Starch-based hard carbon material, preparation thereof and use thereof in sodium-ion batteries

Abstract

The present application relates to hard carbon negative material technical field, specifically to a kind of starch-based hard carbon negative material preparation method and application in sodium ion battery, the preparation step is: the raw material of starch, X2 is pretreated in oxygen-containing atmosphere, at the temperature of 100~400 DEG C, then carbonization treatment is carried out, namely obtained;X2 in the described, X is halogen element.The present application innovatively pretreats the raw material of starch and X2 in oxygen-containing atmosphere, then carries out carbonization treatment, so it can solve the above-mentioned problems that starch faces in the process of preparing hard carbon, can be efficiently, high preservation type, high carbon yield with excellent performance, especially high capacity, high rate and high temperature stability of hard carbon material is prepared without other carbon source auxiliary.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of sodium ion batteries, and particularly relates to a hard carbon material for sodium ion batteries. BACKGROUND

[0002] Lithium ion batteries are one of the fastest growing and most promising electrochemical energy storage systems in commerce. In the past few years, lithium ion batteries have been widely used in portable electronic products, and due to their high energy density and long cycle life, they have promoted the development of the next generation of electric vehicles. Although there may be no shortage of lithium in the short term, the increasingly depleted resources will pose a challenge to the long-term large-scale industrial development of lithium batteries. Unlike lithium, sodium is abundant, low in cost, and available globally, and can be obtained from minerals and brine. Therefore, sodium ion batteries are considered to be the most promising candidate to replace lithium ion batteries for large-scale energy storage applications, which is a key step in developing sustainable and renewable energy systems. However, the radius of sodium ions is larger than that of lithium ions, and the graphite negative electrode widely used in lithium ion batteries is not suitable for the deintercalation of sodium ions due to the small interlayer spacing. In contrast, hard carbon with high disorder and large interlayer spacing has a high sodium storage capacity and good cycle stability as a negative electrode for sodium ion batteries.

[0003] Hard carbon precursors are mainly derived from biomass and polymers. Among them, biomass-derived carbon has become a material technology system for the industrialization of hard carbon. However, due to the activation of impurities in the pyrolysis process, biomass-derived carbon has a large specific surface area, resulting in a low first coulombic efficiency. Therefore, biomass-derived carbon needs to be treated with acid or other surface treatments to improve the microstructure of the material and reduce the specific surface area. In contrast, polymer precursors with low impurity content are easy to achieve fine microstructure control to obtain better electrochemical performance. Among them, starch can be obtained from various high-yield food crops such as corn, potatoes, rice, etc., and has a wide source and stable supply system.

[0004] For example, the Chinese patent document with publication number CN118439586A discloses a preparation method of a starch-based hard carbon negative material. Starch and tannic acid are dissolved in a certain concentration of sulfuric acid solution, heated and stirred for a certain time, the obtained product is washed with several times of suction filtration to remove residual sulfuric acid, and the treated material is carbonized at high temperature under nitrogen atmosphere to obtain a starch-based hard carbon negative material. For another example, the Chinese patent document with publication number CN118439588A discloses a starch-based hard carbon negative material and a preparation method thereof, comprising the following steps: S1. heating the starch to a first temperature of 200-250 DEG C at a first heating rate, maintaining for a first holding time of 8-30 h to obtain a starch-based hard carbon precursor; S2. heating the starch-based hard carbon precursor obtained in step S1 to a second temperature of 550-650 DEG C at a second heating rate under an inert atmosphere, maintaining for a second holding time of 1-4 h to obtain a starch-based hard carbon intermediate; S3. continuing to heat the starch-based hard carbon intermediate obtained in step S2 to a third temperature of 1400-1600 DEG C at a third heating rate, maintaining for a third holding time of 1-4 h to obtain a starch-based hard carbon negative material.

[0005] Although starch has many advantages in preparing hard carbon, starch will produce cross-linking and foaming during heat treatment, and the volume will expand several times. During this process, the carbon-oxygen ring dehydration of starch produces levoglucosan which is finally converted into tar and oxygen-containing compounds, reducing the production efficiency, and losing its original near-spherical morphology. In order to inhibit the cross-linking and foaming of starch, a pretreatment process of more than 20 h is usually required, which increases the energy consumption of actual production and reduces the production efficiency. SUMMARY

[0006] In view of the problems that the existing starch-based hard carbon material is easy to expand and pulverize, difficult to prepare, and the preparation efficiency, fast charging, and high temperature performance of the prepared material are not ideal, the present application provides a preparation method of a starch-based hard carbon material, aiming to provide a method for preparing a starch-based hard carbon material with excellent high temperature and high rate performance, which is efficient, low in energy consumption, and capable of maintaining the shape during carbonization.

[0007] The second object of the present application is to provide a starch-based hard carbon material prepared by the preparation method and its application in sodium ion batteries.

[0008] The third object of the present application is to provide a sodium ion battery comprising the starch-based hard carbon material, and a negative electrode and a negative electrode material thereof.

[0009] During the preparation of hard carbon, starch has a significant problem of foaming and pulverization. In view of this problem, the main idea in the industry is to add other auxiliary carbon sources or prolong the low-temperature treatment time. This scheme will affect the preparation efficiency, and in addition, it is easy to cause the pulverization and degradation of the original morphology, affecting the electrochemical performance of the material at high rate and high temperature. In view of this problem, the present application provides the following improved scheme after in-depth research:

[0010] A preparation method of a starch-based hard carbon material, starch raw material, X2 are pretreated under oxygen-containing atmosphere at a temperature of 100-400 DEG C, and then carbonization treatment is carried out, namely obtained;

[0011] X in the X2 is halogen element.

[0012] In view of the problems that starch raw material is easy to foam and pulverize during the preparation of hard carbon, the preparation efficiency is not high, it is difficult to maintain the shape during carbonization, and the carbon yield and the high temperature and high rate performance of the material are not high, the starch raw material and X2 are pretreated in the oxygen-containing atmosphere in the application, and then carbonization treatment is carried out, so that the above problems of starch during the preparation of hard carbon can be solved, and the hard carbon material with excellent performance, especially high capacity, high rate and high temperature stability can be prepared efficiently and with high shape retention and high carbon yield without other carbon source assistance.

[0013] In the application, the starch raw material can include one or more of corn starch, cassava starch, potato starch, rice starch, wheat starch and potato starch.

[0014] Preferably, the starch raw material has a spherical or spherical-like morphology.

[0015] In the application, the starch is treated under the combined action of X2 and oxygen-containing atmosphere, so that the structure of the starch can be stabilized, the risk of foaming and pulverization can be reduced, and the physicochemical structure can be optimized, which is beneficial to the subsequent carbonization to build the physicochemical structure characteristics suitable for sodium electricity, and thus the sodium electricity performance of the prepared material can be improved.

[0016] In the application, X is Cl, Br or I.

[0017] Preferably, X is I, the starch raw material and X2 are pretreated, and then pretreated;The research of the application shows that when X is I, the heated gasification of I2 and the synchronous combination of gasified I2 and oxygen-containing atmosphere can further optimize the physicochemical structure of the starch, and the shape retention, efficiency and high carbon yield of the starch hard carbon can be further utilized, not only that, but also the material prepared can be more suitable for the requirements of sodium electricity application, and can exhibit better capacity, high rate and high temperature performance.

[0018] In the present application, when the initial state of X2 is gaseous, the volume ratio of X2 in the pretreatment atmosphere can be 1-70v%, preferably 5-30v%. When the initial state of X2 is liquid or solid, the weight ratio of the starch raw material to X2 can be controlled to be 0.1-10:1, preferably 1-5:1, and further preferably 1-2:1. The present application also shows that controlling the ratio can further enhance the synergy of the process, and further improve the preparation effect and the performance of the prepared material at high rate and high temperature.

[0019] In the present application, the oxygen-containing atmosphere is an atmosphere containing at least one functional gas of oxygen and ozone. The content of the functional gas in the oxygen-containing atmosphere can be 10-30v%; further, air can be considered in view of cost.

[0020] Preferably, the pretreatment temperature is 200-280℃.

[0021] Preferably, the holding time at the pretreatment temperature is 1-24h, preferably 2-12h; further, it can be 4-6h.

[0022] In the present application, the carbonization temperature is 1000-2800℃, preferably 1100-1400℃. Studies have shown that at the preferred temperature, the process can be combined with other processes to further synergistically solve the problems existing in the preparation of hard carbon from starch, and better performance can be obtained.

[0023] Preferably, the holding time at the carbonization temperature is 0.5-10h, and further can be 1-3h.

[0024] Preferably, before the carbonization treatment, a pre-carbonization process at a temperature of 300-950℃, preferably 350-650℃, and further preferably 400-500℃ is further included. Studies have shown that at the preferred pre-carbonization, further combined with the joint control of the pre-carbonization temperature, the process can be combined with other processes to further synergistically solve the problems existing in the preparation of hard carbon from starch, and better performance can be obtained.

[0025] Preferably, the holding time at the pre-carbonization temperature is 0.5-10h, and further can be 1-3h.

[0026] The atmosphere of the carbonization and pre-carbonization processes is a protective atmosphere, for example, at least one of nitrogen and inert gas.

[0027] The present application also includes a starch-based hard carbon material prepared by the preparation method.

[0028] The preparation method of the present application can endow the material with physicochemical characteristics suitable for sodium batteries, and the material prepared by the preparation method can exhibit excellent capacity, high rate and high temperature performance in sodium battery applications.

[0029] The application also provides a negative electrode material of a sodium ion battery, which comprises a negative electrode active material, and the active material comprises the starch-based hard carbon material prepared by the preparation method.

[0030] In the application, the content of the starch-based hard carbon material in the negative electrode active material is above 50 wt.%.

[0031] In the negative electrode material, the content of the negative electrode active material is above 60 wt.%, and further 70-95 wt.%.

[0032] In the application, the negative electrode material further comprises a conductive agent and a binder allowed to be added in the field of sodium ion batteries.

[0033] In the application, the content of the conductive agent and the binder can be adjusted as needed, for example, can be below 15 wt.%.

[0034] The application also provides a negative electrode of a sodium ion battery, which comprises a current collector and a negative electrode material compounded on the current collector, and the negative electrode material comprises the starch-based hard carbon material prepared by the preparation method.

[0035] The application also provides a sodium ion battery comprising the negative electrode containing the starch-based hard carbon material.

[0036] The sodium ion battery, the negative electrode and the negative electrode material of the application can be known in the field of sodium ion batteries except that the starch-based hard carbon material prepared by the preparation method of the application is contained.

[0037] Advantages

[0038] The application innovatively uses X2 and an oxygen-containing atmosphere to jointly pretreat and modify starch, so that the dehydration reaction of C6 hydroxyl and C1 hydroxyl in the carbon-oxygen ring of starch molecules into harmful levorotatory glucose is inhibited, the dehydration between starch molecular chains is promoted, the production efficiency is improved, the energy consumption is reduced, in addition, the carbon yield can be improved, the shape can be preserved, and sodium battery materials with excellent rate and high-temperature performance can be prepared. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 SEM image of the pretreated starch in step 2 of Example 1;

[0040] Figure 2 SEM image of the hard carbon negative electrode material finally prepared in step 3 of Example 1;

[0041] Figure 3 Comparison diagram of room temperature charge-discharge curves of the hard carbon negative electrode materials in Example 1, Example 2 and Comparative Example 2;

[0042] Figure 4 Figure 1 is a comparison chart of the rate charging curves of the hard carbon negative electrode material in Example 1, Example 2, and Comparative Example 2;

[0043] Figure 5 Figure 2 is a high temperature charging and discharging curve of the hard carbon negative electrode material in Example 1 at 40℃;

[0044] Figure 6 Figure 3 is a foaming diagram of the pre-carbonized material in Comparative Example 1;

[0045] Figure 7 Figure 4 is a SEM diagram of the hard carbon negative electrode material after carbonization in Comparative Example 1;

[0046] Figure 8 Figure 5 is a SEM diagram of the hard carbon negative electrode material in Comparative Example 5. DETAILED DESCRIPTION

[0047] The application will be further described in conjunction with specific examples. The following examples will help those skilled in the art to further understand the application, but do not limit the scope of protection of the application.

[0048] Example 1

[0049] The application provides a preparation method of a hard carbon negative electrode material, comprising the following steps:

[0050] (1) Raw material preparation: a certain amount of corn starch raw material is uniformly mixed with iodine, and the mass ratio of corn starch to iodine is 1:1;

[0051] (2) The mixture in step (1) is placed in a tube furnace, and air is introduced into the tube furnace, and the temperature is raised to 220℃ (marked as T1) at a rate of 1℃ / min, and the temperature is kept for 6h, and the pretreated material is obtained after the temperature keeping is finished. The SEM is shown in Figure 1 .

[0052] (3) The pretreated material in step (2) is placed in a tube furnace, and the temperature is raised to 400℃ (marked as T2) at a rate of 5℃ / min in an argon atmosphere, and the temperature is kept for 2h for pre-carbonization, and then the temperature is raised to 1200℃ (marked as T3) at a rate of 5℃ / min, and the temperature is kept for 2h for carbonization, and the hard carbon spherical negative electrode material is obtained after cooling. The carbon yield is 26.8%, and the SEM is shown in Figure 2 .

[0053] The specific surface area of the hard carbon microspheres obtained in this example is 1.5m 2 / g, and the carbon layer spacing is 0.42nm.

[0054] Test

[0055] The hard carbon spherical negative active material prepared in step 3, conductive carbon (conductive carbon black), styrene-butadiene rubber (SBR), and sodium carboxymethyl cellulose (CMC) were dissolved in deionized water in a mass ratio of 9:2:1.8:1.2 to prepare a uniform slurry. The slurry was uniformly coated on an aluminum foil current collector, which was then placed in a 100°C drying oven for 12 hours. The hard carbon electrode sheet obtained in this embodiment was punched into small round sheets with a diameter of 10 mm, and the active material loading density of the electrode sheet was about 2 mg cm -2 A CR2032 button cell was assembled using the hard carbon electrode sheet as the working electrode, glass fiber (Whatman, f type) as the separator, metallic sodium as the counter electrode, and a sodium hexafluorophosphate solution (1 M sodium hexafluorophosphate, solvent: a 1:1 mixture of ethyl carbonate (EC) and diethyl carbonate (DEC) by volume) as the electrolyte.

[0056] The battery was subjected to electrochemical performance testing:

[0057] (1) The electrochemical performance was tested at room temperature at a current density of 30 mA / g and a voltage range of 0-2 V. The first-cycle specific charge capacity at room temperature was 335.82 mAh / g, and the first-cycle coulombic efficiency was 88.63%. The charge-discharge curve is shown in Figure 3 .

[0058] (2) The rate charge test was performed at room temperature at 0.1C, 0.3C, 0.5C, 1C, 1.5C, 2C, 3C, and 5C, with 5 cycles at each current and 10 cycles at 0.1C thereafter. The discharge current was fixed at 0.1C, and the voltage range was 0-2 V. The 5C rate charge specific capacity at room temperature was 276.3 mAh / g, as shown in Figure 4 .

[0059] (3) The electrochemical performance was tested at 40°C at a current density of 30 mA / g and a voltage range of 0-2 V. The first-cycle specific charge capacity at 40°C was 434.3 mAh / g, and the first-cycle coulombic efficiency was 87.46%. The charge-discharge curve is shown in Figure 5 .

[0060] Example 2

[0061] Compared with Example 1, the only difference was that in step 1, the corn starch raw material was uniformly mixed with iodine at a mass ratio of 4:1; in step 2, the temperature T1 was 250°C, and the holding time was 4 h; the other operations and parameters were the same as in Example 1, and the testing was performed according to the method of Example 1, and the results were as follows:

[0062] The carbon yield was 23.8%; the first-cycle specific charge capacity at room temperature at 30 mA / g was 316.4 mAh / g, and the first-cycle coulombic efficiency was 90.56%. The charge-discharge curve is shown in Figure 3 . The 5C rate charge specific capacity at room temperature was 244.4 mAh / g, as shown in Figure 4The initial charge specific capacity at 40°C is 388.7 mAh / g, and the initial coulombic efficiency is 88.8%.

[0063] Example 3

[0064] Compared with Example 1, the only difference is that the composition of the element X is changed, and the experimental groups are respectively:

[0065] Group A: A certain amount of corn starch is placed in a quartz tube, and chlorine vapor is introduced, with a chlorine vapor to air atmosphere volume ratio of 2:8;

[0066] Group B: A certain amount of corn starch raw material is uniformly mixed with bromine solution, with a corn starch to bromine mass ratio of 1:1. Other operations and parameters are the same as in Example 1, and electrochemical performance tests (1) are carried out according to the method of Example 1, with the following results:

[0067] Group A: The carbon yield is 23.5%; the initial charge specific capacity at room temperature and 30 mA / g is 306.2 mAh / g, and the initial coulombic efficiency is 86.5%;

[0068] Group B: The carbon yield is 22.2%; the initial charge specific capacity at room temperature and 30 mA / g is 303.4 mAh / g, and the initial coulombic efficiency is 87.8%.

[0069] Example 4

[0070] Compared with Example 1, the only difference is that the conditions of step 2 are changed, and the experimental groups are respectively: the oxygen-containing atmosphere is 30% oxygen-argon atmosphere, T1 = 260°C, the heating rate is 2°C / min, and the holding time is 6h;

[0071] Other operations and parameters are the same as in Example 1, and electrochemical performance tests (1) are carried out according to the method of Example 1, with the following results: the carbon yield is 21.7%; the initial discharge specific capacity at room temperature and 30 mA / g is 310.1 mAh / g, and the initial coulombic efficiency is 88.2%.

[0072] Example 5

[0073] Compared with Example 1, the only difference is that the conditions of step 3 are changed, and the experimental groups are respectively:

[0074] Group A: No holding process at T2 is performed;

[0075] Group B: T2 = 600°C, heating rate 5°C / min, holding time 1h; T3 = 1000°C, heating rate 10°C / min, holding time 1h;

[0076] Other operations and parameters are the same as in Example 1, and electrochemical performance tests (1) are carried out according to the method of Example 1, with the following results:

[0077] Group A: carbon yield 25.5%; room temperature, 30 mA / g first circle charging specific capacity 295.5 mAh / g, first circle coulombic efficiency 83.3%;

[0078] Group B: carbon yield 24.1%; room temperature, 30 mA / g first circle charging specific capacity 285.7 mAh / g, first circle coulombic efficiency 86.6%.

[0079] Comparative Example 1

[0080] Compared with Example 1, the only difference is that iodine is absent in Step 1, and other operations and parameters are the same as those in Example 1, and the electrochemical performance test (1) is carried out according to the method of Example 1, and the results are as follows: after foaming and swelling (see Figure 6 ) after carbonization, SEM is shown in Figure 7 , carbon yield 19.3%; room temperature, 30 mA / g first circle discharge specific capacity 255.3 mAh / g, first circle coulombic efficiency 78.6%;

[0081] Comparative Example 2

[0082] Compared with Example 1, the only difference is that iodine is absent in Step 1, and the holding time in Step 2 is extended to 72 h, and other operations and parameters are the same as those in Example 1, and the test is carried out according to the method of Example 1, and the results are as follows: carbon yield 20.3%; room temperature first circle discharge specific capacity 300.7 mAh / g, first circle coulombic efficiency 85.43%, and the charge-discharge curve is shown in Figure 3 . Room temperature 5C rate charging specific capacity 240.5 mAh / g, see Figure 4 . 40°C, 30 mA / g first circle charging specific capacity 365.6 mAh / g, first circle coulombic efficiency 83.8%.

[0083] From Example 1, Example 2, Comparative Example 1 and Comparative Example 2, it can be seen that the incorporation of iodine and the control of the mass ratio of starch to iodine significantly improve the treatment efficiency of starch, and significantly improve the first efficiency, first circle capacity, high rate performance and high temperature performance of the sodium ion battery of the hard carbon negative electrode.

[0084] Comparative Example 3

[0085] Compared with Example 1, the only difference is that nitrogen is used instead of air in Step 2. Other operations and parameters are the same as those in Example 1, and the electrochemical performance test (1) is carried out according to the method of Example 1, and the results are as follows: starch carbonization foaming and swelling, carbon yield 20.5%; room temperature, 30 mA / g first circle discharge specific capacity 264.3 mAh / g, first circle coulombic efficiency 77.5%;

[0086] Comparative Example 4

[0087] Compared with Example 1, the difference is only that the treatment of Step 2 is not performed, but the mixture is directly subjected to the operation of Step 3, and other operations and parameters are the same as those of Example 1, and the electrochemical performance test (1) is performed according to the method of Example 1, and the results are as follows: after carbonization of the starch, the starch is foamed and expanded, the carbon yield is 18.5%, the specific discharge capacity at room temperature and 30 mA / g in the first circle is 234.7 mAh / g, and the coulombic efficiency in the first circle is 64.4%.

[0088] Comparative Example 5

[0089] Compared with Example 1, the difference is only that in Step 1, the ammonium iodide is used to replace iodine (the amount of iodine element is the same as that of Example 1), other operations and parameters are the same as those of Example 1, and the electrochemical performance test (1) is performed according to the method of Example 1, and the results are as follows: the carbon yield is 23.3%, the specific discharge capacity at room temperature and 30 mA / g in the first circle is 285.6 mAh / g, the coulombic efficiency in the first circle is 83.6%, and the spherical morphology of the starch is corroded, and the SEM is shown in Figure 8 .

[0090] Comparative Example 6

[0091] Compared with Example 1, the difference is only that Step 3 is omitted, other operations and parameters are the same as those of Example 1, and the electrochemical performance test (1) is performed according to the method of Example 1, and the results are as follows: the carbon yield is 19.4%, the specific discharge capacity at room temperature and 30 mA / g in the first circle is 257.3 mAh / g, and the coulombic efficiency in the first circle is 79.8%;

[0092] In summary, the above is only a preferred embodiment of the present application, and is not used to limit the present application, and various modifications, deformations and improvements of the technical solutions of the present application made by the engineering technicians in the art shall fall into the protection scope of the present application.

Claims

1. A method for preparing a starch-based hard carbon material, characterized in that, Starch raw material and X2 are pretreated in an oxygen-containing atmosphere at a temperature of 100~400℃, followed by pre-carbonization and carbonization treatment to obtain the product. In X2, X is Cl, Br, or I; The weight ratio of the starch raw material to X2 is 0.1~10:1; The heat preservation time at the pretreatment temperature is 1~24 h; The temperature for the pre-carbonization process is 300~950 ℃.

2. The method for preparing starch-based hard carbon material as described in claim 1, characterized in that, The starch raw materials mentioned include one or more of corn starch, tapioca starch, potato starch, rice starch, wheat starch, and potato starch.

3. The method for preparing starch-based hard carbon material as described in claim 2, characterized in that, The starch raw material has a spherical or near-spherical morphology.

4. The method for preparing starch-based hard carbon material as described in claim 1, characterized in that, X is I, and the starch raw material and X2 are premixed and then pretreated.

5. The method for preparing starch-based hard carbon material as described in claim 1, characterized in that, The weight ratio of starch raw material to X2 is 1~5:

1.

6. The method for preparing starch-based hard carbon material as described in claim 1, characterized in that, The weight ratio of the starch raw material to X2 is 1~2:

1.

7. The method for preparing starch-based hard carbon material as described in claim 1, characterized in that, The oxygen-containing atmosphere is an atmosphere containing at least one functional gas, namely oxygen or ozone.

8. The method for preparing starch-based hard carbon material as described in claim 1, characterized in that, The pretreatment temperature is 200~280 ℃.

9. The method for preparing starch-based hard carbon material as described in claim 1, characterized in that, The heat treatment time at the pretreatment temperature is 2-12 h.

10. The method for preparing starch-based hard carbon material as described in claim 1, characterized in that, The carbonization temperature is 1000~2800 ℃.

11. The method for preparing starch-based hard carbon material as described in claim 1, characterized in that, The holding time at the carbonization temperature is 0.5~10 h.

12. The method for preparing starch-based hard carbon material as described in claim 1, characterized in that, The temperature for the pre-carbonization process is 350~650℃.

13. The method for preparing starch-based hard carbon material as described in claim 1, characterized in that, The temperature for the pre-carbonization process is 400~500℃.

14. The method for preparing starch-based hard carbon material as described in claim 11, characterized in that, The holding time at the pre-carbonization temperature is 0.5~10 h.

15. The method for preparing starch-based hard carbon material as described in claim 1, characterized in that, The atmosphere used in the carbonization process is a protective atmosphere.

16. A starch-based hard carbon material prepared by the preparation method according to any one of claims 1 to 15.

17. A negative electrode material for a sodium-ion battery, characterized in that, It includes a negative electrode active material, wherein the active material comprises a starch-based hard carbon material prepared by the preparation method according to any one of claims 1 to 15.

18. A negative electrode for a sodium-ion battery, characterized in that, It includes a current collector and a negative electrode material composited on the current collector, wherein the negative electrode material is the negative electrode material as described in claim 17.

19. A sodium-ion battery, characterized in that, It includes the negative electrode as described in claim 18.

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