A high-capacity lithium-ion battery negative electrode material and preparation method thereof

Abstract

The invention discloses a high-capacity lithium-ion battery negative electrode material and a preparation method thereof. The preparation method of the high-capacity lithium-ion battery negative electrode material comprises the following steps: S1, preparing a copper trimesic acid metal organic framework material; S2, preparing a Cu2O porous carbon material; and S3, preparing a Sn-doped Cu2O porous carbon material negative electrode material. Cu particles play a catalytic role in forming the carbon material, thereby forming a highly graphitized carbon matrix. After the copper trimesic acid metal organic framework material is oxidized, the obtained Cu2O porous carbon material has a three-dimensional porous morphology, which is very conducive to Sn metal doping.

Description

Technical Field

[0001] The present invention relates to the field of battery materials, and in particular to a high-capacity lithium-ion battery negative electrode material and a preparation method thereof. Background Art

[0002] As one of the most mainstream rechargeable battery technologies, lithium-ion batteries are widely used in portable electronic devices, electric vehicles, and energy storage systems. With the advancement of technology and the continuous pursuit of energy efficiency, the requirements for battery performance are becoming increasingly stringent, especially for energy density and cycle life. The battery's anode material is one of the key factors affecting these properties.

[0003] Although Cu2O has a high theoretical capacity as a negative electrode material for lithium-ion batteries, it has some shortcomings and disadvantages in practical applications. Cu2O undergoes a large volume change when reacting with lithium ions, which may lead to the rupture of the material structure and the peeling of the electrode, affecting the battery's cycle stability; Cu2O's conductivity is not as good as some carbon-based materials, which limits its performance under rapid charge and discharge conditions. Summary of the Invention

[0004] In view of the above-mentioned deficiencies in the prior art, the present invention proposes a high-capacity lithium-ion battery negative electrode material and a preparation method thereof, aiming to further improve the capacity of the lithium-ion battery.

[0005] To achieve the above object, the present invention provides a method for preparing a negative electrode material for a high-capacity lithium-ion battery, comprising the following steps:

[0006] S1. Preparing a copper trimesic acid metal-organic framework material: dissolving a copper salt and trimesic acid in a mixed solvent for reaction; after the reaction is completed, filtering the mixed solvent to obtain a reaction product, washing the reaction product with DMF, and then soaking the reaction product in a DCM solvent; the DCM solvent used for soaking needs to be replaced with a new DCM solvent every day, and the soaking time is 6 days; drying the soaked product at room temperature to obtain a copper trimesic acid metal-organic framework material;

[0007] S2. Preparation of Cu2O porous carbon material: placing the copper benzene trimesic acid metal organic framework material prepared in S1 in a tube furnace, and first purging the tube furnace with N2 for 2 hours to perform a carbonization treatment, and then cooling to room temperature after the carbonization treatment; then switching the gas flow from N2 to O2 and performing an oxidation treatment to obtain a Cu2O porous carbon material, wherein part of the Cu2O is further oxidized to CuO;

[0008] S3, doping with Sn metal: adding the Cu2O porous carbon material obtained in S2 and the Sn metal powder into a ball mill, and mixing them by ball milling under a protective atmosphere to obtain Sn-doped Cu2O porous carbon material as a negative electrode material;

[0009] Optionally, the copper salt is one of copper nitrate, copper sulfate, and copper chloride;

[0010] Optionally, the concentration of the copper salt in the mixed solvent is 0.15-0.2 mol / L, and the concentration of benzenetricarboxylic acid in the mixed solvent is 0.1-0.15 mol / L;

[0011] Optionally, the mixed solvent is a mixture of DMF, ethanol and deionized water in a volume ratio of 1:1:1;

[0012] Optionally, the reaction time in S1 is 23-24 hours, the reaction temperature is 70-75° C., and the soaking time is 6 days;

[0013] Optionally, the specific steps of the carbonization treatment are: heating the tube furnace to 800°C at a heating rate of 5°C per minute and maintaining it in an N2 atmosphere for 5 hours; the specific steps of the oxidation treatment are: heating the tube furnace to 200°C at a heating rate of 3°C per minute and maintaining it in an O2 gas flow for 9 hours;

[0014] Optionally, the mass ratio of the Cu2O porous carbon material to the Sn metal powder is 1:1-1:2; the ball milling mixing time is 3-4 hours; and the protective atmosphere is argon atmosphere;

[0015] In order to achieve the above object, the present invention also provides a high-capacity lithium-ion battery negative electrode material prepared by the above method.

[0016] In order to achieve the above object, the present invention further provides a high-capacity lithium-ion battery negative electrode, comprising the above-mentioned high-capacity lithium-ion battery negative electrode material.

[0017] The beneficial effects of the present invention are as follows: since the Cu particles play a catalytic role in the formation of carbon materials, a highly graphitized carbon matrix is ​​formed. After oxidation treatment, the obtained Cu2O porous carbon material has a three-dimensional porous morphology, which is very conducive to the doping of Sn metal; the CuO / Cu2O / Sn three-component particles formed after doping with Sn metal have a synergistic effect on the conduction of lithium ions, thereby improving the electrical conductivity of the negative electrode material; at the same time, the Sn-doped Cu2O porous carbon material can effectively alleviate the volume change of the negative electrode material due to its porous structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a flow chart for preparing the Sn-doped Cu2O porous carbon material negative electrode material of Example 1. DETAILED DESCRIPTION

[0019] The following embodiments of the present invention are described in detail. The following embodiments are implemented based on the technical solutions of the present invention, and provide detailed implementation methods and specific operating procedures. However, the protection scope of the present invention is not limited to the following embodiments.

[0020] Example 1

[0021] 0.2 mol of copper nitrate and 0.1 mol of benzene trimecyl acid were dissolved in 1000 ml of a mixed solvent of DMF, ethanol and deionized water, wherein the volume ratio of DMF, ethanol and deionized water was 1:1:1, and the prepared solution was reacted in an oven at 75°C for 24 hours; after the reaction was completed, the mixed solvent was filtered to obtain a reaction product, the reaction product was washed with DMF, and then immersed in a DCM solvent; the DCM solvent used for immersion needed to be replaced with a new DCM solvent every day for 6 days, and the immersed product was dried at room temperature to obtain a copper benzene trimecyl acid metal organic framework material; the prepared copper benzene trimecyl acid metal organic framework material was placed in a tube furnace, and the tube furnace was first purged with N2 for 2 hours, and then the tube furnace was heated to 800°C at a heating rate of 5°C per minute, and maintained under N2 atmosphere for 5 hours, and then cooled to room temperature; then the air flow was switched from N2 to O 2， The tube furnace was heated to 200° C. at a heating rate of 3° C. per minute and maintained in an O 2 gas flow for 9 h to obtain a Cu 2 O porous carbon material, wherein a portion of the Cu 2 O was further oxidized to CuO;

[0022] The prepared Cu2O porous carbon material and Sn metal powder were added into a ball mill at a mass ratio of 1:1, and ball milled for 4 h under an argon atmosphere to obtain a Sn-doped Cu2O porous carbon material negative electrode material;

[0023] Preparation of the negative electrode sheet: Add PVDF binder and N-methylpyrrolidone solvent to a stirrer, stir until the binder is completely dissolved, then add a conductive agent and the Sn-doped Cu2O porous carbon material negative electrode material prepared in Example 1 above, stir to obtain a negative electrode slurry, and evenly coat the negative electrode slurry on aluminum foil serving as a negative electrode current collector, and obtain a negative electrode sheet after rolling and slicing; the negative electrode active material in the negative electrode material accounts for 96% of the total weight, the weight ratio of the binder is 1%, and the weight ratio of the conductive agent is 3%. The binder is PVDF and the conductive agent is carbon black.

[0024] The positive electrode slurry and positive electrode sheet were prepared according to a ratio of 1% by weight of the binder, 2% by weight of the conductive agent, and 97% by weight of the positive electrode active material. The positive electrode active material was lithium iron phosphate, the binder was PVDF, and the conductive agent was carbon black. The preparation method of the positive electrode slurry and the positive electrode sheet is common knowledge in the art and will not be described here.

[0025] The positive electrode sheet, negative electrode sheet and separator are prepared into a battery cell 1. The preparation method of the battery cell is common knowledge in the art and will not be described in detail here.

[0026] The prepared battery cell 1 was heated to 60 mAg -1 The constant current long cycle test was carried out for 200 cycles at a specific current; the specific capacity of the first cycle was 615 mAh g -1 The initial coulombic efficiency is 47.6%. The reason for the low initial coulombic efficiency is that the lithium is consumed at the reaction interface during the first cycle of the battery cell, the SEI film is formed, and the impurities on the surface of CuO, Cu2O and Sn metal are reduced. In the subsequent cycles, as the material is gradually activated, the coulombic efficiency gradually increases to 99%. The specific capacity after 200 cycles is 934 mAh g -1 , the capacity retention rate is 98%.

[0027] Example 2

[0028] The Cu2O porous carbon material was prepared according to the preparation steps of the Cu2O porous carbon material in Example 1, and the prepared Cu2O porous carbon material and Sn metal powder were added to a ball mill at a mass ratio of 1:2. After ball milling and mixing for 4 hours under an argon atmosphere, a Sn-doped Cu2O porous carbon material negative electrode material was obtained; and a battery cell 2 was prepared according to the steps of Example 1.

[0029] The prepared battery cell 2 was heated at 60 mA g -1 The constant current long cycle test was carried out for 200 cycles at a specific current; the specific capacity of the first cycle was 593 mAh g -1 The initial coulombic efficiency is 45.3%. In the subsequent cycles, as the material is gradually activated, the specific capacity after 200 cycles is 813 mAh g -1 , the capacity retention value is 95%.

[0030] Comparative Example 1

[0031] The step of doping S3 with Sn metal was omitted, and Cu2O porous carbon material was used as the negative electrode active material. The steps for preparing the battery cell were the same as those in Example 1, thereby preparing battery cell 3.

[0032] The prepared battery cell 3 was heated to 60 mAg -1 The constant current long cycle test was carried out for 200 cycles at a specific current; the specific capacity of the first cycle was 512 mAh g -1 , the initial coulombic efficiency is 44.9%; in the subsequent cycles, as the material is gradually activated, the specific capacity after 200 cycles is 759 mAh g -1 , the capacity retention value is 89%.

[0033] Comparative Example 2

[0034] 3 g of lignin, 3 g of zinc chloride, 3 g of ammonium bicarbonate, 3 g of ammonium chloride and 3 g of potassium ferrate were ball-milled, the grinding ball diameter was 5 mm, the mass ratio of the grinding ball to the total mass of biomass, zinc chloride, ammonium bicarbonate, ammonium chloride and potassium ferrate was 1:5.3, the rotation speed was 400 r / min, the grinding time was 3 h, and the mixture was uniformly mixed to obtain a mixture; the obtained mixture was placed in a high-temperature carbonization furnace, and inert protective gas nitrogen was continuously introduced at a rate of 25 mL / min, and the temperature was first raised from room temperature to 300 ° C at a rate of 1.5 ° C / min, and then at 2 ° C / min and then heated to 850℃, maintained for 2 hours, and then slowly cooled to room temperature to obtain a black carbon material; washed three times with 5wt% hydrochloric acid solution, washed three times with deionized water, and dried to obtain a porous carbon material; the above-mentioned porous carbon material and Sn metal powder were added into a ball mill according to a mass ratio of 1:1, and ball milled and mixed for 4 hours under an argon atmosphere to obtain a Sn-doped porous carbon material negative electrode material. The Sn-doped porous carbon material negative electrode material was used as the negative electrode active material, and the steps for preparing the battery cell were the same as in Example 1, thereby preparing battery cell 4.

[0035] The prepared battery cell 4 was heated to 60 mAg -1 The constant current long cycle test was carried out for 200 cycles at a specific current; the specific capacity of the first cycle was 454 mAh g -1 , the initial coulombic efficiency is 44.3%; in the subsequent cycles, as the material is gradually activated, the specific capacity after 200 cycles is 739 mAh g -1 , the capacity retention value is 88%.

[0036] Although the preferred embodiments of the present invention have been described in detail above, it should be clearly understood that various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are intended to be included within the scope of protection of the present invention.

Claims

1. A high-capacity lithium-ion battery negative electrode material is prepared by the following preparation method: S1. Preparing a copper trimesic acid metal-organic framework material: dissolving a copper salt and trimesic acid in a mixed solvent for reaction; after the reaction is completed, filtering the mixed solvent to obtain a reaction product, washing the reaction product with DMF, and then soaking the reaction product in a DCM solvent; the DCM solvent used for soaking needs to be replaced with a new DCM solvent every day, and the soaking time is 6 days; drying the soaked product at room temperature to obtain a copper trimesic acid metal-organic framework material; S2. Preparation of Cu2O porous carbon material: placing the copper benzene trimesic acid metal organic framework material prepared in S1 in a tube furnace, and first purging the tube furnace with N2 for 2 hours to perform carbonization treatment, and then cooling to room temperature after carbonization treatment; then switching the gas flow from N2 to O2 and performing oxidation treatment to obtain a Cu2O porous carbon material, wherein part of the Cu2O is further oxidized to CuO; the specific steps of the carbonization treatment are: heating the tube furnace to 800°C at a heating rate of 5°C per minute and maintaining it under N2 atmosphere for 5 hours; the specific steps of the oxidation treatment are: heating the tube furnace to 200°C at a heating rate of 3°C per minute and maintaining it in O2 gas flow for 9 hours; S3. Preparation of Sn-doped Cu2O porous carbon material negative electrode material: adding the Cu2O porous carbon material obtained in S2 and Sn metal powder into a ball mill, and mixing by ball milling under a protective atmosphere to obtain Sn-doped Cu2O porous carbon material negative electrode material; the mass ratio of the Cu2O porous carbon material to the Sn metal powder is 1:1; the Sn-doped Cu2O porous carbon material negative electrode material is a three-component material of CuO / Cu2O / Sn; The mixed solvent is DMF, ethanol and deionized water mixed in a volume ratio of 1:1:1, and the ball milling mixing time is 3-4 hours; the protective atmosphere is argon atmosphere.

2. The preparation method according to claim 1, wherein: The copper salt is one of copper nitrate, copper sulfate and copper chloride.

3. The preparation method according to claim 2, wherein: The concentration of the copper salt in the mixed solvent is 0.15-0.2 mol / L, and the concentration of benzenetricarboxylic acid in the mixed solvent is 0.1-0.15 mol / L.

4. A high-capacity lithium-ion battery negative electrode, comprising the high-capacity lithium-ion battery negative electrode material according to any one of claims 1 to 3.

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