A biomass-based hard carbon negative electrode material for lithium-ion batteries and a preparation method thereof

Abstract

The present invention provides a lithium ion battery biomass-based hard carbon negative electrode material and a preparation method thereof, the preparation method comprising the following steps: S1. cutting balsa wood into wood blocks, immersing the wood blocks in a sodium chloroacetate alkaline solution, taking them out and repeatedly washing them with deionized water, freeze-drying them to obtain an absolutely dry pre-treated wood block; S2. vacuum-immersing the pre-treated wood block in a ferrous ion solution, keeping it at a constant temperature for 2-4 hours, and then transferring it to a potassium nitrate alkaline solution, reacting it at a constant temperature for 5-7 hours, repeatedly washing the reactant with deionized water, freeze-drying it to obtain a magnetic Fe3O4-modified wood block; S3. vacuum-immersing the magnetic Fe3O4-modified wood block in a precursor solution, placing it in a magnetic field for magnetic induction heating, repeatedly washing the reactant, freeze-drying it to obtain a precursor; S4. carbonizing the precursor. The lithium ion battery biomass-based hard carbon negative electrode material prepared by the present invention has excellent rate performance, cycle performance and high specific capacity.

Description

Technical Field

[0001] The invention relates to a negative electrode material, in particular to a biomass-based hard carbon negative electrode material for a lithium ion battery and a preparation method thereof. Background Art

[0002] Generally, according to the lithium storage mechanism, the negative electrode materials of lithium-ion batteries can be divided into embedded negative electrode materials, alloy negative electrode materials, and conversion negative electrode materials. Carbon materials are typical embedded negative electrode materials with good structural stability and cycle performance, especially hard carbon materials. Due to the presence of some pores and defects in the structure, they can provide abundant storage and deintercalation sites for lithium ions. The theoretical specific capacity is as high as 350-400mAh / g, which is a very promising negative electrode material for lithium-ion batteries.

[0003] For example, patent CN111342019B applied by Nankai University directly uses Sn-MOF as the negative electrode material of lithium-ion batteries, patent CN105932291B applied by South China Normal University and patent CN114883526A applied by China University of Petroleum prepare the negative electrode material of lithium-ion batteries by carbonizing pure Zn-MOF precursor. The problem with the above patents is that the preparation process is relatively complicated and the cost is high. Patent CN109119602A applied by Zhejiang University of Technology uses balsa wood as raw material to prepare porous wood carbon modified metal lithium negative electrode material. The problem with this patent is that the specific capacity is not high and the rate performance is not ideal.

[0004] The conductivity of metal organic frameworks is weak, which is not conducive to the transmission of electrons when used directly as negative electrode materials. Studies have shown that lithium-ion batteries with metal organic frameworks as negative electrodes have the disadvantage of small specific capacity. The cost of metal organic frameworks is high. If the negative electrode is entirely made of metal organic frameworks or their derivatives, it will not be conducive to the widespread application of the material. In addition, unmodified biomass hard carbon also has the problem of poor initial efficiency, and the element doping method as a modification method will increase the complexity and cost of the process. The above factors restrict the application of metal organic frameworks in negative electrode materials for lithium-ion batteries. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a method for preparing a biomass-based hard carbon negative electrode material for a lithium-ion battery. The lithium-ion battery biomass-based hard carbon negative electrode material prepared by the preparation method has excellent rate performance, cycle performance and high specific capacity.

[0006] In order to solve the above technical problems, the technical solution of the present invention is:

[0007] A method for preparing a biomass-based hard carbon negative electrode material for a lithium-ion battery comprises the following steps:

[0008] S1. Cut the balsa wood into blocks, immerse the blocks in a sodium chloroacetate alkaline solution for 1-3 hours, take them out and repeatedly wash them with deionized water, and then freeze-dry them to obtain dry pretreated blocks;

[0009] S2. The pretreated wood block obtained in step S1 is vacuum impregnated in a ferrous ion solution, kept at a constant temperature of 80-100°C for 2-4 hours, and then transferred to a potassium nitrate alkaline solution, kept at a constant temperature of 80-100°C for 5-7 hours, and the reactant is repeatedly washed with deionized water, and then freeze-dried to obtain magnetic Fe 3 O 4 Modified wood blocks;

[0010] S3. The magnetic Fe obtained in step S2 3 O 4 The modified wood block was vacuum impregnated in the MOF precursor solution and placed in a magnetic field for magnetic induction heating for 8-10 h. The reactants were repeatedly washed with DMF, ethanol and deionized water, and then freeze-dried to obtain the precursor.

[0011] S4. Carbonize the precursor obtained in step S3 under an inert atmosphere for 2-4 hours to obtain a biomass-based hard carbon negative electrode material for a lithium-ion battery.

[0012] Furthermore, in step S1 of the present invention, the size of the wood block is (8-12) mm×(8-12) mm×(4-6) mm; the temperature during freeze-drying is -40 to -60°C, and the time is 12 to 24 hours.

[0013] Furthermore, in step S1 of the present invention, the sodium chloroacetate alkaline solution consists of sodium chloroacetate, sodium hydroxide and water, wherein the concentration of sodium chloroacetate is 0.2-0.6M, and the concentration of sodium hydroxide is 10-20% w / v.

[0014] Furthermore, in step S2 of the present invention, the ferrous ion solution is FeSO 4 7H 2 O, FeCl 2 ·4H 2 O, citric acid, among which FeSO 4 7H 2 The concentration of O is 0.3-0.5 M, FeCl 2 ·4H 2 The concentration of O is 0.1-0.3 M.

[0015] Furthermore, in step S2 of the present invention, the potassium nitrate alkaline solution consists of potassium nitrate, sodium hydroxide and water, wherein the concentration of potassium nitrate is 0.3-0.5M, and the concentration of sodium hydroxide is 1.2-1.4M.

[0016] Furthermore, in step S2 of the present invention, the temperature during freeze drying is -40 to -60°C, and the time is 12 to 24 hours.

[0017] Furthermore, in step S3 of the present invention, the MOF precursor solution is composed of 2-aminoterephthalic acid, Zn(NO 3 )2·6H 2 O and N,N-dimethylformamide.

[0018] Furthermore, in step S3 of the present invention, the magnetic induction intensity during magnetic induction heating is 10-30 mT, and the temperature is 100-120° C.; the temperature during freeze drying is -40 to -60° C., and the time is 12-24 h.

[0019] Furthermore, in step S4 of the present invention, the inert atmosphere is nitrogen or argon, and the temperature during carbonization is 900-1000°C.

[0020] The present invention also provides a biomass-based hard carbon negative electrode material for a lithium ion battery obtained by the above preparation method.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. The present invention prepares balsa wood into wood blocks, and then pre-treats and treats it with ferrous ions to obtain magnetic Fe 3 O 4 The modified wood block was then vacuum impregnated in a MOF precursor solution to trigger the in-situ growth of Zn-MOF in the wood block by magnetic induction heating, and finally carbonized to obtain a biomass-based hard carbon negative electrode material for lithium-ion batteries. The composite of porous hard carbon and metal-organic framework-derived carbon and the construction of a hierarchical porous structure were successfully achieved, which improved the conductivity of biomass hard carbon and increased the electronic conductivity.

[0023] 2. The boiling point of metallic Zn is low, and Zn can be removed during the carbonization process. The overall porosity and specific surface area of ​​the material are increased during the Zn escape process, providing more sites for the storage of lithium ions. In addition, in addition to the embedded lithium storage mechanism of the carbon material itself, Fe 3 O 4 It also brings additional conversion-type lithium storage mechanisms;

[0024] 3. The present invention retains the original pore structure of biomass-based hard carbon materials, and utilizes the amino group of the organic ligand (2-aminoterephthalic acid) in the metal organic framework to achieve effective doping and uniform distribution of nitrogen elements, which is beneficial to reduce the ion diffusion barrier, reduce polarization, and enhance rate performance;

[0025] 4. Compared with the conventional water bath / oil bath heating method, the local magnetic induction heating method adopted in the present invention effectively improves the in-situ growth efficiency of the metal organic framework inside the biomass, thereby increasing the loading rate of MOF.

[0026] 5. The biomass-based hard carbon negative electrode material for lithium-ion batteries prepared by the present invention has excellent rate performance, cycle performance and high specific capacity. The 0.1C discharge capacity can reach 296.9 mAh / g, and the capacity retention rate can still be maintained at 88.6% after 100 cycles. DETAILED DESCRIPTION

[0027] The present invention will be described in detail below in conjunction with specific embodiments. The illustrative embodiments and descriptions of the present invention are used to explain the present invention but are not intended to limit the present invention.

[0028] Example 1

[0029] The biomass-based hard carbon anode material for lithium-ion batteries was prepared by the following steps:

[0030] S1. Cut balsa wood into wood blocks with a size of 10 mm×10 mm×5 mm, immerse the wood blocks in a sodium chloroacetate alkaline solution for 3 hours, take them out and repeatedly wash them with deionized water, and then freeze-dry them at -60°C for 12 hours to obtain an absolutely dry pretreated wood block; the sodium chloroacetate alkaline solution consists of sodium chloroacetate, sodium hydroxide, and water, wherein the concentration of sodium chloroacetate is 0.6 M and the concentration of sodium hydroxide is 10% w / v;

[0031] S2. The pretreated wood block obtained in step S1 was vacuum impregnated in a ferrous ion solution, kept at a constant temperature of 80°C for 4 hours, and then transferred to a potassium nitrate alkaline solution, kept at a constant temperature of 80°C for 7 hours, and the reactant was repeatedly washed with deionized water, and then freeze-dried at -60°C for 12 hours to obtain a magnetic Fe 3 O 4 Modified wood block; ferrous ion solution consists of FeSO 4 7H 2 O, FeCl 2 ·4H 2 O, citric acid, among which FeSO 4 7H 2 The concentration of O is 0.5 M, FeCl 2 ·4H 2 The concentration of O is 0.1M; the potassium nitrate alkaline solution is composed of potassium nitrate, sodium hydroxide and water, wherein the concentration of potassium nitrate is 0.5M and the concentration of sodium hydroxide is 1.2M;

[0032] S3. The magnetic Fe obtained in step S2 3 O 4The modified wood block was vacuum impregnated with 2-aminoterephthalic acid, Zn(NO 3 )2·6H 2 O and N,N-dimethylformamide in a MOF precursor solution, and placed in a magnetic field with a magnetic induction intensity of 10 mT and a temperature of 100 ° C for magnetic induction heating for 10 h, the reactants were repeatedly washed with DMF, ethanol and deionized water, and then freeze-dried at -60 ° C for 12 h to obtain a precursor;

[0033] S4. The precursor obtained in step S3 was carbonized at 900°C for 4 h under a nitrogen atmosphere to obtain a biomass-based hard carbon negative electrode material for a lithium-ion battery, which was recorded as MBC-10.

[0034] Example 2

[0035] The biomass-based hard carbon anode material for lithium-ion batteries was prepared by the following steps:

[0036] S1. Cut balsa wood into wood blocks with a size of 10 mm×10 mm×5 mm, immerse the wood blocks in a sodium chloroacetate alkaline solution for 3 hours, take them out and repeatedly wash them with deionized water, and then freeze-dry them at -60°C for 12 hours to obtain an absolutely dry pretreated wood block; the sodium chloroacetate alkaline solution consists of sodium chloroacetate, sodium hydroxide, and water, wherein the concentration of sodium chloroacetate is 0.6 M and the concentration of sodium hydroxide is 10% w / v;

[0037] S2. The pretreated wood block obtained in step S1 was vacuum impregnated in a ferrous ion solution, kept at a constant temperature of 80°C for 4 hours, and then transferred to a potassium nitrate alkaline solution, kept at a constant temperature of 80°C for 7 hours, and the reactant was repeatedly washed with deionized water, and then freeze-dried at -60°C for 12 hours to obtain a magnetic Fe 3 O 4 Modified wood block; ferrous ion solution consists of FeSO 4 7H 2 O, FeCl 2 ·4H 2 O, citric acid, among which FeSO 4 7H 2 The concentration of O is 0.5 M, FeCl 2 ·4H 2 The concentration of O is 0.1M; the potassium nitrate alkaline solution is composed of potassium nitrate, sodium hydroxide and water, wherein the concentration of potassium nitrate is 0.5M and the concentration of sodium hydroxide is 1.2M;

[0038] S3. The magnetic Fe obtained in step S2 3 O 4 The modified wood block was vacuum impregnated with 2-aminoterephthalic acid, Zn(NO 3)2·6H 2 O and N,N-dimethylformamide in a MOF precursor solution, and placed in a magnetic field with a magnetic induction intensity of 20mT and a temperature of 100°C for magnetic induction heating for 10h, the reactants were repeatedly washed with DMF, ethanol and deionized water, and then freeze-dried at -60°C for 12h to obtain the precursor;

[0039] S4. The precursor obtained in step S3 was carbonized at 900°C for 4 h under a nitrogen atmosphere to obtain a biomass-based hard carbon negative electrode material for lithium-ion batteries, which was recorded as MBC-20.

[0040] Example 3

[0041] The biomass-based hard carbon anode material for lithium-ion batteries was prepared by the following steps:

[0042] S1. Cut balsa wood into wood blocks with a size of 10 mm×10 mm×5 mm, immerse the wood blocks in a sodium chloroacetate alkaline solution for 3 hours, take them out and repeatedly wash them with deionized water, and then freeze-dry them at -60°C for 12 hours to obtain an absolutely dry pretreated wood block; the sodium chloroacetate alkaline solution consists of sodium chloroacetate, sodium hydroxide, and water, wherein the concentration of sodium chloroacetate is 0.6 M and the concentration of sodium hydroxide is 10% w / v;

[0043] S2. The pretreated wood block obtained in step S1 was vacuum impregnated in a ferrous ion solution, kept at a constant temperature of 80°C for 4 hours, and then transferred to a potassium nitrate alkaline solution, kept at a constant temperature of 80°C for 7 hours, and the reactant was repeatedly washed with deionized water, and then freeze-dried at -60°C for 12 hours to obtain a magnetic Fe 3 O 4 Modified wood block; ferrous ion solution consists of FeSO 4 7H 2 O, FeCl 2 ·4H 2 O, citric acid, among which FeSO 4 7H 2 The concentration of O is 0.5 M, FeCl 2 ·4H 2 The concentration of O is 0.1M; the potassium nitrate alkaline solution is composed of potassium nitrate, sodium hydroxide and water, wherein the concentration of potassium nitrate is 0.5M and the concentration of sodium hydroxide is 1.2M;

[0044] S3. The magnetic Fe obtained in step S2 3 O 4 The modified wood block was vacuum impregnated with 2-aminoterephthalic acid, Zn(NO 3 )2·6H 2O and N,N-dimethylformamide in a MOF precursor solution, and placed in a magnetic field with a magnetic induction intensity of 30mT and a temperature of 100°C for magnetic induction heating for 10h, the reactants were repeatedly washed with DMF, ethanol and deionized water, and then freeze-dried at -60°C for 12h to obtain a precursor;

[0045] S4. The precursor obtained in step S3 is carbonized at 900°C for 4 hours under a nitrogen atmosphere to obtain a biomass-based hard carbon negative electrode material for a lithium-ion battery, which is denoted as MBC-30.

[0046] Comparative example: The only difference from Example 1 is that the magnetic induction heating process in step S3 is changed to oil bath heating, the temperature is 120°C, the time is 8 hours, and the prepared biomass-based hard carbon negative electrode material for lithium-ion batteries is recorded as MBC-0.

[0047] Experimental Example 1: Powder resistivity test

[0048] The powder resistivity of the biomass-based hard carbon negative electrode materials for lithium-ion batteries prepared in Examples 1-3 and the comparative example was tested using a powder compactor, and the test pressure was 500 kg. The test results are shown in Table 1:

[0049] Table 1

[0050] Comparative Example Example 1 Example 2 Example 3 Magnetic induction intensity mT 0 10 20 30 MOF loading wt% 2.1 13.5 29.7 42.6 Powder resistivity Ω·cm 18.3 15.6 12.1 10.4

[0051] It can be seen from Table 1 that the powder resistivity of Examples 1-3 of the present invention is lower than that of the comparative example, indicating that the biomass-based hard carbon negative electrode material for lithium-ion batteries prepared by the present invention has good conductivity. Moreover, the greater the magnetic induction intensity and the greater the MOF loading, the lower the powder resistivity.

[0052] Experimental Example 2: Blue light test

[0053] The gram capacity and the capacity retention rate after 100 cycles of the lithium ion battery biomass-based hard carbon negative electrode material prepared in Example 3 were tested by the buckle blue electric test method. The test results are shown in Table 2:

[0054] Table 2

[0055] Gram capacity (mAh / g) Capacity retention after 100 cycles (%) 0.1C 296.9 88.6 0.5C 267.3 82.1 1C 223.8 78.9 5C 176.7 72.3 10C 152.4 68.3

[0056] It can be seen from Table 2 that the gram capacity and the capacity retention rate after 100 cycles of Example 3 of the present invention are both high, indicating that the biomass-based hard carbon negative electrode material for lithium-ion batteries prepared by the present invention has excellent rate performance, cycle performance and high specific capacity.

[0057] Example 4

[0058] S1. Cut balsa wood into wood blocks of 8 mm×12 mm×4 mm in size, immerse the wood blocks in a sodium chloroacetate alkaline solution for 1 hour, take them out and repeatedly wash them with deionized water, and then freeze-dry them at -40°C for 24 hours to obtain an absolutely dry pretreated wood block; the sodium chloroacetate alkaline solution consists of sodium chloroacetate, sodium hydroxide, and water, wherein the concentration of sodium chloroacetate is 0.2 M and the concentration of sodium hydroxide is 20% w / v;

[0059] S2. The pretreated wood block obtained in step S1 is vacuum impregnated in a ferrous ion solution, kept at a constant temperature of 100°C for 2 hours, and then transferred to a potassium nitrate alkaline solution, kept at a constant temperature of 100°C for 5 hours, and the reactant is repeatedly washed with deionized water, and then freeze-dried at -40°C for 24 hours to obtain a magnetic Fe 3 O 4 Modified wood block; ferrous ion solution consists of FeSO 4 7H 2 O, FeCl 2 ·4H 2 O, citric acid, among which FeSO 4 7H 2 The concentration of O is 0.3 M, FeCl 2 ·4H 2 The concentration of O is 0.3M; the potassium nitrate alkaline solution is composed of potassium nitrate, sodium hydroxide, and deionized water, wherein the concentration of potassium nitrate is 0.3M and the concentration of sodium hydroxide is 1.4M;

[0060] S3. The magnetic Fe obtained in step S2 3 O 4 The modified wood block was vacuum impregnated with 2-aminoterephthalic acid, Zn(NO 3 )2·6H 2 O and N,N-dimethylformamide in a MOF precursor solution, and placed in a magnetic field with a magnetic induction intensity of 20mT and a temperature of 110°C for magnetic induction heating for 9h, the reactants were repeatedly washed with DMF, ethanol and deionized water, and then freeze-dried at -40°C for 24h to obtain a precursor;

[0061] S4. Carbonize the precursor obtained in step S3 at 1000° C. for 2 h under an argon atmosphere to obtain a biomass-based hard carbon negative electrode material for a lithium-ion battery.

[0062] Example 5

[0063] The biomass-based hard carbon anode material for lithium-ion batteries was prepared by the following steps:

[0064] S1. Cut balsa wood into wood blocks with a size of 12 mm×8 mm×6 mm, immerse the wood blocks in a sodium chloroacetate alkaline solution for 2 hours, take them out and repeatedly wash them with deionized water, and then freeze-dry them at -50°C for 18 hours to obtain an absolutely dry pretreated wood block; the sodium chloroacetate alkaline solution consists of sodium chloroacetate, sodium hydroxide, and water, wherein the concentration of sodium chloroacetate is 0.4 M and the concentration of sodium hydroxide is 15% w / v;

[0065] S2. The pretreated wood block obtained in step S1 is vacuum impregnated in a ferrous ion solution, kept at a constant temperature of 90°C for 3 hours, and then transferred to a potassium nitrate alkaline solution, kept at a constant temperature of 90°C for 6 hours, and the reactant is repeatedly washed with deionized water, and then freeze-dried at -50°C for 18 hours to obtain a magnetic Fe 3 O 4 Modified wood block; ferrous ion solution consists of FeSO 4 7H 2 O, FeCl 2 ·4H 2 O, citric acid, among which FeSO 4 7H 2 The concentration of O is 0.4 M, FeCl 2 ·4H 2 The concentration of O is 0.2M; the potassium nitrate alkaline solution is composed of potassium nitrate, sodium hydroxide, and deionized water, wherein the concentration of potassium nitrate is 0.4M and the concentration of sodium hydroxide is 1.3M;

[0066] S3. The magnetic Fe obtained in step S2 3 O 4 The modified wood block was vacuum impregnated with 2-aminoterephthalic acid, Zn(NO 3 )2·6H 2 O and N,N-dimethylformamide in a MOF precursor solution, and placed in a magnetic field with a magnetic induction intensity of 30mT and a temperature of 120°C for magnetic induction heating for 8h, the reactants were repeatedly washed with DMF, ethanol and deionized water, and then freeze-dried at -50°C for 18h to obtain a precursor;

[0067] S4. Carbonize the precursor obtained in step S3 at 950°C for 2.5h under a nitrogen atmosphere to obtain a biomass-based hard carbon negative electrode material for a lithium-ion battery.

[0068] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A method for preparing biomass-based hard carbon negative electrode materials for lithium-ion batteries, Features: The following steps are involved: S1. Cut the balsa wood into blocks, immerse the blocks in a sodium chloroacetate alkaline solution for 1-3 hours, take them out and repeatedly wash them with deionized water, and then freeze-dry them to obtain dry pretreated blocks; S2. The pretreated wood block obtained in step S1 is vacuum impregnated in a ferrous ion solution, kept at a constant temperature of 80-100°C for 2-4 hours, and then transferred to a potassium nitrate alkaline solution, kept at a constant temperature of 80-100°C for 5-7 hours, and the reactant is repeatedly washed with deionized water, and then freeze-dried to obtain magnetic Fe 3 O 4 Modified wood blocks; S3. The magnetic Fe obtained in step S2 3 O 4 The modified wood block was vacuum impregnated in the MOF precursor solution and placed in a magnetic field for magnetic induction heating for 8-10 h. The reactants were repeatedly washed with DMF, ethanol and deionized water, and then freeze-dried to obtain the precursor. The MOF precursor solution consisted of 2-aminoterephthalic acid, Zn(NO 3 )2·6H 2 O and N,N-dimethylformamide; S4. Carbonize the precursor obtained in step S3 under an inert atmosphere for 2-4 hours to obtain a biomass-based hard carbon negative electrode material for a lithium-ion battery.

2. The method for preparing a biomass-based hard carbon negative electrode material for a lithium-ion battery according to claim 1, Features: In step S1, the size of the wood block is (8-12) mm×(8-12) mm×(4-6) mm; the temperature during freeze drying is -40 to -60°C, and the time is 12 to 24 hours.

3. The method for preparing a biomass-based hard carbon negative electrode material for a lithium-ion battery according to claim 1, Features: In step S1, the sodium chloroacetate alkaline solution consists of sodium chloroacetate, sodium hydroxide and water, wherein the concentration of sodium chloroacetate is 0.2-0.6M, and the concentration of sodium hydroxide is 10-20% w / v.

4. The method for preparing a biomass-based hard carbon negative electrode material for a lithium-ion battery according to claim 1, Features: In step S2, the ferrous ion solution is composed of FeSO 4 7H 2 O, FeCl 2 ·4H 2 O, citric acid, among which FeSO 4 7H 2 The concentration of O is 0.3-0.5 M, FeCl 2 ·4H 2 The concentration of O is 0.1-0.3 M.

5. The method for preparing a biomass-based hard carbon negative electrode material for a lithium-ion battery according to claim 1, Features: In step S2, the potassium nitrate alkaline solution consists of potassium nitrate, sodium hydroxide and water, wherein the concentration of potassium nitrate is 0.3-0.5M, and the concentration of sodium hydroxide is 1.2-1.4M.

6. The method for preparing a biomass-based hard carbon negative electrode material for a lithium-ion battery according to claim 1, Features: In step S2, the freeze-drying temperature is -40 to -60°C and the time is 12 to 24 hours.

7. The method for preparing a biomass-based hard carbon negative electrode material for a lithium-ion battery according to claim 1, Features: In step S3, the magnetic induction intensity during magnetic induction heating is 10-30 mT and the temperature is 100-120° C.; the temperature during freeze drying is -40 to -60° C. and the time is 12-24 hours.

8. The method for preparing a biomass-based hard carbon negative electrode material for a lithium-ion battery according to claim 1, Features: In step S4, the inert atmosphere is nitrogen or argon, and the temperature during carbonization is 900-1000°C.

9. A biomass-based hard carbon negative electrode material for lithium-ion batteries obtained according to the preparation method according to any one of claims 1 to 8.