Sodium ion battery negative electrode material, preparation method and application thereof

Abstract

The application relates to a sodium ion battery negative electrode material and a preparation method and application thereof, and belongs to the technical field of sodium ion batteries. The sodium ion battery negative electrode material comprises sodium titanate and a composite coating layer coated on the surface of the sodium titanate, and the composite coating layer comprises titanium carbide and carbon; the mass ratio of the sodium titanate, the titanium carbide and the carbon is (70-90):(5-15):(2-10). Through the compounding of the sodium titanate and the composite coating layer (titanium carbide and carbon), the conductivity is significantly improved, the 10C capacity retention rate is increased from 30% to 70%, and the coulomb efficiency is increased from 65% to 95%.

Description

Technical Field

[0001] This invention belongs to the field of sodium-ion battery technology, and particularly relates to a sodium-ion battery anode material, its preparation method, and its application. Background Technology

[0002] Sodium-ion batteries, with their significant advantages such as abundant and widely distributed sodium resources and low cost, have shown great application potential in large-scale energy storage and have become one of the hot research directions in energy storage. The performance of a battery largely depends on its core components, among which the anode material, as a key factor affecting the energy density, cycle life, and safety of sodium-ion batteries, has always been a focus of research. Currently, a wide variety of sodium-ion battery anode materials have been developed, mainly including carbon-based materials, titanium-based compounds, metal oxides, and metal carbides. Among these materials, sodium titanate (Na2Ti3O7) and metal carbides (such as TiC and Mo2C) have become two promising candidate materials due to their unique sodium storage mechanisms and performance characteristics.

[0003] Sodium titanate (Na₂Ti₃O₇) offers numerous advantages as a negative electrode material for sodium-ion batteries. Its unique layered structure facilitates the reversible insertion and extraction of sodium ions, with a volume change of less than 3% during charge and discharge, enabling batteries to achieve cycle lives exceeding 1000 cycles. Furthermore, sodium titanate exhibits good thermal stability and high safety, making it ideal for large-scale applications. In addition, titanium resources are abundant in nature, and the synthesis process of sodium titanate is relatively simple, including solid-state and sol-gel methods, resulting in low production costs. Moreover, sodium titanate also features a low operating voltage (~0.3V vs. Na₂Ti₃O₇). + The properties of sodium titanate (Na) effectively prevent the formation of sodium dendrites, further enhancing battery safety. Moreover, it is non-toxic, harmless, and easily recyclable. However, sodium titanate also has significant disadvantages; its electrical conductivity is poor, with an electronic conductivity of approximately 10⁻⁶. -9 To improve its conductivity, sodium titanate typically requires carbon coating or composite conductive materials, which undoubtedly increases the complexity of the manufacturing process. Meanwhile, sodium titanate has a low specific capacity, theoretically around 200 mAh / g, but in practical applications it often only reaches 150-180 mAh / g. Furthermore, its rate performance is limited; capacity decays significantly at high current densities, and its fast-charging performance is poor, all of which restrict its applications to some extent.

[0004] Metal carbides (such as TiC and Mo2C) also have certain advantages as anode materials for sodium-ion batteries. They possess high electrical conductivity, with electronic conductivity reaching 10⁻⁶. 2 S / cm-10 3 S / cm, for example, the electronic conductivity of TiC is 10.3 The S / cm ratio eliminates the need for additional conductive agents during battery fabrication, thus improving rate performance. Metal carbides exhibit diverse sodium storage mechanisms, including intercalation and conversion reactions, resulting in high theoretical capacities. For example, Mo2C has a theoretical specific capacity of 400 mAh / g-600 mAh / g, with experimental values ​​reaching 300 mAh / g-400 mAh / g. Furthermore, surface defects and interlayer channels provide abundant active sites, making them suitable for high-energy-density applications. However, metal carbides also have significant drawbacks. Their cycle stability is poor, with dramatic volume expansion during conversion reactions (e.g., TiC's volume change exceeds 100%) leading to particle pulverization and rapid capacity decay, potentially decreasing by more than 50% after cycling. Simultaneously, surface active sites accelerate electrolyte decomposition, resulting in an excessively thick SEI film, low coulombic efficiency, and initial efficiency often below 70%. Additionally, conversion reactions cause asymmetric charge-discharge curves and voltage hysteresis, further reducing energy efficiency.

[0005] Based on the above reasons, this application is hereby submitted. Summary of the Invention

[0006] Therefore, the technical problem to be solved by the present invention is to overcome the problems of low specific capacity and low rate performance of the anode material in the prior art.

[0007] To address the aforementioned technical problems, this invention provides a sodium-ion battery anode material, its preparation method, and its application.

[0008] The first objective of this invention is to provide a sodium-ion battery anode material, the sodium-ion battery anode material comprising sodium titanate and a composite coating layer covering the surface of the sodium titanate, wherein the composite coating layer comprises titanium carbide and carbon.

[0009] The mass ratio of sodium titanate, titanium carbide and carbon is (70-90):(5-15):(2-10).

[0010] A second objective of this invention is to provide a method for preparing the sodium-ion battery anode material, comprising the following steps:

[0011] S1. Add tetrabutyl titanate dropwise to sodium hydroxide solution. After the addition is complete, heat the reaction. After centrifugation, washing and drying, sodium titanate is obtained.

[0012] S2. Add the sodium titanate and titanium source described in S1 to the organic carbon source solution and stir until homogeneous. Then, spray dry and carbonize to obtain the sodium-ion battery anode material.

[0013] In one embodiment of the present invention, in S1, the concentration of the sodium hydroxide solution is 1 mol / L-2 mol / L, for example, it can be 1 mol / L, 1.1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L, 1.5 mol / L, 1.6 mol / L, 1.7 mol / L, 1.8 mol / L, 1.9 mol / L, 2 mol / L, etc.;

[0014] The mass ratio of sodium hydroxide and tetrabutyl titanate is configured according to the stoichiometric ratio of Na2Ti3O7.

[0015] In one embodiment of the present invention, in S1, the dropping rate is 0.4 mL / min to 0.6 mL / min, for example, it can be 0.4 mL / min, 0.5 mL / min, 0.6 mL / min, etc.; to avoid rapid hydrolysis leading to local precipitation or aggregation;

[0016] The heating reaction temperature is 160℃-190℃, for example, it can be 160℃, 161℃, 162℃, 163℃, 164℃, 165℃, 166℃, 167℃, 168℃, 169℃, 170℃, 171℃, 172℃, 173℃, 174℃, 175℃, 176℃, 177℃, 178℃, 179℃, 180℃, 181℃, 182℃, 183℃, 184℃, 185℃, 18... Temperatures can be as follows: 6℃, 187℃, 188℃, 189℃, 190℃, etc.; heating time can be 15h-35h, for example, 15h, 16h, 17h, 18h, 19h, 20h, 21h, 22h, 23h, 24h, 25h, 26h, 27h, 28h, 29h, 30h, 31h, 32h, 33h, 34h, 35h, etc. Heating temperature and time determine crystallinity; excessively high temperatures may generate impurities (such as Na₂Ti₆O). 13 ).

[0017] In one embodiment of the present invention, in S2, the concentration of the organic carbon source solution is 0.08 mol / L-0.12 mol / L, for example, it can be 0.08 mol / L, 0.09 mol / L, 0.1 mol / L, 0.11 mol / L, 0.12 mol / L, etc.

[0018] The organic carbon source is selected from one or more of glucose, citric acid, polyacrylonitrile, and polyvinylpyrrolidone;

[0019] The titanium source is selected from one or more of titanium powder, titanium tetrachloride, and titanium trichloride.

[0020] In one embodiment of the present invention, in S2, the inlet temperature of the spray dryer is 180℃-220℃, for example, it can be 180℃, 181℃, 182℃, 183℃, 184℃, 185℃, 186℃, 187℃, 188℃, 189℃, 190℃, 191℃, 192℃, 193℃, 194℃, 195℃, 196℃, 197℃, 198℃, 199℃, 200℃, 201℃, 202℃, 203℃, 204℃. Temperatures range from 205℃ to 220℃; outlet temperatures are 75℃-85℃, for example, 75℃, 76℃, 77℃, 78℃, 79℃, 80℃, 81℃, 82℃, 83℃, 84℃, 85℃, etc.; spray drying can form a microsphere structure, which is beneficial for subsequent uniform carbonization.

[0021] The carbonization process is carried out in an H2 / Ar atmosphere. First, the temperature is increased to 500℃-700℃ at a rate of 4℃ / min-6℃ / min and held for 1-2 hours. Then, the temperature is increased to 1200℃-1500℃ at a rate of 1℃ / min-3℃ / min and held for 3-8 hours. In the first stage, the organic carbon source is carbonized to generate amorphous carbon. In the second stage, Ti reacts with C to generate TiC. The volume ratio of H2 in the H2 / Ar atmosphere is 3%-5%, for example, 3%, 3.5%, 4%, 4.5%, 5%, etc. H2 assists in reduction to prevent Ti oxidation, but its content needs to be controlled; excessive hydrogen content will cause sodium titanate decomposition.

[0022] The third objective of this invention is to provide a sodium-ion battery negative electrode sheet prepared from the aforementioned sodium-ion battery negative electrode material.

[0023] A fourth objective of this invention is to provide a sodium-ion battery, wherein the cell of the sodium-ion battery includes the aforementioned sodium-ion battery negative electrode, positive electrode, and electrolyte; the active material of the positive electrode is a polyanionic compound.

[0024] In one embodiment of the present invention, the polyanionic compound is selected from Na+ phosphate. x M y (PO4) z Na pyrophosphate x M y (P2O7) z Mixed phosphate Na x M y (PO4) z (P2O7) z Na fluorophosphate x M y (PO4)z F, sulfate Na x M y (SO4) z and silicate Na x M y One or more of (SiO4); wherein M is selected from one or more of Fe, Mn, Ti, V, Ni, Co, Zr and Cr.

[0025] In one embodiment of the present invention, the phosphate Na x M y (PO4) z Selected from one or more of NaFePO4, Na3V(PO4)2, Na3Fe2(PO4)3, Na3Cr2(PO4)3, Na3MnTi(PO4)3, Na3MnZr(PO4)3 and Na3MnV(PO4)3;

[0026] The pyrophosphate Na x M y (P2O7) z Selected from one or more of Na2FeP2O7, Na2MnP2O7, Na2CoP2O7, and Na2VP2O7;

[0027] The mixed phosphate Na x M y (PO4) z (P2O7) z Selected from Na4Fe3(PO4)2(P2O7), Na4Fe 3-x Mn x One or more of (PO4)2(P2O7), Na4Mn3(PO4)2(P2O7), Na4Co3(PO4)2(P2O7) and Na4Ni3(PO4)2(P2O7);

[0028] The fluorophosphate Na x M y (PO4) z F is selected from one or more of Na3V2(PO4)2F3, Na2FePO4F, and Na2CoPO4F;

[0029] The sulfate Na x M y (SO4) z Selected from Na2Fe2(SO4)3 and / or NaFe(SO4)2;

[0030] The silicate Na x M y(SiO4) is selected from one or more of Na2FeSiO4, Na2MnSiO4 and Na2CoSiO4.

[0031] The technical solution of the present invention has the following advantages compared with the prior art:

[0032] (1) In the sodium-ion battery anode material of the present invention, the layered structure of sodium titanate provides a stable channel for sodium ion insertion, but its own conductivity is extremely low (~10). -9 The conductivity (S / cm) severely limits rate performance. To address this, titanium carbide (with an electrical conductivity of ~10) can be used. 3 The sodium titanate particles are encapsulated in a conductive network (S / cm) to improve overall electron transport efficiency and reduce polarization; the composite material exhibits significant performance advantages: conductivity can be improved by 10%. 2 -10 4 The rate performance has also been greatly improved; for example, under 10C conditions, the capacity retention rate can be increased from 30% to over 70%.

[0033] (2) In the sodium-ion battery anode material described in this invention, titanium carbide will undergo a violent volume expansion of more than 100% due to the conversion reaction during the sodium ion insertion / extraction process, which easily leads to particle pulverization; while sodium titanate, although its volume change is only about 3%, is difficult to withstand external stress; the two are combined to form complementary advantages: sodium titanate can act as a rigid skeleton to disperse titanium carbide particles and buffer their volume expansion, while the flexible carbon-based composite structure of titanium carbide (such as TiC@C) can further alleviate stress.

[0034] (3) In the sodium-ion battery anode material described in this invention, sodium titanate stores sodium through ion intercalation, with a theoretical capacity of only about 200 mAh / g; while titanium carbide stores sodium through a combination of intercalation and conversion reaction, resulting in a higher capacity but a slower reaction kinetics. The combination of the two forms a multi-mechanism synergistic advantage, with sodium titanate providing a stable intercalation platform capacity, metal carbides contributing a high-capacity conversion reaction, and the interface between the two may form new active sites (such as Ti-OC bonds) to promote surface adsorption and sodium storage, ultimately significantly improving the actual capacity of the composite material, far exceeding that of a single material.

[0035] (4) In the sodium-ion battery anode material of the present invention, titanium carbide is prone to aggravating electrolyte decomposition due to its high surface catalytic activity, resulting in the formation of a thick and uneven SEI film; although sodium titanate can suppress sodium dendrites with a low voltage of about 0.3V, it cannot cover the high voltage side reaction of titanium carbide; after the two are combined, the stable interface of sodium titanate can reduce the direct contact between electrolyte and titanium carbide, effectively suppress the side reaction, and increase the coulombic efficiency from 65% of pure titanium carbide to 95% of the composite material. Detailed Implementation

[0036] The present invention will be further described below with reference to specific embodiments, so that those skilled in the art can better understand and implement the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. It should be understood that the specific embodiments are only used to explain the present invention, but the embodiments are not intended to limit the present invention.

[0037] In this invention, unless otherwise stated, the technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0038] In this invention, unless otherwise stated, the term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0039] In this invention, unless otherwise specified, the experimental methods used in the embodiments of this invention are conventional methods, and the materials and reagents used are commercially available unless otherwise specified.

[0040] Example 1

[0041] The sodium-ion battery anode material and its preparation method in this embodiment specifically include the following steps:

[0042] Preparation of S1 and sodium titanate (Na2Ti3O7)

[0043] S11. Weigh 3.4g of sodium hydroxide (analytical grade, purity ≥99%) and dissolve it in 60mL of deionized water. Stir magnetically at 800rpm until completely transparent to obtain a sodium hydroxide solution.

[0044] S12. Using a constant pressure dropping funnel, add 2 mL of tetrabutyl titanate to the sodium hydroxide solution at a rate of 0.5 mL / min. The transparent solution gradually turns into a milky white colloid. Continue stirring for 30 min to ensure uniform dispersion and obtain a suspension.

[0045] S13. The suspension was transferred to a 100 mL hydrothermal reactor lined with polytetrafluoroethylene and heated to 180 ± 2 °C at a rate of 2 °C / min for 24 h. After the reaction, the product was collected by centrifugation at 10000 rpm for 10 min using a high-speed centrifuge. The product was washed 5 times alternately with deionized water and anhydrous ethanol until the pH of the supernatant was about 7. Finally, the material was placed in a vacuum drying oven and dried at 60 °C and -0.08 MPa for 12 h to obtain sodium titanate powder (Na2Ti3O7).

[0046] S2, Preparation of sodium-ion battery anode materials

[0047] S21. First, disperse 0.5g of sodium titanate powder into 50mL of 0.1mol / L glucose solution and sonicate for 30min. Then add 0.1g of titanium powder with a particle size of less than 50nm and stir magnetically for 6h to form a homogeneous suspension.

[0048] S22. Spray dry the suspension at an inlet temperature of 200°C and an outlet temperature of 80°C to obtain precursor microspheres.

[0049] S23. The precursor microspheres are placed in a tube furnace and an Ar / H2 mixed gas (volume ratio of 96:4) is introduced. The temperature is first increased to 600℃ at a rate of 5℃ / min and held for 2 hours, then increased to 1350℃ at a rate of 3℃ / min and held for 3 hours. The mixture is then allowed to cool naturally to room temperature. An N2 atmosphere is introduced to passivate the surface active sites, resulting in a sodium-ion battery anode material, denoted as Na2Ti3O7-TiC@C, where the mass ratio of Na2Ti3O7, TiC, and C is 89:9:2.

[0050] Comparative Example 1

[0051] Basically the same as Example 1, except that: no titanium carbide and carbon coating are performed, and the specific steps include:

[0052] S11. Weigh 3.4g of sodium hydroxide (analytical grade, purity ≥99%) and dissolve it in 60mL of deionized water. Stir magnetically at 800rpm until completely transparent to obtain a sodium hydroxide solution.

[0053] S12. Using a constant pressure dropping funnel, add 2 mL of tetrabutyl titanate to the sodium hydroxide solution at a rate of 0.5 mL / min. The transparent solution gradually turns into a milky white colloid. Continue stirring for 30 min to ensure uniform dispersion and obtain a suspension.

[0054] S13. The suspension was transferred to a 100 mL hydrothermal reactor lined with polytetrafluoroethylene and heated to 180±2 °C at a rate of 2 °C / min for 24 h. After the reaction, the product was collected by centrifugation at 10000 rpm for 10 min using a high-speed centrifuge. The product was washed 5 times alternately with deionized water and anhydrous ethanol until the pH of the supernatant was about 7. Finally, the material was placed in a vacuum drying oven and dried at 60 °C and -0.08 MPa for 12 h to obtain sodium titanate powder (Na2Ti3O7) as the anode material for sodium-ion batteries.

[0055] Comparative Example 2

[0056] The process is basically the same as in Example 1, except that sodium titanate powder is not added during the preparation of the sodium-ion battery anode material. Specifically, the process includes the following steps:

[0057] S21. Disperse 0.1g of titanium powder with a particle size of less than 50nm into 50mL of glucose solution with a concentration of 0.1mol / L, and stir magnetically for 6h to form a homogeneous suspension.

[0058] S22. Spray dry the suspension at an inlet temperature of 200°C and an outlet temperature of 80°C to obtain precursor microspheres.

[0059] S23. Place the precursor microspheres in a tube furnace and introduce an Ar / H2 mixed gas (volume ratio of 96:4). First, heat the mixture to 600℃ at a rate of 5℃ / min and hold for 2 hours. Then, heat the mixture to 1350℃ at a rate of 3℃ / min and hold for 3 hours. Then, allow it to cool naturally to room temperature and introduce an N2 atmosphere to passivate the surface active sites, thus obtaining the sodium-ion battery anode material, denoted as TiC@C.

[0060] Test Example 1

[0061] (1) Battery assembly:

[0062] Negative electrode: The negative electrode active material is the sodium-ion battery negative electrode material prepared in Example 1 and Comparative Examples 1-2, respectively. The conductive agent is acetylene black, the binder is polyvinylidene fluoride, and the negative electrode current collector is 6μm aluminum foil. The negative electrode active material, conductive agent, and binder are mixed at a mass ratio of 8:1:1, and N-methylpyrrolidone is added and stirred to form a uniform and stable negative electrode slurry. The negative electrode slurry is uniformly coated on the surface of the negative electrode current collector by 200μm doctor blade coating. After drying and cold pressing, a mass loading of approximately 2.5 mg / cm³ is obtained. 2 The negative electrode.

[0063] Counter electrode: Sodium metal sheet.

[0064] Separating membrane: Polyethylene film, 9μm thick.

[0065] Electrolyte: Sodium hexafluorophosphate is dissolved in polycarbonate to prepare an electrolyte with a concentration of 1 mol / L.

[0066] Sodium-ion battery assembly: Arrange the negative electrode, separator, counter electrode, and separator in sequence to assemble a CR2032 coin cell sodium-ion battery.

[0067] (2) Performance testing:

[0068] First coulombic efficiency test: The prepared CR2032 coin cell sodium-ion battery to be formed was placed at 60℃ for 40 min, then charged at a rate of 0.1C to the upper limit of the activation voltage, and then discharged to the lower limit of the activation voltage. The first coulombic efficiency was measured. The first coulombic efficiency is the ratio of the first discharge capacity to the first charge capacity.

[0069] Specific capacity test: The sodium-ion battery was charged / discharged at rates of 0.1C, 1C, 5C, and 10C within a voltage range of 0V-3V. The specific capacity was determined using the formula C = Q. D / M is used to calculate the specific capacity of the active material, where Q D M represents the discharge capacity, and M represents the mass of the active material.

[0070] Cyclic stability testing was conducted by first performing a 0.1C capacity calibration and recording the discharge capacity as C0. Then, a 10C charge-discharge cycle was performed (charged to 3.9V and discharged to 1.5V). A 0.1C capacity calibration was performed every 1000 cycles, and the capacity retention rate was recorded after the 1000th cycle. The capacity retention rate R = C5 / C0*100% was used to evaluate the 5000-cycle stability of the sodium-ion battery by using the discharge capacity C5 from the 5th 0.1C capacity calibration.

[0071] Table 1 shows the relevant test results:

[0072] Table 1

[0073]

[0074] As shown in Table 1, the sodium-ion pouch battery of the embodiment exhibits high initial coulombic efficiency, specific capacity, and excellent cycle stability. This is attributed to the dual mechanism of intercalation (Na2Ti3O7) and conversion (TiC@C), which increases the 0.1C capacity to 380.3 mAh / g. The sodium titanate framework acts as a buffer to alleviate the volume expansion of the material during charge and discharge, resulting in a cycle stability of 89.8%, which is close to that of pure sodium titanate (92.3%) and much higher than that of pure TiC@C (45.7%). At the same time, the TiC@C conductive network improves the 10C capacity retention rate to 70% (266.4 mAh / g / 380.3 mAh / g), overcoming the shortcomings of pure sodium titanate in rate performance (30% = 52.7 mAh / g / 175.8 mAh / g).

[0075] Comparing Example 1 and Comparative Example 1, it can be seen that pure sodium titanate provides only 175.8 mAh / g specific capacity at 0.1C, which is only 46% of that in Example 1. Its theoretical capacity ceiling (approximately 200 mAh / g) is significantly lower than that of the composite material system. At a high rate of 10C, the capacity drops sharply to 52.7 mAh / g, which is due to its low intrinsic conductivity (approximately 10 mAh / g). -9 Even with the addition of 10% conductive agent (acetylene black), the electron transport efficiency (S / cm) cannot be improved, resulting in severe polarization and slow intercalation reaction kinetics, making it difficult to meet the fast charging requirements. Although its capacity retention rate is still as high as 92.3% after 5000 cycles due to its stable lattice structure, it is not suitable for high specific energy application scenarios due to its low specific capacity.

[0076] Comparing Example 1 and Comparative Example 2, it can be seen that the capacity retention of pure TiC@C after 5000 cycles is only 45.7% (from 321.5 mAh / g to 146.9 mAh / g), which is much lower than the 89.8% of the composite material (from 380.3 mAh / g to 341.5 mAh / g). This is because it will produce a violent volume expansion (>100%) during charging and discharging, resulting in the pulverization of active particles and the failure of TiC to contact the current collector. At the same time, the highly catalytically active surface of TiC will accelerate the decomposition of the electrolyte and form an excessively thick SEI film (>50 nm), resulting in an initial efficiency of only about 65%. In addition, although the capacity of pure TiC@C reaches 321.5 mAh / g at 0.1C (close to the theoretical value of TiC), the actual usable capacity after cycling (146.9 mAh / g) is even lower than that of pure sodium titanate (162.2 mAh / g). It can be seen that a single carbide cannot meet the requirements of long-cycle energy storage.

[0077] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A sodium-ion battery anode material, characterized in that, The sodium-ion battery anode material includes sodium titanate and a composite coating layer covering the surface of the sodium titanate, and the composite coating layer includes titanium carbide and carbon. The mass ratio of sodium titanate, titanium carbide and carbon is (70-90):(5-15):(2-10). The preparation steps of the composite coating layer are as follows: sodium titanate and titanium source are added to an organic carbon source solution and stirred evenly, followed by spray drying and carbonization to obtain the composite coating layer.

2. The method for preparing the sodium-ion battery negative electrode material as described in claim 1, characterized in that, Includes the following steps: S1. Add tetrabutyl titanate dropwise to sodium hydroxide solution. After the addition is complete, heat the reaction. After centrifugation, washing and drying, sodium titanate is obtained. S2. Add the sodium titanate and titanium source described in S1 to the organic carbon source solution and stir until homogeneous. Then, spray dry and carbonize to obtain the sodium-ion battery anode material.

3. The method for preparing the sodium-ion battery negative electrode material according to claim 2, characterized in that, In S1, the concentration of the sodium hydroxide solution is 1 mol / L to 2 mol / L.

4. The method for preparing the sodium-ion battery negative electrode material according to claim 2, characterized in that, In S1, the dropping rate is 0.4 mL / min - 0.6 mL / min; The heating reaction is carried out at a temperature of 160 ℃-190 ℃ for a time of 15 h-35 h.

5. The method for preparing the sodium-ion battery negative electrode material according to claim 2, characterized in that, In S2, the concentration of the organic carbon source solution is 0.08 mol / L-0.12 mol / L; The organic carbon source is selected from one or more of glucose, citric acid, polyacrylonitrile, and polyvinylpyrrolidone; The titanium source is selected from one or more of titanium powder, titanium tetrachloride, and titanium trichloride.

6. The method for preparing the sodium-ion battery negative electrode material according to claim 2, characterized in that, In S2, the inlet temperature of the spray dryer is 180 ℃-220 ℃, and the outlet temperature is 75 ℃-85 ℃; The carbonization is carried out in an H2 / Ar atmosphere by first heating to 500-700℃ at a rate of 4-6℃ / min and holding for 1-2 hours, and then heating to 1200-1500℃ at a rate of 1-3℃ / min and holding for 3-8 hours; the volume ratio of H2 in the H2 / Ar atmosphere is 3%-5%.

7. A sodium-ion battery negative electrode sheet, characterized in that, It is prepared from the sodium-ion battery anode material according to claim 1.

8. A sodium-ion battery, characterized in that, The sodium-ion battery cell includes the sodium-ion battery negative electrode, positive electrode, and electrolyte as described in claim 7; the active material of the positive electrode is a polyanionic compound.

9. The sodium-ion battery according to claim 8, characterized in that, The polyanionic compound is selected from Na+ phosphate. x M y (PO4) z Na pyrophosphate x M y (P2O7) z Mixed phosphate Na x M y (PO4) z (P2O7) z Na fluorophosphate x M y (PO4) z F, sulfate Na x M y (SO4) z and silicate Na x M y One or more of (SiO4); wherein M is selected from one or more of Fe, Mn, Ti, V, Ni, Co, Zr and Cr.

10. The sodium-ion battery according to claim 9, characterized in that, The phosphate Na x M y (PO4) z Selected from one or more of NaFePO4, Na3V(PO4)2, Na3Fe2(PO4)3, Na3Cr2(PO4)3, Na3MnTi(PO4)3, Na3MnZr(PO4)3 and Na3MnV(PO4)3; The pyrophosphate Na x M y (P2O7) z Selected from one or more of Na2FeP2O7, Na2MnP2O7, Na2CoP2O7, and Na2VP2O7; The mixed phosphate Na x M y (PO4) z (P2O7) z Selected from Na4Fe3(PO4)2(P2O7), Na4Fe 3-x Mn x One or more of (PO4)2(P2O7), Na4Mn3(PO4)2(P2O7), Na4Co3(PO4)2(P2O7) and Na4Ni3(PO4)2(P2O7); The fluorophosphate Na x M y (PO4) z F is selected from one or more of Na3V2(PO4)2F3, Na2FePO4F, and Na2CoPO4F; The sulfate Na x M y (SO4) z Selected from Na2Fe2(SO4)3 and / or NaFe(SO4)2; The silicate Na x M y (SiO4) is selected from one or more of Na2FeSiO4, Na2MnSiO4 and Na2CoSiO4.

Images