A sulfur-oxygen co-doped sodium-ion battery negative electrode material, a preparation method thereof, and a negative electrode sheet and a battery comprising the negative electrode material

Abstract

The present disclosure relates to a kind of sodium-ion battery negative electrode material of sulfur-oxygen co-doped and its preparation method and the negative electrode sheet and battery comprising its negative electrode material, the method comprises the following steps: S1: the precursor containing sulfur element is carried out pre-oxidation treatment in air atmosphere, obtains pre-oxidized precursor;S2: the pre-oxidized precursor is carried out calcination treatment;The pre-oxidation treatment condition in S1 includes: temperature is 150~350 ℃, time is 12~48 h;The calcination treatment condition in S2 includes: calcination temperature is 600~900 ℃, calcination time is 1~6 h;The precursor containing sulfur element includes sulfonated lignin.The method of the present disclosure is simple to operate, and the production cost is low, the negative electrode material prepared is amorphous carbon doped with sulfur and oxygen, which can effectively improve the reversible capacity of the battery, and has a high specific capacity at high rate 10C (3A / g).

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of sodium ion battery negative electrode materials, in particular, to a sodium ion battery negative electrode material co-doped with sulfur and oxygen, a preparation method thereof, and a negative electrode sheet and a battery comprising the negative electrode material. BACKGROUND

[0002] Compared with lithium ion batteries, sodium ion batteries have more abundant resources, and sodium and lithium are elements in the same group, which has low development cost. Sodium ion batteries also have higher capacity and better rate performance, and thus are more suitable for large-scale energy storage. The electrochemical performance of sodium ion batteries is mainly limited by the development of electrode materials, and therefore, reasonable design of the structure of electrode materials has become a research hotspot.

[0003] Carbon materials are often used as negative electrode materials for secondary batteries. Since the radius of sodium is larger than that of lithium, traditional graphite-based negative electrodes cannot achieve reversible deintercalation of sodium ions, and therefore, finding suitable negative electrode materials for sodium ion deintercalation is a key to improving the performance of sodium ion batteries. Hard carbon material is a carbon material that is difficult to graphitize, has short-range order and long-range disorder of carbon layer arrangement, and has a large interlayer spacing in the ordered carbon layer, which can achieve reversible deintercalation of sodium ions. In addition, the hard carbon material has abundant nanopores and defect structures, which can provide storage sites for sodium ions. In the prior art, biomass-based materials are often compounded with other materials to prepare sodium ion battery negative electrode materials, which is complex and costly.

[0004] Biomass-based carbon materials have the advantages of wide source and low price, but have defects such as poor rate performance and low capacity, and therefore, it is urgent to develop a simple and easy-to-operate preparation method to improve the rate performance of sodium ion batteries. SUMMARY

[0005] The purpose of the present disclosure is to provide a sodium ion battery negative electrode material co-doped with sulfur and oxygen, a preparation method thereof, and a negative electrode sheet and a battery comprising the negative electrode material. The raw material components of the sodium ion battery negative electrode material are widely available and low in price, which can effectively reduce the cost of the product. The negative electrode material can be used in sodium ion batteries, and can effectively improve the reversible capacity of the battery.

[0006] To achieve the above-mentioned purpose, the first aspect of the present disclosure provides a method for preparing a sodium ion battery negative electrode material co-doped with sulfur and oxygen, which comprises the following steps:

[0007] S1: pre-oxidizing a precursor containing sulfur elements in an air atmosphere to obtain a pre-oxidized precursor;

[0008] S2: calcining the pre-oxidized precursor;

[0009] The pre-oxidation conditions in S1 include a temperature of 150-350℃ and a time of 12-48h.

[0010] The conditions of the calcination treatment in S2 include: a calcination temperature of 600-900℃, and a calcination time of 1-6h.

[0011] The precursor containing sulfur element includes sulfonated lignin.

[0012] Optionally, the sulfonated lignin is selected from one or more of sodium lignosulfonate, calcium lignosulfonate, and magnesium lignosulfonate.

[0013] Optionally, the conditions of the pre-oxidation treatment in S1 include: a temperature of 200-300℃, and a time of 24-30h.

[0014] Optionally, the conditions of the calcination treatment in S2 include: a calcination temperature of 650-850℃, and a calcination time of 2-4h.

[0015] The calcination treatment is performed under an inert atmosphere; the inert atmosphere includes one or more of nitrogen, helium, and argon; the inert atmosphere flow rate is 50-300mL / min, preferably 50-150mL / min.

[0016] Optionally, the method further includes: performing acid washing, water washing, and drying treatment on the product after the calcination treatment in S2.

[0017] The acid washing includes mixing the product after the calcination treatment in S2 with inorganic acid; the inorganic acid is selected from one of hydrochloric acid, sulfuric acid, and acetic acid; the concentration of the inorganic acid is 1-12mol / L, preferably 4-12mol / L.

[0018] The second aspect of the present disclosure provides a sulfur-oxygen co-doped sodium-ion battery negative electrode material prepared by the method of the first aspect of the present disclosure.

[0019] The third aspect of the present disclosure provides a sulfur-oxygen co-doped sodium-ion battery negative electrode material, wherein, based on the weight of the negative electrode material, the weight content of sulfur element is 1-8wt%, the weight content of oxygen element is 4-15wt%, and the weight content of carbon element is 80-95wt%; in the Raman spectrum of the sodium-ion battery negative electrode material, the ratio of I D / I G is above 1.5; the carbon element exists in the form of amorphous carbon.

[0020] Optionally, based on the weight of the negative electrode material, the weight content of sulfur element is 5-8wt%, the weight content of oxygen element is 5-13wt%, and the weight content of carbon element is 82-90wt%.

[0021] In the XPS S2p spectrum of the sodium ion battery negative electrode material, characteristic peaks exist at 168-170 eV, 164-166 eV and 162-164 eV, respectively.

[0022] In the XPS O1s spectrum of the sodium ion battery negative electrode material, characteristic peaks exist at 533-535 eV, 532-534 eV and 530-532 eV, respectively.

[0023] The fourth aspect of the present disclosure provides a sodium ion battery negative electrode sheet, which comprises a current collector, a binder and the negative electrode material of the third aspect of the present disclosure.

[0024] The fifth aspect of the present disclosure provides a sodium ion battery, which comprises the negative electrode sheet of the fourth aspect of the present disclosure, a positive electrode, an electrolyte and a separator between the positive electrode and the negative electrode sheet.

[0025] The positive electrode is one of sodium manganate, sodium cobaltate, sodium vanadium phosphate or sodium iron phosphate.

[0026] Through the above technical solution, the method of the present disclosure introduces sulfur and oxygen atom co-doping into the negative electrode material by pre-oxidizing and calcining the biomass precursor, increases the carbon layer spacing, forms more defects and active sites, thereby providing more reversible storage sites for sodium ions. The method of the present disclosure is simple to operate, the prepared negative electrode material is amorphous carbon doped with sulfur and oxygen, can effectively improve the reversible capacity of the battery, improve the rate performance of the battery, and has a high specific capacity at a high rate of 10C (3A / g).

[0027] Other features and advantages of the present disclosure will be described in detail in the following specific embodiments section. BRIEF DESCRIPTION OF DRAWINGS

[0028] The accompanying drawings are included to provide a further understanding of the present disclosure and constitute a part of the specification, and are used together with the following specific embodiments to explain the present disclosure, but do not constitute a limitation on the present disclosure. In the drawings:

[0029] Figure 1 The figure is the charge-discharge curve of the sodium ion battery of Example 1 of the present disclosure for the first three weeks.

[0030] Figure 2 The figure is the S2p element narrow spectrum of the XPS test of the negative electrode material prepared in Example 1 of the present disclosure.

[0031] Figure 3 The figure is the O1s element narrow spectrum of the XPS test of the negative electrode material prepared in Example 1 of the present disclosure.

[0032] Figure 4 The figure is the XRD spectrum of the negative electrode material prepared in Example 1 of the present disclosure. DETAILED DESCRIPTION

[0033] The specific embodiments of the present disclosure are described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely intended to illustrate and explain the present disclosure, and are not intended to limit the present disclosure.

[0034] The first aspect of the present disclosure provides a method for preparing a sodium-ion battery negative electrode material co-doped with sulfur and oxygen, the method comprising the following steps:

[0035] S1: pre-oxidizing a sulfur element-containing precursor in an air atmosphere to obtain a pre-oxidized precursor;

[0036] S2: performing a calcination treatment on the pre-oxidized precursor;

[0037] The pre-oxidation treatment in S1 includes a temperature of 150-350℃ and a time of 12-48h;

[0038] The calcination treatment in S2 includes a calcination temperature of 600-900℃ and a calcination time of 1-6h;

[0039] The sulfur element-containing precursor includes sulfonated lignin.

[0040] The method of the present disclosure increases the carbon layer spacing by introducing co-doping of sulfur and oxygen atoms in the negative electrode material, forms more defects and active sites, thereby providing more reversible storage sites for sodium ions. The method of the present disclosure is simple to operate, and the prepared negative electrode material is amorphous carbon doped with sulfur and oxygen, which can effectively improve the reversible capacity of the battery and improve the rate performance of the battery, and has a high specific capacity at a high rate of 10C (3A / g).

[0041] According to an embodiment of the present disclosure, the sulfonated lignin is selected from one or more of sodium lignosulfonate, calcium lignosulfonate and magnesium lignosulfonate. The present application uses a widely available and low-cost biomass precursor, making the method simple, easy to operate, and having high practical value, and is also conducive to the prepared negative electrode material having a large number of defects, further improving the reversible capacity and rate performance of the battery.

[0042] According to an embodiment of the present disclosure, the pre-oxidation treatment in S1 includes a temperature of 200-300℃ and a time of 24-30h. The above embodiment is conducive to increasing the carbon layer spacing, and is also conducive to the oxygen content in the precursor being in an appropriate range, so that the biomass precursor achieves a good oxidation degree, further improving the reversible capacity of the battery.

[0043] According to an embodiment of the present disclosure, the conditions of the calcination treatment in S2 include: the calcination temperature is 650-850℃; the calcination time is 2-4h; the calcination treatment is carried out under an inert atmosphere; the inert atmosphere includes one or more of nitrogen, helium and argon; the flow rate of the inert atmosphere is 50-300mL / min, preferably 50-150mL / min. The above-mentioned embodiment is conducive to forming a large number of defects and active sites, and is conducive to keeping the sulfur content in the negative electrode material in an appropriate range, and further improving the reversible sodium storage capacity of the battery.

[0044] According to an embodiment of the present disclosure, the product after the calcination treatment in S2 is subjected to acid washing, water washing and drying treatment; in a further embodiment, the acid washing includes mixing the product after the calcination treatment in S2 with an inorganic acid; the inorganic acid is selected from one of hydrochloric acid, sulfuric acid and acetic acid; the concentration of the inorganic acid is 1-12mol / L, preferably 4-12mol / L; the water washing includes washing the product after the acid washing with water until the pH of the filtrate is 6.5-7.5, and then filtering. The drying conditions include: the temperature can be 80-120℃, preferably 90-120℃; the time can be 20-26h, preferably 22-26h. The drying device can be a conventional drying device in the art, for example, it can be a forced air drying oven. The above-mentioned embodiment is conducive to removing impurity metal ions in the negative electrode material.

[0045] The second aspect of the present disclosure provides a sulfur-oxygen co-doped negative electrode material for sodium ion batteries prepared by the method of the first aspect of the present disclosure.

[0046] The third aspect of the present disclosure provides a sulfur-oxygen co-doped negative electrode material for sodium ion batteries, wherein the weight content of sulfur is 1-8wt%, the weight content of oxygen is 4-15wt%, and the weight content of carbon is 80-95wt%, based on the weight of the negative electrode material; in the Raman spectrum of the negative electrode material for sodium ion batteries, the ratio of I D / I G is above 1.5; and the carbon element exists in the form of amorphous carbon. The I D is the intensity of the D peak, and I G is the intensity of the G peak.

[0047] According to an embodiment of the present disclosure, in the XPS S2p spectrum of the negative electrode material for sodium ion batteries, characteristic peaks exist at 168-170eV, 164-166eV and 162-164eV, respectively, indicating the existence of thiophene-type sulfur and oxidized sulfur.

[0048] In the XPS O1 SIn the spectrum, characteristic peaks exist at 533-535 eV, 532-534 eV and 530-532 eV, respectively. The characteristic peak at 530-532 eV is attributed to inorganic C=O bond, the characteristic peak at 532-534 eV is attributed to organic C=O bond, and the characteristic peak at 533-535 eV is attributed to C-O bond. The content of C-O bond is low, and the content of C=O bond is high, indicating that C-O gradually transforms into C=O bond in the oxidation process, and more oxygen elements are fixed in the negative electrode material in the form of C=O.

[0049] According to an embodiment of the present disclosure, the weight content of the sulfur element is 5-8 wt%, the weight content of the oxygen element is 5-13 wt%, and the weight content of the carbon element is 82-90 wt% based on the weight of the negative electrode material. The above preferred implementation range is beneficial to obtain the negative electrode material with a large amount of amorphous carbon with defect concentration, further improve the adsorption capacity of the battery, and improve the reversible sodium storage capacity and rate performance of the battery.

[0050] According to an embodiment of the present disclosure, the pre-oxidation temperature is 200-300°C, and the pre-oxidation time is 24-30 h; the calcination temperature is 650-850°C, and the calcination time is 2-4 h. In the Raman spectrum of the sodium ion battery negative electrode material, the ratio of I D / I G is greater than 1.7. The above embodiment indicates that the negative electrode material of the present application has a large amount of amorphous carbon with defect concentration, further improves the adsorption capacity of the battery, and improves the reversible sodium storage capacity and rate performance of the battery.

[0051] According to an embodiment of the present disclosure, in the XRD spectrum of the sodium ion battery negative electrode material, characteristic peaks exist between 20-25° and 40-45° at 2θ, and the carbon layer spacing is 0.38-0.41 nm.

[0052] According to an embodiment of the present disclosure, in the charge-discharge curve of the sodium ion battery negative electrode material, the charge and discharge curves of the sodium ion battery negative electrode material only have slopes, indicating that the negative electrode material of the present application is amorphous carbon.

[0053] The fourth aspect of the present disclosure provides a sodium ion battery negative electrode sheet, which comprises a current collector, a binder and the negative electrode material of the third aspect of the present disclosure.

[0054] The fifth aspect of the present disclosure provides a sodium ion battery, which comprises the negative electrode sheet of the fourth aspect of the present disclosure, a positive electrode, an electrolyte and a separator between the positive electrode and the negative electrode sheet.

[0055] The positive electrode is one of sodium manganate, sodium cobaltate, sodium vanadium phosphate or sodium iron phosphate.

[0056] According to one embodiment of the present disclosure, the electrolyte can be a conventional electrolyte in the art, for example, the electrolyte salt can be one of sodium hexafluorophosphate, sodium perchlorate, sodium bis(trifluoromethanesulfonyl)imide or sodium bis(fluorosulfonyl)imide, and the electrolyte solvent can be one or more of ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), ethylene glycol dimethyl ether (DME), diethylene glycol dimethyl ether (DEGDME) and methyl ethyl carbonate (EMC); the separator can be a conventional separator in the art, for example, can be one of a glass fiber separator or a polyolefin porous membrane.

[0057] The present disclosure will be further illustrated by the following examples, but the present disclosure is not limited in any way by the following examples.

[0058] In the following examples of the present disclosure, the X-ray scanning diffractometer (XRD) used is a model X-ray powder diffractometer of Philips Company, USA, the method is to use Cu target anode Kα radiation source, step width 0.02°, scanning speed 2° / min, 2θ=10°-80°.

[0059] Raman spectrum (Raman) is performed on a benchtop Raman spectrometer of model Advantage 532;

[0060] XPS is performed on an instrument of model Thermo Fisher Thermo ESCALAB 250;

[0061] The electrochemical performance test is performed on an instrument of model CT3001A1U-5V 5mA of Wuhan Lan Electric Company;

[0062] Sodium lignosulfonate and lignin are products of Innochem brand of Beijing Innochem Technology Co., Ltd.

[0063] The electrolyte is a sodium ion battery special electrolyte purchased from Suzhou Duoduo Reagent Co., Ltd.

[0064] The binder is a product of Innochem brand of Beijing Innochem Technology Co., Ltd.

[0065] The raw materials and reagents used in the following examples and comparative examples are battery grade;

[0066] Unless otherwise specified, the chemical reagents used in the following examples and comparative examples are commercially available products.

[0067] Example 1

[0068] (1) Take 10 g of sodium lignosulfonate and evenly place it in a corundum boat, put it in a muffle furnace, pre-oxidize at 250°C for 24 h under air atmosphere, and obtain a pre-oxidized precursor, denoted as LNa250.

[0069] (2) Take the pre-oxidized precursor above and evenly place it in a corundum boat, put it in a tube furnace, and after purging with nitrogen, calcine at 800°C for 2 h to obtain an amorphous carbon material with sulfur-oxygen co-doping, denoted as LNa250-800.

[0070] (3) Preparation of sodium ion battery negative electrode sheet. According to the mass ratio of 9:1, take the sodium ion battery negative material and 20% sodium alginate binder above, and stir under magnetic stirring for 6 h. After the sodium ion battery negative material and sodium alginate binder are fully mixed, use a scraper to coat it on a copper foil with a thickness of 150 μm. The coated copper foil is placed in a 80°C air drying oven for 12 h, and then the coated copper foil is cut into a 12 mm diameter electrode sheet using a sheet punching machine. Select the electrode sheet with uniform coating and similar mass to obtain the sodium ion battery negative electrode. The sodium alginate binder is first placed in a 25*25 mm weighing bottle, and then an appropriate amount of deionized water is added. Stir the sodium alginate and deionized water into a uniform gel-like solution under magnetic stirring.

[0071] (4) Assembly of sodium ion half-battery. Use metal sodium as the counter electrode, 1 mol / L NaPF6-DEGDME as the electrolyte, and the above sodium ion negative electrode sheet as the working electrode. The battery separator is Whatman GF / D glass fiber separator. Assemble the CR2032 experimental button symmetrical battery in an argon-filled glove box to evaluate the electrochemical performance of the above sodium ion battery negative material.

[0072] Example 2

[0073] (1) Take 10 g of sodium lignosulfonate and evenly place it in a corundum boat, put it in a muffle furnace, pre-oxidize at 200°C for 24 h under air atmosphere, and obtain a pre-oxidized precursor, denoted as LNa200.

[0074] (2) Take the pre-oxidized precursor above and evenly place it in a corundum boat, put it in a tube furnace, and after purging with nitrogen, calcine at 800°C for 2 h to obtain an amorphous carbon material with sulfur-oxygen co-doping, denoted as LNa200-800.

[0075] Preparation of sodium ion battery negative electrode sheet and assembly of sodium ion half-battery are the same as in Example 1.

[0076] Example 3

[0077] (1) Take 10 g of sodium lignosulfonate and evenly place it in a corundum boat, and place it in a muffle furnace. Under an air atmosphere, pre-oxidize it at a temperature of 300°C for 24 h. Obtain the pre-oxidized precursor, denoted as LNa300.

[0078] (2) Take the pre-oxidized precursor described above and evenly place it in a corundum boat, and place it in a tube furnace. After purging with nitrogen, calcine it at a temperature of 800°C for 2 h to obtain an amorphous carbon material with sulfur-oxygen co-doping, denoted as LNa300-800.

[0079] The preparation of the sodium-ion battery negative electrode sheet and the assembly of the sodium-ion half battery are the same as in Example 1.

[0080] Example 4

[0081] (1) Take 10 g of sodium lignosulfonate and evenly place it in a corundum boat, and place it in a muffle furnace. Under an air atmosphere, pre-oxidize it at a temperature of 250°C for 36 h to obtain the pre-oxidized precursor.

[0082] (2) Take the pre-oxidized precursor described above and evenly place it in a corundum boat, and place it in a tube furnace. After purging with nitrogen, calcine it at a temperature of 800°C for 2 h to obtain an amorphous carbon material with sulfur-oxygen co-doping.

[0083] The preparation of the sodium-ion battery negative electrode sheet and the assembly of the sodium-ion half battery are the same as in Example 1.

[0084] Example 5

[0085] (1) Take 10 g of sodium lignosulfonate and evenly place it in a corundum boat, and place it in a muffle furnace. Under an air atmosphere, pre-oxidize it at a temperature of 150°C for 24 h to obtain the pre-oxidized precursor, denoted as LNa150.

[0086] (2) Take the pre-oxidized precursor described above and evenly place it in a corundum boat, and place it in a tube furnace. After purging with nitrogen, calcine it at a temperature of 800°C for 2 h to obtain an amorphous carbon material with sulfur-oxygen co-doping, denoted as LNa150-800.

[0087] Example 6

[0088] (1) Take 10 g of sodium lignosulfonate and evenly place it in a corundum boat, and place it in a muffle furnace. Under an air atmosphere, pre-oxidize it at a temperature of 250°C for 24 h to obtain the pre-oxidized precursor.

[0089] (2) Take the pre-oxidized precursor described above and evenly place it in a corundum boat, and place it in a tube furnace. After purging with nitrogen, calcine it at a temperature of 900°C for 2 h to obtain an amorphous carbon material with sulfur-oxygen co-doping.

[0090] The preparation of the sodium-ion battery negative electrode sheet and the assembly of the sodium-ion half battery are the same as in Example 1.

[0091] Example 7

[0092] (1) Take 10 g of sodium lignosulfonate and evenly place it in a corundum boat, and place it in a muffle furnace. Under an air atmosphere, pre-oxidize it at a temperature of 250°C for 24 h to obtain a pre-oxidized precursor.

[0093] (2) Take the pre-oxidized precursor described above and evenly place it in a corundum boat, and place it in a tube furnace. After passing in nitrogen, calcine it at a temperature of 800°C for 5 h to obtain an amorphous carbon material with sulfur-oxygen co-doping.

[0094] The preparation of the sodium-ion battery negative electrode sheet and the assembly of the sodium-ion half battery are the same as in Example 1.

[0095] Comparative Example 1

[0096] (1) Take 10 g of lignin and evenly place it in a corundum boat, and place it in a muffle furnace. Under an air atmosphere, pre-oxidize it at a temperature of 250°C for 24 h to obtain a pre-oxidized precursor, which is denoted as L250.

[0097] (2) Take the pre-oxidized precursor described above and evenly place it in a corundum boat, and place it in a tube furnace. After passing in nitrogen, calcine it at a temperature of 800°C for 2 h to obtain an amorphous carbon material, which is denoted as L250-800.

[0098] The preparation of the sodium-ion battery negative electrode sheet and the assembly of the sodium-ion half battery are the same as in Example 1.

[0099] Comparative Example 2

[0100] (1) Take 10 g of lignin and evenly place it in a corundum boat, and place it in a tube furnace. After passing in nitrogen, set a staged calcination program, and calcine it at a temperature of 250°C for 24 h. Then, raise the temperature to 800°C and calcine it for another 2 h to obtain an amorphous carbon material, which is denoted as D250-800.

[0101] The preparation of the sodium-ion battery negative electrode sheet and the assembly of the sodium-ion half battery are the same as in Example 1.

[0102] Comparative Example 3

[0103] (1) Take 10 g of sodium lignosulfonate and evenly place it in a corundum boat, and place it in a tube furnace. After passing in nitrogen, set a staged calcination program, and calcine it at a temperature of 250°C for 24 h. Then, raise the temperature to 800°C and calcine it for another 2 h to obtain an amorphous carbon material, which is denoted as DNa250-800.

[0104] The preparation of the sodium-ion battery negative electrode sheet and the assembly of the sodium-ion half battery are the same as in Example 1.

[0105] Comparative Example 4

[0106] (1) Take 10 g of lignin and 5 g of thiourea, evenly place in corundum boat, put in muffle furnace, pre-oxidize at 250°C for 24 h under air atmosphere, obtain pre-oxidized precursor, recorded as LNa250.

[0107] (2) Take the pre-oxidized precursor above, evenly place in corundum boat, put in tube furnace, after nitrogen is introduced, calcine at 800°C for 2 h, obtain amorphous carbon material.

[0108] The preparation of the negative electrode sheet of the sodium ion battery and the assembly of the sodium ion half battery are the same as in Example 1.

[0109] Comparative Example 5

[0110] (1) Take 10 g of sodium lignosulfonate, evenly place in corundum boat, put in muffle furnace, pre-oxidize at 100°C for 24 h under air atmosphere, obtain pre-oxidized precursor, recorded as LNa100.

[0111] (2) Take the pre-oxidized precursor above, evenly place in corundum boat, put in tube furnace, after nitrogen is introduced, calcine at 800°C for 2 h, obtain amorphous carbon material, recorded as LNa100-800.

[0112] The preparation of the negative electrode sheet of the sodium ion battery and the assembly of the sodium ion half battery are the same as in Example 1.

[0113] Comparative Example 6

[0114] (1) Take 10 g of sodium lignosulfonate, evenly place in corundum boat, put in tube furnace, after nitrogen is introduced, calcine at 800°C for 2 h, obtain amorphous carbon material.

[0115] The preparation of the negative electrode sheet of the sodium ion battery and the assembly of the sodium ion half battery are the same as in Example 1.

[0116] Test Example 1

[0117] The negative electrode materials obtained in Examples 1-7 and Comparative Examples 1-6 are subjected to XPS, elemental analysis and Raman spectrum tests, and the test results are shown in Table 1.

[0118] Table 1

[0119] Carbon content (wt%) Sulfur content (wt%) Oxygen content (wt%) I D / I G ]]> Example 1 83.96 6.62 9.42 2.65 Example 2 82.48 5.28 12.24 1.71 Example 3 85.63 5.23 9.14 1.85 Example 4 84.45 1.02 14.53 1.95 Example 5 94.21 1.17 4.62 1.57 Example 6 89.25 3.37 9.38 1.89 Example 7 92.28 3.35 6.37 1.51 Comparative Example 1 92.54 0.23 7.23 1.75 Comparative Example 2 99.43 0.08 0.49 1.08 Comparative Example 3 98.56 1.12 0.32 1.62 Comparative Example 4 90.2 2.02 7.78 1.92 Comparative Example 5 89.92 1.25 8.83 1.76 Comparative Example 6 93.12 0.51 6.37 1.05

[0120] According to the data in Table 1, the weight content of oxygen element in the negative electrode material prepared by the method of the present disclosure is between 4-15wt%, the weight content of sulfur element is between 1-8wt%, and the weight content of carbon element is 80-95wt%. According to the comparison between Example 1 and Example 4, within the preferred pre-oxidation time range of the present disclosure, the content of oxygen element in the obtained negative electrode material is 5-13wt%, and the rate performance of the obtained negative electrode material is better. According to the comparison between Example 1 and Example 5, within the preferred pre-oxidation temperature range of the present disclosure, the content of oxygen element in the obtained negative electrode material is 5-13wt%, and the rate performance of the obtained negative electrode material is better. According to the comparison between Example 1 and Example 6, within the preferred calcination temperature range of the present disclosure, the content of sulfur element in the obtained negative electrode material is 5-8wt%, and the rate performance of the obtained negative electrode material is better. According to the comparison between Example 1 and Example 7, within the preferred calcination time range of the present disclosure, the content of sulfur element in the obtained negative electrode material is 5-8wt%, and the rate performance of the obtained negative electrode material is better.

[0121] Test Example 2

[0122] The battery pieces of Examples 1-7 and Comparative Examples 1-6 were tested for electrochemical performance, and the specific test conditions were constant current charge and discharge at 0.1C (1C=300mAg -1 ) rate, with a cutoff voltage range of 0.01V-3V. The test results are shown in Table 2.

[0123] Table 2

[0124]

[0125]

[0126] According to the data in Table 3, the preparation method of the present disclosure is simple, has strong operability, and has low production cost. The negative electrode material prepared by the method of the present disclosure has high initial discharge specific capacity and high first-week coulombic efficiency, and also has high specific capacity at 10C. According to the comparison between Example 1 and Example 4, within the preferred pre-oxidation time range of the present disclosure, the rate performance of the obtained negative electrode material is better. According to the comparison between Example 1 and Example 5, within the preferred pre-oxidation temperature range of the present disclosure, the rate performance of the obtained negative electrode material is better. According to the comparison between Example 1 and Example 6, within the preferred calcination temperature range of the present disclosure, the rate performance of the obtained negative electrode material is better. According to the comparison between Example 1 and Example 7, within the preferred calcination time range of the present disclosure, the rate performance of the obtained negative electrode material is better.

[0127] The preferred embodiments of the present disclosure are described in detail above with reference to the drawings, but the present disclosure is not limited to the specific details in the above-described embodiments. Various simple modifications can be made to the technical solutions of the present disclosure within the technical concept of the present disclosure, and these simple modifications all belong to the protection scope of the present disclosure.

[0128] In addition, it should be noted that each specific technical feature described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, various possible combinations are not described again in the present disclosure.

[0129] In addition, various different embodiments of the present disclosure can also be combined in any appropriate manner, as long as they do not deviate from the idea of the present disclosure, and they should also be considered as disclosed by the present disclosure.

Claims

1. A method of preparing a sodium-ion battery anode material co-doped with sulfur and oxygen, characterized in that, The method comprises the following steps: S1: pre-oxidizing a precursor containing sulfur elements in an air atmosphere to obtain a pre-oxidized precursor; S2: calcining the pre-oxidized precursor; The pre-oxidizing in S1 is performed at a temperature of 150-350°C for 12-48h; The calcining in S2 is performed at a temperature of 600-900°C for 1-6h; The precursor containing sulfur elements comprises sulfonated lignin.

2. The method of claim 1, wherein, The sulfonated lignin is selected from one or more of sodium lignosulfonate, calcium lignosulfonate and magnesium lignosulfonate.

3. The method of claim 1, wherein, The pre-oxidizing in S1 is performed at a temperature of 200-300°C for 24-30h.

4. The method of claim 1, wherein, The calcining in S2 is performed at a temperature of 650-850°C for 2-4h; The calcining is performed in an inert atmosphere; the inert atmosphere comprises one or more of nitrogen, helium and argon; the inert atmosphere has a flow rate of 50-300mL / min.

5. The method of claim 4, wherein, The inert atmosphere has a flow rate of 50-150mL / min.

6. The method of claim 1, wherein, The method further comprises: performing acid washing, water washing and drying on the product after the calcining in S2; The acid washing comprises mixing the product after the calcining in S2 with an inorganic acid; the inorganic acid is selected from one of hydrochloric acid, sulfuric acid and acetic acid; the inorganic acid has a concentration of 1-12mol / L.

7. The method of claim 6, wherein, The inorganic acid has a concentration of 4-12mol / L.

8. The sulfur-oxygen co-doped sodium-ion battery anode material prepared by the method in any one of claims 1-7.

9. The sodium-ion battery anode material of claim 8, wherein, The weight content of the sulfur element is 1-8wt%, the weight content of the oxygen element is 4-15wt%, and the weight content of the carbon element is 80-95wt%, based on the weight of the anode material; In the Raman spectrum of the sodium ion battery negative electrode material, the ratio of I D / I G is above 1.5; the carbon element exists in the form of amorphous carbon.

10. The sodium-ion battery anode material of claim 9, wherein, The weight content of the sulfur element is 5-8wt%, the weight content of the oxygen element is 5-13wt%, and the weight content of the carbon element is 82-90wt%, based on the weight of the anode material; In the XPS S2p spectrum of the sodium-ion battery anode material, characteristic peaks exist at 168-170eV, 164-166eV and 162-164eV, respectively; In the XPS O1s spectrum of the sodium-ion battery anode material, characteristic peaks exist at 533-535eV, 532-534eV and 530-532eV, respectively.

11. A sodium-ion battery negative electrode sheet, characterized by, The anode sheet comprises a current collector, a binder and the battery anode material in any one of claims 8-10.

12. A sodium-ion battery, characterized in that, The anode sheet, a cathode, an electrolyte and a separator between the cathode and the anode sheet in claim 11 are included. The cathode is one of sodium manganate, sodium cobaltate, sodium vanadium phosphate or sodium iron phosphate.

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