positive plate to be 1 mu m to obtain the positive plate containing the solidified electrolyte;
3) dissolving polyvinylidene fluoride-hexafluoropropylene copolymer, methyl methacrylate and lithium bis (trifluoromethyl) sulfonyl imide in an organic solvent N, N-Dimethylformamide (DMF) according to a mass ratio of 70:10:20, uniformly mixing to prepare coating slurry, coating the coating slurry on the surface of a positive plate containing a precursor solution, and performing forced air drying at 80 ℃ to obtain a functional coating with the thickness of 5 mu m, so as to obtain the positive plate containing an in-situ curing electrolyte and the functional coating;
4) and 3) carrying out edge cutting, sheet cutting and slitting on the positive plate obtained in the step 3), and taking the positive plate as a positive plate of the lithium ion battery after slitting.
Secondly, preparing the negative plate containing the in-situ solidified electrolyte:
1') preparing negative electrode slurry by using negative electrode active material graphite, a conductive agent superconducting carbon (Super-P), a thickening agent sodium carboxymethyl cellulose (CMC) and a binder Styrene Butadiene Rubber (SBR) according to a mass ratio of 96.5:1.0:1.0:1.5, coating the negative electrode slurry on a current collector copper foil, drying the current collector copper foil at 90 ℃ to form a negative electrode active material layer, and performing cold pressing to obtain a negative electrode sheet containing the negative electrode active material layer;
2 ') uniformly mixing trimethylolpropane triacrylate, polyaniline, azodiisobutyronitrile and commercial electrolyte according to the mass ratio of 7:1:0.07:91.93 to obtain a uniform precursor solution, then completely soaking the cathode plate in the step 1') into the precursor solution in a spraying mode, and heating and curing at 80 ℃ to obtain the cathode plate with a cured electrolyte layer with the thickness of 1 mu m on the surface;
3 ') cutting edges, cutting pieces and dividing into strips of the negative pole pieces obtained in the step 2'), and taking the negative pole pieces as the negative pole pieces of the lithium ion battery after the strips are divided.
Preparing electrolyte and a lithium ion battery: same as in example 1.
Example 5
Firstly, preparing a positive plate containing an in-situ solidified electrolyte and a functional coating:
1) uniformly mixing an NCM8 series positive electrode (positive active material), conductive agent superconducting carbon (Super-P) and binder polyvinylidene fluoride (PVDF) according to the mass ratio of 97:1.5:1.5 to prepare positive slurry, coating the positive slurry on two surfaces of a current collector aluminum foil, drying at 100 ℃ to form a positive active material layer, and carrying out cold pressing to obtain a positive plate containing the active material layer;
2) uniformly mixing polyethylene glycol diacrylate, polyaryl oxadiazole, azodiisobutyronitrile and commercial electrolyte according to the mass ratio of 3:1:0.03:95.97 to obtain a uniform precursor solution, then completely soaking the positive plate containing the active material layer prepared in the step 1) into the precursor solution in a spraying mode, heating at 80 ℃ to solidify the precursor solution, and controlling the thickness of a solidified electrolyte layer on the surface of the positive plate to be 5 microns to obtain the positive plate containing solidified electrolyte;
3) dissolving polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene carbonate and lithium bis (trifluoromethyl) sulfonyl imide in an organic solvent DMAC (dimethylacetamide) according to a mass ratio of 70:10:20, uniformly mixing to prepare coating slurry, coating the coating slurry on the surface of a positive plate containing a precursor solution, and performing forced air drying at 80 ℃ to obtain a functional coating with the thickness of 10 mu m, so as to obtain the positive plate containing an in-situ curing electrolyte and the functional coating;
4) and 3) carrying out edge cutting, sheet cutting and slitting on the positive plate obtained in the step 3), and taking the positive plate as a positive plate of the lithium ion battery after slitting.
Secondly, preparing the negative plate containing the in-situ solidified electrolyte:
1') preparing negative electrode slurry by using negative electrode active material graphite, a conductive agent superconducting carbon (Super-P), a thickening agent sodium carboxymethyl cellulose (CMC) and a binder Styrene Butadiene Rubber (SBR) according to a mass ratio of 96.5:1.0:1.0:1.5, coating the negative electrode slurry on a current collector copper foil, drying the current collector copper foil at 90 ℃ to form a negative electrode active material layer, and performing cold pressing to obtain a negative electrode sheet containing the negative electrode active material layer;
2 ') uniformly mixing polyethylene glycol diacrylate, polyaryl oxadiazole, azodiisobutyronitrile and commercial electrolyte according to the mass ratio of 3:1:0.03:95.97 to obtain a uniform precursor solution, then completely soaking the cathode sheet in the step 1') into the precursor solution in a spraying mode, and heating and curing at 80 ℃ to obtain the cathode sheet with a solidified electrolyte layer with the thickness of 5 mu m on the surface;
3 ') cutting edges, cutting pieces and dividing into strips of the negative pole pieces obtained in the step 2'), and taking the negative pole pieces as the negative pole pieces of the lithium ion battery after the strips are divided.
Preparing electrolyte and a lithium ion battery: same as in example 1.
Example 6
Firstly, preparing a positive plate containing an in-situ solidified electrolyte and a functional coating:
1) uniformly mixing an NCM8 series positive electrode (positive active material), conductive agent superconducting carbon (Super-P) and binder polyvinylidene fluoride (PVDF) according to the mass ratio of 97:1.5:1.5 to prepare positive slurry, coating the positive slurry on two surfaces of a current collector aluminum foil, drying at 100 ℃ to form a positive active material layer, and carrying out cold pressing to obtain a positive plate containing the active material layer;
2) uniformly mixing trimethylolpropane triacrylate, polyaryl oxadiazole, azodiisobutyronitrile and commercial electrolyte according to the mass ratio of 3:1:0.03:95.97 to obtain a uniform precursor solution, then completely soaking the positive plate containing the active material layer prepared in the step 1) into the precursor solution in a spraying mode, heating and curing at 80 ℃, and controlling the thickness of a cured electrolyte layer on the surface of the positive plate to be 1 mu m to obtain the positive plate containing the cured electrolyte;
3) dissolving polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene carbonate and lithium bis (trifluoromethyl) sulfonyl imide in an organic solvent DMAC (dimethylacetamide) according to a mass ratio of 60:10:30, uniformly mixing to prepare coating slurry, coating the coating slurry on the surface of a positive plate containing a precursor solution, and performing forced air drying at 80 ℃ to obtain a functional coating with the thickness of 5 mu m, so as to obtain the positive plate containing an in-situ curing electrolyte and the functional coating;
4) and 3) carrying out edge cutting, sheet cutting and slitting on the positive plate obtained in the step 3), and taking the positive plate as a positive plate of the lithium ion battery after slitting.
Secondly, preparing the negative plate containing the in-situ solidified electrolyte:
1') preparing negative electrode slurry by using negative electrode active material graphite, a conductive agent superconducting carbon (Super-P), a thickening agent sodium carboxymethyl cellulose (CMC) and a binder Styrene Butadiene Rubber (SBR) according to a mass ratio of 96.5:1.0:1.0:1.5, coating the negative electrode slurry on a current collector copper foil, drying the current collector copper foil at 90 ℃ to form a negative electrode active material layer, and performing cold pressing to obtain a negative electrode sheet containing the negative electrode active material layer;
2 ') uniformly mixing trimethylolpropane triacrylate, polyaryl oxadiazole, azodiisobutyronitrile and commercial electrolyte according to the mass ratio of 3:1:0.03:95.97 to obtain a uniform precursor solution, then completely soaking the negative plate obtained in the step 1') into the precursor solution in a spraying mode, and heating and curing at 80 ℃ to obtain a cured electrolyte layer with the surface thickness of 1 mu m of the plate;
3 ') cutting edges, cutting pieces and dividing strips of the negative pole pieces obtained in the step 2') to obtain the negative pole pieces of the lithium ion battery.
Preparing electrolyte and a lithium ion battery: same as in example 1.
Example 7
Firstly, preparing a positive plate containing an in-situ solidified electrolyte and a functional coating:
1) uniformly mixing an NCM8 series positive electrode (positive active material), conductive agent superconducting carbon (Super-P) and binder polyvinylidene fluoride (PVDF) according to the mass ratio of 97:1.5 to prepare positive slurry, coating the positive slurry on two surfaces of a current collector aluminum foil, drying at 100 ℃ to form a positive active material layer, and carrying out cold pressing to obtain a positive plate containing the active material layer;
2) uniformly mixing trimethylolpropane triacrylate, polyaryl oxadiazole, azodiisobutyronitrile and commercial electrolyte according to the mass ratio of 3:1:0.03:95.97 to obtain a uniform precursor solution, then completely soaking the positive plate containing the active material layer prepared in the step 1) into the precursor solution in a spraying mode, heating and curing at 80 ℃, and controlling the thickness of a cured electrolyte layer on the surface of the positive plate to be 1 mu m to obtain the positive plate containing the cured electrolyte;
3) dissolving polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene carbonate and lithium bis (trifluoromethyl) sulfonyl imide in an organic solvent DMAC (dimethylacetamide) according to a mass ratio of 70:10:20, uniformly mixing to prepare coating slurry, coating the coating slurry on the surface of a positive plate containing a precursor solution, and performing forced air drying at 80 ℃ to obtain a functional coating with the thickness of 5 mu m, so as to obtain the positive plate containing an in-situ curing electrolyte and the functional coating;
4) and 3) trimming, cutting and slitting the positive plate obtained in the step 3), and slitting the positive plate to obtain the positive plate of the lithium ion battery.
Secondly, preparing a negative plate containing the in-situ solidified electrolyte and the functional coating:
1') preparing graphite, conductive agent Super-conductive carbon (Super-P), thickening agent carboxymethyl cellulose sodium (CMC) and binder Styrene Butadiene Rubber (SBR) into negative electrode slurry according to the mass ratio of 96.5:1.0:1.0:1.5, coating the negative electrode slurry on a current collector copper foil, drying the current collector copper foil at 90 ℃ to form a negative electrode active substance layer, and then carrying out cold pressing to obtain a negative electrode sheet containing the negative electrode active substance layer;
2 ') uniformly mixing trimethylolpropane triacrylate, polyaryl oxadiazole, azodiisobutyronitrile and commercial electrolyte according to the mass ratio of 3:1:0.03:95.97 to obtain a uniform precursor solution, then completely soaking the negative plate obtained in the step 1') into the precursor solution in a spraying mode, heating and curing at 80 ℃, and controlling the thickness of a cured electrolyte layer on the surface of the plate to be 1 mu m to obtain the negative plate containing the cured electrolyte;
3 ') dissolving polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinyl carbonate and lithium bis (trifluoromethyl) sulfonyl imide in an organic solvent DMAC (dimethylacetamide) according to a mass ratio of 70:10:20, uniformly mixing to prepare coating slurry, coating the coating slurry on the surface of the negative plate obtained in the step 2'), and performing air blast drying at 80 ℃ to obtain a functional coating with the thickness of 5 mu m, so as to obtain the negative plate containing the in-situ cured electrolyte and the functional coating;
and 4 ') cutting edges, cutting pieces and dividing strips of the negative pole pieces obtained in the step 3') to obtain the negative pole pieces of the lithium ion battery.
Preparing electrolyte and a lithium ion battery: same as in example 1.
Example 8
Firstly, preparing a positive plate containing in-situ solidified electrolyte:
1) uniformly mixing an NCM8 series positive electrode (positive active material), conductive agent superconducting carbon (Super-P) and binder polyvinylidene fluoride (PVDF) according to the mass ratio of 97:1.5:1.5 to prepare positive slurry, coating the positive slurry on two surfaces of a current collector aluminum foil, drying at 100 ℃ to form a positive active material layer, and carrying out cold pressing to obtain a positive plate containing the active material layer;
2) uniformly mixing trimethylolpropane triacrylate, polyaryl oxadiazole, azodiisobutyronitrile and commercial electrolyte according to the mass ratio of 3:1:0.03:95.97 to obtain a uniform precursor solution, then completely soaking the positive plate containing the active material layer prepared in the step 1) into the precursor solution in a spraying mode, and heating and curing at 80 ℃ to obtain a cured electrolyte layer with the surface thickness of 1 micron of the plate;
3) and 3) cutting edges, cutting pieces and slitting the positive plate obtained in the step 2), and taking the positive plate as a positive plate of the lithium ion battery after slitting.
Secondly, preparing a negative plate containing the in-situ solidified electrolyte and the functional coating:
1') preparing negative electrode slurry by using negative electrode active material graphite, a conductive agent superconducting carbon (Super-P), a thickening agent sodium carboxymethyl cellulose (CMC) and a binder Styrene Butadiene Rubber (SBR) according to a mass ratio of 96.5:1.0:1.0:1.5, coating the negative electrode slurry on a current collector copper foil, drying the current collector copper foil at 90 ℃ to form a negative electrode active material layer, and performing cold pressing to obtain a negative electrode sheet containing the negative electrode active material layer;
2 ') uniformly mixing trimethylolpropane triacrylate, polyaryl oxadiazole, azodiisobutyronitrile and commercial electrolyte according to the mass ratio of 3:1:0.03:95.97 to obtain a uniform precursor solution, then completely soaking the negative plate obtained in the step 1') into the precursor solution in a spraying mode, heating and curing at 80 ℃, and controlling the thickness of a cured electrolyte layer on the surface of the plate to be 1 mu m to obtain the negative plate containing the cured electrolyte;
3 ') dissolving polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinyl carbonate and lithium bis (trifluoromethyl) sulfonyl imide in an organic solvent DMAC (dimethylacetamide) according to a mass ratio of 70:10:20, uniformly mixing to prepare coating slurry, coating the coating slurry on the surface of the negative plate obtained in the step 2'), and performing air blast drying at 80 ℃ to obtain a functional coating with the thickness of 5 mu m, so as to obtain the negative plate containing the in-situ cured electrolyte and the functional coating;
and 4 ') cutting edges, cutting pieces and dividing strips of the negative pole pieces obtained in the step 3') to obtain the negative pole pieces of the lithium ion battery.
Preparing electrolyte and a lithium ion battery: same as in example 1.
Comparative example 1
Firstly, preparing a positive plate:
1) uniformly mixing an NCM8 series positive electrode (positive active material), conductive agent superconducting carbon (Super-P) and binder polyvinylidene fluoride (PVDF) according to the mass ratio of 97:1.5:1.5 to prepare positive slurry, coating the positive slurry on two surfaces of a current collector aluminum foil, drying at 100 ℃ to form a positive active material layer, and carrying out cold pressing to obtain a positive plate containing the active material layer;
2) and 3) trimming, cutting and slitting the positive plate obtained in the step 1), and slitting the positive plate to obtain the positive plate of the lithium ion battery.
Secondly, preparing a negative plate:
1') preparing graphite, conductive agent Super-conductive carbon (Super-P), thickening agent carboxymethyl cellulose sodium (CMC) and binder Styrene Butadiene Rubber (SBR) into negative electrode slurry according to the mass ratio of 96.5:1.0:1.0:1.5, coating the negative electrode slurry on a current collector copper foil, drying the current collector copper foil at 90 ℃ to form a negative electrode active substance layer, and then carrying out cold pressing to obtain a negative electrode sheet containing the negative electrode active substance layer;
2 ') cutting edges, cutting pieces and dividing strips of the negative pole pieces obtained in the step 1') to obtain the negative pole pieces of the lithium ion battery.
Preparing electrolyte and a lithium ion battery: same as in example 1.
Comparative example 2
Firstly, preparing a positive plate containing a functional coating:
1) uniformly mixing an NCM8 series positive electrode (positive active material), conductive agent superconducting carbon (Super-P) and binder polyvinylidene fluoride (PVDF) according to the mass ratio of 97:1.5:1.5 to prepare positive slurry, coating the positive slurry on two surfaces of a current collector aluminum foil, drying at 100 ℃ to form a positive active material layer, and carrying out cold pressing to obtain a positive plate containing the active material layer;
2) dissolving polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene glycol methyl ether methacrylate and lithium bis (trifluoromethyl) sulfonyl imide in an organic solvent DMAC (dimethylacetamide) according to a mass ratio of 70:10:20, uniformly mixing to prepare coating slurry, coating the coating slurry on the surface of a positive active material layer, and performing air drying at 80 ℃ to obtain a functional coating with the thickness of 6 microns;
3) and 3) cutting edges, cutting pieces and slitting the positive plate obtained in the step 2), and taking the positive plate as a positive plate of the lithium ion battery after slitting.
Secondly, preparing a negative plate: same as in example 1.
Preparing electrolyte and a lithium ion battery: same as in comparative example 1.
Comparative example 3
Firstly, preparing a positive plate containing in-situ solidified electrolyte:
1) uniformly mixing an NCM8 series positive electrode (positive active material), conductive agent superconducting carbon (Super-P) and binder polyvinylidene fluoride (PVDF) according to the mass ratio of 97:1.5:1.5 to prepare positive slurry, coating the positive slurry on two surfaces of a current collector aluminum foil, drying at 100 ℃ to form a positive active material layer, and carrying out cold pressing to obtain a positive plate containing the active material layer;
2) uniformly mixing trimethylolpropane triacrylate, polyaryl oxadiazole, azodiisobutyronitrile and commercial electrolyte according to the mass ratio of 3:1:0.03:95.97 to obtain a uniform precursor solution, then completely soaking the positive plate containing the active material layer prepared in the step 1) into the precursor solution in a spraying mode, heating at 80 ℃ and carrying out in-situ curing to obtain the positive plate containing the solidified electrolyte layer with the thickness of 6 microns on the surface;
3) and 3) cutting edges, cutting pieces and strips of the positive plate containing the solidified electrolyte in the step 2), and taking the positive plate as the positive plate of the lithium ion battery after the strips are cut.
Secondly, preparing the negative plate containing the in-situ solidified electrolyte:
1') preparing negative electrode slurry by using negative electrode active material graphite, a conductive agent superconducting carbon (Super-P), a thickening agent sodium carboxymethyl cellulose (CMC) and a binder Styrene Butadiene Rubber (SBR) according to a mass ratio of 96.5:1.0:1.0:1.5, coating the negative electrode slurry on a current collector copper foil, drying the current collector copper foil at 90 ℃ to form a negative electrode active material layer, and performing cold pressing to obtain a negative electrode sheet containing the negative electrode active material layer;
2 ') uniformly mixing trimethylolpropane triacrylate, polyaryl oxadiazole, azodiisobutyronitrile and commercial electrolyte according to the mass ratio of 3:1:0.03:95.97 to obtain a uniform precursor solution, then completely soaking the negative plate obtained in the step 1') into the precursor solution in a spraying mode, heating at 80 ℃ and curing in situ to obtain the negative plate with the surface containing a cured electrolyte layer with the thickness of 6 microns;
3 ') cutting edges, cutting pieces and dividing the negative pole pieces containing the solidified electrolyte in the step 2') into strips to be used as the negative pole pieces of the lithium ion battery.
Preparing electrolyte and a lithium ion battery: same as in example 1.
Comparative example 4
Firstly, preparing a positive plate containing in-situ solidified electrolyte:
1) uniformly mixing an NCM8 series positive electrode (positive active material), conductive agent superconducting carbon (Super-P) and binder polyvinylidene fluoride (PVDF) according to the mass ratio of 97:1.5:1.5 to prepare positive slurry, coating the positive slurry on two surfaces of a current collector aluminum foil, drying at 100 ℃ to form a positive active material layer, and carrying out cold pressing to obtain a positive plate containing the active material layer;
2) uniformly mixing trimethylolpropane triacrylate, polyaryl oxadiazole, azodiisobutyronitrile and commercial electrolyte according to the mass ratio of 3:1:0.03:95.97 to obtain a uniform precursor solution, then completely soaking the positive plate containing the active material layer prepared in the step 1) into the precursor solution in a spraying mode, heating at 80 ℃ and carrying out in-situ curing to obtain the positive plate containing the solidified electrolyte layer with the thickness of 6 microns on the surface;
3) and 3) cutting edges, cutting pieces and strips of the positive plate containing the solidified electrolyte in the step 2), and taking the positive plate as the positive plate of the lithium ion battery after the strips are cut.
Secondly, preparing the negative plate with the functional coating:
1') preparing negative electrode slurry by using negative electrode active material graphite, a conductive agent superconducting carbon (Super-P), a thickening agent sodium carboxymethyl cellulose (CMC) and a binder Styrene Butadiene Rubber (SBR) according to a mass ratio of 96.5:1.0:1.0:1.5, coating the negative electrode slurry on a current collector copper foil, drying the current collector copper foil at 90 ℃ to form a negative electrode active material layer, and performing cold pressing to obtain a negative electrode sheet containing the negative electrode active material layer;
2 ') dissolving polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinyl carbonate and lithium bis (trifluoromethyl) sulfonyl imide in an organic solvent DMAC (dimethylacetamide) according to a mass ratio of 70:10:20, uniformly mixing to prepare coating slurry, coating the coating slurry on the surface of the negative plate obtained in the step 1'), and performing air blast drying at 80 ℃ to obtain a functional coating with the thickness of 5 mu m, so as to obtain the negative plate containing the functional coating;
3 ') cutting edges, cutting pieces and dividing strips of the negative pole pieces obtained in the step 2') to obtain the negative pole pieces of the lithium ion battery.
Preparing electrolyte and a lithium ion battery: same as in example 1.
Comparative example 5
Firstly, preparing a positive plate containing a functional coating:
1) uniformly mixing an NCM8 series positive electrode (positive active material), conductive agent superconducting carbon (Super-P) and binder polyvinylidene fluoride (PVDF) according to the mass ratio of 97:1.5:1.5 to prepare positive slurry, coating the positive slurry on two surfaces of a current collector aluminum foil, drying at 100 ℃ to form a positive active material layer, and carrying out cold pressing to obtain a positive plate containing the active material layer;
2) dissolving polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene carbonate and lithium bis (trifluoromethyl) sulfonyl imide in an organic solvent DMAC (dimethylacetamide) according to a mass ratio of 70:10:20, uniformly mixing to prepare coating slurry, coating the coating slurry on the surface of a positive plate, and performing forced air drying at 80 ℃ to obtain a functional coating with the thickness of 10 mu m, so as to obtain the positive plate only containing the functional coating;
3) and 3) cutting edges, cutting pieces and slitting the positive plate obtained in the step 2), and taking the positive plate as a positive plate of the lithium ion battery after slitting.
Secondly, preparing a negative plate containing the in-situ solidified electrolyte and the functional coating:
1') preparing graphite, conductive agent Super-conductive carbon (Super-P), thickening agent carboxymethyl cellulose sodium (CMC) and binder Styrene Butadiene Rubber (SBR) into negative electrode slurry according to the mass ratio of 96.5:1.0:1.0:1.5, coating the negative electrode slurry on a current collector copper foil, drying the current collector copper foil at 90 ℃ to form a negative electrode active substance layer, and then carrying out cold pressing to obtain a negative electrode sheet containing the negative electrode active substance layer;
2 ') uniformly mixing polyethylene glycol diacrylate, polyaryl oxadiazole, azodiisobutyronitrile and commercial electrolyte according to the mass ratio of 3:1:0.03:95.97 to obtain a uniform precursor solution, then completely soaking the cathode sheet obtained in the step 1') into the precursor solution in a spraying mode, heating at 80 ℃ to solidify the precursor solution, and controlling the thickness of a solidified electrolyte layer on the surface of the cathode sheet to be 5 microns to obtain a cathode sheet containing solidified electrolyte;
3 ') dissolving polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinyl carbonate and lithium bis (trifluoromethyl) sulfonyl imide in an organic solvent DMAC (dimethylacetamide) according to a mass ratio of 70:10:20, uniformly mixing to prepare coating slurry, coating the coating slurry on the surface of the negative plate obtained in the step 2'), and performing air blast drying at 80 ℃ to obtain a functional coating with the thickness of 10 mu m, so as to obtain the negative plate containing the in-situ cured electrolyte and the functional coating;
and 4 ') cutting edges, cutting pieces and dividing strips of the negative pole pieces obtained in the step 3') to obtain the negative pole pieces of the lithium ion battery.
Preparing electrolyte and a lithium ion battery: same as in example 1.
Comparative example 6
Firstly, preparing a positive plate containing a functional coating:
1) uniformly mixing an NCM8 series positive electrode (positive active material), conductive agent superconducting carbon (Super-P) and binder polyvinylidene fluoride (PVDF) according to the mass ratio of 97:1.5:1.5 to prepare positive slurry, coating the positive slurry on two surfaces of a current collector aluminum foil, drying at 100 ℃ to form a positive active material layer, and carrying out cold pressing to obtain a positive plate containing the active material layer;
2) dissolving polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene carbonate and lithium bis (trifluoromethyl) sulfonyl imide in an organic solvent DMAC (dimethylacetamide) according to a mass ratio of 60:10:30, uniformly mixing to prepare coating slurry, coating the coating slurry on the surface of a positive plate, and performing forced air drying at 80 ℃ to obtain a functional coating with the thickness of 5 mu m, thereby obtaining the positive plate containing the functional coating;
3) and 3) cutting edges, cutting pieces and slitting the positive plate obtained in the step 2), and taking the positive plate as a positive plate of the lithium ion battery after slitting.
Secondly, preparing the negative plate containing the in-situ solidified electrolyte and the functional coating:
1') preparing graphite, conductive agent Super-conductive carbon (Super-P), thickening agent carboxymethyl cellulose sodium (CMC) and binder Styrene Butadiene Rubber (SBR) into negative electrode slurry according to the mass ratio of 96.5:1.0:1.0:1.5, coating the negative electrode slurry on a current collector copper foil, drying the current collector copper foil at 90 ℃ to form a negative electrode active substance layer, and then carrying out cold pressing to obtain a negative electrode sheet containing the negative electrode active substance layer;
2 ') uniformly mixing trimethylolpropane triacrylate, polyaryl oxadiazole, azodiisobutyronitrile and commercial electrolyte according to the mass ratio of 3:1:0.03:95.97 to obtain a uniform precursor solution, then completely soaking the negative plate obtained in the step 1') into the precursor solution in a spraying mode, heating at 80 ℃ to solidify the precursor solution, and controlling the thickness of a solidified electrolyte layer on the surface of the plate to be 1 mu m to obtain the negative plate containing solidified electrolyte;
3 ') dissolving polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinyl carbonate and lithium bis (trifluoromethyl) sulfonyl imide in an organic solvent DMAC (dimethylacetamide) according to the mass ratio of 60:10:30, uniformly mixing to prepare coating slurry, coating the coating slurry on the surface of the negative plate obtained in the step 2'), and performing air blast drying at 80 ℃ to obtain a functional coating with the thickness of 5 mu m, so as to obtain the negative plate containing the in-situ cured electrolyte and the functional coating;
4 ') cutting edges, cutting pieces and dividing strips of the negative pole pieces obtained in the step 3') to obtain the negative pole pieces of the lithium ion battery
Preparing electrolyte and a lithium ion battery: same as in example 1.
Test example
And (3) performance testing:
the lithium ion batteries manufactured in the above examples and comparative examples were subjected to a needle punching test, a heating test, an internal resistance test and a capacity test. (since NCM8 series was used as the positive electrode active material in both examples and comparative examples, the cut-off voltage at 100% SOC was 4.2V, and when other materials such as lithium cobaltate and lithium manganate were used as the positive electrode, the cut-off voltage was adjusted)
1. Needling test conditions: in a test environment of (25 +/-5) DEG C, fully charging the battery to 4.2V, using a high-temperature-resistant steel needle with the diameter of phi 5mm (the conical angle of the needle point is 45-60 degrees, and the surface of the needle is smooth and clean and has no rust, oxidation layer and oil stain), penetrating the battery from the direction vertical to the large surface of the battery at the speed of (25 +/-5) mm/s, wherein the penetrating position is close to the geometric center of the punctured surface, and the steel needle stays in the battery core. And observing whether the battery is on fire or explodes, and recording the temperature rise and the pressure drop of the battery.
2. Heating test conditions: charging to the upper limit voltage at 0.5 ℃ under the environment of 25 +/-5 ℃, stopping at 0.05 ℃, standing for 10min, placing in a thermal shock test box in a full-power state, raising the temperature to 150 ℃ at the speed of 5 +/-2 ℃/min, keeping for 60min, and monitoring whether the fire is on or not. If the battery does not catch fire, the heating test is qualified.
3. Testing internal resistance: obtained by electrochemical impedance spectroscopy analysis.
4. And (3) capacity testing: charging to 4.2V (100% SOC) at 0.33C constant current in a test environment at (25 +/-5) ° C, standing for 10min, discharging to 2.8V at 0.33C constant current, and recording the discharge capacity as C0Standing for 10min, charging to 4.2V (100% SOC) at 0.33C constant current, standing for 10min, discharging to 2.8V at 1C constant current, and recording discharge capacity as C1。
The results of the above tests are shown in Table 1.
TABLE 1
Figure BDA0003334126230000231
From the test results of example 1, it can be seen that the lithium ion battery prepared from the electrode sheet comprising the in-situ cured electrolyte and the functional coating did not ignite during needling, and showed lower temperature rise and pressure drop. The positive and negative electrode sheets of comparative example 1 were not modified at all, and the battery produced therefrom was ignited by needling, had a temperature rise of 563 ℃ and a voltage drop almost to zero, and ignited under an overheat condition. Therefore, the lithium ion battery prepared by the pole piece containing the in-situ cured electrolyte and the functional coating has higher safety under the needling and overheating conditions, and the in-situ cured electrolyte and the functional coating have obvious improvement on the safety under the needling and overheating conditions.
In comparative example 2, the positive electrode sheet contained only a functional coating layer without any other modification. As can be seen from table 1, in the battery of comparative example 2, although ignition did not occur and the temperature rise was low in the case of the needle punching condition, ignition occurred in the case of the overheat condition; it can therefore be seen that the in-situ curing electrolyte plays a decisive role in the safety of heating.
In comparative example 3, both the positive and negative electrode sheets contained the in-situ cured electrolyte, but none of the functional coatings. As can be seen from table 1, the ignition of the battery did not occur under the overheat condition of the battery of comparative example 3, but the ignition of the battery occurred under the nail piercing condition. It can therefore be seen that the functional coating plays a decisive role in the safety of needling.
In comparative example 4, the positive electrode sheet contained an in-situ cured electrolyte and the negative electrode sheet contained a functional coating, and it can be seen from table 1 that the cell ignited under overheating conditions, but the needling did not ignite and had only a low temperature rise and pressure drop. Therefore, the positive electrode and the negative electrode need to contain solidified electrolyte to ensure that fire does not occur under the heating condition.
Compared with the embodiment 1, the thickness of the functional coating of the positive plate in the embodiment 2 is reduced, and the thickness of the functional coating is 5 μm, so that the battery in the embodiment 2 still has no fire, the internal resistance is reduced, and the electrical property is better under the heating and needling tests. Therefore, the electrical property can be improved under the condition of ensuring safety by properly reducing the thickness of the functional coating.
In example 3, no conductive polymer was added to the in-situ cured electrolyte, and it can be seen that ignition still did not occur under heating and needling, but its internal resistance was increased and the electrical properties were slightly decreased as compared to the battery of example 2. Therefore, the in-situ solidified electrolyte contains no conductive agent, the electron conduction in the pole piece is slightly reduced, and certain influence is generated on the electrical property.
In example 4, in which the monomer content in the in-situ cured electrolyte was increased as compared to example 2, it can be seen that although the battery did not ignite during the heating and needling test, its internal resistance was slightly increased and the electrical properties were somewhat affected. Therefore, when the added monomer is excessive, the ionic conductivity of the in-situ solidified electrolyte is reduced, the internal resistance is increased, and certain influence is generated on the electrical property.
The thickness of the in-situ cured electrolyte coating of the positive and negative electrode sheets in example 5 was increased to 5 μm as compared to example 2, and it can be seen from the results of table 1 that the battery of example 5 still did not suffer from ignition under heating and needling, but its internal resistance was increased and the electrical properties were slightly degraded. Therefore, the thickness of the in-situ solidified electrolyte on the electrode plate should be reduced as much as possible on the premise of ensuring the safety.
Compared with example 2, in example 6, the content of lithium salt is increased in the functional coating, and as can be seen from table 1, the internal resistance of the battery in example 6 is smaller, which indicates that the increase of lithium salt can improve the ionic conductivity and facilitate the transmission of lithium ions, but it is also recognized that the increase of lithium salt can lead to the increase of cost and the environmental requirements in the preparation process are more severe.
Compared with example 2, the positive and negative electrode sheets of example 7 both contained the in-situ cured electrolyte and the functional coating, and as can be seen from table 1, under heating and needling, fire still did not occur, temperature rise and pressure drop were both lower, but internal resistance was significantly increased and electrical properties were reduced. In contrast, in example 7, the internal resistance was comparable to that in example 1, but the electrical properties were slightly lowered. This shows that when the functional coating is contained in both the positive and negative electrode sheets, the function of the insulation property of the entire battery is increased, and the electrical performance of the battery is affected to some extent.
In contrast to example 2, where the positive electrode sheet of example 8 had only the in-situ solidified electrolyte and the negative electrode comprised the in-situ solidified electrolyte and the functional coating, it can be seen that the needle-punching safety of the cell can be ensured regardless of whether the functional coating is on the positive or negative electrode.
Compared with example 8, the positive electrode sheet of comparative example 5 replaced the in-situ cured electrolyte with a functional coating; the thickness of the functional coating of comparative example 6 was reduced compared to comparative example 5. It can be seen that the increase or decrease in the thickness of the functional coating layer in the whole battery is a main cause of the increase or decrease in the internal resistance of the battery, and thus it is required to decrease the total thickness of the functional coating layer in the battery while ensuring the safety of the battery.
The exemplary embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments. Any modification, equivalent replacement, improvement and the like made by those skilled in the art within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims (10)

1. An electrode sheet, comprising: a current collector, an active material layer, an electrolyte and a functional coating; wherein the content of the first and second substances,
the current collector has two opposing surfaces;
the active material layer is disposed on at least one surface of the current collector;
the electrolyte is arranged inside and/or on the surface of the active material layer;
the functional coating is disposed on the active material layer including an electrolyte.
2. The electrode sheet according to claim 1, wherein the electrolyte is a solid electrolyte;
and/or the electrolyte comprises a first polymer and an electrolyte dispersed therein;
and/or, the electrolyte further comprises a conductive polymer.
3. The electrode sheet according to claim 2, wherein the first polymer is at least one selected from the group consisting of polymethyl methacrylate or a copolymer thereof, polyhydroxyethyl methacrylate or a copolymer thereof, polyethylene glycol polymethacrylate or a copolymer thereof, polyethylene glycol diacrylate or a copolymer thereof, polytrimethylolpropane triacrylate or a copolymer thereof, polybutyl acrylate or a copolymer thereof, polyvinyl n-butyl ether or a copolymer thereof, and polyethyl acetate or a copolymer thereof;
and/or the conductive polymer is selected from at least one of polyaryl oxadiazole, polythiophene, polypyrrole and polyaniline;
and/or the electrolyte comprises at least a lithium salt and a solvent.
4. Electrode sheet according to any one of claims 1 to 3, characterized in that the functional coating comprises at least a second polymer;
and/or the functional coating further comprises a plasticizer.
5. The electrode sheet according to claim 4, wherein the functional coating comprises the following components in percentage by mass: 30-80 wt% of second polymer, 0-50 wt% of plasticizer and 0-50 wt% of lithium salt.
6. Electrode sheet according to any one of claims 1 to 5, characterized in that the functional coating has a thickness of 0.1 μm to 20 μm.
7. An electrode sheet as claimed in any one of claims 4 to 6, wherein the second polymer includes, but is not limited to, at least one of polyvinylidene fluoride, polyvinyl alcohol, polytetrafluoroethylene, polyvinylidene fluoride-hexafluoropropylene copolymer, polymethyl methacrylate;
and/or the plasticizer comprises a small molecule material, wherein the small molecule material comprises at least one of but not limited to polyethylene carbonate, ethylene carbonate, succinonitrile, methyl methacrylate and polyethylene glycol methyl ether methacrylate;
and/or, the lithium salt includes, but is not limited to, at least one of lithium bistrifluoromethylsulfonyl imide, lithium bisoxalato borate, and lithium difluorooxalato borate.
8. The electrode sheet according to any one of claims 1 to 7, wherein the active material layer comprises an active material, a binder and a conductive agent;
and/or, in the active material layer, the active material layer further comprises a thickening agent, wherein the thickening agent comprises, but is not limited to, sodium carboxymethyl cellulose (CMC).
9. The electrode sheet according to any one of claims 1 to 8, wherein, when the electrode sheet is used for a positive electrode, the electrode sheet is one in which a current collector is selected from positive electrode current collectors and the active material layer includes a positive electrode active material;
and/or, when the electrode sheet is used for an anode, in the electrode sheet, a current collector is selected from anode current collectors, and the active material layer includes an anode active material.
10. A lithium ion battery comprising a positive electrode sheet, a negative electrode sheet, and a separator disposed between the positive electrode and the negative electrode, and an electrolyte, wherein the positive electrode sheet and the negative electrode sheet are independently selected from the electrode sheets of any one of claims 1 to 9.
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CN115411228A (en) * 2022-11-01 2022-11-29 江苏贝特瑞纳米科技有限公司 Lithium iron manganese phosphate positive plate and preparation method thereof
CN116111038A (en) * 2023-04-12 2023-05-12 四川新能源汽车创新中心有限公司 Electrode plate, preparation method thereof and lithium battery

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