CN112952032A - Positive plate and battery - Google Patents
Positive plate and battery Download PDFInfo
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- CN112952032A CN112952032A CN202110225875.1A CN202110225875A CN112952032A CN 112952032 A CN112952032 A CN 112952032A CN 202110225875 A CN202110225875 A CN 202110225875A CN 112952032 A CN112952032 A CN 112952032A
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- electrode sheet
- functional layer
- active material
- positive electrode
- binder
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- 239000010410 layer Substances 0.000 claims abstract description 37
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- 239000000463 material Substances 0.000 claims abstract description 33
- 239000011230 binding agent Substances 0.000 claims description 27
- 239000006258 conductive agent Substances 0.000 claims description 16
- 239000002033 PVDF binder Substances 0.000 claims description 11
- 229920002981 polyvinylidene fluoride Polymers 0.000 claims description 11
- 229910052744 lithium Inorganic materials 0.000 claims description 10
- -1 polytetrafluoroethylene Polymers 0.000 claims description 10
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims description 9
- 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 8
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- 239000001267 polyvinylpyrrolidone Substances 0.000 claims description 4
- 229920000036 polyvinylpyrrolidone Polymers 0.000 claims description 4
- 235000013855 polyvinylpyrrolidone Nutrition 0.000 claims description 4
- OQMIRQSWHKCKNJ-UHFFFAOYSA-N 1,1-difluoroethene;1,1,2,3,3,3-hexafluoroprop-1-ene Chemical group FC(F)=C.FC(F)=C(F)C(F)(F)F OQMIRQSWHKCKNJ-UHFFFAOYSA-N 0.000 claims description 3
- 229910000572 Lithium Nickel Cobalt Manganese Oxide (NCM) Inorganic materials 0.000 claims description 3
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 claims description 3
- PFYQFCKUASLJLL-UHFFFAOYSA-N [Co].[Ni].[Li] Chemical compound [Co].[Ni].[Li] PFYQFCKUASLJLL-UHFFFAOYSA-N 0.000 claims description 3
- FBDMTTNVIIVBKI-UHFFFAOYSA-N [O-2].[Mn+2].[Co+2].[Ni+2].[Li+] Chemical compound [O-2].[Mn+2].[Co+2].[Ni+2].[Li+] FBDMTTNVIIVBKI-UHFFFAOYSA-N 0.000 claims description 3
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 claims description 3
- 229910052748 manganese Inorganic materials 0.000 claims description 3
- 239000011572 manganese Substances 0.000 claims description 3
- 239000004584 polyacrylic acid Substances 0.000 claims description 3
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 29
- 229910001416 lithium ion Inorganic materials 0.000 description 29
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 11
- 239000011248 coating agent Substances 0.000 description 10
- 238000000576 coating method Methods 0.000 description 10
- 239000002245 particle Substances 0.000 description 10
- 238000012360 testing method Methods 0.000 description 9
- 239000002002 slurry Substances 0.000 description 8
- 230000000052 comparative effect Effects 0.000 description 7
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 6
- 238000001035 drying Methods 0.000 description 6
- 239000011267 electrode slurry Substances 0.000 description 6
- 230000006870 function Effects 0.000 description 5
- 238000000034 method Methods 0.000 description 5
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- 229910002804 graphite Inorganic materials 0.000 description 4
- 238000002360 preparation method Methods 0.000 description 4
- 238000004080 punching Methods 0.000 description 4
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 3
- 229910052782 aluminium Inorganic materials 0.000 description 3
- 239000003792 electrolyte Substances 0.000 description 3
- 239000011888 foil Substances 0.000 description 3
- 239000007774 positive electrode material Substances 0.000 description 3
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- 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 description 2
- 239000011889 copper foil Substances 0.000 description 2
- 238000005520 cutting process Methods 0.000 description 2
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- 239000008367 deionised water Substances 0.000 description 2
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- 238000002156 mixing Methods 0.000 description 2
- 238000004806 packaging method and process Methods 0.000 description 2
- 230000035515 penetration Effects 0.000 description 2
- 239000002985 plastic film Substances 0.000 description 2
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- 238000011076 safety test Methods 0.000 description 2
- 238000006467 substitution reaction Methods 0.000 description 2
- 239000002562 thickening agent Substances 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- BQCIDUSAKPWEOX-UHFFFAOYSA-N 1,1-Difluoroethene Chemical compound FC(F)=C BQCIDUSAKPWEOX-UHFFFAOYSA-N 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 239000002041 carbon nanotube Substances 0.000 description 1
- 229910021393 carbon nanotube Inorganic materials 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
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- 229910021389 graphene Inorganic materials 0.000 description 1
- HCDGVLDPFQMKDK-UHFFFAOYSA-N hexafluoropropylene Chemical group FC(F)=C(F)C(F)(F)F HCDGVLDPFQMKDK-UHFFFAOYSA-N 0.000 description 1
- 150000002641 lithium Chemical class 0.000 description 1
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Images
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
- H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
-
- 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
- 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
- H01M4/136—Electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Inorganic Chemistry (AREA)
- Manufacturing & Machinery (AREA)
- Battery Electrode And Active Subsutance (AREA)
- Secondary Cells (AREA)
Abstract
The invention provides a positive plate and a battery, wherein the positive plate comprises a current collector, one side or two sides of the current collector are coated with a functional layer, one side of the functional layer, which is far away from the current collector, is coated with an active material layer, and the functional layer comprises an aluminum phosphate material. The embodiment of the invention can improve the safety of the battery.
Description
Technical Field
The invention relates to the technical field of batteries, in particular to a positive plate and a battery.
Background
Lithium ion batteries are widely used in portable electronic products, energy storage devices and new energy vehicles due to their advantages of high energy density, long cycle life, no memory effect, environmental friendliness, etc. With the coming of the 5G era of mobile phones and the development of new energy automobiles with high endurance mileage, the energy density of lithium ion batteries is higher and higher. However, the higher the energy density of the lithium ion battery is, the worse the safety of the lithium ion battery is, and the spontaneous combustion and explosion accidents of many electric vehicles and hybrid electric vehicles are caused by the safety problem of the power battery, so that the further development of the lithium ion battery in the field of new energy is severely restricted.
In the prior art, the safety performance of the battery cell is usually verified by testing means such as overcharge, furnace temperature, needling, external short circuit and extrusion, wherein the needling is a safety test for simulating the safety of the battery cell when the internal short circuit occurs and is also a safety test which is generally recognized to be the most difficult to pass, and the passing rate of the battery cell needling test which is composed of the pole piece only coated with the active material layer is low at present, which indicates that the safety of the battery in the prior art is low.
Disclosure of Invention
The embodiment of the invention provides a positive plate and a battery, which aim to solve the problem of low safety of the battery in the prior art.
In a first aspect, embodiments of the present invention provide a positive electrode sheet, including a current collector, one or both sides of which are coated with a functional layer, one side of the functional layer, which is away from the current collector, is coated with an active material layer, and the functional layer includes an aluminum phosphate material.
Optionally, the median diameter D50 of the aluminum phosphate material is 0.1-1.2 μm.
Optionally, the thickness of the active material layer is greater than the thickness of the functional layer.
Optionally, the thickness of the functional layer is 3-12 μm.
Optionally, the thickness of the active material layer is greater than or equal to 20 μm.
Optionally, the functional layer further comprises a binder and a conductive agent, and the mass ratio of the aluminum phosphate material to the binder to the conductive agent is 40-98: 1-50: 1-10.
Optionally, the mass ratio of the aluminum phosphate material to the binder to the conductive agent is 70-98: 1-10: 1-20.
Optionally, the binder comprises one or more of polyvinylidene fluoride, copolymers of vinylidene fluoride-hexafluoropropylene, polyamides, polyacrylonitrile, polyacrylates, polyacrylic acids, polyacrylates, sodium carboxymethyl cellulose, polyvinylpyrrolidone, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene, polyhexafluoropropylene, and styrene butadiene rubber.
Optionally, the active material layer includes an active material, a binder, and a conductive agent, and the active material includes one or more of lithium cobaltate, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminate, a lithium rich manganese based material, and lithium iron phosphate.
In a second aspect, embodiments of the present invention further provide a battery, including a separator, a negative electrode sheet, and the positive electrode sheet according to the first aspect, where at least one layer of the separator is present between the positive electrode sheet and the negative electrode sheet.
According to the embodiment of the invention, the functional layer containing the aluminum phosphate material is coated between the current collector of the positive plate and the active material layer, so that the contact between the positive current collector and the negative plate can be avoided or reduced during needling of the battery, the internal short-circuit current is reduced, and the needling safety of the battery is further improved.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required to be used in the description of the embodiments of the present invention will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise.
Fig. 1 is a schematic structural diagram of a positive electrode sheet according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1, an embodiment of the present invention provides a positive electrode sheet including a current collector 100, wherein one or both sides of the current collector 100 are coated with a functional layer 200, one side of the functional layer 200 away from the current collector 100 is coated with an active material layer 300, and the functional layer 200 includes an aluminum phosphate material.
In the embodiment of the present invention, the positive plate may be applied to a cell structure of a lithium battery, in the cell structure of the lithium battery, the positive plate and the negative plate are generally disposed opposite to each other, and a separator is formed between the positive plate and the negative plate. The current collector 100 of the positive electrode sheet may be an aluminum foil, one or both sides of the current collector 100 may be previously coated with a functional layer 200, the functional layer 200 may include an aluminum phosphate material, and then the active material layer 300 may be coated on the side of the functional layer 200 away from the current collector 100. In other words, the functional layer 200 is located between the active material layer 300 and the current collector 100, so that when the needle punching test is performed, due to the coating effect of the functional layer 200 containing aluminum phosphate on the current collector 100, the positive electrode current collector 100 and the negative electrode sheet can be separated in the needle punching test process, and the internal short circuit phenomenon in the needle punching test is effectively reduced.
Meanwhile, the aluminum phosphate material has good heat resistance and chemical stability, is not easy to generate thermal decomposition in the needling process, and is not easy to generate side reaction with other materials such as electrolyte and the like.
According to the embodiment of the invention, the functional layer 200 containing the aluminum phosphate material is coated between the current collector 100 of the positive plate and the active material layer 300, so that the contact between the positive current collector 100 and the negative plate can be avoided or reduced during the needling of the battery, the internal short-circuit current is reduced, and the needling safety of the battery is further improved.
Alternatively, the median diameter D50 of the aluminum phosphate material may be 0.1 μm to 1.2 μm.
The median diameter D50 of the aluminum phosphate material can be set according to actual needs. Since the median diameter of the aluminum phosphate material affects the density of the distribution of the aluminum phosphate particles in the functional layer 200, the smaller the median diameter of the aluminum phosphate material is, the denser the distribution of the aluminum phosphate particles in the functional layer 200 can be. Therefore, in the embodiment of the present invention, the median diameter D50 of the aluminum phosphate material may be a small value, specifically, 0.1 μm to 1.2 μm, so as to improve the protective effect of the functional layer 200 on the current collector 100.
Alternatively, the thickness of the active material layer 300 is greater than that of the functional layer 200.
It is understood that the coating thickness of the active material layer 300 is related to the battery capacity, and the thicker the active material layer 300 is, the larger the battery capacity is, and thus in an embodiment of the present invention, the thickness of the active material layer 300 may be greater than the thickness of the functional layer 200, thereby increasing the capacity of the battery.
Meanwhile, the coating thickness of the functional layer 200 and the coating thickness of the active material layer 300 are both related to the charge rate, and if the coating thickness is increased, the transmission rate of lithium ions is decreased and the charge rate is correspondingly decreased, while the battery capacity is ensured. Therefore, in the embodiment of the present invention, the thicknesses of the active material layer 300 and the functional layer 200 may be set in combination with the battery capacity, the charging speed, and the like.
Specifically, the functional layer 200 may have a thickness of 3 to 12 μm. The thickness of the above active material layer 300 may be greater than or equal to 20 μm.
Optionally, the functional layer 200 may further include a binder and a conductive agent, and a mass ratio of the aluminum phosphate material to the binder to the conductive agent is 40-98: 1-50: 1-10.
In the embodiment of the invention, the conductive agent is used for improving the transfer rate of electrons in the electrode and reducing the ohmic resistance of the electrode. The material can be set according to actual needs, and at least one material of conductive carbon black, carbon nanotubes and graphene can be adopted.
The binder is used for ensuring the uniformity and safety during pulping, plays a role in bonding particles, and bonds the aluminum phosphate particles of the functional layer on the current collector 100. The material can be set according to actual needs. Alternatively, in an embodiment of the present invention, the binder may include one or more of polyvinylidene fluoride, a copolymer of vinylidene fluoride and hexafluoropropylene, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, sodium carboxymethyl cellulose, polyvinylpyrrolidone, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene, polyhexafluoropropylene, and styrene butadiene rubber.
Furthermore, the mass ratio of the aluminum phosphate material, the binder and the conductive agent can be 70-98: 1-10: 1-20, and the mass ratio of the aluminum phosphate material can be properly increased, so that the safety of the battery during needling is further ensured.
In an embodiment of the present invention, the active material layer 300 coated on the current collector 100 of the positive electrode tab may include an active material binder and a conductive agent, where the binder is used to ensure uniformity and safety of active material during active material slurrying, to bind active material particles, and to bind the active material to the current collector 100. The material can be set according to actual needs.
Similarly to the above embodiments, in the embodiments of the present invention, the above binder may also include one or more of polyvinylidene fluoride, a copolymer of vinylidene fluoride-hexafluoropropylene, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, sodium carboxymethyl cellulose, polyvinylpyrrolidone, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene, polyhexafluoropropylene, and styrene-butadiene rubber.
Alternatively, the active material layer 300 may include an active material, a binder, and a conductive agent, and the active material may include one or more of lithium cobaltate, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminate, a lithium rich manganese-based material, and lithium iron phosphate.
The embodiment of the invention also provides a battery, which comprises a diaphragm, a negative plate and the positive plate as described in any one of the embodiments, wherein at least one layer of the diaphragm is arranged between the positive plate and the negative plate.
Since the battery provided by the embodiment of the present invention adopts all the technical solutions of the above embodiments, at least all the beneficial effects brought by the technical solutions of the above embodiments are achieved, and details are not repeated herein.
In order to better understand the invention, specific implementation procedures of the invention will be described in detail in specific implementation modes.
The method of examples 1 to 9 was provided, wherein,
example 1:
(1) preparation of positive plate
Dispersing safety function material aluminum phosphate, binder polyvinylidene fluoride (PVDF) and conductive carbon black in N-methyl pyrrolidone to obtain uniform primer layer slurry (safety function slurry); in the safety function paste, the solid component contained 95 wt% of aluminum phosphate, 3 wt% of PVDF as a binder, and 2 wt% of conductive carbon black. Dispersing Nickel Cobalt lithium manganate (NCM), binder PVDF and conductive carbon black in N-methyl pyrrolidone to obtain uniform active layer slurry; in the active layer slurry, the solid component contained 97 wt% of the mixed active material, 2 wt% of the binder PVDF, and 1 wt% of the conductive carbon black. Coating the prepared safety function slurry on two surfaces of an aluminum foil, and drying at 85 ℃; and continuously coating a layer of active material layer on the two surfaces coated with the functional layer 200, drying at 85 ℃, performing cold pressing, cutting into pieces and die cutting, and drying for 8 hours at 85 ℃ under a vacuum condition to prepare the positive plate P1. The thickness of the functional layer 200 was 6 μm, the particle diameter D50 of the aluminum phosphate of the functional layer 200 was 0.4 μm, and the thickness of the active layer was 60 μm minus the thickness of the functional layer 200.
(2) Preparation of negative plate
Mixing and dispersing graphite, binder styrene butadiene rubber, thickener sodium carboxymethyl cellulose and conductive agent conductive carbon black in deionized water to obtain negative electrode slurry; in the negative electrode slurry, the solid components contained 95 wt% of graphite, 1.5 wt% of sodium carboxymethyl cellulose, 1.5 wt% of conductive carbon black, and 2 wt% of styrene-butadiene rubber. And uniformly coating the negative electrode slurry on two surfaces of a copper foil, drying for 6 hours at 90-130 ℃, and compacting by using a roller press to obtain the negative electrode sheet N1.
(3) Preparing a lithium ion battery:
and preparing the prepared positive plate P1, the negative plate N1 and the diaphragm to obtain a laminated core, packaging by adopting an aluminum-plastic film, baking for 48 hours in a vacuum state to remove moisture, injecting electrolyte, and forming and sorting the battery to obtain the square soft package lithium ion battery, wherein the label is C1.
Example 2 was different from example 1 in that the thickness of the functional layer 200 was 3 μm, and a lithium ion battery C2 was prepared.
Example 3 differs from example 1 in that: the functional layer 200 was 9 μm thick, and a lithium ion battery C3 was prepared.
Example 4 differs from example 1 in that: the functional layer 200 was 12 μm thick, and a lithium ion battery C4 was prepared.
Example 5 differs from example 1 in that: the particle size D50 of the aluminum phosphate in the functional layer 200 was 0.1 μm, and a lithium ion battery C5 was prepared.
Example 6 differs from example 1 in that: the particle size D50 of the aluminum phosphate in the functional layer 200 was 0.8 μm, and a lithium ion battery C6 was prepared.
Example 7 differs from example 1 in that: the particle size D50 of the aluminum phosphate in the functional layer 200 was 1.2 μm, and a lithium ion battery C7 was prepared.
Example 8 differs from example 1 in that: the positive electrode active material is lithium cobaltate, and the lithium ion battery C8 is prepared.
Example 9 differs from example 1 in that: the positive electrode active material is a nickel-cobalt-aluminum ternary material (NCA), and the lithium ion battery C9 is prepared.
Comparative examples 1 to 3 were set, in which,
comparative example 1
(1) Preparation of positive plate
Dispersing nickel cobalt lithium manganate, a binder PVDF and conductive carbon black in N-methyl pyrrolidone to obtain uniform active layer slurry; in the active layer slurry, the solid component contained 97 wt% of the mixed active material, 2 wt% of the binder PVDF, and 1 wt% of the conductive carbon black. And coating the prepared safety function slurry on two surfaces of an aluminum foil, and drying at 85 ℃ to prepare the positive pole piece. Wherein the thickness of the active layer is 60 μm.
(2) Preparation of negative plate
Mixing and dispersing graphite, binder styrene butadiene rubber, thickener sodium carboxymethyl cellulose and conductive agent conductive carbon black in deionized water to obtain negative electrode slurry; in the negative electrode slurry, the solid components contained 95 wt% of graphite, 1.5 wt% of sodium carboxymethyl cellulose, 1.5 wt% of conductive carbon black, and 2 wt% of styrene-butadiene rubber. And uniformly coating the negative electrode slurry on two surfaces of a copper foil, drying for 6 hours at 90-130 ℃, and compacting by using a roller press to obtain the negative electrode sheet.
(3) Preparing a lithium ion battery:
preparing the positive plate, the negative plate and the diaphragm to obtain a laminated core, packaging by adopting an aluminum-plastic film, baking for 48 hours in a vacuum state to remove moisture, injecting a commercially available electrolyte, and forming and sorting the battery to obtain the square soft package lithium ion battery, wherein the D1 is recorded.
Comparative example 2 differs from comparative example 1 in that: the active material is lithium cobaltate, and the lithium ion battery D2 is prepared.
Comparative example 3 differs from comparative example 1 in that: the positive electrode active material is a nickel-cobalt-aluminum ternary material (NCA), and the lithium ion battery D3 is prepared.
The needle punching test was performed on the batteries of examples 1 to 9 and comparative examples 1 to 3, and the specific procedure was as follows:
and (3) placing the lithium ion battery in a constant temperature box at 25 ℃, and standing for 30 minutes to keep the temperature of the lithium ion battery constant. The lithium ion battery reaching the constant temperature was charged at a constant current of 1C to an upper limit voltage (4.3V), and then charged at a constant voltage of 4.3V to a current of 0.05C. And transferring the fully charged lithium ion battery to a nail penetration testing machine, keeping the testing environment temperature at 25 +/-2 ℃, using a steel nail with the diameter of 5mm to uniformly penetrate through the center of the lithium ion battery at the speed of 25mm/s, keeping for 1 hour, and recording that the lithium ion battery is not fired, not exploded, not smoked and passes. And testing 10 lithium ion batteries each time, wherein the number of the lithium ion batteries passing the needling test is used as an index for evaluating the safety performance of the lithium ion batteries.
The results obtained are shown in Table 1:
TABLE 1
As can be seen from table 1, the application of the functional layer 200 including aluminum phosphate between the current collector 100 and the active material layer 300 of the positive electrode sheet can effectively improve the needle penetration rate of the battery. Meanwhile, in order to further improve the needle penetration rate of the battery, the thickness of the functional layer 200 may be greater than 3 μm, and more preferably 9 to 12 μm. The particle size of the aluminum phosphate may be less than 1.2. mu.m, and more preferably 0.1 to 0.8. mu.m.
The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (10)
1. The positive plate comprises a current collector, and is characterized in that one side or two sides of the current collector are coated with a functional layer, one side, far away from the current collector, of the functional layer is coated with an active material layer, and the functional layer comprises an aluminum phosphate material.
2. The positive electrode sheet according to claim 1, wherein the aluminum phosphate material has a median diameter D50 of 0.1 to 1.2 μm.
3. The pole piece of claim 1, wherein the active material layer has a thickness greater than a thickness of the functional layer.
4. The positive electrode sheet according to claim 1, wherein the functional layer has a thickness of 3 to 12 μm.
5. The positive electrode sheet according to claim 1, wherein the thickness of the active material layer is 20 μm or more.
6. The positive electrode sheet according to claim 1, wherein the functional layer further comprises a binder and a conductive agent, and the mass ratio of the aluminum phosphate material to the binder to the conductive agent is 40-98: 1-50: 1-10.
7. The positive electrode sheet according to claim 6, wherein the mass ratio of the aluminum phosphate material to the binder to the conductive agent is 70 to 98:1 to 10:1 to 20.
8. The positive electrode sheet according to claim 6, wherein the binder comprises one or more of polyvinylidene fluoride, a copolymer of vinylidene fluoride-hexafluoropropylene, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, sodium carboxymethyl cellulose, polyvinylpyrrolidone, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene, polyhexafluoropropylene, and styrene-butadiene rubber.
9. The positive electrode sheet according to claim 1, wherein the active material layer includes an active material, a binder, and a conductive agent, and the active material includes one or more of lithium cobaltate, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminate, a lithium rich manganese based material, and lithium iron phosphate.
10. A battery comprising a separator, a negative electrode sheet, and the positive electrode sheet according to any one of claims 1 to 9, wherein at least one layer of the separator is present between the positive electrode sheet and the negative electrode sheet.
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| CN202110225875.1A CN112952032A (en) | 2021-03-01 | 2021-03-01 | Positive plate and battery |
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| CN202110225875.1A CN112952032A (en) | 2021-03-01 | 2021-03-01 | Positive plate and battery |
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Cited By (1)
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| CN114759161A (en) * | 2022-05-12 | 2022-07-15 | 北京卫蓝新能源科技有限公司 | Multilayer positive plate and preparation method thereof |
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Application publication date: 20210611 |