Prime coat current collector and preparation method thereof, pole piece and battery
By introducing lithium iron phosphate material layers and zirconium dioxide into the ternary battery and optimizing the components and structure, the problems of unstable crystal structure, interface side reactions and thermal runaway of the ternary battery were solved, and improvements in high energy density, safety and low-temperature performance were achieved, the process was simplified and the cost was reduced.
Patent Information
- Application Number
- CN202510944774.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-09
- Publication Date
- 2025-10-17
AI Technical Summary
Existing ternary batteries have problems such as unstable crystal structure, many interfacial side reactions, high risk of thermal runaway, high cost and poor environmental protection in high-nickel positive electrode materials, and there are also deficiencies in the composite application of lithium iron phosphate and ternary materials.
A primer current collector scheme is adopted, including a polymer substrate layer, a metal layer and a lithium iron phosphate material layer. By setting a lithium iron phosphate material layer on the metal layer and introducing zirconium dioxide, the component ratio and structure are optimized, a multi-level pore network is formed, the interface compatibility and conductivity are improved, the volume change is buffered, and the thermal stability is enhanced.
It improves the energy density, safety and cycle life of the battery, reduces costs, simplifies the process, improves low-temperature performance and battery consistency, and solves the performance bottleneck of ternary materials.
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Figure BDA0005490646360000081
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of batteries, in particular to a primer current collector and a preparation method thereof, a pole piece and a battery. BACKGROUND
[0002] Currently, the problems of ternary batteries mainly focus on the contradiction between materials and performance. For example, although the high-nickel positive electrode using NCM ternary material can improve the energy density and has a higher specific capacity, the crystal structure stability decreases, which leads to lattice distortion caused by Li + deintercalation during the cycle process, and the interface side reaction increases. Especially in a high-temperature environment, the oxygen release of the positive electrode reacts with the electrolyte to release a large amount of heat, which is easy to induce thermal runaway. At the same time, the high-activity positive electrode has strict requirements on the compatibility of the electrolyte. The traditional carbonate system is easy to decompose at high voltage, and needs to be matched with a high-concentration LiPF6 electrolyte or a new type of solid electrolyte, which increases the cost and process complexity. In addition, the cobalt resource in the ternary material is scarce, the price fluctuates greatly, and the CO2 emission generated during the preparation of the positive electrode is significantly higher than that of lithium iron phosphate. There are obvious shortcomings in safety, cost control and environmental protection.
[0003] To solve the above problems, some research teams and enterprises composite the lithium iron phosphate layer and the ternary material layer to realize the complementary advantages and improve the comprehensive performance of the battery. However, there are still many deficiencies in the actual application of the composite of the lithium iron phosphate layer and the ternary material layer in the prior art. How to make the composite better play its advantages is a problem to be solved. SUMMARY
[0004] The purpose of the present application is to provide a primer current collector and a preparation method thereof, a pole piece and a battery, so as to play the combined advantages of lithium iron phosphate and ternary material and improve the performance of the current collector.
[0005] The present application is realized by the following technical solutions:
[0006] The first aspect of the present application provides a primer current collector, comprising: a high molecular substrate layer, a metal layer and a lithium iron phosphate material layer; the high molecular substrate layer is provided with a metal layer on each of the two sides; the lithium iron phosphate material layer is provided on the metal layer on each side; the lithium iron phosphate material layer comprises the following components: lithium iron phosphate, zirconium dioxide, conductive material and binder.
[0007] To optimize the above technical solutions, the specific measures taken also include:
[0008] The lithium iron phosphate material layer contains 45-58% of lithium iron phosphate, 30-49.5% of conductive material and 5%-10% of binder; the proportion of zirconium dioxide in the lithium iron phosphate material layer is w1, and w1 is 0.5-2%.
[0009] Further, the D50 of the lithium iron phosphate ranges from 1 to 12 microns, the particle size of the conductive material ranges from 5 to 20 microns, and the particle size of the zirconium dioxide ranges from 10 to 100 nanometers.
[0010] Further, the thickness of the lithium iron phosphate material layer is 0.5 to 2 microns.
[0011] Further, the oxygen vacancy concentration of the zirconium dioxide in the lithium iron phosphate material layer is less than 0.5%.
[0012] The second aspect of the application provides a preparation method of a primer current collector, comprising the following steps:
[0013] Preparation of a metal layer on both sides of the polymer substrate layer;
[0014] Preparation of a lithium iron phosphate slurry;
[0015] Coating the lithium iron phosphate slurry on the metal layer on both sides, drying to form a lithium iron phosphate material layer.
[0016] The third aspect of the application provides a positive electrode sheet, comprising the primer current collector described above, and a positive electrode active material layer is arranged on both sides of the lithium iron phosphate material layer of the primer current collector, and the positive electrode active material layer is a NCM ternary active material layer.
[0017] Further, the positive electrode active material layer also contains zirconium dioxide with a proportion of w2, and w2 is 0.5 to 2%, and w2 < w1.
[0018] When w2 is less than w1, the volume expansion can be reduced, the lithium iron phosphate layer crack can be reduced, the lithium iron phosphate layer and the metal layer can be prevented from delaminating, and the interface wettability between the lithium iron phosphate layer and the ternary active material layer can be improved, and the interface impedance can be reduced.
[0019] Further, the oxygen vacancy concentration of the zirconium dioxide in the positive electrode active material layer is greater than the oxygen vacancy concentration of the zirconium dioxide in the lithium iron phosphate material layer.
[0020] By controlling the mass proportion and oxygen vacancy concentration of the zirconium dioxide in different layers, the adjustment of the interlayer structure stability and performance can be realized.
[0021] Further, the oxygen vacancy concentration of the zirconium dioxide in the positive electrode active material layer is 0.5% to 2%.
[0022] Increasing the oxygen vacancy on the surface of the zirconium dioxide increases the lithium ion adsorption site and accelerates the migration of lithium ions.
[0023] The oxygen vacancy concentration of zirconium dioxide in the application can be realized by the prior art, such as calcining ZrO2 in Ar / H2 or other reducing atmosphere, which can significantly increase the oxygen vacancy concentration, and calcining ZrO2 in air, which can reduce the oxygen vacancy concentration. Zirconium dioxide with different oxygen vacancies can also be prepared by hydrothermal method, chemical vapor deposition (CVD) and other methods.
[0024] Compared with the prior art, the application has the following beneficial effects:
[0025] The bottom coating current collector solution of the application uses a lithium iron phosphate material layer to replace the traditional carbon coating layer, and optimizes the components thereof, realizes the triple promotion of structure strengthening, interface optimization and performance synergy by introducing zirconium oxide into the lithium iron phosphate material layer and compounding with the ternary material, and solves the bottleneck of single material in energy density, safety, cycle life and the like. This technical path not only provides a feasible solution for the next generation of high energy density batteries, but also enhances market competitiveness through process simplification and cost control.
[0026] The application compounding the lithium iron phosphate layer and the ternary material layer can realize complementary advantages, improve the comprehensive performance of the battery, optimize the charge and discharge performance and improve the energy density by exerting the characteristics of high energy density of the ternary material and stable structure of the lithium iron phosphate, enhance the safety of the battery by using the excellent thermal stability of the lithium iron phosphate, improve the low temperature performance, optimize the slurry processability, and improve the consistency and service life of the battery, thereby providing an effective technical path for solving the performance bottleneck of single material.
[0027] The lithium iron phosphate layer replaces the traditional carbon coating layer, which exhibits significant advantages in improving the performance of the battery and reducing the cost, the lithium iron phosphate has good chemical compatibility with the active material, can effectively inhibit the side reaction between the current collector and the positive material, reduce the capacity attenuation caused by unstable interface, and the structural characteristics can buffer the volume change in the charge and discharge process, and enhance the structural stability of the pole piece; by compounding with the conductive material, a high-efficiency conductive network is constructed, the internal resistance of the pole piece is reduced, and the rate performance and charge and discharge efficiency of the battery are improved. DETAILED DESCRIPTION
[0028] The above content of the application will be further described in the form of specific embodiments, but it should not be understood that the scope of the above subject matter of the application is limited to the following examples, and any technology realized based on the above content of the application belongs to the scope of the application.
[0029] The application provides a bottom coating current collector, which comprises a polymer substrate layer, a metal layer and a lithium iron phosphate material layer; the polymer substrate layer is provided with a metal layer on each of two sides thereof; the lithium iron phosphate material layer is arranged on the metal layer on each side; and the lithium iron phosphate material layer comprises the following components: lithium iron phosphate, zirconium dioxide and conductive material.
[0030] The bottom fluid collecting scheme of the present application adds zirconium dioxide to the lithium iron phosphate material layer, and the purpose and effect are:
[0031] Relieve volume change and inhibit crack: can effectively buffer the volume change of lithium iron phosphate during charging and discharging, reduce the risk of particle breakage and pole piece pulverization.
[0032] Enhance thermal stability and inhibit thermal runaway: delay heat transfer; in addition, it can also adsorb hydrogen fluoride generated by electrolyte decomposition, reduce corrosion to ternary materials, and inhibit heat accumulation caused by side reactions.
[0033] Improve interface compatibility and conductivity: help to improve the interface wettability of lithium iron phosphate and ternary materials, and thus reduce the interface impedance.
[0034] Optimize low temperature performance: can improve the capacity retention rate of the composite battery, so that it can better meet the use demand in cold regions.
[0035] In some embodiments, the lithium iron phosphate material layer contains 45-58% lithium iron phosphate, 30-49.5% conductive material, and 5%-10% binder; the proportion of zirconium dioxide in the lithium iron phosphate material layer is w1, and w1 is 0.5-2%.
[0036] In some embodiments, the D50 of lithium iron phosphate is in the range of 1-12 μm, the particle size of the conductive material is in the range of 5-20 μm, and the particle size of zirconium dioxide is in the range of 10-100 nm, preferably 60-80 nm.
[0037] Preferably, the particle size relationship of the three materials is: LiFePO4> conductive material> zirconium dioxide, and the particle size is between LiFePO4 and zirconium dioxide, which can efficiently fill the gap of large LiFePO4 particles and form a three-dimensional conductive network; the three materials form a multi-level pore network, and the electrolyte can quickly penetrate into the electrode interior and quickly diffuse.
[0038] In some preferred embodiments, the conductive material is at least one of metal particles, carbon black, graphene, carbon nanotubes, carbon-coated nano-silver, and carbon-coated titanium dioxide.
[0039] The thickness of the lithium iron phosphate material layer is 0.5-2 μm.
[0040] The oxygen vacancy concentration of zirconium dioxide in the lithium iron phosphate material layer is <0.5%, which can control the oxygen vacancy on the surface of zirconium dioxide, reduce lithium ion adsorption sites, reduce lithium ion migration, ensure to reduce the interface contact resistance, improve the electronic conduction efficiency, and increase the stability of the ternary active material layer-lithium iron phosphate material layer-current collector substrate three-layer structure.
[0041] Non-limiting examples of the polymer substrate layer of the present application can include one or more of polyethylene terephthalate (PET), polypropylene (PP), polybutylene terephthalate (PBT), polystyrene (PS), polyphenylene sulfide (PPS), polyethylene (PE), and the like.
[0042] The conductive material and the conductive agent according to the present application are selected from at least one of graphite, carbon black, and carbon nanotubes.
[0043] The present application also provides a preparation method of the primer current collector, comprising the following steps:
[0044] A metal layer is prepared on both sides of the polymer substrate layer;
[0045] A lithium iron phosphate slurry is prepared;
[0046] The lithium iron phosphate slurry is coated on the metal layer on both sides, and dried to form a lithium iron phosphate material layer.
[0047] The present application also provides a positive electrode sheet comprising the primer current collector described above, wherein a positive electrode active material layer is arranged on both sides of the lithium iron phosphate material layer of the primer current collector, and the positive electrode active material layer is an NCM ternary active material layer.
[0048] The positive electrode active material layer also contains zirconium dioxide in a proportion of w2, wherein w2 is 0.5-2%, and w2 < w1. Such an arrangement can reduce volume expansion, reduce cracks in the lithium iron phosphate material layer, avoid delamination of the lithium iron phosphate layer and the metal layer, and improve the interface wettability between the lithium iron phosphate layer and the ternary active material layer, and reduce the interface impedance.
[0049] The oxygen vacancy concentration of the zirconium dioxide in the positive electrode active material layer is greater than the oxygen vacancy concentration of the zirconium dioxide in the lithium iron phosphate material layer. Increasing the oxygen vacancy concentration of the surface of the zirconium dioxide in the positive electrode active material layer can increase the lithium ion adsorption sites and accelerate the migration of lithium ions.
[0050] The present application preferably uses nanoscale zirconium dioxide, which can be embedded in the recesses on the surface of the current collector substrate, increase the adhesion between the lithium iron phosphate material layer and the metal layer, and additionally, the zirconium dioxide has a large hardness, which can be embedded in the surface layer of the metal layer when the electrode sheet is rolled, thereby increasing the adhesion.
[0051] The present application also provides a battery comprising the electrode sheet.
[0052] The technical solutions of the present application are further described in detail below in combination with specific embodiments:
[0053] Embodiment 1
[0054] (1) Preparation method of the current collector substrate:
[0055] The negative current collector substrate: the PET polymer base film is placed in the cabin of vacuum evaporation, the high-purity copper wire (purity greater than 99.99%) in the metal evaporation chamber is melted and evaporated at a high temperature of 1500°C, and the metal atoms after evaporation pass through the cooling system in the vacuum plating chamber and are deposited on the two opposite surfaces of the polymer base film to form a copper metal conductive layer with a thickness of 1 μm.
[0056] The positive current collector substrate: the PET polymer base film is placed in the cabin of vacuum evaporation, the high-purity aluminum wire (purity greater than 99.99%) in the metal evaporation chamber is melted and evaporated at a high temperature of 1300°C, and the metal atoms after evaporation pass through the cooling system in the vacuum plating chamber and are deposited on the two opposite surfaces of the film to form an aluminum metal conductive layer with a thickness of 1 μm.
[0057] (2) Positive current collector
[0058] The preparation of the lithium iron phosphate slurry is carried out according to the following steps:
[0059] Step one, mix NMP with PVDF binder to prepare glue, the viscosity of the glue is 200 mPa·S;
[0060] Step two, transfer the glue into a 200L double-star stirring tank, add conductive particles graphite to the glue in batches, and allow the obtained slurry to be high-speed dispersed at a dispersion speed of 2400 rpm / min for 90 min;
[0061] Step three, add lithium iron phosphate and zirconium dioxide to the slurry obtained in step two, and allow the obtained slurry to be high-speed dispersed at a dispersion speed of 1200 rpm / min for 60 min;
[0062] Step four, add NMP to the slurry obtained in step three to adjust the viscosity of the slurry to 100 mPa·S, and allow the obtained slurry to be high-speed dispersed at a dispersion speed of 2400 rpm / min for 30 min;
[0063] Step five, transfer the slurry prepared in step four into a homogenizer, homogenize twice at a pressure of 300 bar, and discharge to obtain the lithium iron phosphate slurry;
[0064] Coating: the lithium iron phosphate material is coated on the positive current collector, and then dried to obtain a lithium iron phosphate material layer with a thickness of 1 μm.
[0065] The lithium iron phosphate material layer contains the following mass fractions: lithium iron phosphate 46.0%, conductive material 42.5%, zirconium dioxide 1.5%, and PVDF 10%. The oxygen vacancy concentration of zirconium dioxide in the lithium iron phosphate material layer is 0.3%. The lithium iron phosphate D50 is 10 μm, the average particle size of the conductive material is 6 μm, and the average particle size of the zirconium dioxide is 50 nm.
[0066] (3) Negative current collector:
[0067] The negative current collector surface is provided with a carbon coating layer:
[0068] The carbon coating layer comprises 90% by mass of conductive agent graphite and 10% by mass of PVDF.
[0069] (4) Electrode sheet
[0070] The negative current collector surface is coated with a negative active material, and the above materials are taken in a mass ratio of graphite: conductive carbon (Super P): carbon nanotube: carboxymethyl cellulose = 96: 1.0: 0.5: 2.5, and the above materials are added to deionized water to prepare a negative electrode slurry with a solid content of 70%; the above negative electrode slurry is coated on the active material coating area of the negative current collector and dried to form a negative active material layer.
[0071] The positive current collector surface is coated with a positive active material, and the above materials are taken in a mass ratio of NCM622: zirconium dioxide: conductive carbon (Super P): carbon nanotube: polyvinylidene fluoride = 94.7: 1: 1.8: 0.5: 2, and the above materials are added to N-methyl pyrrolidone to prepare a positive electrode slurry with a solid content of 70%; the above positive electrode slurry is coated on the surface of the active material coating area of the positive current collector and dried to form a positive active material layer.
[0072] In the positive active material, the oxygen vacancy concentration of zirconium dioxide is 0.6%.
[0073] (5) Battery assembly
[0074] The selection of the separator uses an aluminum oxide ceramic coated polyethylene separator with a thickness of 25 μm as a separator for assembling a lithium ion battery.
[0075] The preparation of the electrolyte uses propylene carbonate, ethylene carbonate, and methyl ethyl carbonate, and the above materials are mixed in a mass ratio of 1:1:1 to obtain a carbonate solvent, and LiPF6 is added to the above carbonate solvent to prepare a 1 mol·L -1 LiPF6 carbonate solution, which is used as the electrolyte of the lithium ion battery.
[0076] The assembly of the lithium ion battery stacks the above positive electrode sheet, separator, and negative electrode sheet in order to prepare a bare cell; the bare cell is placed in a lithium battery outer packaging shell, dried, and then injected with electrolyte, and after vacuum packaging, standing, formation, shaping, and other processes, a lithium ion battery is obtained.
[0077] Example 2
[0078] The scheme of this example is basically the same as that of Example 1, with the only difference being that the lithium iron phosphate material layer in Example 2 contains the following mass fractions: lithium iron phosphate 45.0%, conductive material 42.5%, PVDF 10%, and zirconium dioxide 2.5%.
[0079] Example 3
[0080] The scheme of this example is basically the same as that of Example 1, with the only difference being that the positive electrode active material coated on the surface of the positive electrode current collector in Example 3 is in accordance with NCM622: zirconium dioxide: conductive carbon (Super P): carbon nanotube: polyvinylidene fluoride = 94: 2: 1.8: 0.5: 1.7.
[0081] Example 4
[0082] The scheme of this example is basically the same as that of Example 1, with the only difference being that the average particle size of the conductive material in the lithium iron phosphate material layer in Example 4 is 12 μm.
[0083] Example 5
[0084] The scheme of this example is basically the same as that of Example 1, with the only difference being that the oxygen vacancy concentration of zirconium dioxide in the lithium iron phosphate material layer in Example 5 is 0.7%.
[0085] Example 6
[0086] The scheme of this example is basically the same as that of Example 1, with the only difference being that the oxygen vacancy concentration of zirconium dioxide in the positive electrode active material in Example 6 is 0.2%.
[0087] Comparative Example 1
[0088] The scheme of this example is basically the same as that of Example 1, with the only difference being that the lithium iron phosphate material layer in Comparative Example 1 contains lithium iron phosphate 47.5%, conductive material 42.5%, PVDF 10%, and no zirconium dioxide.
[0089] Comparative Example 2
[0090] The scheme of this example is basically the same as that of Example 1, with the only difference being that the positive electrode active material coated on the surface of the positive electrode current collector in Comparative Example 2 is in accordance with NCM622: conductive carbon (Super P): carbon nanotube: polyvinylidene fluoride = 96: 1.8: 0.5: 1.7, and contains no zirconium dioxide.
[0091] Adhesion: The positive electrode in the battery after 100 charge-discharge cycles was taken out and dried. A layer of Permacel P-94 double-sided tape was adhered to a 1 mm thick aluminum foil, and the positive electrode tab was adhered to the top of the double-sided tape. A layer of ethylene acrylic acid copolymer film (DuPont Nurcel0903, thickness 50 μm) was then covered on the top of the positive electrode tab, and then a 1.3 x 105 N / m22 The sample was cut into a small strip of 150 mm x 15 mm. The ethylene acrylic acid copolymer film of the sample strip was fixed to the upper clamp of the tensile tester, and the rest was fixed to the lower clamp. After fixing, the two were peeled at an angle of 180° at a speed of 100 mm / min to test the adhesion.
[0092] Battery capacity retention: The assembled battery was subjected to 1000 cycles of battery charging and discharging at a charge-discharge rate of 1C / 2C, and the battery capacity retention after the cycle charging and discharging was recorded.
[0093] The above examples were tested, and the results are shown in Table 1:
[0094] Table 1
[0095]
[0096] The lithium iron phosphate material layer of the present application simultaneously has the characteristics of active material, interface stability and structural buffering effect.
[0097] The adhesion of Example 1 was 689 N / m, which was significantly higher than 516 N / m of Comparative Example 1 and 541 N / m of Comparative Example 2, confirming that the lithium iron phosphate material layer enhanced the interface bonding strength through chemical compatibility.
[0098] When the lithium iron phosphate material layer contained 1.5% zirconium dioxide, the 1C capacity retention reached 89%, which was much higher than 79% of Comparative Example 1 without zirconium dioxide, indicating that the composite structure effectively inhibited the capacity decay.
[0099] When the lithium iron phosphate material layer contained zirconium dioxide increased from 1.5% of Example 1 to 2.5% of Example 2, the adhesion decreased to 645 N, a decrease of 6.4%, and the rate difference value increased from 4% to 7%, indicating that excessive zirconium dioxide may hinder the conductive network.
[0100] Compared with Example 1, the capacity retention of Example 3 decreased by 5.4% when the positive electrode zirconium dioxide addition amount increased from 1% to 2%, which may be due to the excessive zirconium dioxide occupying the active material space and reducing the specific capacity.
[0101] Compared with Example 1, the particle size of the conductive agent in Example 4 increased from 6 μm to 12 μm, and the test results showed that the adhesion decreased by 7.4%, which was due to the large particle size reducing the particle contact area and weakening the conductive network.
[0102] The oxygen vacancy factor of zirconium dioxide also plays a key role in the scheme, when the oxygen vacancy of zirconium dioxide of the lithium iron phosphate material is 0.3%, i.e. the scheme of example 1, the performance is optimal; when it rises to 0.7%, i.e. example 5, it leads to the decrease of adhesion and capacity retention, which shows that excessive vacancies may destroy the structural stability, and the analysis may be that excessive vacancies cause structural defects, reduce the mechanical strength.
[0103] The oxygen vacancy in the positive electrode active material of example 1 is 0.6%, which is better than 0.2% of example 6, which verifies the promoting effect of moderate vacancies on ion transmission.
[0104] Synergistic effect of lithium iron phosphate material layer and ternary positive electrode material: by means of the thermal stability of the lithium iron phosphate material layer, the contradiction between high energy density and safety of the ternary positive electrode material is relieved, and the safety is improved.
[0105] The difference of 1C / 2C capacity retention rate of example 1 is only 4%, which is far lower than 13% of comparative example 1, which shows that the composite structure improves the ion diffusion efficiency under high rate, and indirectly verifies the improvement of low temperature performance, and the scheme of the present application can play a role in optimizing low temperature and service life.
[0106] The above is only the preferred embodiment of the present application, and does not limit the present application in any form, any person skilled in the art, without departing from the technical scheme of the present application, according to the technical essence of the present application, any simple modification, equivalent replacement and improvement of the above examples, etc., still belongs to the protection scope of the technical scheme of the present application.
Claims
1. A primer current collector, characterized in that: include: A polymer substrate layer, a metal layer and a lithium iron phosphate material layer; the metal layers are respectively arranged on the two sides of the polymer substrate layer; the lithium iron phosphate material layers are respectively arranged on the metal layers on both sides; the lithium iron phosphate material layers include the following components: lithium iron phosphate, zirconium dioxide, a conductive material and a binder.
2. The primer current collector according to claim 1, wherein: The lithium iron phosphate material layer contains 45-58% lithium iron phosphate, 30-49.5% conductive material, and 5-10% binder; the proportion of zirconium dioxide in the lithium iron phosphate material layer is w1, and the w1 is 0.5-2%.
3. The primer current collector according to claim 1, wherein: The D50 of the lithium iron phosphate is in the range of 1 to 12 μm, the average particle size of the conductive material is in the range of 5 to 20 μm, and the average particle size of the zirconium dioxide is in the range of 10 to 100 nm. Preferably, the D50 of the lithium iron phosphate is greater than the average particle size of the conductive material and greater than the average particle size of the zirconium dioxide.
4. The primer current collector according to claim 1, wherein: The thickness of the lithium iron phosphate material layer is 0.5-2 μm.
5. The primer current collector according to claim 1, wherein: The oxygen vacancy concentration of zirconium dioxide in the lithium iron phosphate material layer is less than 0.5%, and preferably the oxygen vacancy concentration of zirconium dioxide is in the range of 0.2%-0.5%.
6. The method for preparing the primer current collector according to any one of claims 1 to 5, characterized in that: The following steps are involved: preparing metal layers on both sides of the polymer substrate layer; preparing lithium iron phosphate slurry; Lithium iron phosphate slurry is coated on the metal layers on both sides and dried to form a lithium iron phosphate material layer.
7. A positive electrode sheet, characterized in that: The primer current collector comprises the primer current collector according to any one of claims 1 to 5, characterized in that positive electrode active material layers are respectively provided on both sides of the lithium iron phosphate material layer of the primer current collector, and the positive electrode active material layer is an NCM ternary active material layer.
8. The positive electrode sheet according to claim 7, characterized in that: The positive electrode active material layer further contains zirconium dioxide with a proportion of w2, wherein w2 is 0.5-2%, and w2<w1.
9. The positive electrode sheet according to claim 8, characterized in that: The oxygen vacancy concentration of zirconium dioxide in the positive electrode active material layer is greater than the oxygen vacancy concentration of zirconium dioxide in the lithium iron phosphate material layer.
10. A battery, characterized in that: Comprising the pole piece according to claim 9.