Positive plate, preparation method and application thereof, and lithium ion battery

Abstract

The invention provides a positive plate, a preparation method and application thereof, and a lithium ion battery, and relates to the technical field of batteries. The positive plate provided by the invention comprises a current collector, ceramic conductive coatings coated on the surfaces of two sides of the current collector, and active substance layers coated on the ceramic conductive coatings, the ceramic conductive coating comprises the following components in parts by mass: 10-30 parts of a binder and 70-90 parts of a ceramic coated conductive agent; the porosity of the ceramic conductive coating is 40%-50%. According to the positive plate, good matching of characteristics of a positive electrode material is realized, the electrochemical stability is improved, the safety is enhanced, the wettability of an electrolyte is improved, and the diffusion coefficient of lithium ions and the cycling stability of the battery are improved. The preparation technology of the pole piece is simple, industrial production is easy, and the pole piece has important significance for promoting the development of the lithium ion battery technology.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a positive electrode sheet, a preparation method and application thereof, and a lithium ion battery. Background Art

[0002] Lithium-ion batteries have the advantages of high energy density, high voltage, long cycle life, high rate discharge, low self-discharge and environmental protection, and have been widely used in electric vehicles and energy storage. However, the cost of lithium-ion batteries is relatively high, especially in electric vehicles and electric bicycles, where the cost proportion is still high. Therefore, while consumers are pursuing higher endurance, they also urgently hope that lithium-ion batteries have more efficient charge and discharge rates and longer cycle life.

[0003] Existing technologies have made some progress in improving the cycle performance of lithium-ion batteries. For example, in order to improve conductivity and reduce impedance, a conductive coating is usually applied at the junction of the active material and the current collector. This conductive coating can effectively improve the efficiency of electron conduction and reduce the resistance inside the battery, thereby improving the overall performance of the battery. However, the effect of this method is limited, especially in solving the problem of difficult electrolyte infiltration at the bottom of the pole piece. The uneven distribution of the electrolyte at the bottom of the pole piece will lead to local liquid shortage, which in turn affects the charge and discharge performance and cycle life of the battery, so further optimization is still needed.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] The first object of the present invention is to provide a positive electrode sheet, which improves the rate characteristics and cycle life of the battery by coating a ceramic conductive coating on the current collector to improve the wettability of the electrolyte and the diffusion coefficient of lithium ions.

[0006] The second object of the present invention is to provide a method for preparing the above-mentioned positive electrode sheet.

[0007] The third object of the present invention is to provide the use of the above-mentioned positive electrode sheet in the preparation of lithium-ion batteries.

[0008] A fourth object of the present invention is to provide a lithium ion battery.

[0009] In order to achieve the above objectives, the following technical solutions are adopted: In a first aspect, the present invention provides a positive electrode sheet, comprising a current collector, a ceramic conductive coating coated on both sides of the current collector, and an active material layer coated on the ceramic conductive coating; The ceramic conductive coating comprises, by weight: 10-30 parts of a binder and 70-90 parts of a ceramic-coated conductive agent; The porosity of the ceramic conductive coating is 40%-50%; The porosity of the active material layer is 30%-40%; The porosity of the ceramic conductive coating is greater than the porosity of the active material layer.

[0010] As a further solution, in the ceramic-coated conductive agent, the mass ratio of ceramic to conductive agent is (0.1-8):100.

[0011] As a further embodiment, the ceramic includes at least one of Al2O3, γ-AlOOH, CeO2, SnO2, MgAl2O4, ZrO2, TiO2, SiO2 or LAGP.

[0012] As a further embodiment, the conductive agent includes at least one of carbon nanotubes, carbon fibers, graphene, conductive carbon black or conductive graphite.

[0013] As a further embodiment, the binder includes at least one of polyvinylidene fluoride (PVDF), polyacrylic acid (PAA), polyimide (PI), polyethylene oxide (PEO), sodium carboxymethyl cellulose (CMC) and styrene-butadiene rubber (SBR).

[0014] As a further solution, the thickness of the ceramic conductive coating is 1-5 μm.

[0015] In a second aspect, the present invention provides a method for preparing the above-mentioned positive electrode sheet, comprising the following steps: A slurry of a ceramic conductive coating is coated on the current collector to form a ceramic conductive coating, and then a slurry of an active material layer is coated on the ceramic conductive coating to form an active material layer, so as to prepare a positive electrode sheet.

[0016] In a third aspect, the present invention provides the use of the above-mentioned positive electrode sheet in the preparation of a lithium-ion battery.

[0017] In a fourth aspect, the present invention provides a lithium-ion battery, wherein the positive electrode sheet of the lithium-ion battery is the positive electrode sheet described above.

[0018] Compared with the prior art, the present invention has the following beneficial effects: The positive electrode provided by the present invention achieves a good match with the positive electrode material characteristics by coating the conductive agent with ceramic, improves electrochemical stability, enhances safety, and improves electrolyte wettability. At the same time, the high porosity design of the ceramic conductive coating further enhances the electrolyte infiltration rate, improves the lithium ion diffusion coefficient and the cycle stability of the battery. The preparation process of the electrode is simple and easy to industrialize, which is of great significance for promoting the development of lithium-ion battery technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 Schematic diagram of the structure of the pole piece according to an embodiment of the present invention.

[0021] Icon: 1-current collector; 2-ceramic conductive coating; 3-active material layer. DETAILED DESCRIPTION

[0022] The embodiments of the present invention will be described in detail below in conjunction with the embodiments and examples, but it will be appreciated by those skilled in the art that the following embodiments and examples are only used to illustrate the present invention and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present invention. If specific conditions are not specified, proceed according to normal conditions or conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0023] In a first aspect, the present invention provides a positive electrode sheet, comprising a current collector, a ceramic conductive coating coated on both sides of the current collector, and an active material layer coated on the ceramic conductive coating; The ceramic conductive coating is mainly composed of a binder and a ceramic-coated conductive agent, wherein the mass fraction of the binder may be, for example, but not limited to, 10 parts, 20 parts or 30 parts; the mass fraction of the ceramic-coated conductive agent may be, for example, but not limited to, 70 parts, 80 parts or 90 parts; The porosity of the ceramic conductive coating may be, for example, but not limited to, 40%, 45% or 50%; The porosity of the active material layer may be, for example, but not limited to, 30%, 35% or 40%; The porosity of the ceramic conductive coating is greater than the porosity of the active material layer.

[0024] The positive electrode provided by the present invention has the following advantages: Improve electrolyte wettability: The polar groups in the ceramic and the high porosity design of the coating help the electrolyte infiltration and reduce local liquid deficiency.

[0025] Improve the lithium ion diffusion coefficient: The porous structure of the ceramic conductive layer is conducive to the rapid transmission of lithium ions and improves the charge and discharge performance of the battery.

[0026] Enhanced mechanical strength and structural integrity: Ceramic materials have high hardness and mechanical strength, which can enhance the bonding force between the conductive agent and the active material and prevent the active material from falling off the electrode during the charge and discharge cycle.

[0027] Improved interface contact: The ceramic coating can prevent the agglomeration of conductive agent particles, ensure their uniform distribution in the electrode, and thus maintain an efficient and stable conductive network; at the same time, the ceramic coating can reduce the interface resistance between the conductive agent and the active material, especially under high-rate charge and discharge conditions, which helps to improve the current transmission efficiency.

[0028] Improve cycle stability: Prevent the precipitation of metals and their byproducts and interface deterioration caused by uneven distribution of electrolyte, and improve the cycle stability and service life of the battery.

[0029] High temperature resistance: Ceramic materials generally have excellent thermal stability and can maintain the stability of structure and performance in high temperature environments, making them suitable for applications in high temperature environments.

[0030] Improved safety: The insulating properties and thermal stability of ceramic materials can reduce the risk of thermal runaway and improve the safety performance of batteries, especially when used under extreme conditions.

[0031] In some optional embodiments, in the ceramic-coated conductive agent, the mass ratio of ceramic to conductive agent may be, for example, but not limited to, 0.1:100, 1:100, 3:100, 5:100 or 8:100, preferably (1-5):100.

[0032] In some optional embodiments, the ceramic includes but is not limited to Al2O3, γ-AlOOH, CeO2, SnO2, MgAl2O4, ZrO2, TiO2, SiO2 or LAGP, or other ceramic materials well known to those skilled in the art.

[0033] In some optional embodiments, the ceramic is coated on the conductive agent by a method selected from the group consisting of a sol-gel method, a chemical vapor deposition method, a physical vapor deposition method, a hydrothermal synthesis method, and a co-precipitation method.

[0034] In some optional embodiments, the conductive agent includes but is not limited to carbon nanotubes, carbon fibers, graphene, conductive carbon black or conductive graphite, or other conductive materials known to those skilled in the art.

[0035] In some optional embodiments, the binder includes, but is not limited to, polyvinylidene fluoride, polyacrylic acid, polyimide, polyethylene oxide, sodium carboxymethyl cellulose and styrene-butadiene rubber, or other binders known to those skilled in the art.

[0036] In the present invention, the porosity of the ceramic conductive coating can be adjusted by adjusting the size of the material in the ceramic conductive coating; the surface density of the ceramic conductive coating can be adjusted to adjust the porosity of the ceramic conductive coating; the thickness of the ceramic conductive coating can be adjusted to adjust the porosity of the ceramic conductive coating.

[0037] In some optional embodiments, the thickness of the ceramic conductive coating may be, for example, but not limited to, 1 μm, 3 μm or 5 μm.

[0038] In the present invention, there is no specific limitation on the composition of the active material layer, and any active material layer of a positive electrode sheet known to those skilled in the art may be used.

[0039] In some optional embodiments, the active material layer is mainly composed of active material, conductive agent and binder.

[0040] In a second aspect, the present invention provides a method for preparing the above-mentioned positive electrode sheet, comprising the following steps: A slurry of a ceramic conductive coating is coated on the current collector to form a ceramic conductive coating, and then a slurry of an active material layer is coated on the ceramic conductive coating to form an active material layer, so as to prepare a positive electrode sheet.

[0041] The positive electrode sheet provided by the present invention has a simple preparation process and is easy to industrialize, which is of great significance for promoting the development of lithium-ion battery technology.

[0042] In a third aspect, the present invention provides the use of the above-mentioned positive electrode sheet in the preparation of a lithium-ion battery.

[0043] The positive electrode sheet provided by the present invention achieves a good match with the properties of the positive electrode material and is used in lithium-ion batteries to improve the wettability of the electrolyte, increase the lithium ion diffusion coefficient and the cycle stability of the battery, and enhance safety.

[0044] In a fourth aspect, the present invention provides a lithium-ion battery, wherein the positive electrode sheet of the lithium-ion battery is the positive electrode sheet described above.

[0045] The lithium ion battery provided by the present invention has good safety, good rate characteristics and cycle life.

[0046] The present invention is further described below by means of specific examples and comparative examples. However, it should be understood that these examples are only used for more detailed description and should not be construed as limiting the present invention in any form.

[0047] It should be noted that, in the following embodiments and comparative examples, unless otherwise specified, the percentages of various components are by mass.

[0048] It should be noted that in the following examples and comparative examples, the porosity is adjusted by adjusting the coating surface density or the coating thickness, and the calculation logic is as follows: Porosity = pore volume / total volume of coating; = (total volume of coating - pore-free volume of coating) / total volume of coating; =(coating area × coating thickness - coating surface density × coating area / coating average true density) / (coating area × coating thickness); =1-coating surface density × coating area / coating average true density / (coating area × coating thickness); =1-coating surface density / coating average true density / coating thickness; =1-compression density of coating / average true density of coating.

[0049] Example 1 A positive electrode sheet having a structure such as Figure 1 As shown, it includes a current collector 1, a ceramic conductive coating 2 coated on both sides of the current collector, and an active material layer 3 coated on the ceramic conductive coating; various parameters are shown in Table 1.

[0050] Wherein, the current collector 1 is aluminum foil; The formula of ceramic conductive coating 2 is: 90% Al2O3 coated conductive graphite + 10% PVDF; the mass ratio of Al2O3 to conductive graphite is 3:100; The formula of the active material layer 3 is: 92% lithium iron phosphate + 5% conductive graphite + 3% PVDF.

[0051] The preparation method is as follows: 1) Aluminum nitrate (Al(NO3)3·9H2O) and graphite are dispersed in an ethanol solution, and then the ethanol is evaporated at 80°C, and heat-treated at 600°C for 3h under a protective atmosphere to obtain an Al2O3-coated conductive agent material; 2) The ceramic-coated conductive agent, binder and solvent (NMP) are mixed, and the total mass ratio of the conductive agent and the binder to the solvent is 35:65, and the slurry is prepared, and the slurry is coated on the current collector 1 with a preset surface density and thickness, and the coating speed is 5 m / min. After segmented drying (including: preheating at 80° C. for 30 seconds, drying at 100° C. for 60 seconds, curing at 120° C. for 40 seconds, and naturally cooling to room temperature), a ceramic conductive coating 2 with a high porosity structure is formed; 3) The active material, the conductive agent, the binder and the solvent (NMP) are mixed, and the total mass ratio of the active material and the conductive agent to the solvent is 60:40, and the active material slurry is configured, and coated on the ceramic conductive coating 2 according to a preset surface density, the coating speed is 30m / min, and the active material layer 3 is formed by stepwise drying (including: preheating at 90°C for 3min, drying at 110°C for 7min, curing at 100°C for 3min, and naturally cooling to room temperature).

[0052] 4) Roll-press the electrode according to the preset coating thickness to achieve the preset coating porosity.

[0053] Example 2 A positive electrode such as Figure 1 As shown, it includes a current collector 1, a ceramic conductive coating 2 coated on both sides of the current collector, and an active material layer 3 coated on the ceramic conductive coating; various parameters are shown in Table 1.

[0054] Wherein, the current collector 1 is aluminum foil; The formula of ceramic conductive coating 2 is: 90% Al2O3 coated conductive graphite + 10% PVDF; the mass ratio of Al2O3 to conductive graphite is 3:100; The formula of the active material layer 3 is: 92% lithium iron phosphate + 5% conductive graphite + 3% PVDF.

[0055] The preparation method refers to Example 1. Except for the parameters listed in Table 1, the other parameters are the same as those in Example 1.

[0056] Example 3 A positive electrode such as Figure 1 As shown, it includes a current collector 1, a ceramic conductive coating 2 coated on both sides of the current collector, and an active material layer 3 coated on the ceramic conductive coating; various parameters are shown in Table 1.

[0057] Wherein, the current collector 1 is aluminum foil; The formula of ceramic conductive coating 2 is: 90% Al2O3 coated conductive graphite + 10% PVDF; the mass ratio of Al2O3 to conductive graphite is 3:100; The formula of the active material layer 3 is: 92% lithium iron phosphate + 5% conductive graphite + 3% PVDF.

[0058] The preparation method refers to Example 1. Except for the parameters listed in Table 1, the other parameters are the same as those in Example 1.

[0059] Example 4 A positive electrode such as Figure 1 As shown, it includes a current collector 1, a ceramic conductive coating 2 coated on both sides of the current collector, and an active material layer 3 coated on the ceramic conductive coating; various parameters are shown in Table 1.

[0060] Wherein, the current collector 1 is aluminum foil; The formula of ceramic conductive coating 2 is: 90% Al2O3 coated conductive graphite + 10% PVDF; the mass ratio of Al2O3 to conductive graphite is 3:100; The formula of the active material layer 3 is: 92% lithium iron phosphate + 5% conductive graphite + 3% PVDF.

[0061] The preparation method refers to Example 1. Except for the parameters listed in Table 1, the other parameters are the same as those in Example 1.

[0062] Example 5 A positive electrode such as Figure 1 As shown, it includes a current collector 1, a ceramic conductive coating 2 coated on both sides of the current collector, and an active material layer 3 coated on the ceramic conductive coating; various parameters are shown in Table 1.

[0063] Wherein, the current collector 1 is aluminum foil; The formula of ceramic conductive coating 2 is: 90% Al2O3 coated conductive graphite + 10% PVDF; the mass ratio of Al2O3 to conductive graphite is 1:100; The formula of the active material layer 3 is: 92% lithium iron phosphate + 5% conductive graphite + 3% PVDF.

[0064] The preparation method refers to Example 1. Except for the parameters listed in Table 1, the other parameters are the same as those in Example 1.

[0065] Example 6 A positive electrode such as Figure 1 As shown, it includes a current collector 1, a ceramic conductive coating 2 coated on both sides of the current collector, and an active material layer 3 coated on the ceramic conductive coating; various parameters are shown in Table 1.

[0066] Wherein, the current collector 1 is aluminum foil; The formula of ceramic conductive coating 2 is: 90% Al2O3 coated conductive graphite + 10% PVDF; the mass ratio of Al2O3 to conductive graphite is 5:100; The formula of the active material layer 3 is: 92% lithium iron phosphate + 5% conductive graphite + 3% PVDF.

[0067] The preparation method refers to Example 1. Except for the parameters listed in Table 1, the other parameters are the same as those in Example 1.

[0068] Example 7 A positive electrode such as Figure 1 As shown, it includes a current collector 1, a ceramic conductive coating 2 coated on both sides of the current collector, and an active material layer 3 coated on the ceramic conductive coating; various parameters are shown in Table 1.

[0069] Wherein, the current collector 1 is aluminum foil; The formula of ceramic conductive coating 2 is: 70% ZrO2 coated conductive carbon black + 30% PAA; the mass ratio of ZrO2 to conductive carbon black is 0.1:100; The formula of the active material layer 3 is: 92% lithium iron phosphate + 5% conductive graphite + 3% PVDF.

[0070] The preparation method is as follows: 1) Tetrabutoxy zirconium (Zr(OBu)4) and conductive carbon black are dispersed in an ethanol solution, and then the ethanol is evaporated to dryness at 80°C, and heat-treated at 600°C for 3h under a protective atmosphere to obtain a ZrO2-coated conductive agent material; 2) The ceramic-coated conductive agent, binder and solvent (NMP) are mixed, and the total mass ratio of the conductive agent and the binder to the solvent is 35:65, and the slurry is prepared, and the slurry is coated on the current collector 1 with a preset surface density and thickness, and the coating speed is 5 m / min. After segmented drying (including: preheating at 80° C. for 30 seconds, drying at 100° C. for 60 seconds, curing at 120° C. for 40 seconds, and naturally cooling to room temperature), a ceramic conductive coating 2 with a high porosity structure is formed; 3) The active material, the conductive agent, the binder and the solvent (NMP) are mixed, and the total mass ratio of the active material and the conductive agent to the solvent is 60:40, and the active material slurry is configured, and coated on the ceramic conductive coating 2 according to a preset surface density, the coating speed is 30m / min, and the active material layer 3 is formed by stepwise drying (including: preheating at 90°C for 3min, drying at 110°C for 7min, curing at 100°C for 3min, and naturally cooling to room temperature).

[0071] 4) Roll-press the electrode according to the preset coating thickness to achieve the preset coating porosity.

[0072] Example 8 A positive electrode such as Figure 1 As shown, it includes a current collector 1, a ceramic conductive coating 2 coated on both sides of the current collector, and an active material layer 3 coated on the ceramic conductive coating; various parameters are shown in Table 1.

[0073] Wherein, the current collector 1 is aluminum foil; The formula of ceramic conductive coating 2 is: 80% SiO2-coated carbon nanotubes + 20% PEO; the mass ratio of SiO2 to carbon nanotubes is 8:100; The formula of the active material layer 3 is: 92% lithium iron phosphate + 5% conductive graphite + 3% PVDF.

[0074] The preparation method is as follows: 1) Tetraethyl orthosilicate (TEOS) and carbon nanotubes are dispersed in an ethanol solution, and then the ethanol is evaporated to dryness at 80°C, and heat-treated at 600°C for 3 hours under a protective atmosphere to obtain a SiO2-coated conductive agent material; 2) The ceramic-coated conductive agent, binder and solvent (NMP) are mixed, and the total mass ratio of the conductive agent and the binder to the solvent is 35:65, and the slurry is prepared, and the slurry is coated on the current collector 1 with a preset surface density and thickness, and the coating speed is 5 m / min. After segmented drying (including: preheating at 80° C. for 30 seconds, drying at 100° C. for 60 seconds, curing at 120° C. for 40 seconds, and naturally cooling to room temperature), a ceramic conductive coating 2 with a high porosity structure is formed; 3) The active material, the conductive agent, the binder and the solvent (NMP) are mixed, and the total mass ratio of the active material and the conductive agent to the solvent is 60:40, and the active material slurry is configured, and coated on the ceramic conductive coating 2 according to a preset surface density, the coating speed is 30m / min, and the active material layer 3 is formed by stepwise drying (including: preheating at 90°C for 3min, drying at 110°C for 7min, curing at 100°C for 3min, and naturally cooling to room temperature).

[0075] 4) Roll-press the electrode according to the preset coating thickness to achieve the preset coating porosity.

[0076] Comparative Example 1 A positive electrode sheet, various parameters of which are shown in Table 1, differs from Example 1 in that the conductive agent is not coated with ceramic.

[0077] Comparative Example 2 A positive electrode sheet, various parameters of which are shown in Table 1, differs from Example 1 in that the porosity of the ceramic conductive coating is 30%.

[0078] Comparative Example 3 A positive electrode sheet, various parameters of which are shown in Table 1, is different from Example 1 in that the ceramic is not coated with a conductive agent, but the ceramic and the conductive agent are used as raw materials to prepare a ceramic conductive coating.

[0079] Table 1 .

[0080] The positive electrode sheet, negative electrode sheet and separator are assembled into a lithium-ion battery in the form of a stack: Among them, the negative electrode is: 92% graphite + 3% SBR + 3% conductive carbon black + 2% CMC; The diaphragm is: 16μm PP + 2μm ceramic diaphragm; The electrolyte is: 13% lithium hexafluorophosphate (LiPF6), 25% ethylene carbonate (EC), 59% ethyl methyl carbonate (EMC), and 3% vinylene carbonate (VC).

[0081] The performance of the above batteries was tested (the batteries were charged and discharged, and the rate discharge performance and high temperature cycle performance (1C cycle at 45°C) were tested, and the reversible capacity was observed when the cycle reached 1000 cycles). The results are shown in Table 2.

[0082] Table 2 .

[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A positive electrode sheet, characterized in that: The positive electrode sheet comprises a current collector, a ceramic conductive coating coated on both sides of the current collector, and an active material layer coated on the ceramic conductive coating; The ceramic conductive coating comprises, by weight: 10-30 parts of a binder and 70-90 parts of a ceramic-coated conductive agent; The porosity of the ceramic conductive coating is 40%-50%; The porosity of the active material layer is 30%-40%; The porosity of the ceramic conductive coating is greater than the porosity of the active material layer.

2. The positive electrode sheet according to claim 1, characterized in that: In the ceramic-coated conductive agent, the mass ratio of ceramic to conductive agent is (0.1-8):

100.

3. The positive electrode sheet according to claim 1, characterized in that: The ceramic includes at least one of Al2O3, γ-AlOOH, CeO2, SnO2, MgAl2O4, ZrO2, TiO2, SiO2 or LAGP.

4. The positive electrode sheet according to claim 1, characterized in that: The conductive agent includes at least one of carbon nanotubes, carbon fibers, graphene, conductive carbon black, or conductive graphite.

5. The positive electrode sheet according to claim 1, characterized in that: The binder includes at least one of polyvinylidene fluoride, polyacrylic acid, polyimide, polyethylene oxide, sodium carboxymethyl cellulose and styrene-butadiene rubber.

6. The positive electrode sheet according to claim 1, characterized in that: The thickness of the ceramic conductive coating is 1-5 μm.

7. The method for preparing a positive electrode sheet according to any one of claims 1 to 6, characterized in that: The following steps are involved: A slurry of a ceramic conductive coating is coated on the current collector to form a ceramic conductive coating, and then a slurry of an active material layer is coated on the ceramic conductive coating to form an active material layer, so as to prepare a positive electrode sheet.

8. Use of the positive electrode sheet according to any one of claims 1 to 6 in the preparation of lithium-ion batteries.

9. A lithium ion battery, characterized in that: The positive electrode sheet of the lithium-ion battery is the positive electrode sheet according to any one of claims 1 to 6.

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