High-compaction sodium-ion battery electrode plate and preparation method thereof

Abstract

The invention relates to a high-compaction sodium-ion battery electrode plate and a preparation method thereof, belongs to the technical field of sodium-ion battery electrodes, and solves the problem of low volume energy density of a prepared sodium-ion battery caused by low compaction density of a sodium-ion battery electrode plate in the prior art. The invention discloses a high-compaction sodium-ion battery electrode plate, the electrode plate is prepared from a positive active raw stock, and the positive active raw stock comprises a compound positive active material, a compound binder, a compound conductive agent and an additive; wherein the compound positive electrode active material, the compound binder and the compound conductive agent are compounded according to a preset particle size ratio. Through reasonable design and configuration of the particle size ratio of the raw materials and corresponding optimization of the electrode formula, proper process parameter adjustment is carried out on the basis of the existing preparation process, so that the electrode plate with the compaction density reaching 3.7 g / cm < 3 > or above is obtained, and compared with the existing mainstream process, the compaction density of the electrode plate is improved by 15% or above.

Description

Technical Field

[0001] This invention relates to the field of sodium-ion battery electrode technology, and in particular to a high-pressure sodium-ion battery electrode sheet and its preparation method. Background Technology

[0002] The large-scale use of fossil fuels has brought serious energy and environmental problems to all mankind. Therefore, there is an urgent need to develop safe, long-lasting, low-cost, and environmentally friendly clean energy sources to replace traditional fossil fuels. In recent years, lithium-ion batteries, as the most important clean energy source, have been widely used in various fields of society, especially in the rapidly developing fields of electric vehicles and smart grids, which are advanced energy storage technologies. However, considering the global shortage and uneven distribution of lithium resources, as well as the demand for low-cost energy storage devices, there is an urgent need to develop energy storage systems that are not limited by resources and have lower costs. Sodium-ion batteries, with their abundant reserves of metallic sodium and cost advantages, are expected to be widely used in electric vehicles and large-scale energy storage. Currently, sodium-ion batteries are already in the stage of small-scale mass production and application.

[0003] In existing sodium-ion battery products, cathode materials can be mainly divided into oxides, polyanionic materials, and Prussian blue materials, while anode materials mostly use hard carbon materials. Among cathode materials, oxides have broad application prospects due to their high theoretical specific capacity. However, the electrode sheet compaction density prepared from oxide cathode materials is relatively low, which affects the energy density of downstream sodium-ion battery products, especially the volumetric energy density, resulting in poor battery range performance and hindering the promotion and application of layered oxide sodium-ion batteries.

[0004] Therefore, it is necessary to develop a high-pressure sodium-ion battery electrode preparation method suitable for oxide cathode materials. Summary of the Invention

[0005] Based on the above analysis, the present invention aims to provide a high-compaction sodium-ion battery electrode sheet and its preparation method to solve the problem of insufficient compaction density of existing sodium-ion battery electrode sheets, especially the problem of insufficient compaction density of layered oxide electrode sheets.

[0006] This invention discloses a high-pressure sodium-ion battery electrode sheet, which is made from a positive electrode active slurry. The positive electrode active slurry includes a compound positive electrode active material, a compound binder, a compound conductive agent, and additives.

[0007] The content of each component by mass percentage is as follows: 92-98.5% of compound positive electrode active material, 0.5-3% of compound binder, 1-4% of compound conductive agent, and 0.1-1% of additives.

[0008] The composite positive electrode active material, composite binder and composite conductive agent are compounded according to a preset particle size ratio.

[0009] Specifically, the composite positive electrode active material is a layered oxide with the chemical formula Na. x Cu y Mn z M a O2, where 0.60≤x≤1.20, 0.1≤y≤0.40, 0.30≤z≤0.80, 0≤a≤0.50; M is one of Na, Mg, Ni, Ca, B, Fe, Al, Li, K, Ag, Zr, Ti, W, Mo, Cr, Sr, Y, and Cd.

[0010] Specifically, the compound positive electrode active material is obtained by compounding five specifications of positive electrode active materials, and the particle size range and mass proportion of each specification are as follows:

[0011] Specification 1: 0µm < particle size ≤ 2µm, mass percentage 2% to 7%;

[0012] Specification 2: 2µm < particle size ≤ 4µm, mass percentage 10%–20%;

[0013] Specification 3: 4µm < particle size ≤ 7µm, mass percentage 40%–60%;

[0014] Specification 4: 7µm < particle size ≤ 13µm, mass percentage 10% to 30%;

[0015] Specification 5, with a particle size of 13um < and 20um, accounts for 5% to 15% of the total mass. The total mass percentage of the positive electrode active material of the five specifications is 100%.

[0016] Specifically, the compounded binder is a compounded PVDF; it is obtained by compounding five specifications of PVDF, and the particle size range and mass proportion of each specification are as follows:

[0017] Specification 1: 30um < particle size ≤ 60um, mass percentage 5% to 15%;

[0018] Specification 2: Particle size 60µm < 80µm, mass percentage 20%–30%;

[0019] Specification 3: 80um < particle size ≤ 110um, mass percentage 30% to 40%;

[0020] Specification 4: 110um < particle size ≤ 130um, mass percentage 15% to 20%;

[0021] Specification 5, 130um < particle size ≤ 150um, with a mass percentage of 5% to 10%, and the sum of the mass percentages of the five specifications of PVDF is 100%.

[0022] Specifically, the compound conductive agent is a compound SP; it is obtained by compounding three specifications of SP, and the particle size range and mass ratio of each specification are as follows:

[0023] Specification 1: Particle size ≤ 20nm ≤ 40nm, mass percentage 10%~25%;

[0024] Specification 2: 40nm < particle size ≤ 60nm, mass percentage 60%–85%;

[0025] Specification 3, 60nm < particle size ≤ 80nm, with a mass percentage of 5% to 15%, and the sum of the mass percentages of the three specifications of SP is 100%.

[0026] Specifically, the compaction density of the electrode sheet is not less than 3.7 g / cm³. 3 .

[0027] The present invention also discloses a method for preparing the electrode sheet, specifically including the following steps:

[0028] S1: Weigh or measure different specifications of positive electrode active material, binder and conductive agent according to the preset ratio, and mix them thoroughly and evenly according to the ratio to obtain composite positive electrode material, composite binder and composite conductive agent;

[0029] S2: Measure the compound positive electrode active material, compound binder, compound conductive agent, additives and organic solvent according to the preset ratio; first, mix the compound positive electrode active material, compound binder, compound conductive agent and additives evenly to obtain the positive electrode active slurry; finally, add the organic solvent to obtain the positive electrode active slurry.

[0030] S3: The prepared slurry is uniformly coated onto the aluminum foil current collector, and the electrode sheet is obtained after drying and rolling processes.

[0031] Specifically, in step S2, the mass ratio of the positive electrode active slurry to the organic solvent is 1 to 9:1.

[0032] Specifically, in step S3, the specific parameters for the drying operation are: baking for 1 to 3 minutes at a temperature of 110±20℃ in the baking oven and ensuring a residual liquid rate of ≤0.8%; the specific parameters for the roller pressing operation are: gap width of 10 to 100 μm and pressure of 80 to 300 T.

[0033] The present invention also discloses a sodium-ion battery, comprising the electrode sheet or the electrode sheet prepared by the preparation method.

[0034] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0035] 1. The sodium-ion battery electrode sheet provided by this invention, especially the layered oxide electrode sheet, has a high compaction density, reaching 3.7 g / cm³. 3 The above improvements represent at least 15% over existing technologies, with porosity as low as 5%. This invention, through optimization of the compound component formulation and synergistic effects between components, achieves high-density packing of electrode materials (mainly referring to solids in the positive electrode active slurry) in both two-dimensional and three-dimensional space, reducing the porosity of the electrode sheet to below 12% and increasing the compaction density.

[0036] The formulation of the compound positive electrode active material is as follows: Specification 1, 0um < particle size ≤ 2um, with a mass ratio of 2% to 7%; Specification 2, 2um < particle size ≤ 4um, with a mass ratio of 10% to 20%; Specification 3, 4um < particle size ≤ 7um, with a mass ratio of 40% to 60%; Specification 4, 7um < particle size ≤ 13um, with a mass ratio of 10% to 30%; Specification 5, 13um < particle size ≤ 20um, with a mass ratio of 5% to 15%. The sum of the mass ratios of the five specifications of positive electrode active material is 100%.

[0037] Among them, the formulation of the compound conductive agent (mainly SP) is as follows: Specification 1, 20nm≤particle size≤40nm, mass percentage 10%~25%; Specification 2, 40nm<particle size≤60nm, mass percentage 60%~85%; Specification 3, 60nm<particle size≤80nm, mass percentage 5%~15%, and the sum of the mass percentages of the three specifications of SP is 100%.

[0038] like Figure 6 As shown, the accumulation of unblended material particles creates many pores. By combining particles of different sizes and matching particles within different size ranges, the overall particle packing becomes more compact. The schematic diagram illustrates the reduction of porosity in a two-dimensional plane. The principle of porosity reduction in three-dimensional space is similar to that in a two-dimensional plane and will not be elaborated upon.

[0039] The compounded binder is a compounded PVDF, obtained by compounding five specifications of PVDF. The particle size range and mass percentage of each specification are as follows: Specification 1, 30um < particle size ≤ 60um, mass percentage 5% to 15%; Specification 2, 60um < particle size ≤ 80um, mass percentage 20% to 30%; Specification 3, 80um < particle size ≤ 110um, mass percentage 30% to 40%; Specification 4, 110um < particle size ≤ 130um, mass percentage 15% to 20%; Specification 5, 130um < particle size ≤ 150um, mass percentage 5% to 10%, and the sum of the mass percentages of the five specifications of PVDF is 100%.

[0040] It is worth emphasizing that the mechanism by which the binder improves the compaction density of the electrode sheet differs from that of the compounded positive electrode active material and the compounded conductive agent. The main purpose of compounding the positive electrode active material and the compounded conductive agent is to achieve a tight stacking in both planar and three-dimensional structures. Based on their different structural characteristics, appropriate particle sizes and compounding ratios are selected to reduce the porosity of the compacted electrode sheet (i.e., components of different particle sizes squeeze and fill each other, reducing pores). The compounding of the binder is mainly to enable the binder to be more evenly distributed among other solid components, improve the bonding effect, and thus increase the compaction density. In fact, during the drying and rolling processes, a considerable portion of the binder will volatilize, and the binder content in the final product is relatively limited.

[0041] In addition to the internal compounding optimization of each component, the components in the positive electrode active slurry or positive electrode active paste of the present invention also have a synergistic effect. The present invention has carried out a stacking design of different particle sizes at the positive electrode layer. Through a stacking design of different particle sizes among different material systems in multiple dimensions, a high-compact positive electrode is obtained.

[0042] Dimension 1: Firstly, the sodium ion cathode material improves the compaction density of the cathode material itself through a combination design between different particle sizes;

[0043] Dimension Two: Subsequently, the compaction density of each material system and the overall solids (mainly referring to the cathode material, conductive agent, and binder) is improved by combining conductive agents, binders, and additives (additives have no particle size requirements) with different particle sizes.

[0044] Dimension 3: These high-compacted positive electrode active materials, conductive agents, binders, and additives are stacked in a certain ratio and then uniformly coated onto an aluminum foil current collector to form a high-compacted sodium ion positive electrode sheet.

[0045] High-density electrode sheets help improve the volumetric energy density of sodium-ion batteries. The volumetric energy density of layered oxide cylindrical sodium-ion batteries prepared using the above-mentioned electrode sheets can reach 350Wh / L.

[0046] 2. The compound formulation provided by the present invention ensures that the porosity of the electrode sheet is between 5% and 15% while increasing the compaction density, thus avoiding the phenomenon of "overpressure" which would prevent the electrolyte from fully contacting the electrode sheet and thereby reduce battery performance.

[0047] In fact, the achievement of high compaction density is related not only to the particle size distribution but also to the powder morphology and hardness of various raw materials. If one blindly pursues high compaction density by using mathematically optimal compaction ratios and large rolling pressures, it may lead to excessively low porosity of the electrode sheet or even damage to the internal structure of each component. This is one of the key inventive points of this invention. This invention first achieves a suitable density increase through particle size compounding and comprehensively considers the characteristics of the structure, morphology, and structural strength of the positive electrode active material (mainly layered oxides), conductive agent, and binder (which plays an auxiliary role). Through a combination of theoretical design and experimental practice, the most suitable compounding formula and production process in this field are obtained, thereby obtaining layered oxide electrode sheets with high compaction density and moderate porosity.

[0048] It is worth emphasizing that, given the complexity of the morphology, particle size distribution, and structural strength of each component material, the most suitable ratio cannot be obtained through exhaustive theoretical or experimental methods alone. Furthermore, due to the complexity of the parameters and actual processes, existing simulation and modeling methods are also unable to obtain ideal results for the time being. This is one of the core achievements that highlights the creativity of this application.

[0049] The electrode sheet and sodium-ion battery provided by this invention have a simple preparation process, readily available raw materials, and a low difficulty in the compounding process. With almost no increase in cost, the implementation requirements of this invention can be met by making appropriate optimizations or parameter adjustments based on existing processes and equipment, making it suitable for large-scale promotion and application.

[0050] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0051] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0052] Figure 1 SEM images of the composite positive electrode active material in Example 1;

[0053] Figure 2 Here is a SEM image of the PVDF composite adhesive from Example 1;

[0054] Figure 3 This is a SEM image of the composite conductive agent SP in Example 1;

[0055] Figure 4This is a SEM image of the surface of the positive electrode sheet in Example 1;

[0056] Figure 5 This is a SEM image of the cross-section of the positive electrode sheet in Example 1;

[0057] Figure 6 A schematic diagram (two-dimensional) illustrating the mechanism of porosity reduction in composite materials. Detailed Implementation

[0058] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0059] This invention discloses a high-pressure sodium-ion battery electrode sheet, which is made from a positive electrode active slurry. The positive electrode active slurry includes a compound positive electrode active material, a compound binder, a compound conductive agent, and additives.

[0060] The content of each component by mass percentage is as follows: 92-98.5% of compound positive electrode active material, 0.5-3% of compound binder, 1-4% of compound conductive agent, and 0-1% of additives.

[0061] The composite positive electrode active material, composite binder and composite conductive agent are compounded according to a preset particle size ratio.

[0062] The selection criteria for the roles and content ranges of each component in the positive electrode active material are as follows:

[0063] Compound positive electrode active material: The positive electrode active material mainly improves the activity of sodium ions and contributes to the capacity. In this invention, it mainly refers to layered oxides. The content of active material ranges from 92% to 98.5%. If the content is too low, it will affect the overall energy density of the battery. If the content is too high, the conductivity and adhesion of the entire electrode will decrease.

[0064] Compound binder: The binder mainly provides the bonding effect, bonding the active material and conductive agent to the current collector aluminum foil; the content of the binder ranges from 0.5% to 3%. If the content is too low, the adhesion of the entire electrode will decrease, and if the content is too high, it will affect the energy density of the battery.

[0065] Compound conductive agent: The conductive agent mainly provides conductivity; the content of the conductive agent is in the range of 1-4%. If the content is too low, the conductivity of the entire electrode will decrease, and if the content is too high, it will affect the energy density of the battery.

[0066] Additives: The additives are citric acid or oxalic acid (ethanedioic acid), which are used to improve the state of the slurry and make it easier to process. The content of the additives ranges from 0 to 1%. If the content is too low, it will affect the quality of the slurry. If the content is too high, it will affect the quality of the electrode.

[0067] After the components are compounded, the active material provides capacity, the binder provides adhesion, the conductive agent improves conductivity, and the additives improve processing performance. The synergistic effect of the components results in a high-compact positive electrode sheet, thereby obtaining a high-energy-density sodium-ion battery.

[0068] Specifically, the composite positive electrode active material is a layered oxide with the chemical formula Na. x Cu y Mn z M a O2, where 0.60≤x≤1.20, 0.1≤y≤0.40, 0.30≤z≤0.80, 0≤a≤0.50; M is one of Na, Mg, Ni, Ca, B, Fe, Al, Li, K, Ag, Zr, Ti, W, Mo, Cr, Sr, Y, and Cd. The structure of layered oxides is mainly composed of fixed bonds between different types of elements, thus exhibiting a nanoscale layered structure and a unique multi-layered stacked structure, possessing a large surface area and porosity, and excellent electrochemical performance. Due to limitations in experimental conditions and the inability to exhaustively list all layered oxide-based cathode active materials, this invention cannot assert that the described compounding method is applicable to all layered oxides. However, layered oxides conforming to the above general formula, after compounding, have been experimentally verified to have good electrochemical performance and suitable compaction density.

[0069] Specifically, the compound positive electrode active material is obtained by compounding five specifications of positive electrode active materials, and the particle size range and mass proportion of each specification are as follows:

[0070] Specification 1: 0µm < particle size ≤ 2µm, mass percentage 2% to 7%;

[0071] Specification 2: 2µm < particle size ≤ 4µm, mass percentage 10%–20%;

[0072] Specification 3: 4µm < particle size ≤ 7µm, mass percentage 40%–60%;

[0073] Specification 4: 7µm < particle size ≤ 13µm, mass percentage 10% to 30%;

[0074] Specification 5, with a particle size of 13um < ≤ 20um and a mass percentage of 5% to 15%, and the total mass percentage of the five specifications of positive electrode active materials is 100%. Using this formula for compounding can effectively reduce porosity at the two-dimensional and three-dimensional scales, thereby achieving high compaction at the material level.

[0075] Specifically, the compounded binder is a compounded PVDF; it is obtained by compounding five specifications of PVDF, and the particle size range and mass proportion of each specification are as follows:

[0076] Specification 1: 30um < particle size ≤ 60um, mass percentage 5% to 15%;

[0077] Specification 2: Particle size 60µm < 80µm, mass percentage 20%–30%;

[0078] Specification 3: 80um < particle size ≤ 110um, mass percentage 30% to 40%;

[0079] Specification 4: 110um < particle size ≤ 130um, mass percentage 15% to 20%;

[0080] Specification 5, 130um < particle size ≤ 150um, with a mass percentage of 5% to 10%, and the sum of the mass percentages of the five specifications of PVDF is 100%.

[0081] Specifically, the compound conductive agent is a compound SP; it is obtained by compounding three specifications of SP, and the particle size range and mass ratio of each specification are as follows:

[0082] Specification 1: Particle size ≤ 40nm, mass percentage 10%–25%;

[0083] Specification 2: 40nm < particle size ≤ 60nm, mass percentage 60%–85%;

[0084] Specification 3, 60nm < particle size ≤ 80nm, with a mass percentage of 5% to 15%, and the sum of the mass percentages of the three specifications of SP is 100%.

[0085] The high-compacted material, composed of different particle sizes, is then further compounded with active materials, conductive agents, and binders to form a high-compacted sodium-ion positive electrode sheet.

[0086] Specifically, the compaction density of the electrode sheet is not less than 3.7 g / cm³. 3 Porosity ≤15%.

[0087] The present invention also discloses a method for preparing the electrode sheet, specifically including the following steps:

[0088] S1: Weigh or measure different specifications of positive electrode active material, binder and conductive agent according to the preset ratio, and mix them thoroughly and evenly according to the ratio to obtain composite positive electrode material, composite binder and composite conductive agent;

[0089] S2: Measure the compound positive electrode active material, compound binder, compound conductive agent, additives and organic solvent according to the preset ratio; first, mix the compound positive electrode active material, compound binder, compound conductive agent and additives evenly to obtain the positive electrode active slurry; finally, add the organic solvent to obtain the positive electrode active slurry.

[0090] S3: The prepared slurry is uniformly coated onto the aluminum foil current collector, and the electrode sheet is obtained after drying and rolling processes.

[0091] Specifically, in step S2, the positive electrode active slurry is prepared first and then the organic solution is added in order to better control the solid composition in the positive electrode active slurry. If the organic solvent is added uniformly, it may cause confusion and errors in the early calculation and ratio determination. Under the premise of not affecting the performance of the slurry, it is more prudent to prepare the positive electrode active slurry first.

[0092] Specifically, the organic solvent is NMP.

[0093] Specifically, in step S2, the mass ratio of active slurry to organic solvent is 1 to 9:1. If the active slurry content is too low, the slurry will be too thin, making it difficult to coat and subsequently difficult to dry, affecting the overall production cycle and reducing production efficiency; if the active slurry content is too high, the slurry will be difficult to coat onto the current collector, affecting the quality of the electrode.

[0094] Specifically, in step S3, the slurry coating thickness is 50um to 200um, and the specific parameters for the drying operation are: baking for 1 to 3 minutes at an oven temperature of 110±20℃ while ensuring a residual liquid rate of ≤0.8%.

[0095] The specific parameters for the roller pressing operation are: gap width 10~100μm and pressure 80~300T.

[0096] The present invention also discloses a sodium-ion battery, including the electrode sheet, wherein the volumetric energy density of the battery can reach more than 380Wh / L.

[0097] For example, consider the fabrication method of a cylindrical battery:

[0098] Using the electrode sheet provided by this invention as the positive electrode, a hard carbon negative electrode as the counter electrode, a PE film as the separator (14 μm thick), and a NaPF6 solution with a sodium ion concentration of 1 mol / L (the solvent is one or a mixture of DMC / DEC / EMC / EC) as the electrolyte, a 32140 cylindrical battery is assembled in a battery manufacturing workshop.

[0099] Example 1

[0100] Prepare five different particle size specifications of sodium ion cathode material NaCu 0.2 Fe 0.2 Mn 0.6O2, Specification 1: Particle size 2um; Specification 2: Particle size 4um; Specification 3: Particle size 7um; Specification 4: Particle size range 10um; Specification 5: Particle size 15um; These five specifications are thoroughly mixed in the following proportions: Specification 1: Specification 2: Specification 3: Specification 4: Specification 5 = 5%: 15%: 50%: 20%: 10%.

[0101] Prepare three SP materials with different particle sizes: Size 1: 30nm; Size 2: 50nm; Size 3: 70nm. Mix these three sizes thoroughly in the ratio of Size 1: Size 2: Size 3 = 20%: 70%: 10%.

[0102] Prepare five PVDF materials with different particle sizes: Size 1: 40µm; Size 2: 70µm; Size 3: 100µm; Size 4: 120µm; Size 5: 140µm. Mix the PVDF materials thoroughly in the following ratio: Size 1: Size 2: Size 3: Size 4: Size 5 = 10%: 20%: 40%: 20%: 10%.

[0103] The prepared positive electrode active material, binder PVDF material, conductive agent SP material and additive oxalic acid material are mixed in a ratio of 96%:1.3%:2.3%:0.4% to obtain the positive electrode active slurry. NMP is added at a mass ratio of 50% of the total mixture to prepare the positive electrode active slurry.

[0104] The prepared slurry was uniformly coated onto the aluminum foil current collector (100 μm thickness). The electrode was baked at 110°C for 2 minutes, and the residual liquid content after drying was 0.5%. The dried electrode was then rolled on a roller press with the following parameters: gap width 50 μm, pressure 180 T. The compacted density of this electrode, with its mixture of different particle sizes, reached 3.8 g / cm³. 3 Porosity 10%.

[0105] Using the electrode sheet described in this embodiment as the positive electrode, a hard carbon negative electrode as the counter electrode, a PE film as the separator (14 μm thick), and a NaPF6 solution with a sodium ion concentration of 1 mol / L (DMC as the solvent) as the electrolyte, a 32140 cylindrical battery was assembled in a battery manufacturing workshop. The battery's volumetric energy density can reach 380 Wh / L.

[0106] Example 2

[0107] Prepare five different particle size specifications of sodium ion cathode material NaCu 0.3 Mg 0.3 Mn 0.4O2, Specification 1: Particle size 1um; Specification 2: Particle size 3um; Specification 3: Particle size 7um; Specification 4: Particle size range 11um; Specification 5: Particle size 14um; These five specifications are thoroughly mixed in the following ratio: Specification 1: Specification 2: Specification 3: Specification 4: Specification 5 = 4%: 18%: 55%: 18%: 5%.

[0108] Prepare three SP materials with different particle sizes: Size 1: 40nm; Size 2: 60nm; Size 3: 80nm. Mix these three sizes thoroughly in the ratio of Size 1: Size 2: Size 3 = 25%: 65%: 10%.

[0109] Prepare five PVDF materials with different particle sizes: Size 1: 50µm; Size 2: 80µm; Size 3: 110µm; Size 4: 130µm; Size 5: 150µm. Mix the PVDF materials thoroughly in the following ratio: Size 1: Size 2: Size 3: Size 4: Size 5 = 10%: 30%: 30%: 20%: 10%.

[0110] The prepared positive electrode active material, binder PVDF material, conductive agent SP material and additive citric acid material are mixed in a ratio of 95.5%:1.8%:2.3%:0.4% to obtain the positive electrode active slurry. NMP is added at a mass ratio of 30% of the total mixture to prepare the positive electrode active slurry.

[0111] The prepared slurry was uniformly coated onto the aluminum foil current collector (120 μm thickness). The electrode was baked at 120°C for 3 minutes, and the residual liquid content after drying was 0.6%. The dried electrode was then rolled on a roller press with the following parameters: gap width 60 μm, pressure 200 T. The compacted density of this electrode, with its mixture of different particle sizes, reached 3.7 g / cm³. 3 Porosity 15%.

[0112] Using the electrode sheet described in this embodiment as the positive electrode, a hard carbon negative electrode as the counter electrode, a PE film as the separator (14 μm thick), and a NaPF6 solution with a sodium ion concentration of 1 mol / L (DMC as the solvent) as the electrolyte, a 32140 cylindrical battery was assembled in a battery manufacturing workshop. The battery's volumetric energy density can reach 375 Wh / L.

[0113] Example 3

[0114] Prepare five different particle size specifications of sodium ion cathode material NaCu 0.2 Fe 0.3 Mn 0.5O2, Specification 1: Particle size 1um; Specification 2: Particle size 3um; Specification 3: Particle size 6um; Specification 4: Particle size range 12um; Specification 5: Particle size 15um; These five specifications are thoroughly mixed in the following proportions: Specification 1: Specification 2: Specification 3: Specification 4: Specification 5 = 5%: 10%: 45%: 25%: 15%.

[0115] Prepare three SP materials with different particle sizes: Size 1: 25nm; Size 2: 50nm; Size 3: 70nm. Mix these three sizes thoroughly in the ratio of Size 1: Size 2: Size 3 = 15%: 75%: 10%.

[0116] Prepare five PVDF materials with different particle sizes: Size 1: 40µm; Size 2: 65µm; Size 3: 90µm; Size 4: 115µm; Size 5: 140µm. Mix the PVDF materials thoroughly in the following ratio: Size 1: Size 2: Size 3: Size 4: Size 5 = 9%: 25%: 38%: 18%: 10%.

[0117] The prepared positive electrode active material, binder PVDF material, conductive agent SP material and additive oxalic acid material are mixed in a ratio of 97%:1.3%:1.5%:0.2% to obtain the positive electrode active slurry. NMP is added at a mass ratio of 40% of the total mixture to prepare the positive electrode active slurry.

[0118] The prepared slurry was uniformly coated onto the aluminum foil current collector (150 μm thickness). The electrode was baked at 110°C for 2 minutes, and the residual liquid content after drying was 0.5%. The dried electrode was then rolled on a roller press with the following parameters: gap width 35 μm, pressure 150 T. The compacted density of this electrode, with its mixture of different particle sizes, reached 3.9 g / cm³. 3 The porosity is 7.5%.

[0119] Using the electrode sheet described in this embodiment as the positive electrode, a hard carbon negative electrode as the counter electrode, a PE film as the separator (14 μm thick), and a NaPF6 solution with a sodium ion concentration of 1 mol / L (DMC as the solvent) as the electrolyte, a 32140 cylindrical battery was assembled in a battery manufacturing workshop. The battery's volumetric energy density can reach 390 Wh / L.

[0120] Example 4

[0121] Prepare five different particle size specifications of sodium ion cathode material NaCu 0.2 Fe 0.3 Mn 0.5O2, Specification 1: Particle size 1.5um; Specification 2: Particle size 2.5um; Specification 3: Particle size 5um; Specification 4: Particle size range 12um; Specification 5: Particle size 15um; These five specifications are thoroughly mixed in the following proportions: Specification 1: Specification 2: Specification 3: Specification 4: Specification 5 = 3%: 12%: 45%: 25%: 15%.

[0122] Prepare three SP materials with different particle sizes: Size 1: 25nm; Size 2: 50nm; Size 3: 80nm. Mix these three sizes thoroughly in the ratio of Size 1: Size 2: Size 3 = 15%: 75%: 10%.

[0123] Prepare five PVDF materials with different particle sizes: Size 1: 40µm; Size 2: 65µm; Size 3: 90µm; Size 4: 115µm; Size 5: 140µm. Mix the PVDF materials thoroughly in the following ratio: Size 1: Size 2: Size 3: Size 4: Size 5 = 9%: 25%: 38%: 20%: 8%.

[0124] The prepared positive electrode active material, binder PVDF material, conductive agent SP material and additive citric acid material are mixed in a ratio of 97%:1.1%:1.5%:0.4% to obtain the positive electrode active slurry. NMP is added at a mass ratio of 20% of the total mixture to prepare the positive electrode active slurry.

[0125] The prepared slurry was uniformly coated onto the aluminum foil current collector (180 μm thickness). The electrode was baked at 110°C for 2 minutes, and the residual liquid content after drying was 0.5%. The dried electrode was then rolled on a roller press with the following parameters: gap width 30 μm, pressure 150 T. The compacted density of this electrode, with its mixture of different particle sizes, reached 3.8 g / cm³. 3 Porosity 10%.

[0126] Using the electrode sheet described in this embodiment as the positive electrode, a hard carbon negative electrode as the counter electrode, a PE film as the separator (14 μm thick), and a NaPF6 solution with a sodium ion concentration of 1 mol / L (DMC as the solvent) as the electrolyte, a 32140 cylindrical battery was assembled in a battery manufacturing workshop. The battery's volumetric energy density can reach 380 Wh / L.

[0127] Example 5

[0128] Prepare five sodium-ion cathode materials, NaCu0.1Fe0.4Mn0.5O2, with particle sizes of 1µm, 3µm, 5µm, 12µm, and 18µm respectively. Mix these five materials thoroughly in the following ratio: 3% : 12% : 50% : 30% : 5%.

[0129] Prepare three SP materials with different particle sizes: Size 1: 20nm; Size 2: 60nm; Size 3: 75nm. Mix these three sizes thoroughly in the ratio of Size 1: Size 2: Size 3 = 15%: 70%: 15%.

[0130] Prepare five PVDF materials with different particle sizes: Size 1: 30µm; Size 2: 65µm; Size 3: 90µm; Size 4: 115µm; Size 5: 145µm. Mix the PVDF materials thoroughly in the following ratio: Size 1: Size 2: Size 3: Size 4: Size 5 = 9%: 25%: 38%: 18%: 10%.

[0131] The prepared positive electrode active material, binder PVDF material, conductive agent SP material and additive oxalic acid material are mixed in a ratio of 96.5%:1.1%:2.0%:0.4% to obtain the positive electrode active slurry. NMP is added at a mass ratio of 10% of the total mixture to prepare the positive electrode active slurry.

[0132] The prepared slurry was uniformly coated onto the aluminum foil current collector (120 μm thickness). The electrode was baked at 100°C for 2 minutes, and the residual liquid content after drying was 0.5%. The dried electrode was then rolled on a roller press with the following parameters: gap width 55 μm, pressure 200 T. The compacted density of this electrode, with its mixture of different particle sizes, reached 4.0 g / cm³. 3 Porosity 5%.

[0133] Using the electrode sheet described in this embodiment as the positive electrode, a hard carbon negative electrode as the counter electrode, a PE film as the separator (14 μm thick), and a NaPF6 solution with a sodium ion concentration of 1 mol / L (DMC as the solvent) as the electrolyte, a 32140 cylindrical battery was assembled in a battery manufacturing workshop. The battery's volumetric energy density can reach 400 Wh / L.

[0134] Comparative Example 1 (no components were mixed)

[0135] Prepare sodium ion cathode material NaCu0.4Fe0.3Mn0.3O2 with a particle size of about 5um.

[0136] Prepare SP materials with a particle size of around 60nm.

[0137] Prepare PVDF material with a particle size of approximately 90µm.

[0138] The prepared positive electrode active material, binder PVDF material, conductive agent SP material and additive oxalic acid material are mixed in a ratio of 96%:1.3%:2.3%:0.4% to obtain the positive electrode active slurry. NMP is added at a mass ratio of 50% of the total mixture to prepare the positive electrode active slurry.

[0139] The prepared slurry was uniformly coated onto an aluminum foil current collector (80 μm thick). The electrode was baked at 110°C for 2 minutes, and the residual liquid content after drying was 0.5%. The dried electrode was then rolled on a roller press with the following parameters: gap width 80 μm, pressure 250 T. The compacted density of this electrode, with its mixture of different particle sizes, was only 3.0 g / cm³. 3 The porosity is 29%.

[0140] Using the electrode sheet from this comparative example as the positive electrode, a hard carbon negative electrode as the counter electrode, a PE film as the separator (140 μm thick), and a NaPF6 solution with a sodium ion concentration of 1 mol / L (DMC as the solvent) as the electrolyte, a 32140 cylindrical battery was assembled in a battery manufacturing workshop. The battery's volumetric energy density is 300 Wh / L.

[0141] Comparative Example 2 (Positive electrode active material not compounded)

[0142] Prepare sodium ion cathode material NaCu0.2Fe0.3Mn0.5O2 with a particle size of about 7um.

[0143] Prepare three SP materials with different particle sizes: Size 1: 30nm; Size 2: 50nm; Size 3: 70nm. Mix these three sizes thoroughly in the ratio of Size 1: Size 2: Size 3 = 20%: 70%: 10%.

[0144] Prepare five PVDF materials with different particle sizes: Size 1: 40µm; Size 2: 70µm; Size 3: 100µm; Size 4: 120µm; Size 5: 140µm. Mix the PVDF materials thoroughly in the following ratio: Size 1: Size 2: Size 3: Size 4: Size 5 = 10%: 20%: 40%: 20%: 10%.

[0145] The prepared positive electrode active material, binder PVDF material, conductive agent SP material and additive oxalic acid material are mixed in a ratio of 96%:1.3%:2.3%:0.4% to obtain the positive electrode active slurry. NMP is added at a mass ratio of 40% of the total mixture to prepare the positive electrode active slurry.

[0146] The prepared slurry was uniformly coated onto the aluminum foil current collector (120 μm thickness). The electrode was baked at 100°C for 3 minutes, and the residual liquid content after drying was 0.5%. The dried electrode was then rolled on a roller press with the following parameters: gap width 50 μm, pressure 180 T. The compacted density of this electrode, with its mixture of different particle sizes, reached 3.1 g / cm³. 3 The porosity is 26.5%.

[0147] Using the electrode sheet from this comparative example as the positive electrode, a hard carbon negative electrode as the counter electrode, a PE film as the separator (14 μm thick), and a NaPF6 solution with a sodium ion concentration of 1 mol / L (DMC as the solvent) as the electrolyte, a 32140 cylindrical battery was assembled in a battery manufacturing workshop. The battery's volumetric energy density was 310 Wh / L.

[0148] Comparative Example 3 (Conductive agent not formulated)

[0149] Prepare five sodium-ion cathode materials, NaCu0.4Fe0.3Mn0.3O2, with particle sizes of 2µm, 4µm, 7µm, 10µm, and 15µm respectively. Mix these five materials thoroughly in the following ratio: 5% : 15% : 50% : 20% : 10%.

[0150] Prepare SP materials with a particle size of around 70nm.

[0151] Prepare five PVDF materials with different particle sizes: Size 1: 40µm; Size 2: 70µm; Size 3: 100µm; Size 4: 120µm; Size 5: 140µm. Mix the PVDF materials thoroughly in the following ratio: Size 1: Size 2: Size 3: Size 4: Size 5 = 10%: 20%: 40%: 20%: 10%.

[0152] The prepared positive electrode active material, binder PVDF material, conductive agent SP material and additive oxalic acid material are mixed in a ratio of 96%:1.3%:2.3%:0.4% to obtain the positive electrode active slurry. NMP is added at a mass ratio of 30% of the total mixture to prepare the positive electrode active slurry.

[0153] The prepared slurry was uniformly coated onto the aluminum foil current collector (120 μm thickness). The electrode was baked at 120°C for 2 minutes, and the residual liquid content after drying was 0.5%. The dried electrode was then rolled on a roller press with the following parameters: gap width 50 μm, pressure 180 T. The compacted density of this electrode, with its mixture of different particle sizes, reached 3.45 g / cm³. 3 The porosity is 18%.

[0154] Using the electrode sheet from this comparative example as the positive electrode, a hard carbon negative electrode as the counter electrode, a PE film as the separator (14 μm thick), and a NaPF6 solution with a sodium ion concentration of 1 mol / L (DMC as the solvent) as the electrolyte, a 32140 cylindrical battery was assembled in a battery manufacturing workshop. The battery's volumetric energy density was 345 Wh / L.

[0155] Comparative Example 4 (Particle size exceeding specifications)

[0156] Prepare five different particle size specifications of sodium ion cathode material NaCu 0.2 Fe 0.2 Mn 0.6 O2, Specification 1: Particle size 3um; Specification 2: Particle size 5um; Specification 3: Particle size 8um; Specification 4: Particle size range 15um; Specification 5: Particle size 25um; These five specifications are thoroughly mixed in the following proportions: Specification 1: Specification 2: Specification 3: Specification 4: Specification 5 = 5%: 15%: 50%: 20%: 10%.

[0157] Prepare three SP materials with different particle sizes: Size 1: 30nm; Size 2: 50nm; Size 3: 70nm. Mix these three sizes thoroughly in the ratio of Size 1: Size 2: Size 3 = 20%: 70%: 10%.

[0158] Prepare five PVDF materials with different particle sizes: Size 1: 40µm; Size 2: 70µm; Size 3: 100µm; Size 4: 120µm; Size 5: 140µm. Mix the PVDF materials thoroughly in the following ratio: Size 1: Size 2: Size 3: Size 4: Size 5 = 10%: 20%: 40%: 20%: 10%.

[0159] The prepared positive electrode active material, binder PVDF material, conductive agent SP material and additive oxalic acid material are mixed in a ratio of 96%:1.3%:2.3%:0.4% to obtain the positive electrode active slurry. NMP is added at a mass ratio of 50% of the total mixture to prepare the positive electrode active slurry.

[0160] The prepared slurry was uniformly coated onto the aluminum foil current collector (100 μm thickness). The electrode was baked at 110°C for 2 minutes, and the residual liquid content after drying was 0.5%. The dried electrode was then rolled on a roller press with the following parameters: gap width 50 μm, pressure 180T. The compacted density of this electrode, with its mixture of different particle sizes, reached 3.4 g / cm³. 3 The porosity is 19.5%.

[0161] Using the electrode sheet described in this embodiment as the positive electrode, a hard carbon negative electrode as the counter electrode, a PE film as the separator (14 μm thick), and a NaPF6 solution with a sodium ion concentration of 1 mol / L (DMC as the solvent) as the electrolyte, a 32140 cylindrical battery was assembled in a battery manufacturing workshop. The battery's volumetric energy density can reach 340 Wh / L.

[0162] Comparative Example 5 (Size Reduction)

[0163] Prepare sodium-ion cathode materials NaCu with three particle size specifications. 0.2 Fe 0.3 Mn 0.5 O2, Specification 1: Particle size 1um; Specification 2: Particle size 5um; Specification 5: Particle size 15um; These five specifications are thoroughly mixed in a ratio of Specification 1: Specification 2: Specification 3 = 20%: 50%: 30%.

[0164] Prepare three SP materials with different particle sizes: Size 1: 25nm; Size 2: 50nm; Size 3: 70nm. Mix these three sizes thoroughly in the ratio of Size 1: Size 2: Size 3 = 15%: 75%: 10%.

[0165] Prepare five PVDF materials with different particle sizes: Size 1: 40µm; Size 2: 65µm; Size 3: 90µm; Size 4: 115µm; Size 5: 140µm. Mix the PVDF materials thoroughly in the following ratio: Size 1: Size 2: Size 3: Size 4: Size 5 = 9%: 25%: 38%: 18%: 10%.

[0166] The prepared positive electrode active material, binder PVDF material, conductive agent SP material and additive oxalic acid material are mixed in a ratio of 97%:1.3%:1.5%:0.2% to obtain the positive electrode active slurry. NMP is added at a mass ratio of 40% of the total mixture to prepare the positive electrode active slurry.

[0167] The prepared slurry was uniformly coated onto the aluminum foil current collector (150 μm thickness). The electrode was baked at 110°C for 2 minutes, and the residual liquid content after drying was 0.5%. The dried electrode was then rolled on a roller press with the following parameters: gap width 35 μm, pressure 150 T. The compacted density of this electrode, with its mixture of different particle sizes, reached 3.3 g / cm³. 3 Porosity 22%.

[0168] Using the electrode sheet described in this embodiment as the positive electrode, a hard carbon negative electrode as the counter electrode, a PE film as the separator (14 μm thick), and a NaPF6 solution with a sodium ion concentration of 1 mol / L (DMC as the solvent) as the electrolyte, a 32140 cylindrical battery was assembled in a battery manufacturing workshop. The battery's volumetric energy density can reach 330 Wh / L.

[0169] Comparative Example 6 (the proportions of each component exceeded the specifications)

[0170] Prepare five different particle size specifications of sodium ion cathode material NaCu 0.2 Fe 0.2 Mn 0.6 O2, Specification 1: Particle size 2um; Specification 2: Particle size 4um; Specification 3: Particle size 7um; Specification 4: Particle size range 10um; Specification 5: Particle size 15um; These five specifications are thoroughly mixed in the following proportions: Specification 1: Specification 2: Specification 3: Specification 4: Specification 5 = 5%: 15%: 50%: 20%: 10%.

[0171] Prepare three SP materials with different particle sizes: Size 1: 30nm; Size 2: 50nm; Size 3: 70nm. Mix these three sizes thoroughly in the ratio of Size 1: Size 2: Size 3 = 20%: 70%: 10%.

[0172] Prepare five PVDF materials with different particle sizes: Size 1: 40µm; Size 2: 70µm; Size 3: 100µm; Size 4: 120µm; Size 5: 140µm. Mix the PVDF materials thoroughly in the following ratio: Size 1: Size 2: Size 3: Size 4: Size 5 = 10%: 20%: 40%: 20%: 10%.

[0173] The prepared positive electrode active material, binder PVDF material and conductive agent SP material are mixed in a ratio of 90%:5%:5% to obtain the positive electrode active slurry. NMP is added at a mass ratio of 50% of the total mixture to make the positive electrode active slurry.

[0174] The prepared slurry was uniformly coated onto the aluminum foil current collector (100 μm thickness). The electrode was baked at 110°C for 2 minutes, and the residual liquid content after drying was 0.5%. The dried electrode was then rolled on a roller press with the following parameters: gap width 50 μm, pressure 180 T. The compacted density of this electrode, with its mixture of different particle sizes, reached 3.8 g / cm³. 3 Porosity 10%.

[0175] Using the electrode sheet described in this embodiment as the positive electrode, a hard carbon negative electrode as the counter electrode, a PE film as the separator (14 μm thick), and a NaPF6 solution with a sodium ion concentration of 1 mol / L (DMC as the solvent) as the electrolyte, a 32140 cylindrical battery was assembled in a battery manufacturing workshop. The battery's volumetric energy density can reach 350 Wh / L.

[0176] In Comparative Example 1, none of the three materials were blended, resulting in poor overall material particle packing and low electrode compaction density.

[0177] In Comparative Example 2, the positive electrode active material was not compounded because the positive electrode active material accounts for the highest proportion in the entire compounding process. Therefore, the lack of compounding of the positive electrode active material resulted in the low compaction density of the electrode sheet in Comparative Example 2.

[0178] In Comparative Example 3, no conductive agent was compounded, resulting in uneven particle distribution of the conductive agent and consequently a lower overall electrode compaction density.

[0179] In Comparative Example 4, the positive electrode active material was compounded with larger particle sizes across the entire particle size range. This particle size matching was not the optimal choice, resulting in a low compaction density in Comparative Example 4.

[0180] In Comparative Example 5, the particle size range of the positive electrode active material was reduced to three sizes for compounding. The reduction in the number of sizes led to an unsuitable particle size distribution, which in turn resulted in low compaction density.

[0181] In Comparative Example 6, the proportions of each component exceeded the specifications, and the proportion of positive electrode active material exceeded the specifications. Although the compaction density was high, the proportion of active material was reduced, which in turn led to a decrease in battery energy density.

[0182] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A high-pressure sodium-ion battery electrode sheet, characterized in that: The electrode sheet is made from a positive electrode active slurry, which includes a compound positive electrode active material, a compound binder, a compound conductive agent, and additives. The content of each component by mass percentage is as follows: 92-98.5% of compound positive electrode active material, 0.5-3% of compound binder, 1-4% of compound conductive agent, and 0.1-1% of additives. The composite positive electrode active material, composite binder and composite conductive agent are compounded according to a preset particle size ratio.

2. The electrode sheet according to claim 1, characterized in that, The composite positive electrode active material is a layered oxide with the chemical formula Na. x Cu y Mn z M a O2, where 0.60≤x≤1.20, 0.1≤y≤0.40, 0.30≤z≤0.80, 0≤a≤0.50; M is one of Na, Mg, Ni, Ca, B, Fe, Al, Li, K, Ag, Zr, Ti, W, Mo, Cr, Sr, Y, and Cd.

3. The electrode sheet according to claim 1, characterized in that, The composite positive electrode active material is obtained by blending five specifications of positive electrode active materials, and the particle size range and mass proportion of each specification are as follows: Specification 1: 0µm < particle size ≤ 2µm, mass percentage 2% to 7%; Specification 2: 2µm < particle size ≤ 4µm, mass percentage 10%–20%; Specification 3: 4µm < particle size ≤ 7µm, mass percentage 40%–60%; Specification 4: 7µm < particle size ≤ 13µm, mass percentage 10% to 30%; Specification 5, with a particle size of 13um < and 20um, accounts for 5% to 15% of the total mass. The total mass percentage of the positive electrode active material of the five specifications is 100%.

4. The electrode sheet according to claim 1, characterized in that, The compound adhesive is a compound PVDF; It was obtained by blending five specifications of PVDF, and the particle size range and mass proportion of each specification are as follows: Specification 1: 30um < particle size ≤ 60um, mass percentage 5% to 15%; Specification 2: Particle size 60µm < 80µm, mass percentage 20%–30%; Specification 3: 80um < particle size ≤ 110um, mass percentage 30% to 40%; Specification 4: 110um < particle size ≤ 130um, mass percentage 15% to 20%; Specification 5, 130um < particle size ≤ 150um, with a mass percentage of 5% to 10%, and the sum of the mass percentages of the five specifications of PVDF is 100%.

5. The electrode sheet according to claim 1, characterized in that, The composite conductive agent is a composite SP; it is obtained by blending three specifications of SP, and the particle size range and mass percentage of each specification are as follows: Specification 1: Particle size ≤ 20nm ≤ 40nm, mass percentage 10%~25%; Specification 2: 40nm < particle size ≤ 60nm, mass percentage 60%–85%; Specification 3, 60nm < particle size ≤ 80nm, with a mass percentage of 5% to 15%, and the sum of the mass percentages of the three specifications of SP is 100%.

6. The electrode sheet according to claim 1, characterized in that, The compaction density of the electrode sheet is not less than 3.7 g / cm³. 3 .

7. A method for preparing the electrode sheet according to any one of claims 1 to 6, characterized in that, Specifically, the following steps are included: S1: Weigh or measure different specifications of positive electrode active material, binder and conductive agent according to the preset ratio, and mix them thoroughly and evenly according to the ratio to obtain composite positive electrode material, composite binder and composite conductive agent; S2: Measure the compound positive electrode active material, compound binder, compound conductive agent, additives and organic solvent according to the preset ratio; first, mix the compound positive electrode active material, compound binder, compound conductive agent and additives evenly to obtain the positive electrode active slurry; finally, add the organic solvent to obtain the positive electrode active slurry. S3: The prepared slurry is uniformly coated onto the aluminum foil current collector, and the electrode sheet is obtained after drying and rolling processes.

8. The preparation method according to claim 7, characterized in that: In step S2, the mass ratio of the positive electrode active slurry to the organic solvent is 1 to 9:

1.

9. The preparation method according to claim 7, characterized in that: In step S3, the specific parameters for the drying operation are: baking for 1 to 3 minutes at an oven temperature of 110±20℃ while ensuring a residual liquid rate of ≤0.8%; the specific parameters for the roller pressing operation are: gap width of 10 to 100 μm and pressure of 80 to 300 T.

10. A sodium-ion battery, characterized in that, This includes the electrode sheet as described in any one of claims 1 to 6 or the electrode sheet prepared by the preparation method described in any one of claims 7 to 9.

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