CN117174905A - High-conductivity high-capacity positive electrode plate, lithium battery and preparation method of lithium battery - Google Patents
High-conductivity high-capacity positive electrode plate, lithium battery and preparation method of lithium battery Download PDFInfo
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- 229910052744 lithium Inorganic materials 0.000 title claims abstract description 36
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 title claims abstract description 35
- 238000002360 preparation method Methods 0.000 title abstract description 26
- 239000006258 conductive agent Substances 0.000 claims abstract description 98
- 239000002109 single walled nanotube Substances 0.000 claims abstract description 66
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 53
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims abstract description 35
- 239000002033 PVDF binder Substances 0.000 claims abstract description 25
- 229920002981 polyvinylidene fluoride Polymers 0.000 claims abstract description 25
- 239000007774 positive electrode material Substances 0.000 claims abstract description 13
- 229910052799 carbon Inorganic materials 0.000 claims description 32
- 239000011149 active material Substances 0.000 claims description 15
- 239000011248 coating agent Substances 0.000 claims description 10
- 238000000576 coating method Methods 0.000 claims description 10
- 239000003292 glue Substances 0.000 claims description 10
- 238000000034 method Methods 0.000 claims description 9
- 239000003792 electrolyte Substances 0.000 claims description 8
- 239000002002 slurry Substances 0.000 claims description 8
- 238000003756 stirring Methods 0.000 claims description 8
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 6
- 239000011267 electrode slurry Substances 0.000 claims description 6
- HFCVPDYCRZVZDF-UHFFFAOYSA-N [Li+].[Co+2].[Ni+2].[O-][Mn]([O-])(=O)=O Chemical compound [Li+].[Co+2].[Ni+2].[O-][Mn]([O-])(=O)=O HFCVPDYCRZVZDF-UHFFFAOYSA-N 0.000 claims description 5
- 238000007731 hot pressing Methods 0.000 claims description 5
- 238000003825 pressing Methods 0.000 claims description 5
- 239000007787 solid Substances 0.000 claims description 5
- 238000004804 winding Methods 0.000 claims description 5
- 239000000919 ceramic Substances 0.000 claims description 4
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 3
- 229910052782 aluminium Inorganic materials 0.000 claims description 3
- 239000006183 anode active material Substances 0.000 claims description 3
- 238000001035 drying Methods 0.000 claims description 3
- 229910052759 nickel Inorganic materials 0.000 claims description 3
- 238000004806 packaging method and process Methods 0.000 claims description 3
- 239000002985 plastic film Substances 0.000 claims description 3
- 229920006255 plastic film Polymers 0.000 claims description 3
- 239000002904 solvent Substances 0.000 claims description 3
- 229910013415 LiNixCoyMn(1-x-y)O2 Inorganic materials 0.000 claims description 2
- 229910013424 LiNixCoyMn(1−x−y)O2 Inorganic materials 0.000 claims description 2
- 238000005520 cutting process Methods 0.000 claims description 2
- 238000004519 manufacturing process Methods 0.000 claims description 2
- 238000009517 secondary packaging Methods 0.000 claims description 2
- 239000000523 sample Substances 0.000 claims 1
- 150000002500 ions Chemical class 0.000 abstract description 12
- 230000005540 biological transmission Effects 0.000 abstract description 9
- 230000000052 comparative effect Effects 0.000 description 16
- 239000006245 Carbon black Super-P Substances 0.000 description 14
- 238000007792 addition Methods 0.000 description 14
- 229910000572 Lithium Nickel Cobalt Manganese Oxide (NCM) Inorganic materials 0.000 description 13
- 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 description 12
- 239000000463 material Substances 0.000 description 8
- 239000011230 binding agent Substances 0.000 description 7
- 238000011068 loading method Methods 0.000 description 7
- 238000006243 chemical reaction Methods 0.000 description 5
- 239000002153 silicon-carbon composite material Substances 0.000 description 5
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 4
- 238000013461 design Methods 0.000 description 4
- 238000009826 distribution Methods 0.000 description 4
- 238000004146 energy storage Methods 0.000 description 4
- 230000006872 improvement Effects 0.000 description 4
- 229910001416 lithium ion Inorganic materials 0.000 description 4
- 238000001179 sorption measurement Methods 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- 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 description 3
- 230000009286 beneficial effect Effects 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 3
- 239000001768 carboxy methyl cellulose Substances 0.000 description 3
- 239000003795 chemical substances by application Substances 0.000 description 3
- 230000007547 defect Effects 0.000 description 3
- 230000007774 longterm Effects 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 235000019812 sodium carboxymethyl cellulose Nutrition 0.000 description 3
- 229920001027 sodium carboxymethylcellulose Polymers 0.000 description 3
- 229920002134 Carboxymethyl cellulose Polymers 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- 238000004220 aggregation Methods 0.000 description 2
- 230000002776 aggregation Effects 0.000 description 2
- 235000010948 carboxy methyl cellulose Nutrition 0.000 description 2
- 239000002131 composite material Substances 0.000 description 2
- 239000011889 copper foil Substances 0.000 description 2
- 239000008367 deionised water Substances 0.000 description 2
- 229910021641 deionized water Inorganic materials 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- QHGJSLXSVXVKHZ-UHFFFAOYSA-N dilithium;dioxido(dioxo)manganese Chemical compound [Li+].[Li+].[O-][Mn]([O-])(=O)=O QHGJSLXSVXVKHZ-UHFFFAOYSA-N 0.000 description 2
- 238000003487 electrochemical reaction Methods 0.000 description 2
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 description 2
- 230000005012 migration Effects 0.000 description 2
- 238000013508 migration Methods 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 230000035945 sensitivity Effects 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 230000032258 transport Effects 0.000 description 2
- 238000003466 welding Methods 0.000 description 2
- 229910010707 LiFePO 4 Inorganic materials 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 239000010405 anode material Substances 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 125000004432 carbon atom Chemical group C* 0.000 description 1
- 239000006229 carbon black Substances 0.000 description 1
- 239000002041 carbon nanotube Substances 0.000 description 1
- 229910021393 carbon nanotube Inorganic materials 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 239000010406 cathode material Substances 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- 239000000306 component Substances 0.000 description 1
- 239000000356 contaminant Substances 0.000 description 1
- 239000008358 core component Substances 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 239000007772 electrode material Substances 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000011888 foil Substances 0.000 description 1
- 229910021389 graphene Inorganic materials 0.000 description 1
- 230000037427 ion transport Effects 0.000 description 1
- VGYDTVNNDKLMHX-UHFFFAOYSA-N lithium;manganese;nickel;oxocobalt Chemical compound [Li].[Mn].[Ni].[Co]=O VGYDTVNNDKLMHX-UHFFFAOYSA-N 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 239000003607 modifier Substances 0.000 description 1
- 239000002048 multi walled nanotube Substances 0.000 description 1
- 239000002086 nanomaterial Substances 0.000 description 1
- 230000037361 pathway Effects 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 230000001502 supplementing effect Effects 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
Classifications
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
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- Battery Electrode And Active Subsutance (AREA)
Abstract
The application relates to the field of lithium batteries, in particular to a high-conductivity high-capacity positive electrode plate, a lithium battery and a preparation method thereof, wherein the positive electrode plate comprises a current collector and a dressing coated on the surface of the current collector; wherein the dressing comprises a positive electrode active material, a single-walled carbon nanotube conductive agent, conductive carbon black and polyvinylidene fluoride; wherein, the pipe diameter of the single-wall carbon nano-tube conductive agent is less than or equal to 3nm, the length-diameter ratio is more than or equal to 3000, and the G/D ratio is more than 80. The application adopts the single-wall carbon nanotube conductive agent with small pipe diameter, high length-diameter ratio and high G/D ratio, and can obviously improve the conductivity of the positive plate of the lithium battery. The increased specific surface area, conductive path and mechanical strength can reduce the internal resistance of the battery and improve the transmission speed of electrons and ions, thereby improving the charge and discharge efficiency and capacity of the battery. In addition, the stability of the single-walled carbon nanotube conductive agent also helps to improve the cycle life and safety of the battery.
Description
Technical Field
The application relates to the field of lithium batteries, in particular to a high-conductivity high-capacity positive electrode plate, a lithium battery and a preparation method thereof.
Background
Lithium batteries have become the first energy storage device in the fields of mobile devices, electric vehicles, energy storage systems, and the like as a battery type with high energy density and environmental protection. The lithium battery has the advantages of light weight, high voltage, long service life, low self-discharge rate and the like, and therefore, the lithium battery is widely applied to electronic products. However, lithium batteries still face challenges such as capacity limitations, cycle life, and safety issues, which have prompted researchers to continually seek improvements and innovations.
The positive electrode plate of the lithium battery is one of core components of the lithium ion battery, and the performance of the positive electrode plate directly relates to the capacity, the cycle life and the charge and discharge efficiency of the battery. The traditional lithium battery positive electrode plate mainly comprises an active material, a conductive agent and a binder, wherein the active material is a key for realizing electrochemical reaction. Currently, commonly used cathode materials include lithium iron phosphate (LiFePO 4 ) Ternary materials (such as lithium nickel manganese cobalt oxide), lithium manganate, and the like. However, these materials have problems of limited capacity, low electrical conductivity, poor structural stability, etc., and limit the performance and application range of lithium batteries.
In order to improve the conductivity and the capacity of the positive electrode plate of the lithium battery, researchers adopt various methods and strategies:
(1) Searching for novel active materials: researchers are looking for new positive electrode materials with higher capacities and better electrical conductivity, such as lithium cobaltate, lithium manganate, lithium iron phosphate, etc. The materials have higher specific capacity and better conductivity, and are expected to improve the overall performance of the lithium battery.
(2) Improving the conductivity agent: the conductive agent plays a role in conducting electricity in the positive electrode plate, and influences the charge and discharge efficiency of the whole battery. The conductivity of the positive electrode plate can be improved by optimizing the selection and the addition amount of the conductive agent. For example, the use of a conductive agent such as carbon nanotubes or graphene can improve the conductivity of the battery.
(3) Optimizing structural design: by optimizing the structural design of the positive electrode plate, such as increasing the surface area, regulating the pore structure and the like, the contact area and the ion diffusion rate of the positive electrode material can be increased, so that the capacity and the conductivity of the battery are improved.
(4) Surface modification: the conductivity and electrochemical reactivity of the material can be improved by modifying the surface of the positive electrode material, such as coating a conductivity modifier, a nano material and the like, so that the performance of the positive electrode plate is improved.
Wherein, the conductivity of the traditional conductive agent such as carbon black and the like in the positive electrode plate of the lithium battery is relatively low for the conductive agent in the lithium battery. Since the conductivity agent is a key component for realizing the conduction of electrons and ions in the battery, insufficient conductivity can cause the increase of the internal resistance of the battery, thereby reducing the charge and discharge efficiency of the battery.
The patent with the application number of CN202111014716.3 discloses a positive plate of a high-energy-density lithium ion battery and a preparation method thereof, wherein the positive plate comprises a pole plate body, a dressing layer is arranged on the surface of the pole plate body, and the dressing layer comprises a lithium ion supplementing material, a positive electrode material, conductive carbon black, a conductive carbon tube, polyvinylidene fluoride and a solvent. In the application, the prepared electrode plate can effectively inhibit the problem of mass gas production of the battery in a voltage range of 4.1-4.2V after the lithium ion supplementary material is added, and simultaneously improves the stability of the battery. However, there is no targeted improvement in the conductivity of the positive electrode sheet and the capacity of the lithium battery.
Disclosure of Invention
The application aims to overcome the defect that the charge and discharge efficiency and capacity of a battery are reduced due to the defect of insufficient conductivity of a positive electrode plate of a lithium battery in the prior art, and provides a high-conductivity high-capacity positive electrode plate, a lithium battery and a preparation method thereof so as to overcome the defects.
In a first aspect, the present application provides a high conductivity high capacity positive electrode sheet,
comprises a current collector and a dressing coated on the surface of the current collector; wherein,
the dressing comprises an anode active material, a single-walled carbon nanotube conductive agent, conductive carbon black and polyvinylidene fluoride; wherein,
the pipe diameter of the single-wall carbon nano-pipe conductive agent is less than or equal to 3nm, the length-diameter ratio is more than or equal to 3000, and the G/D ratio is more than 80.
The conductive agent added in the positive electrode sheet in the prior art is usually a multi-wall carbon tube, and compared with the single-wall carbon nanotube conductive agent adopted in the application, the traditional multi-wall carbon tube has higher internal resistance due to more connection between carbon atoms in the tube. This results in a slower electron transport rate in the electrode material, thereby affecting the charge-discharge efficiency of the battery. The multi-walled carbon nanotubes have poor electrical conductivity relative to single-walled carbon nanotubes.
Meanwhile, the pipe diameters of the multi-wall carbon pipes may be inconsistent, resulting in a larger size distribution range of the conductive agent. This may lead to uneven distribution of the conductive pathways, which in turn affects the transport and distribution of electrons in the positive electrode sheet, reducing the conductivity and uniformity of the battery.
In addition, the multi-walled carbon tube is susceptible to structural changes and volume expansion during charge and discharge due to the structure having a plurality of arms. This may lead to structural failure of the positive electrode tab, stripping or aggregation of the active material, affecting the cycle life and capacity retention of the battery.
Therefore, for the reasons, the single-walled carbon nanotube conductive agent is adopted to replace the traditional multi-walled carbon tube, so that the conductivity and the stability of the positive electrode plate can be greatly improved.
However, the inventor finds in experiments that the structure of the single-walled carbon nanotube conductive agent also has a remarkable effect on various performances of the positive electrode plate. In some existing positive electrode plates, the structural size of the conductive agent using the single-walled carbon nanotubes is usually larger, and the individual pipe diameter is even tens of nanometers. An excessively large pipe diameter causes a drastic decrease in the specific surface area thereof, and thus is unfavorable for contact between the battery positive electrode sheet and the electrolyte. The pipe diameter of the single-wall carbon nano-tube conductive agent is less than or equal to 3nm, and the small pipe diameter of the single-wall carbon nano-tube conductive agent is adopted to enable the single-wall carbon nano-tube conductive agent to have higher specific surface area and more surface active sites, which is beneficial to increasing the contact area between the positive electrode plate and electrolyte of the battery and improving the reaction rate and ion transmission rate of the battery. Therefore, the internal resistance of the battery can be reduced, and the charge and discharge efficiency of the battery can be improved.
In addition, the length-diameter ratio of the single-wall carbon nanotube conductive agent is greater than or equal to 3000, and compared with the prior art, the length-diameter ratio of the single-wall carbon nanotube conductive agent is greater, so that the conductive agent can provide a longer conductive path, and the transmission distance of electrons in the positive electrode plate is increased. This helps to improve the migration velocity of electrons in the positive electrode sheet, reduce scattering and obstruction of electrons, thereby reducing the internal resistance of the battery and improving the charge and discharge performance of the battery.
Meanwhile, the G/D ratio of the single-wall carbon nanotube conductive agent is larger than 80, which indicates that the wall thickness is larger relative to the diameter, so that the single-wall carbon nanotube conductive agent is stronger and more stable. The conductive agent with high G/D ratio has better mechanical strength and durability, can maintain the stability of the structure in the charge and discharge process of the battery, reduce the stripping or falling of the conductive agent, and improve the cycle life and long-term stability of the battery.
Therefore, in summary, the conductive performance of the positive electrode plate of the lithium battery can be obviously improved by adopting the single-wall carbon nano tube conductive agent with small pipe diameter, high length-diameter ratio and high G/D ratio. The increased specific surface area, conductive path and mechanical strength can reduce the internal resistance of the battery and improve the transmission speed of electrons and ions, thereby improving the charge and discharge efficiency and capacity of the battery. In addition, the stability of the single-walled carbon nanotube conductive agent also helps to improve the cycle life and safety of the battery. Therefore, the conductive agent has important application potential in improving the performance of the lithium battery.
Preferably, the pipe diameter of the single-wall carbon nano-pipe conductive agent is 1-3nm, the pipe length is 1500-50000nm, and the G/D ratio is 85-95.
Further limitations are imposed on the properties of the single-walled carbon nanotube conductive agent in other embodiments of the present application. Through setting the pipe diameter of the single-wall carbon nano-tube conductive agent within the range of 1-3nm, setting the pipe length within the range of 1500-50000nm and setting the G/D ratio within the range of 85-95, the conductive performance can be optimized, the active material loading capacity can be increased, the stability can be improved, and flexible adjustment can be carried out according to specific requirements so as to meet the requirements of different battery designs.
Preferably, the specific surface area of the single-walled carbon nanotube conductive agent is 600-1200m 2 /g。
The specific surface area of the single-walled carbon nanotube conductive agent is higher than that of the existing conductive agent. Given such a high specific surface area, this means that more active sites can undergo electrochemical reactions. In the positive electrode sheet of the battery, the specific surface area of the conductive agent determines the contact area with the active material, thereby affecting the reaction rate between the positive electrode material and the electrolyte. The larger specific surface area can provide more reaction interfaces, and the transmission speed of electrons and ions is increased, so that the reaction rate and the power density of the battery are increased.
At the same time, a larger specific surface area may provide more surface area for storing charge. In a battery positive electrode sheet, the energy storage capacity of an active material is directly related to its surface area. The specific surface area of the conductive agent is increased, so that the loading amount of the active material in the positive electrode plate can be increased, and the capacity and the energy density of the battery are improved.
In addition, the larger specific surface area can disperse the uneven stress and charge distribution in the charge and discharge process of the battery, and reduce the peeling and aggregation phenomena of the active material, thereby improving the cycle life and long-term stability of the battery.
Finally, the larger specific surface area can increase the contact area between the conductive agent and the electrolyte, and promote the adsorption and diffusion of ions in the electrolyte. This helps to increase the ion transport rate of the battery, reduce the internal resistance of the battery, and thereby improve the charge-discharge efficiency and cycle life of the battery.
However, the larger the specific surface area of the single-walled carbon nanotube conductive agent is, the more preferable. First, larger specific surface area single-walled carbon nanotube conductive agents typically require special preparation methods and materials, which may involve higher costs. And a larger specific surface area may increase sensitivity of the conductive agent to external environments, such as oxidation, adsorption of pollutants, etc., which may lead to degradation of stability and life of the battery in actual use. Meanwhile, a larger specific surface area increases the internal resistance of the conductive agent, resulting in limited transmission of electrons and ions, affecting the charge and discharge efficiency and power density of the battery.
Thus, in summary, the specific surface area of the single-walled carbon nanotube conductive agent is set to 600-1200m 2 In the range of/g, the reaction rate, charge storage capacity, cycle life and adsorption performance of the battery can be improved. This helps to optimize battery performance, improving its energy density, power density and long term stability.
Preferably, the mass ratio of the single-walled carbon nanotube conductive agent to the conductive carbon black is (1-4): (6-9).
In the application, the mass ratio of the single-walled carbon nanotube conductive agent to the conductive carbon black is further limited, which is as follows: the conductive carbon black has good conductivity, and the single-wall carbon nano tube conductive agent has larger specific surface area and conductivity. Through proper combination of mass ratio, the advantages of the single-walled carbon nanotube conductive agent and the conductive carbon black can be considered, and more excellent conductive performance can be realized. This helps to reduce the internal resistance of the battery and improve the conductivity and charge-discharge efficiency of the battery. Meanwhile, the conductive carbon black has higher specific surface area and can be used as a loading matrix of an active material. The single-walled carbon nanotube conductive agent has a larger tube diameter and tube length, providing more surface area for loading the active material. By proper mass ratio setting, the loading of the active material can be improved to the maximum extent, and the capacity and energy density of the battery can be increased. Finally, conductive carbon black generally has a lower cost, while single-walled carbon nanotube conductive agents are relatively expensive due to their higher cost of preparation. Through reasonable mass ratio setting, the cost of the conductive agent can be reduced and the economical efficiency of the battery can be improved while the better conductive performance is maintained.
In summary, the mass ratio of the single-walled carbon nanotube conductive agent to the conductive carbon black is set at (1-4): in the range of (6-9), it is possible to optimize the conductive properties, improve the active material loading, regulate the battery performance and stability, and consider the economy of the battery. Such an arrangement facilitates a high performance, high efficiency and economically viable battery design.
Preferably, the mass ratio of the positive electrode active material, the single-walled carbon nanotube conductive agent, the conductive carbon black and the polyvinylidene fluoride in the positive electrode sheet is 98: (0.1-0.4): (0.6-0.9): 1.
the mass ratio of the positive electrode active material in the positive electrode plate is set to 98%, so that the loading capacity of the active material in the positive electrode plate can be improved to the maximum extent. This helps to increase the capacity and energy density of the battery, improving the energy storage performance of the battery. And the mass ratio of the polyvinylidene fluoride is set to be 1, so that the structural stability and durability of the pole piece can be ensured. Thus, the addition of suitable conductive agents and binders may improve the cycle life of the battery. The addition of the single-walled carbon nanotube conductive agent and the conductive carbon black is helpful for improving the conductivity and the ion transmission speed of the battery and reducing the internal resistance. The addition of polyvinylidene fluoride is beneficial to improving the structural stability and chemical corrosion resistance of the pole piece and prolonging the service life of the battery.
Preferably, the positive electrode active material is of the formula LiNixCoyMn (1-x-y) O 2 (X>0.83 Lithium nickel cobalt manganate).
The nickel cobalt lithium manganate serving as the positive electrode active material has high capacity characteristic and better cycle stability compared with other materials. By adjusting the proportion of nickel, cobalt and manganese, the structural stability and electrochemical performance of the anode material can be optimized, and the capacity attenuation and structural damage of the pole piece can be reduced, so that the cycle life of the battery can be prolonged. By ensuring a nickel content of x >0.83, the specific capacity of the positive electrode active material can be increased. This helps to increase the capacity and energy density of the battery, providing longer run times.
In a second aspect, the present application also provides a method for preparing the positive electrode sheet, comprising the steps of:
(S.1) dissolving polyvinylidene fluoride in a solvent to obtain a glue solution;
(S.2) adding the positive electrode active material, the single-walled carbon nanotube conductive agent and the conductive carbon black into the glue solution and uniformly stirring to obtain positive electrode slurry;
and (S.3) coating the slurry on the surface of the positive electrode current collector, drying, cold pressing and cutting to obtain the positive electrode plate.
Preferably, the solid content of the positive electrode slurry in the step (S.2) is 70-80%;
the viscosity of the positive electrode slurry is 2500 mpa.s-350 mpa.s.
In a third aspect, the application also provides a lithium battery comprising the positive electrode sheet as described above.
In a fourth aspect, the present application also provides a method for preparing a lithium battery as described above, comprising the steps of:
and winding the positive pole piece, the negative pole piece and the double-sided coating ceramic diaphragm, wherein the diaphragm coats the negative pole by more than 2mm, the negative pole coats the positive pole by more than 1mm, obtaining a battery cell after winding is completed, carrying out hot pressing on the battery cell, welding a tab in a white area of the positive pole and the negative pole, then carrying out aluminum-plastic film packaging on the welded battery cell, baking the packaged battery cell to remove moisture, injecting an upper electrolyte into the battery cell, and carrying out hot pressing formation, high Wen Gezhi, secondary packaging and capacity division in sequence to obtain the lithium battery.
Preferably, the negative electrode plate comprises a negative electrode current collector and a negative electrode dressing coated on the surface of the negative electrode current collector;
the negative electrode dressing comprises a carbon-silicon composite material, conductive carbon black, conductive carbon tubes, sodium carboxymethyl cellulose and a binder, wherein the weight ratio of the carbon-silicon composite material to the conductive carbon black to the conductive carbon tubes is 96.2:0.95:0.05:1.0:1.8.
preferably, the preparation method of the negative electrode plate comprises the following steps: mixing deionized water and sodium carboxymethyl cellulose, stirring to obtain a glue solution, setting the solid content to 50% according to the formula proportion, adding the living substance silicon-carbon composite material, the conductive carbon black and the conductive carbon tube into the glue solution, stirring uniformly, adding the binder, and stirring uniformly to obtain the slurry with the viscosity of 2000 mpa.s. And then coating the slurry on two sides of a negative electrode current collector (copper foil) with the thickness of 6um according to a certain width and thickness, and carrying out cold pressing and slicing to obtain the negative electrode plate.
The application has the following beneficial effects:
the application adopts the single-wall carbon nanotube conductive agent with small pipe diameter, high length-diameter ratio and high G/D ratio, and can obviously improve the conductivity of the positive plate of the lithium battery. The increased specific surface area, conductive path and mechanical strength can reduce the internal resistance of the battery and improve the transmission speed of electrons and ions, thereby improving the charge and discharge efficiency and capacity of the battery. In addition, the stability of the single-walled carbon nanotube conductive agent also helps to improve the cycle life and safety of the battery.
Drawings
FIG. 1 is a graph showing the capacity comparison of the added amounts of different Swcnt.
FIG. 2 is a graph showing the comparison of ACR with different Swcnt addition amounts.
FIG. 3 is a graph showing the comparison of DCR 1C 10S with respect to the addition amount of Swcnt.
FIG. 4 is a graph of DCR for different Swcnt additions.
FIG. 5 is a 25℃cycle chart for different amounts of Swcnt addition.
FIG. 6 is a 45℃cycle chart of different amounts of Swcnt added.
Detailed Description
The application is further described below in connection with specific embodiments. Those of ordinary skill in the art will be able to implement the application based on these descriptions. In addition, the embodiments of the present application referred to in the following description are typically only some, but not all, embodiments of the present application. Therefore, all other embodiments, which can be made by one of ordinary skill in the art without undue burden, are intended to be within the scope of the present application, based on the embodiments of the present application.
Example 1
The high-conductivity high-capacity positive electrode plate comprises a current collector and a positive electrode dressing coated on the surface of the current collector; wherein,
the positive electrode dressing comprises 98 percent of nickel cobalt lithium manganate (811 positive electrode), 0.1 percent of single-wall carbon nano tube conductive agent and 0.9 percent of Super-P (conductive carbon black) by weight percent1% polyvinylidene fluoride; wherein the pipe diameter of the single-wall carbon nano-pipe conductive agent is 1-3nm, the pipe length is 1500-30000nm, the G/D ratio is 90, and the specific surface area is 1000m 2 /g。
The preparation method of the positive plate comprises the following steps: NMP (N, N-dimethyl pyrrolidone) is mixed with PVDF and stirred uniformly to obtain a glue solution, then the solid content is set to 75% according to the formula proportion, and living material NCM and a conductive agent are added into the glue solution and stirred uniformly to obtain a slurry with the viscosity of about 3000mpa.s and mixed uniformly. And then uniformly coating the slurry on two sides of a positive electrode current collector (aluminum foil) with the thickness of 12 mu m according to a certain width and thickness, drying, and carrying out cold pressing and slitting to obtain the positive electrode plate.
Example 2
The high-conductivity high-capacity positive electrode plate comprises a current collector and a positive electrode dressing coated on the surface of the current collector; wherein,
the positive electrode dressing comprises, by weight, 98% of lithium nickel cobalt manganese oxide (811 positive electrode), 0.2% of single-walled carbon nanotube conductive agent, 0.8% of Super-P (conductive carbon black) and 1% of polyvinylidene fluoride; wherein,
the pipe diameter of the single-wall carbon nano-pipe conductive agent is 1-3nm, the pipe length is 1500-30000nm, the G/D ratio is 90, and the specific surface area is 1000m 2 /g。
The preparation method of the positive electrode sheet is described in example 1.
Example 3
The high-conductivity high-capacity positive electrode plate comprises a current collector and a positive electrode dressing coated on the surface of the current collector; wherein,
the positive electrode dressing comprises, by weight, 98% of lithium nickel cobalt manganese oxide (811 positive electrode), 0.4% of single-walled carbon nanotube conductive agent, 0.6% of Super-P (conductive carbon black) and 1% of polyvinylidene fluoride; wherein,
the pipe diameter of the single-wall carbon nano-pipe conductive agent is 1-3nm, the pipe length is 1500-30000nm, the G/D ratio is 90, and the specific surface area is 1000m 2 /g。
The preparation method of the positive electrode sheet is described in example 1.
Example 4
The high-conductivity high-capacity positive electrode plate comprises a current collector and a positive electrode dressing coated on the surface of the current collector; wherein,
the positive electrode dressing comprises, by weight, 98% of lithium nickel cobalt manganese oxide (811 positive electrode), 0.1% of single-walled carbon nanotube conductive agent, 0.9% of Super-P (conductive carbon black) and 1% of polyvinylidene fluoride; wherein,
the pipe diameter of the single-wall carbon nano-pipe conductive agent is 1-3nm, the pipe length is 10000-25000nm, the G/D ratio is 90, and the specific surface area is 1000m 2 /g。
The preparation method of the positive electrode sheet is described in example 1.
Example 5
The high-conductivity high-capacity positive electrode plate comprises a current collector and a positive electrode dressing coated on the surface of the current collector; wherein,
the positive electrode dressing comprises, by weight, 98% of lithium nickel cobalt manganese oxide (811 positive electrode), 0.1% of single-walled carbon nanotube conductive agent, 0.9% of Super-P (conductive carbon black) and 1% of polyvinylidene fluoride; wherein,
the pipe diameter of the single-wall carbon nano-pipe conductive agent is 1-3nm, the pipe length is 30000-50000nm, the G/D ratio is 90, and the specific surface area is 1000m 2 /g。
The preparation method of the positive electrode sheet is described in example 1.
Example 6
The high-conductivity high-capacity positive electrode plate comprises a current collector and a positive electrode dressing coated on the surface of the current collector; wherein,
the positive electrode dressing comprises, by weight, 98% of lithium nickel cobalt manganese oxide (811 positive electrode), 0.1% of single-walled carbon nanotube conductive agent, 0.9% of Super-P (conductive carbon black) and 1% of polyvinylidene fluoride; wherein,
the pipe diameter of the single-wall carbon nano-pipe conductive agent is 1-3nm, the pipe length is 10000-25000nm, the G/D ratio is 85, and the specific surface area is 1000m 2 /g。
The preparation method of the positive electrode sheet is described in example 1.
Example 7
The high-conductivity high-capacity positive electrode plate comprises a current collector and a positive electrode dressing coated on the surface of the current collector; wherein,
the positive electrode dressing comprises, by weight, 98% of lithium nickel cobalt manganese oxide (811 positive electrode), 0.1% of single-walled carbon nanotube conductive agent, 0.9% of Super-P (conductive carbon black) and 1% of polyvinylidene fluoride; wherein,
the pipe diameter of the single-wall carbon nano-pipe conductive agent is 1-3nm, the pipe length is 10000-25000nm, the G/D ratio is 95, and the specific surface area is 1000m 2 /g。
The preparation method of the positive electrode sheet is described in example 1.
Example 8
The high-conductivity high-capacity positive electrode plate comprises a current collector and a positive electrode dressing coated on the surface of the current collector; wherein,
the positive electrode dressing comprises, by weight, 98% of lithium nickel cobalt manganese oxide (811 positive electrode), 0.1% of single-walled carbon nanotube conductive agent, 0.9% of Super-P (conductive carbon black) and 1% of polyvinylidene fluoride; wherein,
the pipe diameter of the single-wall carbon nano-pipe conductive agent is 1-3nm, the pipe length is 10000-25000nm, the G/D ratio is 90, and the specific surface area is 600m 2 /g。
The preparation method of the positive electrode sheet is described in example 1.
Example 9
The high-conductivity high-capacity positive electrode plate comprises a current collector and a positive electrode dressing coated on the surface of the current collector; wherein,
the positive electrode dressing comprises, by weight, 98% of lithium nickel cobalt manganese oxide (811 positive electrode), 0.1% of single-walled carbon nanotube conductive agent, 0.9% of Super-P (conductive carbon black) and 1% of polyvinylidene fluoride; wherein,
the pipe diameter of the single-wall carbon nano-pipe conductive agent is 1-3nm, the pipe length is 10000-25000nm, the G/D ratio is 90, and the specific surface area is 1200m 2 /g。
The preparation method of the positive electrode sheet is described in example 1.
Comparative example 1
The high-conductivity high-capacity positive electrode plate comprises a current collector and a positive electrode dressing coated on the surface of the current collector; wherein,
the positive electrode dressing comprises, in weight percent, 98% of lithium nickel cobalt manganate (811 positive electrode), 1% of Super-P (conductive carbon black) and 1% of polyvinylidene fluoride.
The preparation method of the positive electrode sheet is described in example 1.
Comparative example 2
The high-conductivity high-capacity positive electrode plate comprises a current collector and a positive electrode dressing coated on the surface of the current collector; wherein,
the positive electrode dressing comprises, by weight, 98% of lithium nickel cobalt manganese oxide (811 positive electrode), 1% of single-walled carbon nanotube conductive agent and 1% of polyvinylidene fluoride; wherein,
the pipe diameter of the single-wall carbon nano-pipe conductive agent is 1-3nm, the pipe length is 1500-30000nm, the G/D ratio is 90, and the specific surface area is 1000m 2 /g。
The preparation method of the positive electrode sheet is described in example 1.
Comparative example 3
The positive electrode dressing comprises, by weight, 98% of lithium nickel cobalt manganese oxide (811 positive electrode), 0.1% of single-walled carbon nanotube conductive agent, 0.9% of Super-P (conductive carbon black) and 1% of polyvinylidene fluoride; wherein,
the pipe diameter of the single-wall carbon nano-pipe conductive agent is 1-3nm, the pipe length is 1000-1500nm, the G/D ratio is 90, and the specific surface area is 1000m 2 /g。
The preparation method of the positive electrode sheet is described in example 1.
Comparative example 4
The high-conductivity high-capacity positive electrode plate comprises a current collector and a positive electrode dressing coated on the surface of the current collector; wherein,
the positive electrode dressing comprises, by weight, 98% of lithium nickel cobalt manganese oxide (811 positive electrode), 0.1% of single-walled carbon nanotube conductive agent, 0.9% of Super-P (conductive carbon black) and 1% of polyvinylidene fluoride; wherein,
the pipe diameter of the single-wall carbon nano-pipe conductive agent is 1-3nm, the pipe length is 1500-30000nm, the G/D ratio is 70, and the specific surface area is 1000m 2 /g。
The preparation method of the positive electrode sheet is described in example 1.
Comparative example 5
The high-conductivity high-capacity positive electrode plate comprises a current collector and a positive electrode dressing coated on the surface of the current collector; wherein,
the positive electrode dressing comprises, by weight, 98% of lithium nickel cobalt manganese oxide (811 positive electrode), 0.1% of single-walled carbon nanotube conductive agent, 0.9% of Super-P (conductive carbon black) and 1% of polyvinylidene fluoride; wherein,
the pipe diameter of the single-wall carbon nano-pipe conductive agent is 5-10nm, the pipe length is 1500-30000nm, the G/D ratio is 90, and the specific surface area is 1600m 2 /g。
The preparation method of the positive electrode sheet is described in example 1.
The parameters of the positive electrode dressing of the positive electrode sheets of examples 1 to 9 and comparative examples 1 to 5 are summarized in the following table 1.
TABLE 1
。
The positive electrode plate and the negative electrode plate in examples 1-9 and comparative examples 1-5 are matched to prepare the high-performance soft package battery.
The preparation method of the negative electrode plate comprises the following steps:
the formula proportion is as follows: carbon-silicon composite material: super-P: SW-CNT: CMC (water-based binder, sodium carboxymethyl cellulose): the weight ratio of the binder (SBR+PAA composite binder) is 96.2:0.95:0.05:1.0:1.8.
mixing deionized water and CMC, stirring to obtain glue solution, setting solid content of 50% in certain proportion, adding active matter silicon-carbon composite material and conducting agent SP/SWCNT into the glue solution, stirring, adding SBR and PAA composite adhesive, stirring to obtain slurry with viscosity of 2000 mpa.s. And then coating the slurry on two sides of a negative electrode current collector (copper foil) with the thickness of 6um according to a certain width and thickness, and carrying out cold pressing and slicing to obtain the negative electrode plate.
The preparation method of the high-performance soft package battery comprises the following steps: winding the positive and negative electrode plates and a double-sided coating ceramic diaphragm (the diaphragm coating ceramic layer is more than 2 um) according to set technological parameters, wherein the diaphragm coats the negative electrode by more than 2mm, and the negative electrode coats the positive electrode by more than 1mm; then, after hot pressing, welding the tab on the anode and cathode blank area, and then packaging the welded battery core with an aluminum plastic film;
baking the packaged battery cell at 90 ℃ to remove water, and injecting electrolyte (PC-8) into the battery cell according to the ratio of 3-5 g/Ah;
finally, according to certain hot press formation process parameters, carrying out formation, high-temperature laying, secondary sealing and capacity division, preparing the high-performance soft package battery with positive electrode gram capacity of more than 191mAh/g and 25 ℃ cycle of more than 85% @1000 cyc.
The high performance pouch batteries including the positive electrode sheets of examples 1 to 9 and comparative examples 1 to 5 were tested, and the test results are shown in table 2 below.
TABLE 2
。
[ analytical description ]
As can be seen from table 1 and table 2, the conductivity of the positive electrode sheet of the lithium battery can be significantly improved by adding a certain amount of single-walled carbon nanotube conductive agent to the positive electrode sheet of the high-lithium battery. Taking example 1 as an example, fig. 1 to 6 are performance test charts of the high performance soft pack battery obtained in example 1 and comparative example 1, respectively. Wherein, fig. 1 is a capacity comparison chart, fig. 2 is an ACR comparison chart, fig. 3 is a DCR 1c 10s comparison chart, fig. 4 is a DCR chart, fig. 5 is a 25 ℃ cycle chart, and fig. 6 is a 45 ℃ cycle chart. It can be seen from fig. 1 that the addition of the single-walled carbon tube can significantly increase the capacity of the pouch cell. It can be seen from fig. 2 that the addition of single-walled carbon tubes can significantly reduce the resistance ACR of the pouch cell. It can be seen from fig. 3 that the addition of the single-walled carbon tube can significantly improve the high-rate discharge performance of the soft-packed battery. It can be seen from fig. 4 that the addition of single-walled carbon tubes can significantly reduce the reduced resistance DCR of the pouch cell. It can be seen from fig. 5 that the addition of the single-walled carbon tube can significantly improve the cycle performance of the soft-packed battery at 25 ℃. It can be seen from fig. 6 that the addition of the single-walled carbon tube can significantly improve the cycle performance of the soft-packed battery at 45 ℃.
As can be seen from the data in comparative example 2, after the conductive carbon black is completely replaced by the single-walled carbon nanotube, the cycle performance is improved to some extent, but the improvement is limited, and the selling price of the single-walled carbon nanotube is greatly improved compared with that of the conductive carbon black, which finally results in a great improvement of the preparation cost of the battery.
As can be seen from the data of comparative example 3, the length of the single-walled carbon nanotubes in comparative example 3 is shorter than that of examples 1 to 9, resulting in a significant decrease in the electrical conductivity.
As can be seen from the data in comparative example 4, the G/D ratio of the single-walled carbon nanotubes in comparative example 4 is smaller than that of examples 1 to 9, indicating that the wall thickness is smaller than the diameter, resulting in a slower migration rate of electrons in the positive electrode sheet, and increased scattering and blocking of electrons, thereby improving the internal resistance of the battery and reducing the charge/discharge performance of the battery.
As is apparent from the data in comparative example 5, the specific surface area of the single-walled carbon nanotube in comparative example 5 is larger, but the larger specific surface area increases the internal resistance of the conductive agent, resulting in limited transfer of electrons and ions, affecting the charge-discharge efficiency and power density of the battery, and the larger specific surface area may increase the sensitivity of the conductive agent to external environments, such as oxidation, adsorption of contaminants, etc., which results in a decrease in the stability and lifetime of the battery in practical use.
In summary, the small pipe diameter, the length-diameter ratio and the G/D ratio of the single-walled carbon nanotubes are compared to a certain extent, and as can be seen from the data in Table 2, the conductivity of the positive electrode sheet of the lithium battery can be remarkably improved by adopting the single-walled carbon nanotube conductive agent with the small pipe diameter, the high length-diameter ratio and the high G/D ratio. The increased specific surface area, conductive path and mechanical strength can reduce the internal resistance of the battery and improve the transmission speed of electrons and ions, thereby improving the charge and discharge efficiency and capacity of the battery. In addition, the stability of the single-walled carbon nanotube conductive agent also helps to improve the cycle life and safety of the battery.
Claims (10)
1. A high-conductivity high-capacity positive electrode plate is characterized in that,
comprises a current collector and a dressing coated on the surface of the current collector; wherein,
the dressing comprises an anode active material, a single-walled carbon nanotube conductive agent, conductive carbon black and polyvinylidene fluoride; wherein,
the pipe diameter of the single-wall carbon nano-pipe conductive agent is less than or equal to 3nm, the length-diameter ratio is more than or equal to 3000, and the G/D ratio is more than 80.
2. The high-conductivity high-capacity positive electrode sheet according to claim 1, wherein,
the pipe diameter of the single-wall carbon nano-pipe conductive agent is 1-3nm, the pipe length is 1500-50000nm, and the G/D ratio is 85-95.
3. A high conductivity high capacity positive electrode sheet according to claim 2, wherein,
the specific surface area of the single-wall carbon nano tube conductive agent is 600-1200m 2 /g。
4. The high-conductivity high-capacity positive electrode sheet according to any one of claims 1 to 3, characterized in that,
the mass ratio of the single-wall carbon nanotube conductive agent to the conductive carbon black is (1-4): (6-9).
5. The high-conductivity high-capacity positive electrode sheet according to claim 4, wherein,
the mass ratio of the nickel anode active material, the single-wall carbon nano tube conductive agent, the conductive carbon black and the polyvinylidene fluoride in the anode sheet is 98: (0.1-0.4): (0.6-0.9): 1.
6. the high-conductivity high-capacity positive electrode sheet according to claim 4, wherein,
the positive electrodeThe active material is LiNixCoyMn (1-x-y) O 2 (X>0.83 Lithium nickel cobalt manganate).
7. A method for producing the positive electrode sheet according to any one of claims 1 to 6, characterized in that,
the method comprises the following steps:
(S.1) dissolving polyvinylidene fluoride in a solvent to obtain a glue solution;
(S.2) adding the positive electrode active material, the single-walled carbon nanotube conductive agent and the conductive carbon black into the glue solution and uniformly stirring to obtain positive electrode slurry;
and (S.3) coating the slurry on the surface of the positive electrode current collector, drying, cold pressing and cutting to obtain the positive electrode plate.
8. The method of claim 7, wherein the step of determining the position of the probe is performed,
the solid content of the positive electrode slurry in the step (S.2) is 70-80 percent;
the viscosity of the positive electrode slurry is 2500 mpa.s-350 mpa.s.
9. A lithium battery comprising the positive electrode sheet according to any one of claims 1 to 6.
10. The method for preparing a lithium battery according to claim 9, comprising the steps of:
(1) Winding the positive electrode plate, the negative electrode plate and the double-sided coating ceramic diaphragm according to any one of claims 1-6, wherein the diaphragm coats the negative electrode by more than 2mm, the negative electrode coats the positive electrode by more than 1mm, a battery cell is obtained after winding is completed, the battery cell is subjected to hot pressing, a tab is welded on a white area of the positive electrode and the negative electrode, then the welded battery cell is subjected to aluminum plastic film packaging, the packaged battery cell is baked to remove moisture, an upper electrolyte is injected into the battery cell, and the lithium battery is obtained through hot pressing, high Wen Gezhi, secondary packaging and capacity division in sequence.
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