Negative electrode material, preparation method and application thereof

Abstract

The application relates to the technical field of batteries, in particular to a negative electrode material and a preparation method and application thereof. The negative electrode material comprises a composite of CrSbS3 and reduced graphene oxide; the mass content of the reduced graphene oxide in the negative electrode material is 15%-25%. The negative electrode material obtained by compounding CrSbS3 and reduced graphene oxide has high capacity, excellent stability and conductivity.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, in particular to a negative electrode material and a preparation method and application thereof. BACKGROUND

[0002] Hard carbon has been widely studied as a negative electrode material for sodium ion batteries, but its limited theoretical specific capacity cannot be ignored, and other non-carbon negative electrode materials mainly have poor cycle stability. According to the charge storage mechanism, sodium ion battery negative electrode materials are mainly divided into three types, namely intercalation type materials, conversion type materials and alloying materials, among which conversion type materials and alloying materials can provide higher specific capacity. Therefore, how to construct a negative electrode material that can not only undergo conversion reaction but also undergo alloying reaction, which can overall improve the specific capacity of the negative electrode material and the cycle stability and rate performance of the battery, is crucial.

[0003] In view of this, the present application is proposed. SUMMARY

[0004] An object of the present application is to provide a negative electrode material to solve the technical problems of insufficient specific capacity, poor cycle performance and stability of the sodium ion battery negative electrode material in the prior art.

[0005] Another object of the present application is to provide a preparation method of the negative electrode material, which is simple, easy to operate, and can obtain a negative electrode material with higher stability and conductivity.

[0006] Another object of the present application is to provide a negative electrode sheet.

[0007] Another object of the present application is to provide a sodium ion battery.

[0008] In order to achieve the above objects of the present application, the following technical solutions are adopted:

[0009] The negative electrode material comprises a composite of CrSbS3 and reduced graphene oxide; the mass content of the reduced graphene oxide in the negative electrode material is 15% to 25%.

[0010] In an embodiment, the reduced graphene oxide can be partially or completely replaced by a first carbon material; the first carbon material is at least one of carbon nanotubes, carbon nanofibers, hollow carbon spheres, hard carbon and soft carbon.

[0011] The preparation method of the negative electrode material as described above comprises the following steps:

[0012] The mixture of CrSbS3 and reduced graphene oxide is subjected to ball milling treatment.

[0013] In an embodiment, before the ball milling treatment, the method further comprises: grinding the CrSbS3 and the reduced graphene oxide.

[0014] In an embodiment, the rotating speed of the ball milling treatment is 300-500 r / min, and the time of the ball milling treatment is 6-10 h.

[0015] In an embodiment, the mass of the reduced graphene oxide is 15%-25% of the total mass of the reduced graphene oxide and the CrSbS3.

[0016] In an embodiment, during the preparation of the negative electrode material, the reduced graphene oxide is partially or entirely replaced by a first carbon material; the first carbon material is at least one of carbon nanotubes, carbon nanofibers, hollow carbon spheres, hard carbon and soft carbon.

[0017] In an embodiment, the raw material for preparing the CrSbS3 comprises Cr2S3 and Sb2S3.

[0018] In an embodiment, the method for preparing the CrSbS3 comprises: first grinding Cr2S3 and Sb2S3 to obtain a first mixture; and performing heat treatment on the first mixture in a sealed environment.

[0019] In an embodiment, the heat treatment specifically comprises: placing the first mixture in a glass container, sealing the glass container; placing the sealed glass container in an iron container, and then placing the iron container in a heat treatment device.

[0020] In an embodiment, the mass ratio of the Cr2S3 to the Sb2S3 is 1:1.7.

[0021] In an embodiment, the temperature of the heat treatment is 550-700 °C, and the time of the heat treatment is 65-75 h.

[0022] In an embodiment, the heating rate of the heat treatment is 2-4 °C / min.

[0023] In an embodiment, the raw material for preparing the CrSbS3 comprises elemental Cr, elemental Sb and elemental S.

[0024] In an embodiment, the method for preparing the CrSbS3 comprises: solid-phase sintering elemental Cr, elemental Sb and elemental S under vacuum conditions; and the molar ratio of the elemental Cr, the elemental Sb and the elemental S is 1:1:3.

[0025] In an embodiment, the temperature of the solid-phase sintering is 440-460 °C, and the time of the solid-phase sintering is 1.5-2.5 h.

[0026] In an embodiment, the elemental Cr, the elemental Sb and the elemental S are ground before the solid phase sintering, and the grinding time is 50-70 min.

[0027] In an embodiment, the solid phase sintering is carried out under nitrogen condition.

[0028] In an embodiment, the heating rate of the solid phase sintering is 1-3℃ / min.

[0029] The negative electrode sheet comprises the negative electrode material or the negative electrode material prepared by the preparation method of the negative electrode material.

[0030] The sodium ion battery comprises the negative electrode sheet.

[0031] Compared with the prior art, the present application has the following beneficial effects:

[0032] (1) The negative electrode material prepared by compounding CrSbS3 and reduced graphene oxide can improve the problem of limited capacity of the existing negative electrode material, and the reversible capacity is improved, and the negative electrode material still has excellent stability and good fast charging and discharging capacity in the charging and discharging cycle process.

[0033] (2) The preparation method of the negative electrode material is simple and easy to operate.

[0034] (3) The sodium ion battery prepared by the negative electrode material has excellent cycle stability and rate performance; the initial discharge capacity is 1172.6mAh·g -1 and above, the capacity retention rate (compared with the second discharge capacity) after 70 cycles is 77.3% and above, and the coulombic efficiency after 70 cycles is 95.3% and above. BRIEF DESCRIPTION OF DRAWINGS

[0035] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the drawings needed in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0036] Figure 1 The cycle capacity graph of the negative electrode material in Example 1 of the present application and CrSbS3;

[0037] Figure 2 The AC impedance spectrum graph of the battery prepared by the negative electrode material in Example 1 of the present application and the battery prepared by CrSbS3. DETAILED DESCRIPTION

[0038] The embodiments of the present application will be described in detail below with examples, but those skilled in the art will understand that the following examples are only for illustration of the present application and should not be regarded as limiting the scope of the present application. The specific conditions not noted in the examples are carried out according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used are not noted by the manufacturer, which are all conventional products that can be obtained by purchase.

[0039] According to one aspect of the present application, the present application relates to a negative electrode material, which comprises a composite material of CrSbS3 and reduced graphene oxide (rGO); the mass content of reduced graphene oxide in the negative electrode material is 15% to 25%.

[0040] In the negative electrode material of the present application, Cr in CrSbS3 is a sodium inert element, which does not chemically react with sodium, thereby improving the structural stability of the material during the charge and discharge cycle; Sb can alloy with sodium, and S can transform with sodium. The composite material of CrSbS3 and reduced graphene oxide has more excellent stability and conductivity.

[0041] Compared with CrSbS3, the composite negative electrode material of the present application has the significant advantage of better cycle stability; with the increase of the charge and discharge cycle number, the capacity of CrSbS3 will quickly decay due to the volume expansion; compared with reduced graphene oxide, the composite material of the present application has the significant advantage of much higher capacity. In the composite material of the present application, CrSbS3 is the main part, i.e., the part providing capacity, and the reduced graphene oxide has two functions, first, the reduced graphene oxide can buffer the volume expansion of CrSbS3 during the charge and discharge process, thereby enhancing the cycle stability, and second, the reduced graphene oxide can improve the conductivity of the material, thereby enhancing the high-rate performance; therefore, the reduced graphene oxide in the negative electrode material of the present application needs to be used in a suitable proportion; too high amount of the reduced graphene oxide will result in much lower capacity of the negative electrode material compared with pure CrSbS3, and too low amount of the reduced graphene oxide will not obviously enhance the cycle stability.

[0042] The composite material of CrSbS3 and reduced graphene oxide as the negative electrode material of a sodium ion battery has improved reversible capacity and rate capacity compared with hard carbon during the cycle process.

[0043] The reduced graphene oxide in the present application is derived from Kainan Carbon New Material Co., Ltd.

[0044] In an embodiment, the mass content of the reduced graphene oxide in the negative electrode material includes but is not limited to 15%, 15.5%, 16%, 16.5%, 17%, 18%, 18.5%, 19%, 19.5%, 20%, etc. In an embodiment, the mass content of CrSbS3 in the negative electrode material is 75%-85%, for example, 75%, 75.5%, 76%, 76.5%, 77%, 78%, 79%, 79.5%, or 80%, etc. By limiting the appropriate proportion of reduced graphene oxide and CrSbS3, the stability and conductivity of the negative electrode material can be further improved through the synergistic effect of CrSbS3 and reduced graphene oxide.

[0045] In an embodiment, the reduced graphene oxide can be partially or completely replaced by a first carbon material; the first carbon material is at least one of carbon nanotubes, carbon nanofibers, hollow carbon spheres, hard carbon, and soft carbon. In an embodiment, the reduced graphene oxide is partially replaced by a first carbon material, and the mass ratio of the reduced graphene oxide to the first carbon material is (7-9):(1-3).

[0046] According to another aspect of the present application, the present application also relates to a preparation method of the negative electrode material, comprising the following steps:

[0047] The mixture of CrSbS3 and reduced graphene oxide is subjected to ball milling treatment.

[0048] The present application mixes CrSbS3 and reduced graphene oxide and subjects them to ball milling treatment, which is simple to operate, and the obtained negative electrode material has high capacity, which can improve the stability and cycle performance of the battery prepared therefrom.

[0049] In an embodiment, before the ball milling treatment, the method further comprises: grinding CrSbS3 and reduced graphene oxide. Through grinding, CrSbS3 and reduced graphene oxide form a uniform mixture.

[0050] In an embodiment, the rotation speed of the ball milling treatment is 300-500 r / min, for example, 300 r / min, 320 r / min, 350 r / min, 370 r / min, 400 r / min, 420 r / min, 450 r / min, 470 r / min, 500 r / min, etc. In an embodiment, the time of the ball milling treatment is 6-10 h, for example, 6 h, 6.5 h, 7 h, 7.5 h, 8 h, 8.5 h, 9 h, 9.5 h, or 10 h, etc. The present application adopts appropriate ball milling rotation speed and time, which can further ensure the electrochemical performance of the negative electrode material.

[0051] In an embodiment, the mass of the reduced graphene oxide is 15% to 25% of the total mass of the reduced graphene oxide and the CrSbS3, such as 15%, 15.5%, 16%, 16.5%, 17%, 18%, 18.5%, 19%, 19.5%, 20%, etc.

[0052] In an embodiment, during the preparation of the negative electrode material, the reduced graphene oxide is partially or entirely replaced by a first carbon material; the first carbon material is at least one of carbon nanotubes, carbon nanofibers, hollow carbon spheres, hard carbon, and soft carbon. In an embodiment, a method for preparing a negative electrode material, comprising: subjecting a mixture of CrSbS3, reduced graphene oxide, and a first carbon material to ball milling.

[0053] In an embodiment, the raw materials for preparing the CrSbS3 include Cr2S3 (disulfide chromium) and Sb2S3 (disulfide antimony). In combination with the high capacity characteristics of Sb2S3 and the semiconductor characteristics of Cr2S3, the bimetallic sulfide CrSbS3 with certain electrochemical performance is obtained.

[0054] In an embodiment, the method for preparing the CrSbS3 includes: subjecting Cr2S3 and Sb2S3 to first grinding to obtain a first mixture; and subjecting the first mixture to heat treatment in a sealed environment.

[0055] In an embodiment, the heat treatment specifically includes: placing the first mixture in a glass container, sealing the glass container; placing the sealed glass container in an iron container, and then placing the iron container in a heat treatment device. The glass container includes a glass tube; the iron container includes an iron tube; and the heat treatment device includes a tube furnace.

[0056] The material prepared by the above method is characterized as CrSbS3 using Cr2S3 and Sb2S3 as raw materials.

[0057] The above preparation method of the present application can obtain CrSbS3 with high stability and conductivity, and can further improve the cycle stability and rate performance of the negative electrode material.

[0058] In an embodiment, the raw materials for preparing the CrSbS3 include elemental Cr, elemental Sb, and elemental S.

[0059] In an embodiment, the mass ratio of the Cr2S3 and the Sb2S3 is 1:1.7.

[0060] In an embodiment, the temperature of the heat treatment is 550-700℃, such as 550℃, 570℃, 590℃, 600℃, 620℃, 650℃, 660℃, 670℃, 680℃, 690℃ or 700℃, etc. The time of the heat treatment is 65-75h, such as 65h, 66h, 67h, 68h, 69h, 70h, 71h, 72h, 75h, etc. The present application can obtain CrSbS3 with high purity and stable performance by appropriate heat treatment temperature and heat treatment time.

[0061] In an embodiment, the heating rate of the heat treatment is 2-4℃ / min, such as 2℃ / min, 2.5℃ / min, 3℃ / min, 3.5℃ / min, 4℃ / min, etc.

[0062] In another embodiment, the method for preparing CrSbS3 comprises: performing solid phase sintering on a mixture of elemental Cr, elemental Sb and elemental S under vacuum condition; the molar ratio of the elemental Cr, the elemental Sb and the elemental S is 1:1:3.

[0063] In an embodiment, the temperature of the solid phase sintering is 440-460℃ (such as 445℃, 450℃, 455℃, etc.), and the time of the solid phase sintering is 1.5-2.5h (such as 1.8h, 2h, 2.2h, etc.).

[0064] In an embodiment, the elemental Cr, the elemental Sb and the elemental S are ground before the solid phase sintering, and the grinding time is 50-70min (such as 55min, 60min, 65min, etc.).

[0065] In an embodiment, the solid phase sintering is performed under nitrogen condition.

[0066] In an embodiment, the heating rate of the solid phase sintering is 1-3℃ / min (such as 1.5℃ / min, 2℃ / min or 2.5℃ / min, etc.).

[0067] Specifically, in an embodiment, 0.052g of Cr powder, 0.121g of Sb powder and 0.096g of S powder are uniformly mixed by grinding for 1h, then sulfurized at 450℃ under N2 atmosphere for 2h with a heating rate of 2℃ / min, and finally washed with deionized water and ethanol by centrifugation for 3 times, and dried to obtain CrSbS3.

[0068] The material prepared by the above-mentioned solid phase sintering method is characterized as CrSbS3.

[0069] According to another aspect of the present application, the present application also relates to a negative electrode sheet comprising the negative electrode material or the negative electrode material prepared by the preparation method of the negative electrode material.

[0070] According to another aspect of the present application, the present application also relates to a sodium ion battery comprising the negative electrode sheet.

[0071] Reaction equation: According to the alloying mechanism of the negative electrode material (referring to the alloying reaction of the negative electrode material with sodium ions to provide capacity), 9 mol of electrons are transferred in the reaction of 1 mol of CrSbS3 with sodium ions, and according to the theoretical capacity calculation formula: 96485*n / (M*3.6), the theoretical specific capacity of CrSbS3 can be calculated as 893.35 mAh / g. -1 .

[0072] The following will be further explained in combination with specific examples and comparative examples.

[0073] Example 1

[0074] The preparation method of the negative electrode material comprises the following steps:

[0075] (1) 0.17 g of Sb2S3 and 0.10 g of Cr2S3 are mixed and ground uniformly, and then the mixture is placed in a glass tube and sealed; the glass tube is placed in an iron tube, and the iron tube is placed in a tube furnace, heated at 550℃ for 72 h, and the heating rate is 2℃ / min; after cooling to room temperature after heating is completed, the glass tube is taken out and exploded with pliers to obtain the powder CrSbS3;

[0076] (2) 0.1 g of CrSbS3 and 0.025 g of reduced graphene oxide are mixed and ground uniformly, and then placed in a planetary ball mill and ball milled at a speed of 400 r / min for 8 h to prepare the CrSbS3 / rGO negative electrode material.

[0077] Example 2

[0078] The preparation method of the negative electrode material comprises the following steps:

[0079] (1) 0.255 g of Sb2S3 and 0.15 g of Cr2S3 are mixed and ground uniformly, and then the mixture is placed in a glass tube and sealed; the glass tube is placed in an iron tube, and the iron tube is placed in a tube furnace, heated at 600℃ for 72 h, and the heating rate is 3℃ / min; after cooling to room temperature after heating is completed, the glass tube is taken out and exploded with pliers to obtain the powder CrSbS3;

[0080] (2) Take 0.1 g of CrSbS3 and 0.025 g of reduced graphene oxide, mix and grind uniformly, put into a planetary ball mill, and ball mill at a speed of 400 r / min for 8 h to prepare a CrSbS3 / rGO negative electrode material.

[0081] Example 3

[0082] The preparation method of the negative electrode material comprises the following steps:

[0083] (1) 0.17 g of Sb2S3 and 0.10 g of Cr2S3 are mixed and ground uniformly, and then the mixture of the two is placed in a glass tube and sealed. The glass tube is placed in an iron tube, and the iron tube is placed in a tube furnace. The temperature is raised to 650°C at a rate of 4°C / min and heated for 68 h. After cooling to room temperature, the glass tube is taken out and broken by pliers to obtain a powder of CrSbS3;

[0084] (2) Take 0.1 g of CrSbS3 and 0.025 g of reduced graphene oxide, mix and grind uniformly, put into a planetary ball mill, and ball mill at a speed of 400 r / min for 8 h to prepare a CrSbS3 / rGO negative electrode material.

[0085] Example 4

[0086] The preparation method of the negative electrode material comprises the following steps:

[0087] (1) 0.17 g of Sb2S3 and 0.10 g of Cr2S3 are mixed and ground uniformly, and then the mixture of the two is placed in a glass tube and sealed. The glass tube is placed in an iron tube, and the iron tube is placed in a tube furnace. The temperature is raised to 650°C at a rate of 4°C / min and heated for 68 h. After cooling to room temperature, the glass tube is taken out and broken by pliers to obtain a powder of CrSbS3;

[0088] (2) Take 0.1 g of CrSbS3 and 0.025 g of reduced graphene oxide, mix and grind uniformly, put into a planetary ball mill, and ball mill at a speed of 400 r / min for 8 h to prepare a CrSbS3 / rGO negative electrode material.

[0089] Example 5

[0090] The preparation method of the negative electrode material comprises the following steps:

[0091] (1) 0.17 g of Sb2S3 and 0.10 g of Cr2S3 are mixed and ground uniformly, and then the mixture of the two is placed in a glass tube and sealed. The glass tube is placed in an iron tube, and the iron tube is placed in a tube furnace. The temperature is raised to 650°C at a rate of 4°C / min and heated for 68 h. After cooling to room temperature, the glass tube is taken out and broken by pliers to obtain a powder of CrSbS3;

[0092] (2) Take 0.1 g of CrSbS3 and 0.025 g of reduced graphene oxide, mix and grind uniformly, put into a planetary ball mill, and ball mill at a speed of 500 r / min for 8 h to prepare a CrSbS3 / rGO negative electrode material.

[0093] Example 6

[0094] The preparation method of the negative electrode material comprises the following steps:

[0095] (1) 0.17 g of Sb2S3 and 0.10 g of Cr2S3 are mixed and ground uniformly, and then the mixture of the two is placed in a glass tube, sealed, and the glass tube is placed in an iron tube, which is then placed in a tube furnace, heated at 700℃ for 72 h, and the heating rate is 2℃ / min; after cooling to room temperature after heating is completed, the glass tube is taken out, and the powder CrSbS3 is obtained by clamping and exploding;

[0096] (2) Take 0.1 g of CrSbS3 and 0.025 g of reduced graphene oxide, mix and grind uniformly, put into a planetary ball mill, and ball mill at a speed of 500 r / min for 6 h to prepare a CrSbS3 / rGO negative electrode material.

[0097] Example 7

[0098] The preparation method of the negative electrode material is the same as that of Example 1, except that 0.085 g of CrSbS3 and 0.015 g of reduced graphene oxide are mixed and ground uniformly.

[0099] Example 8

[0100] The preparation method of the negative electrode material is the same as that of Example 1, except that 0.075 g of CrSbS3 and 0.025 g of reduced graphene oxide are mixed and ground uniformly.

[0101] Comparative Example 1

[0102] The preparation method of the negative electrode material is the same as that of Example 1, except that only 0.075 g of CrSbS3 is ground and put into a planetary ball mill and ball milled at a speed of 500 r / min for 6 h.

[0103] Comparative Example 2

[0104] The negative electrode material of this comparative example is the reduced graphene oxide in Example 1.

[0105] Experimental Example

[0106] The negative electrode materials of each example and comparative example are prepared into batteries respectively, and the specific preparation methods are as follows:

[0107] (1) The negative electrode material, the conductive agent (super-p) and the binder (sodium carboxymethyl cellulose) with a mass ratio of 80:10:10 are ground, uniformly mixed together, and an appropriate amount of deionized water is taken as a solvent by a needle tube, and the mixture is made into a slurry;

[0108] (2) The slurry is uniformly coated on a copper foil on a magnetic stirrer for 9h, and then the surface is dried, and finally the electrode sheet is dried in a vacuum oven at 80℃ overnight;

[0109] (3) The 2032 type button cell is prepared in an Ar-filled glove box, in addition, glass fiber is used as the separator material of the battery, a manually rolled sodium sheet is used as the counter electrode in the battery, and a reference electrode; the diameter of the prepared circular electrode sheet of the negative electrode material of the sodium ion battery is 14mm.

[0110] The performance of the above battery prepared from the negative electrode material of each example and comparative example is tested, and the results are shown in Table 1, Figure 1 and Figure 2 .

[0111] The negative electrode material CrSbS3 / rGO and CrSbS3 obtained in Example 1 are subjected to a 0.1A·g -1 cycle test by using a land battery test system, and the cycle data of Example 1 at 0.1A·g -1 are obtained. Figure 1 It can be found that the reversible capacity of CrSbS3 / rGO is about 800mAh·g -1 , and the coulombic efficiency of the subsequent cycle numbers is relatively stable and close to 100%; while the capacity of CrSbS3 attenuates greatly, and the coulombic efficiency presents a trend of first decreasing and then increasing, which also shows that the composite negative electrode material formed by adding an appropriate amount of rGO can buffer the volume expansion in the charge and discharge cycle process. Figure 2 The electrochemical impedance spectrograms of the negative electrode material CrSbS3 / rGO and CrSbS3 of Example 1 are given, and it can be found that the charge transfer impedance of the electrode of the composite negative electrode material formed by adding an appropriate amount of rGO is smaller, which shows that the CrSbS3 / rGO negative electrode material has more excellent conductivity.

[0112] Table 1 shows the first discharge capacity, capacity retention rate after 70 cycles and coulombic efficiency after 70 cycles of the battery prepared from the negative electrode material of each example and comparative example, and it can be known that the battery prepared from the negative electrode material of the application has high first discharge capacity, capacity retention rate after 70 cycles and coulombic efficiency after 70 cycles, wherein the first discharge capacity is 1172.6mAh·g -1and above, the capacity retention rate after 70 cycles (compared with the second discharge capacity) is 77.3% and above, and the coulombic efficiency after 70 cycles is 95.3% and above. Compared with CrSbS3 of Comparative Example 1, the negative electrode material of the present application can significantly improve the capacity retention rate after 70 cycles; compared with reduced graphene oxide of Comparative Example 2, the negative electrode material of the present application can significantly improve the first discharge capacity.

[0113] Table 1 test results

[0114]

[0115] In summary, the negative electrode material obtained by compounding CrSbS3 and reduced graphene oxide can improve the problem of limited capacity of the existing negative electrode material, has high first discharge capacity, and still has excellent stability and good fast charging and discharging capacity in the charging and discharging cycle process.

[0116] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit it; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A negative electrode material, characterized by, The negative electrode material comprises a composite of CrSbS3 and reduced graphene oxide; the mass content of the reduced graphene oxide in the negative electrode material is 15-25%; The preparation method of the negative electrode material comprises the following steps: ball-milling the mixture of CrSbS3 and reduced graphene oxide; The raw materials for preparing the CrSbS3 comprise Cr2S3 and Sb2S3; The preparation method of the CrSbS3 comprises: first grinding Cr2S3 and Sb2S3 to obtain a first mixture; and heat-treating the first mixture in a sealed environment; the heat-treating specifically comprises: placing the first mixture in a glass container, sealing the glass container; placing the sealed glass container in an iron container, and then placing the iron container in a heat-treating device; the temperature of the heat-treating is 550-700 DEG C, the time of the heat-treating is 65-75 h, and the heating rate of the heat-treating is 2-4 DEG C / min.

2. The negative electrode material according to claim 1, characterized in that, At least one of the following features (1) and (2) is included: (1) before the ball-milling, further comprising: grinding CrSbS3 and reduced graphene oxide; (2) the rotating speed of the ball-milling is 300-500 r / min, and the time of the ball-milling is 6-10 h.

3. The negative electrode material process according to claim 1, characterized in that, In the preparation method of the negative electrode material, the mass of the reduced graphene oxide is 15-25% of the total mass of the reduced graphene oxide and the CrSbS3.

4. The negative electrode material of claim 1, wherein, The mass ratio of the Cr2S3 and Sb2S3 is 1:1.

7.

5. A negative electrode sheet characterized by The negative electrode material of any one of claims 1-4 is included.

6. Sodium-ion battery, characterized in that, The negative electrode sheet of claim 5 is included.

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