Negative active material, method for preparing the same, and battery

Abstract

The application relates to the field of electrochemistry, and specifically provides a negative electrode active material, a preparation method thereof and a battery. The preparation method of the negative electrode active material comprises the following steps: mixing high-sulfur petroleum coke, isotropic coke, an organic titanium-based crosslinking agent and a binder, and then performing carbonization under the condition of 300 DEG C to 500 DEG C; after the carbonization is completed, the temperature is increased to 1000 DEG C to 1200 DEG C, then phosphine is introduced, the phosphorus element is doped into the carbonized material, and a phosphorus-doped graphite precursor is obtained; the phosphorus-doped graphite precursor is graphitized to obtain phosphorus-doped graphite; the phosphorus-doped graphite is soaked in an organic solution containing molybdenum sulfide and lithium benzenesulfonate compounds, and dried to obtain the negative electrode active material. The negative electrode active material obtained through the above preparation method can significantly improve the cycle performance and rate performance of the battery, and the molybdenum sulfide and lithium benzenesulfonate compounds coated on the surface of the graphite can further improve the low-temperature resistance and high-temperature resistance of the negative electrode active material.

Description

TECHNICAL FIELD

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

[0002] The performance of a negative electrode material, as an important component of a lithium ion battery, is mainly determined by raw materials. Currently, the raw materials for preparing the negative electrode material are mainly petroleum coke, needle coke and pitch coke, which are sequentially prepared through carbonization, graphitization and granulation. The selection of the raw materials has an important influence on the specific capacity, cycle life, rate capability and tap density of the battery. In a traditional preparation scheme, high-sulfur petroleum coke is used as the raw material to prepare a graphite negative electrode material. However, when the graphite negative electrode material is applied to a lithium ion battery as a negative electrode, the lithium ion battery still has the problems of poor cycle performance and rate capability. SUMMARY

[0003] Therefore, it is necessary to provide a preparation method of a negative electrode active material, which can significantly improve the cycle performance and rate capability of a battery. Furthermore, a negative electrode active material and a battery are also provided.

[0004] The first aspect of the present application provides a preparation method of a negative electrode active material, comprising the following steps:

[0005] mixing high-sulfur petroleum coke, isotropic coke, an organic titanium-based crosslinking agent and a binder, and then carbonizing at 300-500°C; after the carbonization is completed, the temperature is raised to 1000-1200°C, and then phosphine is introduced to dope phosphorus elements into the carbonized material, to obtain a phosphorus-doped graphite precursor;

[0006] graphitizing the phosphorus-doped graphite precursor to obtain phosphorus-doped graphite;

[0007] immersing the phosphorus-doped graphite in an organic solution containing a molybdenum sulfide and a lithium benzenesulfonate compound, and drying to obtain a negative electrode active material.

[0008] In some embodiments, the mass ratio of the high-sulfur petroleum coke, the isotropic coke, the organic titanium-based crosslinking agent and the binder is 100: (50-200): (5-20): (2-10).

[0009] Preferably, the S content of the high-sulfur petroleum coke is 3-6 wt%.

[0010] In some embodiments, the binder is selected from pitch and unsaturated resin; the pitch is selected from one of medium-temperature pitch and high-temperature pitch; the unsaturated resin is selected from at least one of bisphenol A type vinyl unsaturated polyester and isophthalic acid type vinyl unsaturated resin; and the mass ratio of the pitch to the unsaturated resin is 1: (0.2-5).

[0011] In some embodiments, the method for introducing phosphoranes comprises: mixing phosphoranes with nitrogen, and then introducing the mixed gas; the volume ratio of phosphoranes to nitrogen is (1-5):10; the total flow rate of the mixed gas introduced is 100 mL / min-500 mL / min; the time for introducing the mixed gas is 30 min-300 min.

[0012] In some embodiments, the preparation method satisfies at least one of the following conditions:

[0013] (1) the carbonization time is 2 h-12 h;

[0014] (2) the graphitization time is 2 h-12 h;

[0015] (3) the graphitization temperature is 2800℃-3200℃.

[0016] In some embodiments, the preparation method of the organic titanium-based crosslinking agent comprises the following steps:

[0017] mixing titanate, ethylene glycol, organic acid and hydroxybenzaldehyde compound in a mass ratio of (5-15):100:(10-30):(10-30), and then reacting at a temperature of 50℃-100℃ for 2 h-12 h; filtering and vacuum drying to obtain the organic titanium-based crosslinking agent;

[0018] the titanate is selected from one of tetrabutyl titanate, tetraisopropyl titanate, tetra-2-methyl-2-butanol-based titanate and n-propyl titanate;

[0019] the organic acid is selected from one of benzoic acid, p-aminobenzenesulfonic acid, tartaric acid, oxalic acid, malic acid, citric acid and ascorbic acid;

[0020] the hydroxybenzaldehyde compound is selected from one of m-hydroxybenzaldehyde, 2,5-dihydroxybenzaldehyde, 3,4-dihydroxybenzaldehyde, 2,3-dihydroxybenzaldehyde, 2-hydroxy-5-methylbenzaldehyde and 2-hydroxy-4-methylbenzaldehyde.

[0021] In some embodiments, the preparation method satisfies at least one of the following conditions:

[0022] (1) the lithium benzenesulfonate compound is selected from one of 4-methyl lithium benzenesulfonate, 3-(diphenylphosphino) lithium benzenesulfonate, 4-(diphenylphosphino) lithium benzenesulfonate and polyvinyl lithium benzenesulfonate;

[0023] (2) the organic solvent in the organic solution is selected from one of diethyl ether, dipropyl ether, diisopropyl ether, ethyl butyl ether, dibutyl ether, dipentyl ether and diisopentyl ether;

[0024] (3) The dispersant is added in the organic solution; the dispersant is selected from one of polyisobutylene succinate, propylene glycol methyl ether acetate and styrene-acrylic acid copolymer; preferably, the mass ratio of the dispersant to the phosphorus-doped graphite in the organic solution is (1-5):100;

[0025] (4) The mass concentration of the molybdenum sulfide in the organic solution is 1wt%-10wt%;

[0026] (5) The mass concentration of the lithium benzene sulfonate compound in the organic solution is 1wt%-10wt%.

[0027] The second aspect of the application provides a negative electrode active material, which is prepared according to the preparation method provided in the first aspect of the application; or the negative electrode active material comprises a core and a shell layer arranged on the surface of the core, the core comprises phosphorus-doped graphite, and the shell layer comprises molybdenum sulfide and a lithium benzene sulfonate compound.

[0028] In some embodiments, the mass fraction of the shell layer in the negative electrode active material is 2wt%-5wt% based on 100% of the total mass of the negative electrode active material.

[0029] The third aspect of the application provides a battery, which comprises a positive electrode, a negative electrode, an electrolyte and a separator, wherein the negative electrode comprises the negative electrode active material prepared according to the preparation method provided in the first aspect of the application, or the negative electrode comprises the negative electrode active material provided in the second aspect of the application.

[0030] Advantages:

[0031] (1) In the above preparation method, high-sulfur petroleum coke and isotropic coke are used as the coke source, which is cross-linked and bonded under the action of the organic titanium-based cross-linking agent and the binder, and then is subjected to carbonization and graphitization treatment; the high-sulfur petroleum coke has good kinetic performance and can improve the fast-charging performance, and the isotropic coke has low expansion rate and good cycle performance, so that the advantages of the two can be synergistically exerted to improve the cycle performance and power performance of the battery. Meanwhile, the organic titanium-based cross-linking agent is used to form titanium-doped amorphous carbon after carbonization, which can improve the fast-charging and cycle performance of the battery due to the large interlayer spacing characteristics of titanium itself.

[0032] (2) The phosphine is introduced under the condition of 1000℃-1200℃ to make the phosphine crack to generate elemental phosphorus doped in the pores and on the surface of the graphite precursor, which can further improve the specific capacity of the graphite negative electrode material and the discharge specific capacity of the battery due to the high specific capacity characteristics of phosphorus itself.

[0033] (3) The graphite surface is coated with molybdenum sulfide and lithium benzenesulfonate compound. The solvation ability of the negative electrode material is improved by the strong solvation ability of the sulfonic acid group in the lithium benzenesulfonate organic compound and the strong solvation ability of the molybdenum sulfide inorganic compound, thereby improving the embedding and stripping rate of lithium ions in the charging and discharging process of the battery, improving the rate performance and cycle performance. The phenyl group grafted on the surface of the sulfonated compound has a stable structure, which can improve the cycle performance of the battery. Further, the graphite surface is coated with molybdenum sulfide and lithium benzenesulfonate compound, which can further improve the structural stability of SEI in the charging and discharging process of the battery, and improve the low-temperature resistance and high-temperature resistance of the material.

[0034] (4) The binder in the present application uses asphalt and unsaturated resin. The unsaturated resin binder contains unsaturated double bonds, which can easily form a cross-linked structure, thereby improving the bonding force between the materials. After carbonization, soft carbon can be formed. The asphalt binder has good fluidity and can form soft carbon after carbonization. The soft carbon can cooperate with the hard carbon formed by the carbonization of the unsaturated resin to improve the adhesion of the graphite negative electrode active material, thereby improving the tap density of the negative electrode active material and reducing the impedance. BRIEF DESCRIPTION OF DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiments of the present application will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0036] Figure 1 SEM image of the negative electrode active material prepared in Example 1. DETAILED DESCRIPTION

[0037] The embodiments described in the specification are only for the purpose of explaining the present application, and are not intended to limit the present application.

[0038] For simplicity, only some numerical ranges are explicitly disclosed herein. However, any lower limit can be combined with any upper limit to form a range not explicitly recited; and any lower limit can be combined with other lower limits to form a range not explicitly recited, and likewise any upper limit can be combined with any other upper limit to form a range not explicitly recited. In addition, although not explicitly recited, every point or single numerical value between the range endpoints is included in the range. Thus, each point or single numerical value can be combined as a lower limit or an upper limit with any other point or single numerical value or with other lower limits or upper limits to form a range not explicitly recited.

[0039] The present application is further described in connection with the following examples. It will be understood that these examples are merely for illustrative purposes and that various modifications and changes in the procedures can be made by one skilled in the art without departing from the scope of the present application. Unless otherwise indicated, all parts, percentages, and ratios reported in the following examples are on a mass basis, and all reagents used in the examples are commercially available or synthesized according to conventional methods and used without further purification, and the instruments used in the examples are commercially available. In particular, the raw materials used in the examples of the present application and their information are as follows:

[0040] High-sulfur petroleum coke used: Sinopec Xinjiang Tahe Petrochemical Co., Ltd.; its S content is 3wt%~6wt%.

[0041] Isotropic coke: Anshan Thermal Energy Research Institute Co., Ltd.

[0042] Medium temperature pitch: Liaoning Xinde Co., Ltd.; softening point 70~90℃.

[0043] High temperature pitch: Liaoning Xinde Co., Ltd.; softening point 180℃; model: 180#.

[0044] Mesophase pitch: Jinan Chaolian New Material Technology Co., Ltd.; model: 8175.

[0045] Bisphenol A type vinyl unsaturated polyester: Changzhou Tianma Group; model: TM3301.

[0046] Isophthalic acid type vinyl unsaturated resin: Shandong Kaiwei New Material Co., Ltd.

[0047] Styrene-acrylic acid copolymer: Wuhu Fuguan New Material Co., Ltd.

[0048] Example 1

[0049] Preparation of organic titanium-based crosslinking agent:

[0050] 10g of tetrabutyl titanate, 100g of ethylene glycol, 20g of p-aminobenzenesulfonic acid and 20g of benzaldehyde were added to a three-necked flask, and reacted at 80℃ for 6h, filtered, and the obtained material was dried at 80℃ under vacuum for 24h to obtain an organic titanium composite crosslinking agent.

[0051] Preparation of negative electrode active material from composite coke raw material:

[0052] Step S1, 100g high-sulfur petroleum coke, 100g isotropic coke, 10g organic titanium-based crosslinking agent and 3g medium temperature pitch, 3g bisphenol A type vinyl unsaturated polyester are mixed uniformly, and are treated at 400℃ for 6h, then heated to 1100℃, and a mixed gas of phosphine and nitrogen (volume ratio, phosphine:nitrogen=3:10) is introduced at a total flow rate of 300ml / min for 150min, then the obtained composite coke material is heated to 3000℃ for graphitization for 48h, to obtain a graphite material.

[0053] Step S2, 3g of 4-methylbenzenesulfonic acid lithium, 3g of molybdenum sulfide are added to 120g of ethyl ether organic solvent to configure a solution, then 3g of polyisobutylene succinate, 100g of graphite material are dispersed uniformly; spray drying is performed, the drying medium inlet temperature is 220℃, the outlet temperature is 80℃, the flow rate is 0.2kg / h, and the drying time is 5h, to obtain a negative electrode active material.

[0054] Example 2

[0055] Preparation of organic titanium-based crosslinking agent:

[0056] 5g of tetrabutyl titanate, 100g of ethylene glycol, 10g of p-aminobenzenesulfonic acid and 10g of 2,5-dihydroxybenzaldehyde are added to a three-necked flask, and reacted at 50℃ for 12h, filtered, and the obtained material is dried at 80℃ under vacuum for 24h to obtain an organic titanium composite crosslinking agent.

[0057] Preparation of negative electrode active material from composite coke raw material:

[0058] Step S1: 100g of high-sulfur petroleum coke, 50g of isotropic coke, 5g of organic titanium-based crosslinking agent and 1g of high-temperature pitch, 1g of isophthalic acid type vinyl unsaturated resin are mixed uniformly, and are treated at 300℃ for 12h, then heated to 1000℃, and a mixed gas of phosphine and nitrogen (volume ratio, phosphine:nitrogen=5:10) is introduced at a total flow rate of 100ml / min for 300min, then the obtained composite coke material is heated to 2800℃ for graphitization for 48h, to obtain a graphite material.

[0059] 1g of 3-(diphenylphosphino)benzenesulfonic acid lithium, 1g of molybdenum sulfide are added to 200g of dipropyl ether to configure a solution, then 1g of propylene glycol methyl ether acetate, 100g of graphite material are dispersed uniformly; spray drying is performed, the drying medium inlet temperature is 220℃, the outlet temperature is 80℃, the flow rate is 0.2kg / h, and the drying time is 5h, to obtain a negative electrode active material.

[0060] Example 3

[0061] Preparation of organic titanium-based crosslinking agent:

[0062] Into a three-necked flask, 15 g of tetra-2-methyl-2-butanol titanium ester, 100 g of ethylene glycol, 30 g of tartaric acid and 30 g of 3,4-dihydroxybenzaldehyde were added, and reacted at 100 ℃ for 2 h, and then filtered and dried at 80 ℃ under vacuum for 24 h to obtain an organic titanium composite crosslinking agent.

[0063] Preparation of a negative electrode active material from a composite coke raw material:

[0064] Step S1: 100 g of high-sulfur petroleum coke, 200 g of isotropic coke, 20 g of a titanium-based crosslinking agent, 5 g of mesophase pitch thereof, and 5 g of an isophthalic acid type ethylene unsaturated resin were uniformly mixed, and then carbonized at 500 ℃ for 2 h, and then heated to 1200 ℃, and a mixed gas of phosphorane and nitrogen (volume ratio, phosphorane:nitrogen = 1:10) was introduced at a total flow rate of 500 mL / min for 30 min; and then the obtained composite coke material was graphitized at 3200 ℃ for 24 h to obtain a graphite material.

[0065] Step S2: 5 g of lithium polyvinylbenzenesulfonate and 5 g of molybdenum sulfide were added to 100 g of ethyl butyl ether to form a solution, and then 5 g of a styrene-acrylic acid copolymer and 100 g of the graphite material were uniformly dispersed; and then spray drying was performed, wherein the drying medium inlet temperature was 220 ℃, the outlet temperature was 80 ℃, the flow rate was 0.2 kg / h, and the drying time was 5 h to obtain a negative electrode active material.

[0066] Comparative Example 1

[0067] The preparation method of the present comparative example was basically the same as that of Example 1, except that the present comparative example did not add an organic titanium-based crosslinking agent in Step S1, and the other preparation conditions and parameters were the same as those of Example 1.

[0068] Comparative Example 2

[0069] The preparation method of the present comparative example was basically the same as that of Example 1, except that the present comparative example omitted Step S2.

[0070] Comparative Example 3

[0071] The preparation method of the present comparative example is basically the same as that of Example 1, except that the present comparative example does not pass phosphorane gas in step S1. Specifically, step S1 of the present comparative example is: 100 g high-sulfur petroleum coke, 50 g isotropic coke, 5 g organic titanium-based crosslinking agent and 1 g high-temperature pitch, 1 g isophthalic acid type vinyl unsaturated resin are mixed uniformly, and are subjected to 12 h heat preservation treatment at 300 ℃, then heated to 1000 ℃, and nitrogen gas is passed in, the gas flow is controlled at 100 mL / min for 300 min, then the obtained composite coke material is heated to 2800 ℃ for 48 h of high temperature graphitization, to obtain a graphite material.

[0072] Comparative Example 4

[0073] The preparation method of the present comparative example is basically the same as that of Example 1, except that the present comparative example uses high titanium slag to replace the organic titanium-based crosslinking agent in the preparation of the negative electrode active material. The preparation steps of the present comparative example are as follows:

[0074] Composite coke raw material preparation of negative electrode active material:

[0075] Step S1, 100 g high-sulfur petroleum coke, 100 g isotropic coke, 10 g high-titanium slag and 3 g medium-temperature pitch, 3 g bisphenol A type vinyl unsaturated polyester are mixed uniformly, and are subjected to 6 h heat preservation treatment at 400 ℃, then heated to 1100 ℃, and a mixed gas of phosphorane and nitrogen (volume ratio, phosphorane:nitrogen = 3:10) is passed in, the total flow of the mixed gas is controlled at 300 ml / min for 6 h, then the obtained composite coke material is heated to 3000 ℃ for 48 h of high temperature graphitization, to obtain a graphite material.

[0076] Step S2, 3 g of lithium 4-methylbenzenesulfonate and 3 g of molybdenum sulfide are added to 120 g of ethyl ether organic solvent to prepare a solution, then 3 g of polyisobutylene succinate and 100 g of graphite material are added and dispersed uniformly; spray drying is performed, wherein the inlet temperature of the drying medium is 220 ℃, the outlet temperature is 80 ℃, the flow rate is 0.2 kg / h, and the drying time is 5 h, to obtain a negative electrode active material.

[0077] Performance test:

[0078] (1) Performance test of negative electrode active material

[0079] SEM test: the negative electrode active material prepared in Example 1 is subjected to SEM test, and the results are shown in Figure 1 It can be seen from Figure 1 that the material presents a single particle structure with a particle size of 8-12 μm and slight adhesion.

[0080] Physicochemical property test: The specific surface area, tap density, and 2T compaction density of the negative active materials prepared in each example and the comparative examples were tested according to the test method in the standard GB / T-24533-2019 "Graphite-based negative materials for lithium ion batteries". The diffusion coefficient of the powder material was tested by the constant current intermittent titration method (GITT). The powder resistivity was tested by a four-probe tester, and the powder graphite orientation degree (OI) value was tested by XRD; the specific test results are shown in Table 1. Among them, the graphite material prepared in Comparative Example 2 was directly tested without step S2.

[0081]

[0082] As can be seen from Table 1, the diffusion coefficient and tap density of the negative active materials prepared in Examples 1-3 are obviously better than those in Comparative Examples 1-4. The reason is that when the negative active materials are prepared in Examples 1-4, the titanium-based crosslinking agent added improves the bonding force and density of the material, and the shell coated with phenyllithium and molybdenum sulfide improves the lithium ion intercalation and deintercalation rate in the charging and discharging process, and improves the diffusion coefficient; at the same time, the isotropic coke is blended to reduce the expansion and reduce the OI value of the powder.

[0083] (2) Button cell test

[0084] The button cells were assembled according to the following method: the negative active materials of Examples 1-3 and Comparative Examples 1 and 3-4, and the graphite material prepared in Comparative Example 2 were respectively used as the negative materials, and were assembled into button cells with lithium sheets, electrolyte, and separators in an argon glove box with water content less than 0.1 ppm. Among them, the separator was celegard 2400; the electrolyte was a solution of LiPF6, the concentration of LiPF6 in the electrolyte was 1 mol / L, and the solvent was a mixed solution of ethylene carbonate (EC) and dimethyl carbonate (DMC) obtained by mixing in a weight ratio of 1:1.

[0085] The performance of each button cell was tested by a blue electric tester, and the test conditions were as follows:

[0086] Rate performance: 0.1C rate charge and discharge, voltage range 0.005V-2V, stop after 3 cycles, then test the discharge specific capacity of each button cell under 1C condition, and calculate the rate performance of 1C / 0.1C.

[0087] Cycle performance: the charge and discharge rate was 1C / 1C, the voltage range was 2.5V-3.65V, and the cycle performance of the battery after 1000 cycles was tested at a temperature of 25±3℃.

[0088] Full charge expansion rate: dissection of the full charge electrode sheet, and test the full charge expansion. The specific test results are shown in Table 2.

[0089]

[0090] As can be seen from Table 2, the discharge capacity and the first efficiency of the button cell using the graphite composite material of Examples 1-3 are obviously higher than those of Comparative Examples 1-4. The reason is that the negative electrode material prepared in the examples has a high diffusion coefficient, and the surface of the negative electrode active material is coated with phenyllithium, which reduces the irreversible capacity of the negative electrode active material, thereby improving the first efficiency of the button cell and also improving the cycle performance of the button cell.

[0091] (3) Performance test of soft pack battery

[0092] The negative electrode active materials prepared in Examples 1-3 and Comparative Examples 1, 3-4 and the graphite material prepared in Comparative Example 2 were used as negative electrode materials, respectively, and were assembled into 5 Ah soft pack batteries together with the positive electrode active material lithium iron phosphate, the electrolyte and the separator. The separator was celegard 2400, and the electrolyte was LiPF6 solution (the solvent was a mixed solution of EC and DEC at a volume ratio of 1:1, and the concentration of LiPF6 was 1.1 mol / L).

[0093] The cycle performance of each soft pack battery was tested. The specific test conditions were as follows: the charge and discharge rate was 1C / 1C, the voltage range was 2.5-3.65 V, and the cycle performance of the battery was tested for 500 cycles and 1000 cycles at a temperature of 25±3°C. The specific test results are shown in Table 3.

[0094]

[0095] As can be seen from Table 3, when the negative electrode active material prepared in Examples 1-3 is used as the negative electrode, the cycle performance of the corresponding soft pack battery is obviously better than that of the comparative examples. The reason is that the negative electrode active material of the examples has a low expansion rate and a high diffusion coefficient, which can improve the structural stability of the negative electrode. At the same time, the surface of the material is coated with phenyllithium compounds, which provides lithium ions during the charging and discharging process, reduces the loss of lithium ions during the cycle process, and thus improves the cycle performance of the soft pack battery.

[0096] The above is merely a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art can easily think of various equivalent modifications or replacements within the technical scope disclosed in the present application, and these modifications or replacements should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for producing a negative electrode active material, characterized by, The method comprises the following steps: mixing high-sulfur petroleum coke, isotropic coke, organic titanium-based crosslinking agent and binder, and then carbonizing at 300-500 DEG C; after the carbonization is completed, the temperature is raised to 1000-1200 DEG C, and then phosphine is introduced to dope phosphorus element into the carbonized material to obtain a phosphorus-doped graphite precursor; the binder is selected from pitch and unsaturated resin, and the mass ratio of the pitch to the unsaturated resin is 1:(0.2-5); graphitizing the phosphorus-doped graphite precursor to obtain phosphorus-doped graphite; immersing the phosphorus-doped graphite in an organic solution containing molybdenum sulfide and lithium benzenesulfonate compound, and drying to obtain the negative electrode active material; the preparation method of the organic titanium-based crosslinking agent comprises the following steps: mixing titanate, ethylene glycol, organic acid and hydroxybenzaldehyde compound in a mass ratio of (5-15):100:(10-30):(10-30), and then reacting at 50-100 DEG C for 2-12 h; filtering and vacuum drying to obtain the organic titanium-based crosslinking agent; the organic acid is selected from one of benzoic acid, p-aminobenzenesulfonic acid, tartaric acid, oxalic acid, malic acid, citric acid and ascorbic acid; the hydroxybenzaldehyde compound is selected from one of m-hydroxybenzaldehyde, 2,5-dihydroxybenzaldehyde, 3,4-dihydroxybenzaldehyde, 2,3-dihydroxybenzaldehyde, 2-hydroxy-5-methylbenzaldehyde and 2-hydroxy-4-methylbenzaldehyde; the negative electrode active material comprises a core and a shell layer arranged on the surface of the core; the core comprises phosphorus-doped graphite, and the shell layer comprises molybdenum sulfide and lithium benzenesulfonate compound; in the negative electrode active material, the mass fraction of the shell layer accounts for 2-5% of the total mass of the negative electrode active material.

2. The production method according to claim 1, characterized by, The mass ratio of the high-sulfur petroleum coke, the isotropic coke, the organic titanium-based crosslinking agent and the binder is 100:(50-200):(5-20):(2-10).

3. The preparation method according to claim 1, characterized in that, The pitch is selected from one of medium-temperature pitch and high-temperature pitch; the unsaturated resin is selected from at least one of bisphenol A type vinyl unsaturated polyester and isophthalic acid type vinyl unsaturated resin.

4. The production method according to any one of claims 1 to 3, characterized by, The method for introducing phosphine comprises: mixing phosphine with nitrogen, and then introducing the mixed gas; the volume ratio of the phosphine to the nitrogen is (1-5):10; the total flow rate of the mixed gas introduced is 100-500 mL / min; and the time for introducing the mixed gas is 30-300 min.

5. The method of any one of claims 1 to 3, wherein the method further comprises, The preparation method meets at least one of the following conditions: (1) the carbonization time is 2-12 h; (2) the graphitization time is 2-12 h; (3) the graphitization temperature is 2800-3200 DEG C.

6. The method of any one of claims 1 to 3, wherein, The titanate is selected from one of tetrabutyl titanate, tetraisopropyl titanate, tetra-2-methyl-2-butanol titanate and n-propyl titanate.

7. The method of any one of claims 1 to 3, wherein the method further comprises the step of: The preparation method meets at least one of the following conditions: ​ (1) the lithium benzenesulfonate compound is selected from one of lithium 4-methylbenzenesulfonate, lithium 3-(diphenylphosphino)benzenesulfonate, lithium 4-(diphenylphosphino)benzenesulfonate and lithium polyvinylbenzenesulfonate; (2) the organic solvent in the organic solution is selected from one of diethyl ether, dipropyl ether, diisopropyl ether, ethyl butyl ether, dibutyl ether, diamyl ether and diisopentyl ether; (3) the organic solution further comprises a dispersant, and the dispersant is selected from one of polyisobutylene succinate, propylene glycol methyl ether acetate and styrene-acrylic acid copolymer; (4) the mass concentration of the molybdenum sulfide in the organic solution is 1wt%-10wt%; (5) the mass concentration of the lithium benzenesulfonate compound in the organic solution is 1wt%-10wt%.

8. A negative electrode active material, characterized by, The negative electrode active material is prepared according to the preparation method of any one of claims 1-7.

9. A battery, characterized by The battery comprises a positive electrode, a negative electrode, an electrolyte and a separator, and the negative electrode comprises the negative electrode active material prepared according to the method of any one of claims 1-7.

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