Cathode material, preparation method thereof, cathode sheet, energy storage device, and electric equipment

Abstract

The application provides a positive electrode material, a preparation method thereof, a positive electrode plate, an energy storage device and an electric device. The positive electrode material comprises a plurality of particles, each of the particles comprises lithium iron phosphate, a first type of carbon and a second type of carbon, the first type of carbon and the second type of carbon are covered on the surface of the lithium iron phosphate, and the plurality of particles comprises a first particle group, a second particle group and a third particle group; wherein the particle quantity ratio of the first particle group, the second particle group and the third particle group is (1-3):(8-10):(39-41). The application adds a first carbon source and a second carbon source, so that the lithium iron phosphate is covered by the first type of carbon and the second type of carbon, the growth state of the lithium iron phosphate is regulated, the first particle group, the second particle group and the third particle group with a preset ratio are obtained, the particle size gradient of the plurality of particles is formed, and then the porosity of the positive electrode material is reduced, and the compaction density of the positive electrode plate prepared from the material is improved.

Description

Technical Field

[0001] This application belongs to the field of energy storage device technology, specifically relating to cathode materials and their preparation methods, cathode plates, energy storage devices, and electrical equipment. Background Technology

[0002] With the rapid development of lithium-ion batteries, lithium-ion cathode materials have also made significant progress, while simultaneously placing higher demands on their performance. Improving the energy density of lithium-ion batteries is a current research hotspot, and existing technologies often increase the energy density of the battery by increasing the compaction density of the material. However, the compaction density of cathode sheets prepared from lithium iron phosphate cathode materials is currently relatively low, making it difficult to improve. Summary of the Invention

[0003] In view of this, the first aspect of this application provides a cathode material comprising a plurality of particles, each particle comprising lithium iron phosphate, a first type of carbon, and a second type of carbon, the first type of carbon and the second type of carbon covering the surface of the lithium iron phosphate, the plurality of particles comprising a first particle group, a second particle group, and a third particle group, the first particle group having a first particle size range, the second particle group having a second particle size range, and the third particle group having a third particle size range, the minimum value of the first particle size range being greater than the maximum value of the second particle size range, and the minimum value of the second particle size range being greater than the maximum value of the third particle size range; wherein the particle number ratio of the first particle group, the second particle group, and the third particle group is (1-3):(8-10):(39-41).

[0004] The cathode material provided in the first aspect of this application comprises, in each particle, lithium iron phosphate, a first type of carbon, and a second type of carbon. The first type of carbon is obtained from a first carbon source, and the second type of carbon is obtained from a second carbon source. It should be noted that the particle size here refers to the total particle size of the entire particle covered by the first and second types of carbon on the surface of the lithium iron phosphate. Alternatively, it can be understood as the total particle size of the lithium iron phosphate particle covered by the first and second types of carbon. Particles within the first particle size range can be considered large particles. Particles within the second particle size range can be considered medium particles. Particles within the third particle size range can be considered small particles.

[0005] During the preparation of cathode materials, lithium iron phosphate can form particles with different sizes, exhibiting a subtle particle size gradient. Furthermore, the carbon source coating on the surface of lithium iron phosphate can inhibit its self-growth, thereby altering the particle size of lithium iron phosphate and consequently changing the particle size of at least some cathode material particles.

[0006] First, by adding a first carbon source and a second carbon source to prepare the cathode material, the first carbon source can form relatively dense first-type carbon, inhibiting the growth of lithium iron phosphate and controlling the formation of at least a portion of the third particle group with a smaller particle size; the second carbon source can form relatively loose second-type carbon, reducing the inhibitory effect on the growth of lithium iron phosphate and controlling the formation of at least a portion of the first particle group with a larger particle size. Furthermore, the first and second carbon sources work together to ensure that the growth of lithium iron phosphate reaches a predetermined state, controlling the formation of at least a portion of the second particle group with a medium particle size.

[0007] Secondly, the second carbon source can also play a dispersing role, dispersing the particles in the raw materials, reducing particle agglomeration, making them uniformly dispersed, and giving lithium iron phosphate more room to grow.

[0008] The first and second carbon sources work together to achieve different coating degrees on each lithium iron phosphate particle. Combined with the dispersing effect of the second carbon source, they provide different growth spaces for each lithium iron phosphate particle, resulting in significant differences in particle size. This leads to cathode material particles with distinctly different sizes, achieving differentiated growth of cathode material particles. Specifically, when the particle number ratio of the first, second, and third particle groups is (1-3):(8-10):(39-41), the number of large, medium, and small particles within a specific ratio range is reduced, which decreases the porosity of the cathode material and increases the compaction density of the cathode sheet prepared from it.

[0009] Therefore, this application adds a first carbon source and a second carbon source to coat lithium iron phosphate with the first type of carbon and the second type of carbon, thereby regulating the growth state of lithium iron phosphate and obtaining a composite first particle group, a second particle group and a third particle group with a preset ratio. This results in a particle size gradient among the multiple particles, thereby reducing the porosity of the cathode material and increasing the compaction density of the cathode sheet prepared from the material.

[0010] Wherein, the first particle size range D1 is 1.5≤D1≤4μm, the second particle size range D2 is 0.8≤D2<1.5μm, and the third particle size range D3 is 0.2≤D3<0.8μm.

[0011] The sum of the mass of the first type of carbon and the mass of the second type of carbon accounts for 1-1.3% of the total mass of the cathode material.

[0012] The raw materials for preparing the cathode material include a first carbon source and a second carbon source. The first type of carbon is obtained from the first carbon source, and the second type of carbon is obtained from the second carbon source. The mass ratio of the first carbon source to the second carbon source is (3-4):(6-7).

[0013] The first carbon source includes one or more of glucose, polyaniline, sucrose, citric acid, cellulose, acetylene black, and graphene.

[0014] The second carbon source includes one or more of polyethylene glycol, polyvinyl alcohol, starch, and polyvinylpyrrolidone.

[0015] The sum of the mass of the first carbon source and the mass of the second carbon source accounts for 7-8% of the total mass of the raw materials used in the preparation.

[0016] The cathode material further includes titanium and vanadium, and the raw materials for preparing the cathode material further include a titanium source and a vanadium source. The titanium is obtained from the titanium source, and the vanadium is obtained from the vanadium source. The mass ratio of the titanium source to the vanadium source is 1:(0.8-1.2).

[0017] The mass ratio of the titanium source, the vanadium source, the first carbon source, and the second carbon source is 1:(0.8-1.2):(8-12):(7-11).

[0018] The sum of the mass of the titanium source and the mass of the vanadium source accounts for 0.2-0.4% of the total mass of the raw materials used in the preparation.

[0019] The titanium source includes titanium dioxide; the vanadium source includes one or more of vanadium pentoxide, vanadium trioxide, and vanadium dioxide.

[0020] A second aspect of this application provides a method for preparing a cathode material, the method comprising:

[0021] It provides iron source, lithium source, first carbon source, and second carbon source;

[0022] The iron source, the lithium source, the first carbon source, and the second carbon source are mixed and sintered to obtain a cathode material; wherein the cathode material comprises a plurality of particles, each particle comprising lithium iron phosphate, a first type of carbon, and a second type of carbon, the first type of carbon being obtained from the first carbon source, the second type of carbon being obtained from the second carbon source, the first type of carbon and the second type of carbon covering the surface of the lithium iron phosphate, the plurality of particles comprising a first particle group, a second particle group, and a third particle group, the first particle group having a first particle size range, the second particle group having a second particle size range, and the third particle group having a third particle size range, the minimum value of the first particle size range being greater than the maximum value of the second particle size range, and the minimum value of the second particle size range being greater than the maximum value of the third particle size range; wherein the particle number ratio of the first particle group, the second particle group, and the third particle group is (1-3):(8-10):(39-41).

[0023] The method for preparing the cathode material provided in the second aspect of this application is simple, low-cost, and highly operable. Specifically, the first carbon source and the second carbon source work together to achieve different coating degrees on each lithium iron phosphate particle. Furthermore, the dispersion effect of the second carbon source provides different growth spaces for each lithium iron phosphate particle, resulting in significant differences in particle size among the final lithium iron phosphate particles. This yields cathode material particles with distinctly different particle sizes, achieving differentiated growth of cathode material particles in a single step. When the ratio of the number of particles in the first, second, and third particle groups is (1-3):(8-10):(39-41), the number of large, medium, and small particles within a specific ratio range is achieved, which reduces the porosity of the cathode material and increases the compaction density of the cathode sheet prepared from this material.

[0024] Therefore, this application adds a first carbon source and a second carbon source to coat lithium iron phosphate with the first type of carbon and the second type of carbon, thereby regulating the growth state of lithium iron phosphate and obtaining a composite first particle group, a second particle group and a third particle group with a preset ratio. This results in a particle size gradient among the multiple particles, thereby reducing the porosity of the cathode material and increasing the compaction density of the cathode sheet prepared from the material.

[0025] A third aspect of this application provides a positive electrode sheet, comprising the positive electrode material as provided in the first aspect of this application.

[0026] The positive electrode sheet provided in the third aspect of this application, by using the positive electrode material provided in the first aspect of this application, adds a first carbon source and a second carbon source, so that lithium iron phosphate is coated with a first type of carbon and a second type of carbon, and regulates the growth state of lithium iron phosphate, to obtain a composite first particle group, a second particle group and a third particle group with a preset ratio, thereby forming a particle size gradient among multiple particles, thereby reducing the porosity of the positive electrode material and increasing the compaction density of the positive electrode sheet prepared from the material.

[0027] The compaction density ρ of the positive electrode sheet is 2.64-2.70 g / cm³. 3 .

[0028] The fourth aspect of this application provides an energy storage device, including a diaphragm, an electrolyte, a negative electrode, and a positive electrode as provided in the third aspect of this application.

[0029] The energy storage device provided in the fourth aspect of this application adopts the positive electrode sheet provided in the third aspect of this application. In the positive electrode material, a first carbon source and a second carbon source are added so that lithium iron phosphate is coated with the first type of carbon and the second type of carbon. The growth state of lithium iron phosphate is controlled to obtain a composite first particle group, a second particle group and a third particle group with a preset ratio. This makes the particle size gradient of multiple particles form a particle size gradient, thereby reducing the porosity of the positive electrode material and increasing the compaction density of the positive electrode sheet prepared from the material.

[0030] A fifth aspect of this application provides an electrical appliance, the electrical appliance comprising:

[0031] Equipment body; and

[0032] As provided in the fourth aspect of this application, the energy storage device supplies power to the device body.

[0033] The electrical equipment provided in the fifth aspect of this application, by employing the energy storage device provided in the fourth aspect of this application, adds a first carbon source and a second carbon source to its positive electrode material, causing lithium iron phosphate to be coated with the first type of carbon and the second type of carbon, thereby controlling the growth state of lithium iron phosphate and obtaining a composite first particle group, a second particle group, and a third particle group with a preset ratio. This results in a particle size gradient among the multiple particles, thereby reducing the porosity of the positive electrode material and increasing the compaction density of the positive electrode sheet prepared from the material. When the energy storage device supplies power to the device body, the energy storage device can provide a stable power supply to the device body. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the embodiments of this application will be described below.

[0035] Figure 1 This is a SEM image of the cathode material in one embodiment of this application.

[0036] Figure 2 This is a process flow diagram of the preparation method of the positive electrode material in one embodiment of this application. Detailed Implementation

[0037] The following are preferred embodiments of this application. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principles of this application, and these improvements and modifications are also considered to be within the scope of protection of this application.

[0038] The following are preferred embodiments of this application. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principles of this application, and these improvements and modifications are also considered to be within the scope of protection of this application.

[0039] In the description of this invention, it should be understood that the weights of the relevant components mentioned in the embodiments of this invention can refer not only to the specific content of each component, but also to the proportional relationship between the weights of the components. Therefore, any scaling up or down of the content of the relevant components according to the embodiments of this invention is within the scope of this invention. Specifically, the weights mentioned in the embodiments of this invention can be well-known units of mass in the chemical industry, such as μg, mg, g, and kg.

[0040] Furthermore, unless the context explicitly uses it otherwise, the singular form of a word should be understood as encompassing the plural form of the word. The terms "comprising" or "having" are intended to specify the presence of a feature, quantity, step, operation, element, part, or combination thereof, but are not intended to exclude the presence or possible addition of one or more other features, quantities, steps, operations, elements, parts, or combinations thereof.

[0041] Please refer to Figure 1 , Figure 1 This is a SEM image of the cathode material in one embodiment of this application. It should be noted that in the SEM image, the accelerating voltage is 5 kV, the working distance is 3.8 mm, the magnification is 10 k, the scale bar is 1 μm, the detector type is InLens, and the aperture size is 30 μm.

[0042] This application provides a cathode material comprising a plurality of particles, each particle comprising lithium iron phosphate, a first type of carbon, and a second type of carbon, wherein the first type of carbon and the second type of carbon cover the surface of the lithium iron phosphate. The plurality of particles comprises a first particle group, a second particle group, and a third particle group. The first particle group has a first particle size range, the second particle group has a second particle size range, and the third particle group has a third particle size range. The minimum value of the first particle size range is greater than the maximum value of the second particle size range, and the minimum value of the second particle size range is greater than the maximum value of the third particle size range. The particle number ratio of the first particle group, the second particle group, and the third particle group is (1-3):(8-10):(39-41).

[0043] The cathode material provided in this embodiment comprises lithium iron phosphate, a first type of carbon, and a second type of carbon in each particle. The cathode material in this embodiment can also be understood as a lithium iron phosphate cathode material. The first type of carbon is obtained from a first carbon source, and the second type of carbon is obtained from a second carbon source. Furthermore, at least one chemical element of the first carbon source is different from the chemical element constituting the second carbon source.

[0044] In each particle, type I carbon and type II carbon cover the surface of lithium iron phosphate. This can also be understood as type I carbon and type II carbon forming a carbon layer that coats lithium iron phosphate, thus forming a particle.

[0045] It should be noted that the particle size here refers to the total particle size of the lithium iron phosphate particles covered by both type I and type II carbon. In other words, it refers to the total particle size of the lithium iron phosphate particles coated with both type I and type II carbon. Particles within the first particle size range can be considered large particles. Particles within the second particle size range can be considered medium particles. Particles within the third particle size range can be considered small particles.

[0046] During the preparation of cathode materials, lithium iron phosphate can form particles with different sizes, exhibiting a subtle particle size gradient. Furthermore, the carbon source coating on the surface of lithium iron phosphate can inhibit its self-growth, thereby altering the particle size of lithium iron phosphate and consequently changing the particle size of at least some cathode material particles.

[0047] First, by adding a first carbon source and a second carbon source to prepare the cathode material, the first carbon source can form relatively dense first-type carbon, inhibiting the growth of lithium iron phosphate and controlling the formation of at least a portion of the third particle group with a smaller particle size; the second carbon source can form relatively loose second-type carbon, reducing the inhibitory effect on the growth of lithium iron phosphate and controlling the formation of at least a portion of the first particle group with a larger particle size. Furthermore, the first and second carbon sources work together to ensure that the growth of lithium iron phosphate reaches a predetermined state, controlling the formation of at least a portion of the second particle group with a medium particle size.

[0048] Secondly, the second carbon source can also play a dispersing role, dispersing the particles in the raw materials, reducing particle agglomeration, making them uniformly dispersed, and giving lithium iron phosphate more room to grow.

[0049] The first and second carbon sources work together to coat each lithium iron phosphate particle to different degrees. In addition, the second carbon source provides different growth spaces for each lithium iron phosphate particle with different dispersion effects, resulting in a large difference in the particle size of each lithium iron phosphate particle. This leads to cathode material particles with significantly different particle sizes, thus achieving differentiated growth of cathode material particles.

[0050] Alternatively, the first type of carbon and the second type of carbon work together to provide different growth spaces for each lithium iron phosphate particle, thereby altering at least a portion of the particle size. For example, changing the particle size of some particles. Or, for example, changing the particle size of all particles. Specifically, the particle size of at least a portion of the lithium iron phosphate particles increases or decreases; and / or, the particle size of at least a portion of the first type of carbon particles increases; and / or, the particle size of at least a portion of the second type of carbon particles increases. Optionally, the particle size D50 of the multiple particles is 0.7-1.3 μm.

[0051] Specifically, in the process of preparing the cathode material, the first carbon source can form relatively dense type I carbon, while the second carbon source can form relatively loose type II carbon. In other words, the carbon arrangement states formed by the first and second carbon sources during carbonization are different. The interaction between type I and type II carbon regulates the growth space of lithium iron phosphate during the preparation process, thereby obtaining particles of different sizes and realizing differentiated growth of primary particles.

[0052] The particle number ratio of the first particle group, the second particle group, and the third particle group is (1-3):(8-10):(39-41). In other words, the percentages of particles meeting the first particle size range, the second particle size range, and the third particle size range in the total particles are 2-6%:16-20%:78-82%. Optionally, the particle number ratio of the first particle group, the second particle group, and the third particle group is 1:8:39; or 1:8:40; or 1:8:41; or 2:9:39; or 2:9:40; or 2:9:41; or 3:10:39; or 3:10:40; or 3:10:41.

[0053] When the particle number ratio of the first, second, and third particle groups is (1-3):(8-10):(39-41), the number of large, medium, and small particles in the multiple particles is within a specific ratio range, which can reduce the porosity of the cathode material and increase the compaction density of the cathode sheet prepared from the material. If the particle number ratio of the first, second, and third particle groups is less than (1-3):(8-10):(39-41), it will result in a large number of large and / or medium particles, which is not conducive to lithium-ion transport, resulting in reduced material capacity and poor rate performance, thus leading to a decrease in the compaction density of the cathode sheet. If the particle number ratio of the first, second, and third particle groups is greater than (1-3):(8-10):(39-41), it will result in a large number of small particles, with excessively dense particles, which is not conducive to the formation of a significant particle size gradient among multiple particles, thus leading to a decrease in the compaction density of the cathode sheet.

[0054] Therefore, this embodiment adds a first carbon source and a second carbon source to coat lithium iron phosphate with the first type of carbon and the second type of carbon, thereby controlling the growth state of lithium iron phosphate and obtaining a composite first particle group, a second particle group and a third particle group with a preset ratio. This results in a particle size gradient among the multiple particles, thereby reducing the porosity of the cathode material and increasing the compaction density of the cathode sheet prepared from the material.

[0055] In one embodiment, the first particle size range D1 is 1.5 ≤ D1 ≤ 4 μm, the second particle size range D2 is 0.8 ≤ D2 < 1.5 μm, and the third particle size range D3 is 0.2 ≤ D3 < 0.8 μm.

[0056] Optionally, the first particle size is 1.5 μm; or, 2.0 μm; or, 2.5 μm; or, 3.0 μm; or, 3.5 μm; or, 4.0 μm. The second particle size is 0.8 μm; or, 1.0 μm; or, 1.2 μm; or, 1.4 μm; or, 1.4 μm. The third particle size is 0.2 μm; or, 0.4 μm; or, 0.6 μm; or, 0.7 μm.

[0057] When the first, second, and third particle size ranges are within the aforementioned particle size ranges and in accordance with the aforementioned quantity ratios, the porosity of the cathode material can be reduced, thereby increasing the compaction density of the cathode sheet prepared from the material. If the first, second, and third particle size ranges are large, the overall particle size of multiple particles will be too large, which is not conducive to lithium-ion transport, resulting in reduced material capacity and poor rate performance, thus leading to a decrease in the compaction density of the cathode sheet. If the first, second, and third particle size ranges are small, the overall particle size of multiple particles will be too small, with excessively dense particles, which is not conducive to the formation of a significant particle size gradient among multiple particles, thus leading to a decrease in the compaction density of the cathode sheet.

[0058] In one embodiment, the sum of the mass of the first type of carbon and the mass of the second type of carbon accounts for 1-1.3% of the total mass of the cathode material.

[0059] Optionally, the sum of the mass of the first type of carbon and the mass of the second type of carbon accounts for 1% of the total mass of the cathode material; or, 1.1%; or, 1.2%; or, 1.3%.

[0060] The sum of the mass of the first type of carbon and the mass of the second type of carbon accounts for 1-1.3% of the total mass of the cathode material. This range of carbon content ensures that the conductivity and lithium-ion diffusion of the cathode material are in balance, thereby ensuring improved conductivity of the cathode electrode sheet made from this cathode material.

[0061] In one embodiment, the raw materials for preparing the cathode material include a first carbon source and a second carbon source, wherein the first type of carbon is obtained from the first carbon source and the second type of carbon is obtained from the second carbon source; wherein the mass ratio of the first carbon source to the second carbon source is (3-4):(6-7).

[0062] Optionally, the first carbon source includes one or more of glucose, polyaniline, sucrose, citric acid, cellulose, acetylene black, and graphene. Optionally, the second carbon source includes one or more of polyethylene glycol (PEG), polyvinyl alcohol (PVA), starch, and polyvinylpyrrolidone (PVP).

[0063] Both the first and second carbon sources can form carbon. The first carbon source forms a relatively dense carbon layer, which restricts particle growth and promotes the formation of small and medium-sized particles. The second carbon source readily forms highly graphitized carbon, which is beneficial for the formation of large particles. Furthermore, the second carbon source also acts as a dispersant, dispersing particles in the raw materials and facilitating the formation of a significant particle size gradient.

[0064] During the preparation of cathode materials, the carbon from the first carbon source and the second carbon source have different carbon arrangements during carbonization. The interaction between the first and second types of carbon provides different growth spaces for lithium iron phosphate during the preparation process, which is beneficial for obtaining particles of different sizes. This achieves differentiated growth of primary particles, thereby reducing the porosity of the cathode material and increasing the compaction density of the cathode sheet prepared from this material.

[0065] Furthermore, the second carbon source can also play a dispersing role, reducing particle agglomeration and making them uniformly dispersed. This prevents the carbon layer formed by the first and second types of carbon from being too dense, which is conducive to the formation of medium and large particles. This, in turn, creates a particle size gradient among multiple particles, thereby reducing the porosity of the cathode material and increasing the compaction density of the cathode sheet prepared from this material.

[0066] Therefore, this embodiment uses a specific ratio of a first carbon source and a second carbon source to coat lithium iron phosphate with a first type of carbon and a second type of carbon, thereby controlling the growth state of lithium iron phosphate and obtaining a composite first particle group, a second particle group, and a third particle group with a preset ratio. This results in a particle size gradient among the multiple particles, thereby reducing the porosity of the cathode material and increasing the compaction density of the cathode sheet prepared from the material.

[0067] Optionally, the mass ratio of the first carbon source to the second carbon source is 3:6; or 3:7; or 4:6; or 4:7.

[0068] A mass ratio of the first carbon source to the second carbon source of (3-4):(6-7) ensures a particle size gradient among multiple particles, reducing the porosity of the cathode material and increasing the compaction density of the cathode sheet prepared from this material. If the mass ratio of the first to the second carbon source is too large, it will result in an excessive amount of the first carbon source, leading to a denser carbon layer, which is not conducive to the formation of large particles or a significant particle size gradient, thus reducing the compaction density of the cathode sheet. Conversely, if the mass ratio of the first to the second carbon source is too small, it will result in an excessive amount of the second carbon source, leading to an increase in the density of the carbon layer. This insufficient density will cause primary particles to grow larger and will result in severe material agglomeration, hindering dispersion and grinding; it will also be detrimental to the formation of large particles, resulting in an excessive number of small particles.

[0069] In one embodiment, the sum of the mass of the first carbon source and the mass of the second carbon source accounts for 7-8% of the total mass of the raw materials used in the preparation.

[0070] Optionally, the raw materials include an iron source, a lithium source, a first carbon source, and a second carbon source. Optionally, the sum of the mass of the first type of carbon and the mass of the second type of carbon accounts for 7%; or 7.3%; or 7.5%; or 7.8%; or 8% of the total mass of the raw materials.

[0071] The sum of the masses of the first and second carbon sources should account for 7-8% of the total mass of the raw materials. This ensures a particle size gradient among the particles, improving the compaction density of the cathode material and guaranteeing high capacity utilization and rate performance. If the sum of the masses of the first and second carbon sources is too large, it results in an excess of both, with less lithium iron phosphate and lithium ions, leading to reduced capacity utilization and poorer rate performance. Conversely, if the sum of the masses of the first and second carbon sources is too small, it hinders the formation of a significant particle size gradient, thus reducing the compaction density of the cathode material.

[0072] In one embodiment, the cathode material further includes titanium and vanadium, and the raw materials for preparing the cathode material further include a titanium source and a vanadium source, wherein the titanium is obtained from the titanium source and the vanadium is obtained from the vanadium source; wherein the mass ratio of the titanium source to the vanadium source is 1:(0.8-1.2).

[0073] Optionally, the raw materials include an iron source, a lithium source, a first carbon source, a second carbon source, a titanium source, and a vanadium source. In the cathode material, titanium and vanadium are doped into lithium iron phosphate. They typically replace the Fe sites of lithium iron phosphate. Optionally, the titanium source includes titanium dioxide; the vanadium source includes one or more of vanadium pentoxide, vanadium trioxide, and vanadium dioxide.

[0074] This embodiment adds titanium and vanadium sources, which have a synergistic effect. Based on the first and second carbon sources, it can further achieve differentiated growth of primary particles, so that the particle size of multiple particles forms a significant particle size gradient, thereby further reducing the porosity of the cathode material and further improving the compaction density of the cathode sheet prepared from the material.

[0075] Optionally, the mass ratio of titanium source to vanadium source is 1:0.8; or 1:0.9; or 1:1; or 1:1.1; or 1:1.2.

[0076] A titanium-to-vanadium source mass ratio of 1:(0.8-1.2) enables the formation of a significant particle size gradient among multiple particles, further improving the compaction density of the cathode electrode prepared from this material. If the titanium-to-vanadium source mass ratio is too high or too low, it will result in an excess of either titanium or vanadium source, preventing them from working together synergistically and hindering the formation of a significant particle size gradient, thus reducing the compaction density of the cathode electrode.

[0077] In one embodiment, the mass ratio of the titanium source, the vanadium source, the first carbon source, and the second carbon source is 1:(0.8-1.2):(8-12):(7-11).

[0078] Optionally, the mass ratio of the titanium source, vanadium source, first carbon source, and second carbon source is 1:0.8:8:7; or, 1:0.9:9:8; or, 1:1:10:9; or, 1:1.1:11:10; or, 1:1.2:12:11.

[0079] A mass ratio of titanium source, vanadium source, first carbon source, and second carbon source of 1:(0.8-1.2):(8-12):(7-11) enables a significant particle size gradient among multiple particles, further improving the compaction density of the positive electrode sheet prepared from this material. If the mass ratio of titanium source, vanadium source, first carbon source, and second carbon source is less than 1:(0.8-1.2):(8-12):(7-11), there will be too little titanium and vanadium source, preventing them from exerting their synergistic effect and hindering the formation of a significant particle size gradient. If the mass ratio of titanium source, vanadium source, first carbon source, and second carbon source is greater than 1:(0.8-1.2):(8-12):(7-11), there will be too much titanium and vanadium source, hindering the function of the first and second carbon sources and preventing the formation of a significant particle size gradient, thus reducing the compaction density of the positive electrode sheet.

[0080] In one embodiment, the sum of the mass of the titanium source and the mass of the vanadium source accounts for 0.2-0.4% of the total mass of the raw materials.

[0081] Optionally, the sum of the mass of the titanium source and the mass of the vanadium source accounts for 0.2%; or 0.3%; or 0.4% of the total mass of the raw materials.

[0082] The sum of the mass of the titanium source and the vanadium source should account for 0.2-0.4% of the total mass of the raw materials. This allows for a significant particle size gradient among the particles, further improving the compaction density of the cathode material and ensuring high capacity utilization and rate performance. If the sum of the mass of the titanium and vanadium sources is too high, there will be an excess of titanium and vanadium, and a deficiency of lithium iron phosphate and lithium ions, resulting in reduced capacity utilization and poorer rate performance. Conversely, if the sum of the mass of the titanium and vanadium sources is too low, there will be insufficient titanium and vanadium, hindering the synergistic effect of the titanium and vanadium sources and preventing the formation of a significant particle size gradient, thus reducing the compaction density of the cathode material.

[0083] Please refer to Figure 2 , Figure 2 This is a process flow diagram of a method for preparing a cathode material according to one embodiment of this application. This application also provides a method for preparing a cathode material, the method comprising:

[0084] S100 provides an iron source, a lithium source, a first carbon source, and a second carbon source;

[0085] S200, the iron source, the lithium source, the first carbon source, and the second carbon source are mixed and sintered to obtain a cathode material; wherein, the cathode material comprises a plurality of particles, each particle comprising lithium iron phosphate, a first type of carbon, and a second type of carbon, the first type of carbon being obtained from the first carbon source, the second type of carbon being obtained from the second carbon source, the first type of carbon and the second type of carbon covering the surface of the lithium iron phosphate, the plurality of particles comprising a first particle group, a second particle group, and a third particle group, the first particle group having a first particle size range, the second particle group having a second particle size range, the third particle group having a third particle size range, the minimum value of the first particle size range being greater than the maximum value of the second particle size range, and the minimum value of the second particle size range being greater than the maximum value of the third particle size range; wherein, the particle number ratio of the first particle group, the second particle group, and the third particle group is (1-3):(8-10):(39-41).

[0086] The cathode material preparation method provided in this embodiment is simple, low-cost, and highly operable. Specifically, the first carbon source and the second carbon source work together to achieve different coating degrees on each lithium iron phosphate particle. Furthermore, the dispersion effect of the second carbon source provides different growth spaces for each lithium iron phosphate particle, resulting in significant differences in particle size among the final lithium iron phosphate particles. This yields cathode material particles with distinctly different particle sizes, achieving differentiated growth of cathode material particles in a single step. When the particle number ratio of the first, second, and third particle groups is (1-3):(8-10):(39-41), the number of large, medium, and small particles within a specific ratio range is maintained, which reduces the porosity of the cathode material and increases the compaction density of the cathode sheet prepared from this material.

[0087] Therefore, this embodiment adds a first carbon source and a second carbon source to coat lithium iron phosphate with the first type of carbon and the second type of carbon, thereby controlling the growth state of lithium iron phosphate and obtaining a composite first particle group, a second particle group and a third particle group with a preset ratio. This results in a particle size gradient among the multiple particles, thereby reducing the porosity of the cathode material and increasing the compaction density of the cathode sheet prepared from the material.

[0088] This application also provides a positive electrode sheet, including the positive electrode material as described above.

[0089] The positive electrode sheet provided in this embodiment uses the positive electrode material provided in this application, adds a first carbon source and a second carbon source, so that lithium iron phosphate is coated with a first type of carbon and a second type of carbon, and regulates the growth state of lithium iron phosphate to obtain a composite first particle group, a second particle group and a third particle group with a preset ratio, so that the particle size of multiple particles forms a particle size gradient, thereby reducing the porosity of the positive electrode material and increasing the compaction density of the positive electrode sheet prepared from the material.

[0090] In one embodiment, the compaction density ρ of the positive electrode sheet is 2.64-2.70 g / cm³. 3 Optionally, the compaction density of the positive electrode sheet is 2.64 g / cm³. 3 Or, 2.65 g / cm³ 3 Or, 2.66 g / cm³ 3 Or, 2.67 g / cm³ 3 Or, 2.68 g / cm³ 3 Or, 2.69 g / cm³ 3 Or, 2.70 g / cm³ 3 .

[0091] This application also provides an energy storage device, including a diaphragm, an electrolyte, a negative electrode, and a positive electrode as described above.

[0092] The energy storage devices can be multiple, connected in series or parallel, and supported and electrically connected by an isolation plate (not shown). In this embodiment, "multiple" refers to two or more. An energy storage box can also be provided externally to house the energy storage devices.

[0093] It is understood that energy storage devices may include, but are not limited to, single-cell batteries, battery modules, battery packs, and battery systems. When the energy storage device is a single-cell battery, it can be at least one of cylindrical batteries, prismatic batteries, etc. The actual application form of the energy storage device provided in this application embodiment can be, but is not limited to, the listed products, and can also be other application forms. This application embodiment does not strictly limit the application form of the energy storage device.

[0094] The energy storage device provided in this embodiment adopts the positive electrode sheet provided in this application. In the positive electrode material, a first carbon source and a second carbon source are added so that lithium iron phosphate is coated with the first type of carbon and the second type of carbon. The growth state of lithium iron phosphate is controlled to obtain a composite first particle group, a second particle group and a third particle group with a preset ratio. This makes the particle size gradient of multiple particles form a particle size gradient, thereby reducing the porosity of the positive electrode material and increasing the compaction density of the positive electrode sheet prepared from the material.

[0095] Optionally, the separator, positive electrode, and negative electrode are stacked in sequence, with the separator acting as a separator between the positive and negative electrodes. Electrolyte is then added, and the cells are assembled into a button cell.

[0096] This application also provides an electrical device, which includes a device body and an energy storage device as described above, wherein the energy storage device supplies power to the device body.

[0097] The electrical device provided in this embodiment, by employing the energy storage device described above, adds a first carbon source and a second carbon source to its positive electrode material, causing lithium iron phosphate to be coated with the first and second types of carbon. This regulates the growth state of the lithium iron phosphate, resulting in composite first, second, and third particle groups with preset proportions. This creates a particle size gradient among the multiple particles, thereby reducing the porosity of the positive electrode material and increasing the compaction density of the positive electrode sheet prepared from this material. When the energy storage device supplies power to the device body, it provides a stable power source.

[0098] Optionally, the electrical equipment in this application embodiment can be, but is not limited to, portable electronic devices such as mobile phones, tablets, laptops, desktop computers, smart toys, smart bracelets, smartwatches, e-readers, game consoles, and toys; it can also be large equipment such as energy storage battery cabinets, electric vehicles, electric cars, ships, and spacecraft.

[0099] It is understood that the electrical equipment described in this embodiment is merely one form of electrical equipment used in energy storage devices, and should not be construed as a limitation on the electrical equipment provided in this application, nor should it be construed as a limitation on the energy storage devices provided in the various embodiments of this application.

[0100] To enable those skilled in the art to clearly understand the above-described implementation details and operations of the present invention, and to demonstrate the significant improvement in the performance of the electrolyte preparation method in the embodiments of the present invention, the above technical solutions are illustrated below through multiple embodiments.

[0101] In one embodiment, the cathode material is prepared using a solid-state method. An iron source, a lithium source, a first carbon source, and a second carbon source are dispersed in a dispersion tank. The powder is then ground using a sand mill to control the particle size D50 to be less than 0.4 μm. After drying in a spray dryer, powder with a particle size D50 of less than 22 μm is obtained. This powder is then sintered in a kiln at 700℃-800℃. Finally, it is pulverized in an air jet mill to obtain the lithium iron phosphate cathode active material. Optionally, the sintering temperature is 700℃; or, 720℃; or, 740℃; or, 760℃; or, 780℃; or, 800℃.

[0102] In another embodiment, the raw materials also include a titanium source and a vanadium source. The titanium source, vanadium source, iron source, lithium source, first carbon source, and second carbon source are mixed and the above steps are continued.

[0103] Comparative Examples 1-2 and Examples 1-12 used different types and proportions of raw materials, and then used the above preparation method to obtain the cathode material. The raw materials used in each example are described in detail below.

[0104] Comparative Example 1:

[0105] The raw materials for preparation include an iron source, a lithium source, and a first carbon source; wherein the molar ratio of the lithium source to the iron source is 1.04; and the mass percentage of the first carbon source to the iron source is 11.6%.

[0106] Comparative Example 2:

[0107] The raw materials for preparation include an iron source, a lithium source, and a second carbon source; wherein the molar ratio of the lithium source to the iron source is 1.04; and the mass percentage of the second carbon source to the iron source is 11.6%.

[0108] Example 1:

[0109] The raw materials for preparation include an iron source, a lithium source, a first carbon source, and a second carbon source; wherein, the molar ratio of the lithium source to the iron source is 1.04; the sum of the masses of the first carbon source and the second carbon source and the mass percentage of the iron source is 11.6%; and the mass ratio of the first carbon source to the second carbon source is 8:2.

[0110] Example 2:

[0111] Based on Example 1, the mass ratio of the first carbon source to the second carbon source was changed to 4:6. Specifically, the raw materials included an iron source, a lithium source, a first carbon source, and a second carbon source; wherein, the molar ratio of the lithium source to the iron source was 1.04; the sum of the masses of the first carbon source and the second carbon source and the mass percentage of the iron source was 11.6%; and the mass ratio of the first carbon source to the second carbon source was 4:6.

[0112] Example 3:

[0113] Based on Example 2, the material of the first carbon source was changed from glucose to polyaniline.

[0114] Example 4:

[0115] Based on Example 2, the material of the second carbon source was changed from PEG to PVA.

[0116] Example 5:

[0117] Based on Example 1, the mass ratio of the first carbon source to the second carbon source was changed to 3:7. Specifically, the raw materials included an iron source, a lithium source, a first carbon source, and a second carbon source; wherein, the molar ratio of the lithium source to the iron source was 1.04; the sum of the masses of the first carbon source and the second carbon source and the mass percentage of the iron source was 11.6%; and the mass ratio of the first carbon source to the second carbon source was 3:7.

[0118] Example 6:

[0119] Based on Example 1, the mass ratio of the first carbon source to the second carbon source was changed to 2:8. Specifically, the raw materials included an iron source, a lithium source, a first carbon source, and a second carbon source; wherein, the molar ratio of the lithium source to the iron source was 1.04; the sum of the masses of the first carbon source and the second carbon source and the mass percentage of the iron source was 11.6%; and the mass ratio of the first carbon source to the second carbon source was 2:8.

[0120] Example 7:

[0121] Based on Example 2, a titanium source was added. Specifically, the raw materials included an iron source, a lithium source, a first carbon source, a second carbon source, and a titanium source; wherein, the molar ratio of the lithium source to the iron source was 1.04; the sum of the masses of the first carbon source and the second carbon source, and the mass percentage of the iron source, was 11.6%; the mass ratio of the first carbon source to the second carbon source was 4:6; and the mass of the titanium source accounted for 0.2% of the total mass of the raw materials.

[0122] Example 8:

[0123] Based on Example 2, a vanadium source was added. Specifically, the raw materials included an iron source, a lithium source, a first carbon source, a second carbon source, and a vanadium source; wherein, the molar ratio of the lithium source to the iron source was 1.04; the sum of the masses of the first carbon source and the second carbon source, and the mass percentage of the iron source, was 11.6%; the mass ratio of the first carbon source to the second carbon source was 4:6; and the mass of the vanadium source accounted for 0.2% of the total mass of the raw materials.

[0124] Example 9:

[0125] Based on Example 2, titanium and vanadium sources were added. Specifically, the raw materials included an iron source, a lithium source, a first carbon source, a second carbon source, a titanium source, and a vanadium source; wherein, the molar ratio of lithium source to iron source was 1.04; the sum of the masses of the first carbon source and the second carbon source and the mass percentage of iron source was 11.6%; the mass ratio of the first carbon source to the second carbon source was 4:6; the mass of vanadium source accounted for 0.2% of the total mass of the raw materials; and the mass ratio of titanium source to vanadium source was 1:1.

[0126] Example 10:

[0127] Based on Example 9, the mass ratio of the first carbon source to the second carbon source was changed to 3:7. Specifically, the raw materials included an iron source, a lithium source, a first carbon source, a second carbon source, a titanium source, and a vanadium source; wherein, the molar ratio of the lithium source to the iron source was 1.04; the sum of the masses of the first carbon source and the second carbon source, and the mass percentage of the iron source, was 11.6%; the mass ratio of the first carbon source to the second carbon source was 3:7; the mass of the vanadium source accounted for 0.2% of the total mass of the raw materials; and the mass ratio of the titanium source to the vanadium source was 1:1.

[0128] Example 11:

[0129] Based on Example 9, the mass ratio of the first carbon source to the second carbon source was changed to 2:8. Specifically, the raw materials included an iron source, a lithium source, a first carbon source, a second carbon source, a titanium source, and a vanadium source; wherein, the molar ratio of the lithium source to the iron source was 1.04; the sum of the masses of the first carbon source and the second carbon source, and the mass percentage of the iron source, was 11.6%; the mass ratio of the first carbon source to the second carbon source was 2:8; the mass of the vanadium source accounted for 0.2% of the total mass of the raw materials; and the mass ratio of the titanium source to the vanadium source was 1:1.

[0130] Example 12:

[0131] Based on Example 9, the mass ratio of the first carbon source to the second carbon source was changed to 8:2. Specifically, the raw materials included an iron source, a lithium source, a first carbon source, a second carbon source, a titanium source, and a vanadium source; wherein, the molar ratio of the lithium source to the iron source was 1.04; the sum of the masses of the first carbon source and the second carbon source, and the mass percentage of the iron source, was 11.6%; the mass ratio of the first carbon source to the second carbon source was 8:2; the mass of the vanadium source accounted for 0.2% of the total mass of the raw materials; and the mass ratio of the titanium source to the vanadium source was 1:1.

[0132] Please refer to Tables 1 and 2. Table 2 shows the compaction density and energy density of the positive electrode sheets prepared from the positive electrode materials of each comparative example. Table 1 shows the compaction density and energy density of the positive electrode sheets prepared from the positive electrode materials of each embodiment. It should be noted that the energy density is calculated using the energy storage device as a battery. The energy density is the volumetric energy density of the battery; therefore, the formula for energy density is battery capacity * 3.2V / (thickness * length * width).

[0133] Table 1

[0134]

[0135] Table 2

[0136]

[0137] As can be seen from Comparative Examples 1-2 in Table 1 and Examples 1-12 in Table 2, compared with adding the first carbon source and the second carbon source alone, by utilizing the synergy between the first carbon source and the second carbon source, the compaction density of the positive electrode sheet is increased by 9.5%-12%.

[0138] As shown in Tables 2 (Examples 1-5), the compaction density of the positive electrode sheet initially increases and then decreases with the mass ratio of the first carbon source to the second carbon source. As the mass percentage of the second carbon source increases, the compaction density of the positive electrode sheet also initially increases and then decreases. Therefore, a mass ratio of the first carbon source to the second carbon source of (3-4):(6-7) results in a higher compaction density for the positive electrode sheet. In related technologies, the limiting compaction density of the positive electrode sheet is approximately 2.75.

[0139] As shown in Examples 2 and 7-9 of Table 2, adding only a titanium source will lead to a decrease in the compaction density of the positive electrode sheet; adding only a vanadium source cannot improve the compaction density of the positive electrode sheet. Only by adding both a titanium source and a vanadium source simultaneously can the titanium source and the vanadium source interact to further improve the compaction density of the positive electrode sheet.

[0140] As shown in Table 2, Examples 1 and 12, Examples 2 and 9, and Examples 6 and 11, adding titanium and vanadium sources to a first carbon source to second carbon source mass ratio of 2:8 increases the compaction density of the positive electrode sheet by 0.4%. Adding titanium and vanadium sources to a first carbon source to second carbon source mass ratio of 8:2 increases the compaction density of the positive electrode sheet by 1.2%. Adding titanium and vanadium sources to a first carbon source to second carbon source mass ratio of 4:6 increases the compaction density of the positive electrode sheet by 2.2%.

[0141] Compared to adding titanium and vanadium sources when the mass ratio of the first carbon source to the second carbon source is 2:8 or 8:2, adding titanium and vanadium sources when the mass ratio of the first carbon source to the second carbon source is (3-4):(6-7) significantly improves the compaction density of the positive electrode sheet. Therefore, when the mass ratio of the first carbon source to the second carbon source is (3-4):(6-7) and the mass ratio of the titanium source to the vanadium source is 1:(0.8-1.2), that is, when the mass ratio of titanium source, vanadium source, first carbon source, and second carbon source is 1:(0.8-1.2):(8-12):(7-11), the first carbon source, second carbon source, titanium source, and vanadium source can interact, further improving the compaction density of the positive electrode sheet.

[0142] In one embodiment, the lithium iron phosphate cathode material obtained in this application is added to an N-methylpyrrolidone (NMP) solution in the following ratio: lithium iron phosphate cathode material (LFP): polyvinylidene fluoride (PVDF): styrene-modified phenol (SP) = 90:5:5. The mixture is stirred for 15 minutes at 2000 rpm in a high-speed homogenizer. It is then coated, dried at 110°C for 1-2 hours, rolled to the required compaction density, punched, and weighed. Finally, it is dried in a vacuum oven at 105°C for 12 hours to obtain the cathode sheet. A lithium sheet is used as the anode sheet.

[0143] Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a volume ratio of 1:1:1. Then, thoroughly dried lithium salt LiPF6 was dissolved in the mixed organic solvent at a ratio of 1 mol / L to prepare the electrolyte. A 12-micron polyethylene film was selected as the separator.

[0144] Stack the positive electrode, separator, and negative electrode in sequence, with the separator positioned between the positive and negative electrodes to provide isolation. Add the electrolyte and assemble into a button cell to obtain an energy storage device.

[0145] The above provides a detailed description of the embodiments provided in this application. This document elucidates and explains the principles and implementation methods of this application. The above description is only intended to help understand the methods and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A positive electrode material, characterized in that, The system comprises multiple particles, each particle comprising lithium iron phosphate, a first type of carbon, and a second type of carbon, the first type of carbon and the second type of carbon covering the surface of the lithium iron phosphate. The multiple particles comprise a first particle group, a second particle group, and a third particle group. The first particle group has a first particle size range, the second particle group has a second particle size range, and the third particle group has a third particle size range. The minimum value of the first particle size range is greater than the maximum value of the second particle size range, and the minimum value of the second particle size range is greater than the maximum value of the third particle size range. The particle number ratio of the first particle group, the second particle group, and the third particle group is (1-3):(8-10):(39-41). The raw materials for preparing the cathode material include a first carbon source and a second carbon source. The first type of carbon is obtained from the first carbon source, and the second type of carbon is obtained from the second carbon source. The mass ratio of the first carbon source to the second carbon source is (3-4):(6-7). The first carbon source includes one or more of glucose, polyaniline, sucrose, citric acid, cellulose, acetylene black, and graphene; The second carbon source includes one or more of polyethylene glycol, polyvinyl alcohol, starch, and polyvinylpyrrolidone.

2. The cathode material as described in claim 1, characterized in that, The first particle size range D1 is 1.5≤D1≤4μm, the second particle size range D2 is 0.8≤D2<1.5μm, and the third particle size range D3 is 0.2≤D3<0.8μm.

3. The positive electrode material as described in claim 1, characterized in that, The sum of the mass of the first type of carbon and the mass of the second type of carbon accounts for 1-1.3% of the total mass of the cathode material.

4. The positive electrode material as described in claim 1, characterized in that, The sum of the mass of the first carbon source and the mass of the second carbon source accounts for 7-8% of the total mass of the raw materials used in the preparation.

5. The positive electrode material as described in claim 1, characterized in that, The cathode material further includes titanium and vanadium, and the raw materials for preparing the cathode material further include a titanium source and a vanadium source. The titanium is obtained from the titanium source, and the vanadium is obtained from the vanadium source. The mass ratio of the titanium source to the vanadium source is 1:(0.8-1.2).

6. The cathode material as described in claim 5, characterized in that, The mass ratio of the titanium source, the vanadium source, the first carbon source, and the second carbon source is 1:(0.8-1.2):(8-12):(7-11).

7. The cathode material as described in claim 5, characterized in that, The sum of the mass of the titanium source and the mass of the vanadium source accounts for 0.2-0.4% of the total mass of the raw materials used in the preparation.

8. The cathode material as described in claim 5, characterized in that, The titanium source includes titanium dioxide; the vanadium source includes one or more of vanadium pentoxide, vanadium trioxide, and vanadium dioxide.

9. A method for preparing a positive electrode material, characterized in that, The preparation method includes: It provides iron source, lithium source, first carbon source, and second carbon source; The iron source, the lithium source, the first carbon source, and the second carbon source are mixed and sintered to obtain a cathode material; wherein the cathode material comprises a plurality of particles, each particle comprising lithium iron phosphate, a first type of carbon, and a second type of carbon, the first type of carbon being obtained from the first carbon source, the second type of carbon being obtained from the second carbon source, the first type of carbon and the second type of carbon covering the surface of the lithium iron phosphate, the plurality of particles comprising a first particle group, a second particle group, and a third particle group, the first particle group having a first particle size range, the second particle group having a second particle size range, the third particle group having a third particle size range, the minimum value of the first particle size range being greater than the maximum value of the second particle size range, and the minimum value of the second particle size range being greater than the maximum value of the third particle size range; wherein the particle number ratio of the first particle group, the second particle group, and the third particle group is (1-3):(8-10):(39-41); The raw materials for preparing the cathode material include a first carbon source and a second carbon source. The first type of carbon is obtained from the first carbon source, and the second type of carbon is obtained from the second carbon source. The mass ratio of the first carbon source to the second carbon source is (3-4):(6-7). The first carbon source includes one or more of glucose, polyaniline, sucrose, citric acid, cellulose, acetylene black, and graphene; The second carbon source includes one or more of polyethylene glycol, polyvinyl alcohol, starch, and polyvinylpyrrolidone.

10. A positive electrode plate, characterized in that, Includes the cathode material as described in any one of claims 1-8.

11. The positive electrode sheet as described in claim 10, characterized in that, The compaction density ρ of the positive electrode sheet is 2.64-2.70 g / cm³. 3 .

12. An energy storage device, characterized in that, It includes a diaphragm, an electrolyte, a negative electrode, and a positive electrode as described in any one of claims 10-11.

13. An electrical appliance, characterized in that, The electrical equipment includes: Equipment body; and The energy storage device as described in claim 12 provides power to the device body.

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