Negative pole piece of high-rate rechargeable sodium ion battery, preparation method of negative pole piece and sodium ion battery

Abstract

The invention discloses a high-rate rechargeable sodium-ion battery negative pole piece, a preparation method thereof and a sodium-ion battery, and belongs to the field of sodium-ion batteries. The high-rate rechargeable sodium-ion battery negative pole piece comprises a first carbon material layer, a second carbon material layer and a sodium-philic conductive carbon layer which are sequentially stacked on the two sides of a current collector layer respectively, the carbon particle size D50 of the first carbon material layer is larger than that of the second carbon material layer, and the carbon particle size D50 of the second carbon material layer is larger than that of the sodium-philic conductive carbon layer. The carbon particle size D50 of the second carbon material layer is larger than the carbon particle size D50 of the sodium-philic conductive carbon layer. The high-rate charging sodium ion battery negative pole piece provided by the invention has good rate charging performance.

Description

Technical Field

[0001] The present invention relates to the field of sodium ion batteries, and in particular to a high-rate charging sodium ion battery negative electrode sheet and a preparation method thereof, and a sodium ion battery. Background Art

[0002] As a new type of electrochemical energy storage technology, sodium-ion batteries have the advantages of low cost, abundant resources, and environmental friendliness. They are gradually becoming an important competitor in the electrochemical energy storage market. Power cells refer to cells that can meet fast charging or fast discharging requirements. For fast-charging cells, they can greatly save charging time, and for fast-discharging cells, they can increase instantaneous power, thereby enabling small batteries to drive large equipment to work normally. When the charging and discharging current increases, on the one hand, it will cause the battery polarization to increase, and the battery energy retention rate to decay rapidly. If it is a charging process, sodium precipitation may also occur; on the other hand, the heat generation of the cell will increase sharply, and the risk of thermal runaway of the battery will increase, thus posing a safety hazard. The hard carbon negative electrode of the current sodium-ion battery has serious problems of slow kinetics and sodium precipitation under rate charging, and poor fast charging performance. Summary of the invention

[0003] In view of the above-mentioned deficiencies in the prior art, the present invention proposes a high-rate charging sodium ion battery negative electrode plate and a preparation method thereof, and a sodium ion battery, aiming to solve the problem of poor fast charging performance of current sodium ion batteries.

[0004] To achieve the above-mentioned objectives, the present invention proposes a high-rate charging sodium-ion battery negative electrode plate, comprising a first carbon material layer, a second carbon material layer and a sodium-philic conductive carbon layer stacked in sequence on both sides of a current collector layer, wherein the carbon particle size D50 of the first carbon material layer is greater than the carbon particle size D50 of the second carbon material layer, and the carbon particle size D50 of the second carbon material layer is greater than the carbon particle size D50 of the sodium-philic conductive carbon layer.

[0005] Optionally, the carbon particle size D50 of the first carbon material layer is greater than 9 μm and less than or equal to 15 μm; and / or, the carbon particle size D50 of the second carbon material layer is 4 μm to 9 μm; and / or, the carbon particle size D50 of the sodium-philic conductive carbon layer is less than 4 μm.

[0006] Optionally, the thickness of the first carbon material layer is 20 μm to 150 μm; and / or the thickness of the second carbon material layer is 10 μm to 50 μm; and / or the thickness of the sodium-philic conductive carbon layer is 6 μm to 16 μm.

[0007] Optionally, the sodium-philic conductive carbon layer comprises a conductive carbon nanostructure with a surface modified with sodium-philic oxygen-containing functional groups.

[0008] Optionally, the sodium-philic oxygen-containing functional group includes one of a carboxyl group, a hydroxyl group, an ether group, a ketone group, an ester group, and an anhydride group.

[0009] Optionally, the material of the current collector layer is aluminum foil, copper foil, carbon-coated copper foil or carbon-coated aluminum foil.

[0010] Optionally, the thickness of the current collector layer is 6 μm to 16 μm.

[0011] In order to achieve the above-mentioned purpose, the present invention also proposes a method for preparing the above-mentioned high-rate charging sodium ion battery negative electrode sheet, comprising the following steps: coating the raw material of the first carbon material layer on both sides of the current collector layer, drying, and obtaining the first carbon material layer; coating the raw material of the second carbon material layer on the side of the first carbon material layer away from the current collector layer, drying, and obtaining the second carbon material layer; coating the raw material of the sodium-philic conductive carbon layer on the side of the second carbon material layer away from the first carbon material layer, drying, and obtaining the sodium-philic conductive carbon layer; and rolling the current collector layer, the first carbon material layer, the second carbon material layer, and the sodium-philic conductive carbon layer to obtain the high-rate charging sodium ion battery negative electrode sheet.

[0012] In order to achieve the above-mentioned purpose, the present invention also proposes a sodium ion battery, comprising the above-mentioned high-rate charging sodium ion battery negative electrode plate; or comprising the negative electrode plate prepared by the above-mentioned preparation method.

[0013] Optionally, the positive electrode material of the sodium ion battery is sodium iron pyrophosphate.

[0014] Beneficial effects of the present invention: The negative electrode plate for a high-rate charging sodium-ion battery provided by the present invention has a gradient distribution of sodium affinity and sodium embedding ability in the outward direction of the current collector, and is combined with a reasonable particle distribution design, which is conducive to maintaining Na + The deintercalation rate balance is achieved. As the D50 in each layer gradually increases, a gradient distribution of sodium ion concentration from high to low can be formed in the direction of electrolyte diffusion to the current collector when the battery is fast charged, thereby effectively improving the overall rate charging performance of the negative electrode sheet. At the same time, the negative electrode sheet of the present invention maintains Na + After the deintercalation rate is balanced, the risk of sodium precipitation can be reduced, thereby improving the capacity decay and safety issues caused by sodium precipitation. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0016] Figure 1 Schematic diagram of the structure of the negative electrode sheet of an embodiment of the present invention, wherein 1 is a current collector, 2 is a first carbon material layer, 3 is a second carbon material layer, and 4 is a sodium-philic conductive carbon layer;

[0017] Figure 2 is the rate charging curve of Example 1 of the present invention;

[0018] Figure 3 The high-rate cycle curves of the batteries of the embodiments of the present invention and the comparative examples are shown.

[0019] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. It should be understood that the following embodiments are only used to explain the present invention and are not used to limit the present invention.

[0021] Unless otherwise specified, all technical and scientific terms used herein have the common meanings in the field to which the claimed subject matter pertains, and all reagents used are industrial or analytically pure.

[0022] In addition, the drawings and the following description are provided for those skilled in the art to fully understand the present application, and are not intended to limit the subject matter described in the claims.

[0023] "Scope" disclosed in the present application is limited in the form of lower limit and upper limit, and a given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a special range. The scope limited in this way can be including end values ​​or not including end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a scope. For example, if the scope of 60-120 and 80-110 is listed for a specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following scope can be all expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise specified, the numerical range "ab" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0024] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0025] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0026] If there is no special explanation, the "include" and "comprising" mentioned in this application are open-ended or closed-ended. For example, the "include" and "comprising" may mean that other components not listed may also be included or only the listed components may be included or only the listed components may be included.

[0027] As a new type of electrochemical energy storage technology, sodium-ion batteries have the advantages of low cost, abundant resources, and environmental friendliness. They are gradually becoming an important competitor in the electrochemical energy storage market. Power cells refer to cells that can meet fast charging or fast discharging requirements. For fast-charging cells, they can greatly save charging time, and for fast-discharging cells, they can increase instantaneous power, thereby enabling small batteries to drive large equipment to work normally. When the charging and discharging current increases, on the one hand, it will cause the battery polarization to increase, and the battery energy retention rate to decay rapidly. If it is a charging process, sodium precipitation may also occur; on the other hand, the heat generation of the cell will increase sharply, and the risk of thermal runaway of the battery will increase, thus posing a safety hazard. The hard carbon negative electrode of the current sodium-ion battery has serious problems of slow kinetics and sodium precipitation under rate charging, and poor fast charging performance.

[0028] To solve the above problems, the present invention proposes a high-rate charging sodium-ion battery negative electrode plate, comprising a first carbon material layer, a second carbon material layer and a sodium-philic conductive carbon layer stacked in sequence on both sides of a current collector layer, wherein the carbon particle size D50 of the first carbon material layer is greater than the carbon particle size D50 of the second carbon material layer, and the carbon particle size D50 of the second carbon material layer is greater than the carbon particle size D50 of the sodium-philic conductive carbon layer.

[0029] Carbon coating can improve the conductivity of negative electrode materials, form a stable SEI layer, reduce the direct contact between electrolyte and active materials, and thus improve cycle stability and safety. In addition, the carbon coating can buffer the volume change during charge and discharge and maintain the integrity of the electrode structure. Surface carbon coating can improve the electronic conductivity of the material, and the porous morphology is conducive to the infiltration of the electrolyte into the material, ultimately obtaining a high-performance sodium ion battery negative electrode material.

[0030] In this scheme, since the entire negative electrode sheet structure presents a gradient distribution of sodium affinity and sodium embedding ability in the outward direction of the current collector, and is matched with a reasonable carbon particle distribution design, it is beneficial to maintain Na +The deintercalation rate balance is achieved. As the D50 in each layer gradually increases, a gradient distribution of sodium ion concentration from high to low can be formed in the direction of electrolyte diffusion to the current collector when the battery is fast charged, thereby effectively improving the overall rate charging performance of the negative electrode sheet. At the same time, the negative electrode sheet of the present invention maintains Na + After the deintercalation rate is balanced, the risk of sodium precipitation can be reduced, thereby improving the capacity decay and safety issues caused by sodium precipitation.

[0031] Furthermore, the carbon particle size D50 of the first carbon material layer is greater than 9 μm and less than or equal to 15 μm; and / or the carbon particle size D50 of the second carbon material layer is 4 μm to 9 μm; and / or the carbon particle size D50 of the sodium-philic conductive carbon layer is less than 4 μm.

[0032] In some embodiments, the carbon particle size D50 of the first carbon material layer is any value between 10 μm and 15 μm, such as 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, and 15 μm.

[0033] In some embodiments, the carbon particle size D50 of the second carbon material layer is any value between 4 μm and 9 μm, such as 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, or 9 μm.

[0034] In some embodiments, the carbon particle size D50 of the sodium-philic conductive carbon layer is 20nm, 50nm, 100nm, 200nm, 0.5μm, 1μm, 2μm, 3μm, 3.5μm, etc., any value less than 4μm. The carbon material of the sodium-philic conductive carbon layer includes conductive carbon, carbon nanotubes, etc.

[0035] Further, the thickness of the first carbon material layer is 20 μm to 150 μm; and / or the thickness of the second carbon material layer is 10 μm to 50 μm; and / or the thickness of the sodium-philic conductive carbon layer is 6 μm to 16 μm.

[0036] The thickness of the carbon coating has an important influence on the migration and diffusion of ions. Appropriate carbon coating thickness can optimize the migration and diffusion of ions and improve the electrochemical performance of the material. However, if the carbon content is too high, it may lead to obstruction of ion transmission channels, damage the reaction kinetics of the electrode, and cause performance degradation.

[0037] Furthermore, the sodium-philic conductive carbon layer comprises a conductive carbon nanostructure with a surface modified with sodium-philic oxygen-containing functional groups.

[0038] Sodium-philic oxygen-containing functional groups can form strong chemical adsorption with sodium ions, thereby improving the adsorption capacity of negative electrode materials for sodium ions, and participating in the intercalation and deintercalation reactions of sodium ions as active sites, which helps to improve the charge and discharge efficiency and reversibility of the battery. During the first charge and discharge process of the battery, oxygen-containing functional groups can promote the decomposition of the electrolyte to form a stable solid electrolyte interface (SEI) layer, which helps to protect the electrode material and improve the cycle stability of the battery. The presence of sodium-philic functional groups can increase the diffusion rate of sodium ions, thereby improving the performance of the battery under high-rate conditions.

[0039] Furthermore, the sodium-philic oxygen-containing functional group includes one of a carboxyl group, a hydroxyl group, an ether group, a ketone group, an ester group, and an anhydride group.

[0040] In some embodiments, the sodium-philic oxygen-containing functional group is preferably a hydroxyl group (OH), a ketone (C═O), or the like.

[0041] Furthermore, the material of the current collector layer is aluminum foil, copper foil, carbon-coated copper foil or carbon-coated aluminum foil. In this embodiment, copper foil and carbon-coated copper foil are more suitable for use in pole pieces of high energy density fast-charge batteries due to their excellent conductivity and mechanical strength.

[0042] Furthermore, the current collector has a thickness of 6 μm to 16 μm.

[0043] The current collector is a junction or component in a sodium battery that collects current. It collects the current generated by the active materials of the battery to form a larger current output, thereby realizing the process of converting chemical energy into electrical energy.

[0044] In some embodiments, the current collector includes aluminum foil, carbon-coated aluminum foil, and the like.

[0045] In some embodiments, the thickness of the current collector is any value between 6 μm and 16 μm, such as 6 μm, 8 μm, 10 μm, 12 μm, 14 μm, or 16 μm.

[0046] In order to solve the above problems, the present invention also proposes a method for preparing the above-mentioned high-rate charging sodium ion battery negative electrode sheet, comprising the following steps:

[0047] S1: coating the raw materials of the first carbon material layer on both sides of the current collector layer (the first carbon material layer comprises the following weight percentages: 90-96% of the first carbon material, 1-3% of the conductive agent SP-Li, 1-4% of the binder SBR (styrene-butadiene rubber), and 1-3% of the thickener sodium carboxymethyl cellulose (CMC-Na)) and drying to obtain the first carbon material layer;

[0048] S2: coating the raw material of the second carbon material layer on the side of the first carbon material layer away from the current collector layer (the second carbon material layer comprises the following weight percentages: 90-96% of the second carbon material, 1-3% of the conductive agent SP-Li, 1-4% of the binder SBR (styrene-butadiene rubber), and 1-3% of the thickener sodium carboxymethyl cellulose (CMC-Na)), and drying to obtain the second carbon material layer;

[0049] S3: coating a raw material of a sodium-philic conductive carbon layer on the side of the second carbon material layer away from the first carbon material layer (the sodium-philic conductive carbon layer comprises the following weight percentages: 80-94% sodium-philic conductive carbon material, 4-10% binder SBR (styrene-butadiene rubber), and 2-10% thickener sodium carboxymethyl cellulose (CMC-Na)), and drying to obtain a sodium-philic conductive carbon layer;

[0050] S4: After rolling the current collector layer, the first carbon material layer, the second carbon material layer, and the sodium-philic conductive carbon layer, a high-rate charging sodium ion battery negative electrode sheet is obtained.

[0051] The pole piece coated with two layers of electrode coating is fed into the gap between the two rollers. The coating is compacted under the action of the roller line load. After coming out of the roller gap, the pole piece will rebound elastically. The rolling pressure affects the coating density and porosity of the pole piece.

[0052] To solve the above problems, the present invention also proposes a sodium ion battery, including the above-mentioned high-rate charging sodium ion battery negative electrode plate; or including the high-rate charging sodium ion battery negative electrode plate prepared by the above-mentioned preparation method. The sodium ion battery of this scheme can be applied to low-speed electric vehicles, energy storage systems, renewable energy power stations and other fields.

[0053] Furthermore, the positive electrode material of the sodium ion battery is sodium iron phosphate pyrophosphate. The high-rate charging sodium ion battery negative electrode prepared above is matched with a NFPP (Na4Fe3(PO4)2P2O7)) positive electrode, and processes such as lamination, packaging, injection, aging, and formation are performed to prepare a sodium ion battery with excellent fast charging performance.

[0054] Example 1

[0055] Preparation of negative electrode plates for sodium ion batteries: The negative electrode plates are coated with three layers using the above-mentioned coating method. The first carbon material layer uses hard carbon with a D50 of 12 μm and a coating thickness of 100 μm. The negative electrode materials are configured into a slurry in the following proportions: 94 parts of hard carbon, 2 parts of conductive agent SP, 2.5 parts of binder SBR, and 1.5 parts of thickener CMC. The negative electrode slurry is evenly coated on a 12 μm negative electrode current collector aluminum foil and dried to obtain the first carbon material layer.

[0056] The second carbon material layer uses hard carbon with a D50 of 6 μm and a coating thickness of 50 μm. The negative electrode material is configured into a slurry in the following proportions: 94 parts of hard carbon, 2 parts of conductive agent SP, 2.5 parts of binder SBR, and 1.5 parts of thickener CMC.

[0057] The sodium-philic conductive carbon layer is a carbon nanostructure modified by hydroxyl and ketone groups, with a D50 of 2μm and a coating thickness of 16μm. The conductive carbon is prepared into a slurry in the following proportions: 90 parts of conductive carbon nanostructure, 6 parts of binder SBR, and 4 parts of thickener CMC. Then the negative electrode is obtained by drying, rolling, and cutting. The high-rate charging sodium ion battery negative electrode prepared above is matched with a NFPP (Na4Fe3(PO4)2P2O7)) positive electrode, and processes such as lamination, packaging, injection, aging, and formation are carried out to prepare a sodium ion battery.

[0058] Example 2

[0059] Preparation of negative electrode plates for sodium ion batteries: The negative electrode plates are coated with three layers using the above-mentioned coating method. The first carbon material layer uses hard carbon with a D50 of 12 μm and a coating thickness of 100 μm. The negative electrode materials are configured into a slurry in the following proportions: 94 parts of hard carbon, 2 parts of conductive agent SP, 2.5 parts of binder SBR, and 1.5 parts of thickener CMC. The negative electrode slurry is evenly coated on a 12 μm negative electrode current collector aluminum foil and dried to obtain the first carbon material layer.

[0060] The second carbon material layer uses soft carbon with a D50 of 7 μm and a coating thickness of 50 μm. The negative electrode material is configured into a slurry in the following proportions: 94 parts of soft carbon, 2 parts of conductive agent SP, 2.5 parts of binder SBR, and 1.5 parts of thickener CMC.

[0061] The sodium-philic conductive carbon layer is a carbon nanostructure modified by hydroxyl and ketone groups, with a D50 of 2.5 μm and a coating thickness of 16 μm. The conductive carbon is prepared into a slurry in the following proportions: 90 parts of conductive carbon nanostructure, 6 parts of binder SBR, and 4 parts of thickener CMC. Then, the negative electrode sheet is obtained through drying, rolling, and slitting.

[0062] Example 3

[0063] Preparation of negative electrode plates for sodium ion batteries: The negative electrode plates are coated with three layers using the above-mentioned coating method. The first carbon material layer uses hard carbon with a D50 of 13 μm and a coating thickness of 100 μm. The negative electrode materials are configured into a slurry in the following proportions: 94 parts of hard carbon, 2 parts of conductive agent SP, 2.5 parts of binder SBR, and 1.5 parts of thickener CMC. The negative electrode slurry is evenly coated on a 12 μm negative electrode current collector aluminum foil and dried to obtain the first carbon material layer.

[0064] The second carbon material layer uses hard carbon with a D50 of 8 μm and a coating thickness of 50 μm. The negative electrode material is configured into a slurry in the following proportions: 94 parts of hard carbon, 2 parts of conductive agent SP, 2.5 parts of binder SBR, and 1.5 parts of thickener CMC.

[0065] The sodium-philic conductive carbon layer is a carbon nanostructure modified by hydroxyl and ketone groups, with a D50 of 2.5 μm and a coating thickness of 16 μm. The conductive carbon is prepared into a slurry in the following proportions: 86 parts of conductive carbon nanostructure, 9 parts of binder SBR, and 5 parts of thickener CMC. Then, the negative electrode sheet is obtained through drying, rolling, and slitting.

[0066] Comparative Example 1

[0067] The preparation process of Comparative Example 1 is exactly the same as that of Example 1, except that: the negative electrode sheet is coated with a single layer using the above-mentioned coating method, and does not include a second carbon material layer and a sodium-philic conductive carbon layer. The first carbon material layer uses hard carbon, D50 is 8μm, and the coating thickness is 150μm. The negative electrode material is configured into a slurry in the following proportions: 94 parts of hard carbon, 2 parts of conductive agent SP, 2.5 parts of binder SBR, and 1.5 parts of thickener CMC. The negative electrode slurry is evenly coated on a 12μm negative electrode current collector aluminum foil and dried to obtain the first carbon material layer.

[0068] Furthermore, electrical performance tests were performed on the embodiments and comparative examples, and the test contents included: a small rate charge and discharge test, in which the batteries of the embodiments and comparative examples were charged and discharged at 0.2C, and the test was repeated 3 times and the discharge capacity was recorded.

[0069] For the fast charging performance test, the battery was charged at different rates of 0.5C, 1C, 3C, 5C, 8C, and 10C to a full battery cutoff voltage of 3.4V, and then discharged at 0.5C to 1.5V, and the charging capacity at different rates was recorded.

[0070] For the high-rate cycle test, at 25°C, the above-mentioned battery cell was charged to 3.4V using 8C constant current and constant voltage, with a cut-off current of 0.05C, and left for 40 minutes. Then, it was discharged to 1.5V using 8C and left for 40 minutes. This process was repeated for 100 cycles, and the capacity retention rate at 100 cycles was recorded.

[0071] The above test results are summarized in Table 1:

[0072] Table 1. Electrochemical performance test results

[0073]

[0074] The results show that compared with Comparative Example 1, the sodium ion battery made by using the negative electrode sheet with multi-layer coating D50 gradient distribution shows excellent rate charging performance, see Figure 2, the best can reach the 10C rate charge retention rate of 91.79% of Example 1. Examples 2 and 3 also show good performance, while Comparative Example 1 only uses a single-layer coating D50=8μm negative electrode and does not use a sodium-philic conductive carbon layer, and its rate charge performance is significantly lower than that of the example. Please refer to Figure 3 According to the data, the high-rate cycle performance of Example 1 is higher than that of the comparative example, and the sodium precipitation of the battery of the example after cycling is also better than that of the comparative example.

[0075] The above performance experimental results confirm that the high-rate charging negative electrode sheet provided by the present invention, through the combination of reasonable particle distribution design, presents a gradient distribution of sodium affinity and sodium embedding ability, which not only effectively improves the overall rate charging performance and cycle performance of the sodium ion battery, but also reduces the loss of active sodium ions and the risk of sodium precipitation.

[0076] The above are only preferred embodiments of the present invention, and do not limit the patent scope of the present invention. For those skilled in the art, the present invention may have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the patent protection scope of the present invention.

Claims

1. A high-rate charging sodium ion battery negative electrode plate, characterized in that: It includes a first carbon material layer, a second carbon material layer and a sodium-philic conductive carbon layer stacked in sequence on both sides of a current collector layer, wherein the carbon particle size D50 of the first carbon material layer is greater than the carbon particle size D50 of the second carbon material layer, and the carbon particle size D50 of the second carbon material layer is greater than the carbon particle size D50 of the sodium-philic conductive carbon layer.

2. The high-rate charging sodium ion battery negative electrode sheet according to claim 1, characterized in that: The carbon particle size D50 of the first carbon material layer is greater than 9 μm and less than or equal to 15 μm; and / or, the carbon particle size D50 of the second carbon material layer is 4 μm to 9 μm; And / or, the carbon particle size D50 of the sodium-philic conductive carbon layer is less than 4 μm.

3. The high-rate charging sodium ion battery negative electrode sheet according to claim 1, characterized in that: The thickness of the first carbon material layer is 20 μm to 150 μm; and / or, the thickness of the second carbon material layer is 10 μm to 50 μm; And / or, the thickness of the sodium-philic conductive carbon layer is 6 μm to 16 μm.

4. The high-rate charging sodium ion battery negative electrode sheet according to claim 1, characterized in that: The sodium-philic conductive carbon layer comprises a conductive carbon nanostructure with sodium-philic oxygen-containing functional groups modified on the surface.

5. The high-rate charging sodium ion battery negative electrode sheet according to claim 4, characterized in that: The sodium-philic oxygen-containing functional group includes one of a carboxyl group, a hydroxyl group, an ether group, a ketone group, an ester group, and an anhydride group.

6. The high-rate charging sodium ion battery negative electrode plate according to claim 1, characterized in that: The material of the current collector layer is aluminum foil, copper foil, carbon-coated copper foil or carbon-coated aluminum foil.

7. The high-rate charging sodium ion battery negative electrode sheet according to claim 6, characterized in that: The thickness of the current collector layer is 6 μm to 16 μm.

8. A method for preparing a negative electrode sheet for a high-rate charging sodium ion battery according to any one of claims 1 to 7, characterized in that: The following steps are involved: Coating the raw material of the first carbon material layer on both sides of the current collector layer, and drying to obtain the first carbon material layer; Coating a raw material for a second carbon material layer on a side of the first carbon material layer away from the current collector layer, and drying the coating to obtain a second carbon material layer; Coating a raw material of a sodium-philic conductive carbon layer on a side of the second carbon material layer facing away from the first carbon material layer, and drying the layer to obtain a sodium-philic conductive carbon layer; After rolling the current collector layer, the first carbon material layer, the second carbon material layer, and the sodium-philic conductive carbon layer, a high-rate charging sodium ion battery negative electrode sheet is obtained.

9. A sodium ion battery, characterized in that: It comprises the negative electrode plate of a high-rate charging sodium ion battery as claimed in any one of claims 1 to 7; or it comprises the negative electrode plate prepared by the preparation method as claimed in claim 8.

10. The sodium ion battery according to claim 9, characterized in that: The positive electrode material of the sodium ion battery is sodium iron pyrophosphate.

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