Negative electrode material and sodium ion battery

Abstract

A negative electrode material and a sodium ion battery. The negative electrode material comprises a carbon matrix having a three-dimensional porous structure, and a doping element loaded in the pores of the carbon matrix. A relational expression between the doping element content and the gas adsorption amount of the negative electrode material is as follows: 0<α / β×103≤1, α being the content of the doping element in the negative electrode material, in ppm, and β being the gas adsorption capacity of the negative electrode material, in cm3 / g. By means of controlling the doping element content and the gas adsorption capacity of the negative electrode material, and regulating the pore structure of the negative electrode material, the negative electrode material can have a relatively high reversible specific capacity and initial coulombic efficiency.

Description

A negative electrode material and sodium ion battery Technical Field

[0001] The present application belongs to the field of battery technology and relates to a negative electrode material and a sodium ion battery. Background Art

[0002] Hard carbon is an amorphous carbon material with a low plateau potential, good structural stability, and low cost. It is considered one of the most promising negative electrode materials for commercial applications in sodium-ion batteries. However, hard carbon also has some disadvantages, such as low first-cycle coulombic efficiency, low specific capacity, and poor rate performance.

[0003] To improve the sodium storage performance of hard carbon, a common approach is to modulate its bulk and surface structure through element doping. Element doping can optimize the multi-scale structure and regulate the functionality of hard carbon materials, thereby enhancing their performance in sodium-ion batteries.

[0004] During element doping, the content of the doping element affects the pore structure of the hard carbon material, thereby affecting the material's capacity, Coulombic efficiency, and rate performance. Therefore, exploring the relationship between the doping element content and pore structure is of great significance for improving the performance of hard carbon materials.

[0005] Summary of the Invention

[0006] The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims.

[0007] This application provides a negative electrode material and a sodium-ion battery. By controlling the doping element content and gas adsorption capacity of the negative electrode material and regulating the pore structure of the negative electrode material, the negative electrode material has a high reversible specific capacity and first coulombic efficiency, thereby enabling the assembled sodium-ion battery to have a high energy density and excellent rate performance.

[0008] In a first aspect, the present application provides a negative electrode material, comprising a carbon matrix having a three-dimensional porous structure, and a doping element loaded in the pores of the carbon matrix;

[0009] The relationship between the doping element content of the negative electrode material and the gas adsorption capacity is as follows:

[0010] 0<α / β×10 3 ≤1;

[0011] Wherein, α is the content of the doping element in the negative electrode material, in ppm;

[0012] β is the gas adsorption capacity of the negative electrode material, unit: cm 3 / g.

[0013] The α / β×10 3 For example, it can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 or 1, etc.

[0014] The present application provides a negative electrode material, wherein the carbon matrix has a three-dimensional porous structure, and the pores of the carbon matrix are loaded with doping elements, and the relationship between the doping element content and the gas adsorption amount of the negative electrode material is defined as 0<α / β×10 3 ≤1, in particular, the characteristic pore range of the negative electrode material is manifested as the gas adsorption capacity.

[0015] When the doping element content and gas adsorption amount satisfy the above relationship, the doping element can not only support the structure of the carbon material, but also form certain characteristic pores in the material. During the charging and discharging process, sodium ions can form sodium clusters in the characteristic pores, thereby providing a high specific capacity, thereby affecting the intercalation and filling process of sodium ions; at the same time, under the limitation of this relationship, the doping element can change the electronic structure of the carbon material, thereby affecting the adsorption and diffusion process of sodium ions; in addition, the doping element can also change the interfacial chemical reaction between the carbon matrix (such as hard carbon) and the electrolyte, such as the formation and composition of the solid electrolyte interface phase (SEI), thereby affecting the transport and storage dynamics of sodium ions.

[0016] Therefore, when the doping element content and the gas adsorption amount satisfy the relationship of the present application, the capacity, coulombic efficiency and rate performance of the negative electrode material can be improved.

[0017] When the content of doping elements is much larger than the range defined by the relationship, there are a large number of doping elements in the material, and the characteristic pores will be destroyed, thereby reducing the specific capacity; it will also affect the formation of SEI, and due to the increase in macropores and defects, the cycle performance will decrease.

[0018] Preferably, the doping element includes any one or a combination of at least two of P, S, N, O, H, B, Mg, Ti, Zn or Fe.

[0019] In this application, doping elements can change the microstructure of carbon materials, such as interlayer spacing, porosity, and defect content, thereby affecting the intercalation and filling process of sodium ions. For example, the doping element P can form a three-dimensional structure with carbon, making the carbon layer more stable. At the same time, due to the larger radius of the P atom, it can stretch the carbon layer nearby, increasing the interlayer spacing and facilitating the migration of sodium ions. Excess P elements can also etch the carbon layer, forming specific pores that facilitate sodium storage; the same applies to defect content.

[0020] Doping elements can alter the electronic structure of carbon materials, such as the Fermi level, local electric field, and charge transfer, thereby affecting the adsorption and diffusion of sodium ions. Because the doping element itself is highly electronegative, it strongly attracts electrons. Furthermore, the electronegativity and number of valence electrons of the doping element differ from those of hard carbon atoms, causing changes in the energy band and Fermi level of hard carbon. Doping the material can alter its conductivity. For example, doping with P (Va group) can transform hard carbon into an n-type semiconductor, while doping with B (IIIa group) can transform it into a p-type semiconductor.

[0021] Doping elements can change the electron affinity and charge density of hard carbon, thereby affecting the decomposition potential of the electrolyte and the formation and composition of the SEI, which in turn affects the thickness, stability, and impedance of the SEI, all of which affect the transport and storage dynamics of sodium ions in hard carbon. For example, nitrogen doping can increase the electron affinity of hard carbon, inhibit the decomposition of the electrolyte, reduce the thickness of the SEI, and lower the interfacial impedance, thereby improving the diffusion and insertion / deinsertion rate and efficiency of sodium ions.

[0022] Multi-element doping can increase the number and diversity of doping sites, thereby providing more sodium storage sites and a wider sodium storage voltage platform. Synergistic effects can further regulate the electronic state and spatial distribution of doping sites, thereby optimizing the diffusion and storage dynamics of sodium ions. For example, NS co-doped hard carbon can utilize the charge transfer and steric hindrance of N and S to form more pyridinic N and thioether S, thereby improving the sodium storage capacity and rate performance of hard carbon.

[0023] Preferably, the range of α is 0-3000ppm and is not 0. For example, it can be 1ppm, 5ppm, 10ppm, 20ppm, 50ppm, 100ppm, 200ppm, 500ppm, 1000ppm, 1100ppm, 1200ppm, 1500ppm, 1800ppm, 2000ppm, 2100ppm, 2200ppm, 2500ppm, 2800ppm or 3000ppm, etc., but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0024] In this application, if the content α of the doping element in the negative electrode material is too low, no suitable characteristic pores will be generated, or the generated characteristic pores will be insufficient, resulting in a decrease in specific capacity; if the content α of the doping element in the negative electrode material is too high, the generated characteristic pores will collapse, which will also affect the performance.

[0025] Preferably, the carbon matrix comprises hard carbon.

[0026] Preferably, the relative pressure corresponding to the gas adsorption amount is less than 0.03, and may be, for example, 0.029, 0.025, 0.023, 0.02, 0.019, 0.015, or 0.01, etc., but is not limited to the listed values, and other values ​​not listed within this numerical range are also applicable. That is, β is the cumulative gas adsorption amount of the negative electrode material when the relative pressure is less than 0.03.

[0027] In the present application, the relative pressure corresponding to the gas adsorption amount is less than 0.03, and the relative pressure (P / P0) is the ratio of the pressure of the gas phase at the adsorption equilibrium to the saturated vapor pressure of the gas at the adsorption temperature; when P / P0 < 0.03, the sum of the adsorption amounts represents the adsorption amount of useful characteristic pores.

[0028] Preferably, the gas in the gas adsorption amount includes nitrogen.

[0029] Preferably, the range of β is 0-20cm 3 / g, and is not 0, for example, it can be 1cm 3 / g, 2cm 3 / g, 5cm 3 / g, 10cm 3 / g, 12cm 3 / g, 14cm 3 / g, 16cm 3 / g、18cm 3 / g or 20cm 3 / g, etc., but are not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0030] Preferably, the pore volume V of the negative electrode material satisfies: 0<V≤0.02cm 3 / g, for example, it can be 0.001cm 3 / g, 0.002cm 3 / g, 0.005cm 3 / g, 0.01cm 3 / g, 0.015cm 3 / g or 0.02cm 3 / g, etc., but are not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0031] Preferably, the pores of the negative electrode material include micropores, and the pore diameter d of the micropores satisfies: d≤77nm, for example, it can be 77nm, 76nm, 75nm, 70nm, 65nm, 60nm, 50nm, 40nm, 30nm or 20nm, etc., but is not limited to the listed values. Other values ​​not listed within this numerical range are also applicable.

[0032] In the present application, the negative electrode material is tested by the nitrogen gas adsorption method, and the gas adsorption amount β when the relative pressure is less than 0.03, as well as the pore volume V and pore diameter d can be measured.

[0033] The pore volume V and pore diameter d of the negative electrode material are closely related to its gas adsorption capacity β. The larger the pore volume V of the negative electrode material is and the more moderate the pore diameter is, the greater the gas adsorption capacity is; while the larger the pore diameter d is, the gas adsorption capacity is not necessarily greater, which is related to its pore volume V.

[0034] Preferably, the X-ray diffraction (XRD) pattern of the negative electrode material has a characteristic peak in the range of 20° to 30°, and the half-peak width of the characteristic peak is 5 to 20, for example, it can be 5, 7, 10, 12, 15, 17 or 20, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0035] In the present application, the characteristic peaks within the range of 20° to 30° reflect the carbon layer spacing and the degree of interlayer order.

[0036] Preferably, the X-ray diffraction pattern of the negative electrode material has a characteristic peak in the range of 35° to 50°, and the half-peak width of the characteristic peak is 1 to 10, for example, it can be 1, 2, 5, 7, 9 or 10, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0037] In the present application, the characteristic peak within the range of 35° to 50° reflects the order degree and grain size within the carbon layer.

[0038] During sodium removal capacity testing using metallic sodium as the counter electrode, sodium ions within the pores of the negative electrode material typically release between 0 and 0.15V. Therefore, the capacity of the negative electrode material is highly correlated with the pore structure within the material, and the doping element is also highly correlated with the formation of the pore structure. When these conditions are met, it means that the pore structure within the negative electrode material can provide more reversible capacity, allowing the negative electrode material to achieve a higher sodium removal capacity at a low voltage platform. The low-voltage platform capacity ratio helps further reduce the average sodium removal potential of the negative electrode material.

[0039] The present application does not specifically limit the preparation method of the negative electrode material described in the first aspect. Specifically, the preparation method includes:

[0040] (1) Mechanically mixing the carbon matrix raw material and the doping source to achieve a uniform state;

[0041] (2) pre-carbonizing the mixed material under inert gas / air conditions at 200-600° C., and then crushing the material into 3-20 μm to obtain a doped negative electrode material precursor;

[0042] (3) purifying the negative electrode material precursor under acid / alkaline conditions to obtain a better doping element content;

[0043] (4) The material obtained in step (3) is then subjected to high-temperature carbonization at 1000-1800° C. to obtain the negative electrode material.

[0044] This application improves the element content in the carbon matrix raw material by doping the carbon matrix raw material and can change the cross-linking structure inside the carbon matrix raw material. Using the above-mentioned negative electrode material preparation method, different precursors can be precisely doped to control the type, amount and distribution of the doping elements. The obtained negative electrode material has a suitable pore structure and doping element content, which can satisfy the relationship 0<α / β×10 3 ≤1.

[0045] Preferably, the carbon matrix raw material includes any one of biomass, coal, asphalt or resin, or a combination of at least two thereof. Specifically, the doping source may be, for example, melamine, sulfuric acid or phosphoric acid.

[0046] In a second aspect, the present application provides a sodium ion battery, wherein the negative electrode of the sodium ion battery includes the negative electrode material described in the first aspect.

[0047] The numerical range described in this application includes not only the point values ​​listed above, but also any point values ​​between the above numerical ranges that are not listed. Due to limited space and for the sake of simplicity, this application no longer exhaustively lists the specific point values ​​included in the range.

[0048] Compared with the related art, the beneficial effects of this application are:

[0049] The present application provides a negative electrode material, wherein the carbon matrix has a three-dimensional porous structure, and the pores of the carbon matrix are loaded with doping elements, and the relationship between the doping element content and the gas adsorption amount of the negative electrode material is defined as 0<α / β×10 3 ≤1, in particular, the characteristic pore range of the negative electrode material is manifested as the gas adsorption capacity;

[0050] When the doping element content and the gas adsorption amount satisfy the above relationship, the doping element can not only support the structure of the carbon material, but also form certain characteristic pores in the material. During the charge and discharge process, sodium ions can form sodium clusters in the characteristic pores, thereby providing a high specific capacity, thereby affecting the intercalation and filling process of sodium ions; at the same time, under the limitation of this relationship, the doping element can change the electronic structure of the carbon material, thereby affecting the adsorption and diffusion process of sodium ions; in addition, the doping element can also change the interfacial chemical reaction between the carbon matrix (such as hard carbon) and the electrolyte, such as the formation and composition of the solid electrolyte interface phase (SEI), thereby affecting the transport and storage dynamics of sodium ions;

[0051] Therefore, when the doping element content and the gas adsorption amount satisfy the relationship of the present application, the capacity, coulombic efficiency and rate performance of the negative electrode material can be improved.

[0052] Still other aspects will become apparent upon reading and understanding the accompanying drawings and detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] FIG1 is an XRD diagram of the negative electrode material provided in Example 1 of the present application. DETAILED DESCRIPTION

[0054] The technical solution of this application is further explained below through specific implementation methods.

[0055] Example 1

[0056] This embodiment provides a negative electrode material, comprising a carbon matrix having a three-dimensional porous structure, and a doping element loaded in the pores of the carbon matrix, wherein the carbon matrix is ​​hard carbon, the doping element is P, and the content α of the doping element is 1000 ppm;

[0057] The nitrogen gas adsorption method can be used to measure the cumulative gas adsorption capacity β of the negative electrode material when the relative pressure is less than 0.03, which is 7.77 cm 3 / g,α / β×10 3 =0.1287, the micropore volume V of the negative electrode material is 0.009 cm 3 / g, and the micropore diameter d is 0.37-0.45nm and 0.48-0.83nm.

[0058] Figure 1 shows the XRD pattern of the negative electrode material of this embodiment, which has a characteristic peak in the range of 20° to 30°, which is the (002) peak, reflecting the carbon layer spacing and the degree of interlayer order; and has a characteristic peak in the range of 35° to 50°, which is the (100) peak, reflecting the order within the carbon layer and the grain size.

[0059] Example 2

[0060] This embodiment provides a negative electrode material, comprising a carbon matrix having a three-dimensional porous structure, and a doping element loaded in the pores of the carbon matrix, wherein the carbon matrix is ​​hard carbon, the doping element is P, and the content α of the doping element is 1500 ppm;

[0061] The nitrogen gas adsorption method can be used to measure the cumulative gas adsorption capacity β of the negative electrode material when the relative pressure is less than 0.03, which is 3.24 cm 3 / g,α / β×10 3 =0.463, the micropore volume V of the negative electrode material is 0.004 cm 3 / g, and the pore size d is 0.12-77nm.

[0062] Example 3

[0063] This embodiment provides a negative electrode material, comprising a carbon matrix having a three-dimensional porous structure, and a doping element loaded in the pores of the carbon matrix, wherein the carbon matrix is ​​hard carbon, the doping element is P, and the content α of the doping element is 2000 ppm;

[0064] The nitrogen gas adsorption method can be used to measure the cumulative gas adsorption capacity β of the negative electrode material when the relative pressure is less than 0.03, which is 2.25 cm 3 / g,α / β×10 3 =0.89, the micropore volume V of the negative electrode material is 0.002cm 3 / g, and the pore size d is 0.12-77nm.

[0065] Example 4

[0066] This embodiment provides a negative electrode material, comprising a carbon matrix having a three-dimensional porous structure, and a doping element loaded in the pores of the carbon matrix, wherein the carbon matrix is ​​hard carbon, the doping element is P, and the content α of the doping element is 3000 ppm;

[0067] The nitrogen gas adsorption method can be used to measure the cumulative gas adsorption capacity β of the negative electrode material when the relative pressure is less than 0.03, which is 3.0 cm 3 / g,α / β×10 3 =1, the micropore volume V of the negative electrode material is 0.02m 3 / g, and the micropore diameter d is 0.12-77nm.

[0068] Example 5

[0069] This embodiment provides a negative electrode material, comprising a carbon matrix having a three-dimensional porous structure, and a doping element loaded in the pores of the carbon matrix, wherein the carbon matrix is ​​hard carbon, the doping element is P, and the content α of the doping element is 1000 ppm;

[0070] The nitrogen gas adsorption method can be used to measure the cumulative gas adsorption capacity β of the negative electrode material when the relative pressure is less than 0.03, which is 25 cm 3 / g,α / β×10 3 =0.04, the micropore volume V of the negative electrode material is 0.025m 3 / g, and the micropore diameter d is 0.12-77nm.

[0071] Example 6

[0072] This embodiment provides a negative electrode material, comprising a carbon matrix having a three-dimensional porous structure, and a doping element loaded in the pores of the carbon matrix, wherein the carbon matrix is ​​hard carbon, the doping element is P, and the content α of the doping element is 1000 ppm;

[0073] The nitrogen gas adsorption method can be used to measure the cumulative gas adsorption capacity β of the negative electrode material when the relative pressure is less than 0.04, which is 9.53 cm 3 / g,α / β×10 3 =0.105, the micropore volume V of the negative electrode material is 0.009m 3 / g, and the micropore diameter d is 0.37-0.45nm and 0.48-0.83nm.

[0074] Comparative Example 1

[0075] This comparative example provides a negative electrode material, comprising a carbon matrix having a three-dimensional porous structure, wherein the carbon matrix is ​​hard carbon, and the content of the doping element α in the pores of the carbon matrix is ​​1000 ppm;

[0076] The nitrogen gas adsorption method can be used to measure the cumulative gas adsorption capacity β of the negative electrode material when the relative pressure is less than 0.03, which is 0.9 cm 3 / g,α / β×10 3 =1.11, the micropore volume V of the negative electrode material is 0.009 cm 3 / g, and the micropore diameter d is 80nm.

[0077] Comparative Example 2

[0078] This comparative example provides a negative electrode material, comprising a carbon matrix having a three-dimensional porous structure, wherein the carbon matrix is ​​hard carbon, and the content of the doping element α in the pores of the carbon matrix is ​​0 ppm;

[0079] The nitrogen gas adsorption method can be used to measure the cumulative gas adsorption amount β of the negative electrode material when the relative pressure is less than 0.03, which is 0.002 cm 3 / g,α / β×10 3 =0, the micropore volume V of the negative electrode material is 0.0001cm 3 / g, and the micropore diameter d is 10nm.

[0080] Performance Testing

[0081] (1) The negative electrode material, polyvinylidene fluoride (PVDF) and conductive agent (SP) provided in the above embodiments and comparative examples were dispersed and dissolved in N-methylpyrrolidone (NMP) at a mass ratio of 90:5:5, and stirred and dispersed to obtain a slurry with a solid content of 55%. After coating, drying and rolling, the slurry was punched into button battery original sheets; a metal sodium sheet was used as the counter electrode, polypropylene (PP) was used as the separator material, and a small amount of sodium ion battery electrolyte was dripped into it to prepare a negative electrode material button battery, wherein the electrolyte solute was 1M NaPF6 and the solvent was an ethylene carbonate-dimethyl carbonate (EC-DMC) system.

[0082] In the voltage range of 0-2V, (1) rest for 2h; (2) rate discharge (0.1C, 0V); (3) rest for 10min; (4) rate discharge (0.02C, 0V); (5) rest for 30s; (6) rate charge (0.1C, 2.0V), and record the first charge specific capacity and first coulombic efficiency. The test results are shown in Table 1.

[0083] (2) The negative electrode materials provided in the above embodiments and comparative examples were prepared into negative electrode sheets by the method of test (1), and the negative electrode sheets, positive electrode sheets and separators were assembled into sodium ion batteries, wherein the preparation method of the positive electrode sheet was as follows: the active material, PVDF and SP were mixed in a mass ratio of 90:5:5 to prepare a positive electrode slurry, and the positive electrode sheet was obtained after coating; the electrolyte was a solute of 1M NaPF6 and a solvent of ethylene carbonate-dimethyl carbonate (EC-DMC) system.

[0084] Perform charge and discharge tests at a voltage of 2.5-4.05V and a rate of 0.2C, and record the initial discharge capacity;

[0085] The charge and discharge test was carried out at a voltage of 2.5-4.05V and a rate of 2C, and the first discharge capacity was recorded.

[0086] (1) Energy density

[0087] Energy density (Wh / L) = first discharge capacity at 0.2C (mAh) × 3.7 (V) / thickness (cm) / width (cm) / length (cm). The calculation results are shown in Table 1.

[0088] (2)Magnification

[0089] The rate data was calculated as 2C first discharge capacity / 0.2C first discharge capacity × 100%. The calculation results are shown in Table 1.

[0090] Table 1

[0091] analyze:

[0092] From the data results of Examples 1-3, it can be seen that the negative electrode material provided by this application has a high adsorption capacity when the doping element content and gas adsorption capacity meet 0<α / β×10 3 When ≤1, the negative electrode material has a good sodium storage capacity, so that the negative electrode material has a higher reversible specific capacity and first coulombic efficiency, and thus the assembled sodium ion battery has a higher energy density and excellent rate performance.

[0093] From the data of Example 1 and Example 4, it can be seen that when the content of the doping element α is high, the gas adsorption amount β will be small, that is, α / β×10 3 The higher the value, the lower the specific capacity, first efficiency, energy density and rate performance.

[0094] From the data of Example 1 and Example 5, it can be seen that when the pore volume V of the negative electrode material is too large, α / β×10 3 A lower value will result in a decrease in specific capacity, first efficiency, energy density and rate performance.

[0095] From the data of Examples 1 and 6, it can be seen that if the cumulative gas adsorption amount β is obtained at a higher relative pressure, it is found that the performance is not affected, indicating that the point of characteristic pore size adsorption should be below the relative pressure of 0.03.

[0096] From the data of Example 1 and Comparative Example 1, it can be seen that when the pore size d of the negative electrode material is too large, α / β×10 3 >1, it will cause a significant decrease in specific capacity, first efficiency, energy density and rate performance.

[0097] From the data of Example 1 and Comparative Example 2, it can be seen that when the content of doping elements is 0, α / β×10 3 =0, that is, no doping is performed, which will cause a significant decrease in specific capacity, first efficiency, energy density and rate performance.

[0098] The above description is only a specific implementation method of the present application, but the protection scope of the present application is not limited thereto. Those skilled in the art should understand that any changes or replacements that can be easily thought of by those skilled in the art within the technical scope disclosed in the present application fall within the protection scope and disclosure scope of the present application.

Claims

1. A negative electrode material comprising a carbon matrix having a three-dimensional porous structure, and a doping element loaded in the pores of the carbon matrix; The relationship between the doping element content and gas adsorption amount of the negative electrode material is as follows: 0＜α / β×10 3 ≤1； in, α is the content of the doping element in the negative electrode material, in ppm; β is the gas adsorption capacity of the negative electrode material, in cm 3 / g.

2. The negative electrode material according to claim 1, wherein The doping element includes any one or a combination of at least two of P, S, N, O, H, B, Mg, Ti, Zn or Fe elements; The range of α is 0-3000 ppm, and is not 0.

3. The negative electrode material according to claim 1, wherein The carbon matrix includes hard carbon.

4. The negative electrode material according to claim 1, wherein The relative pressure corresponding to the gas adsorption amount is less than 0.

03.

5. The negative electrode material according to claim 1, wherein The gas in the gas adsorption amount includes nitrogen.

6. The negative electrode material according to claim 1, wherein The range of β is 0-20cm 3 / g and is not 0.

7. The negative electrode material according to claim 1, wherein The pore volume V of the negative electrode material satisfies: 0<V≤0.02cm 3 / g.

8. The negative electrode material according to claim 1, wherein The pores in the negative electrode material include micropores, and the pore diameter d of the micropores satisfies: d≤77nm.

9. The negative electrode material according to claim 1, wherein In the X-ray diffraction spectrum of the negative electrode material, there is a characteristic peak in the range of 20° to 30°, and the half-peak width of the characteristic peak is 5 to 20; The X-ray diffraction spectrum of the negative electrode material has a characteristic peak in the range of 35° to 50°. The half-width of the characteristic peak is 1 to 10.

10. A sodium ion battery, wherein the negative electrode of the battery comprises the negative electrode material according to any one of claims 1 to 9.

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