Sodium-ion battery hard carbon negative electrode material coated with high-molecular polyurea coating and preparation method of sodium-ion battery hard carbon negative electrode material

Abstract

The invention discloses a preparation method of a high-molecular polyurea coating coated sodium ion battery hard carbon negative electrode material, which is specifically implemented according to the following steps: step 1, carrying out acid pickling treatment on pulverized coal, and then washing and drying; step 2, performing pre-carbonization treatment on the treated pulverized coal in an argon atmosphere, performing carbonization treatment, cooling to room temperature, and filtering by using a metal screen; 3, the hard carbon powder screened to be uniform is flatly laid in a stainless steel tray, and the stainless steel tray is placed in an atomic layer deposition cavity to be heated to the temperature the same as that of the cavity; step 4, adding an isocyanate precursor and an amine precursor, and respectively preheating to a target temperature set by the precursors; and 5, sequentially introducing the isocyanate precursor and the amine precursor into the reaction chamber according to a pulse-purging sequence, and carrying out repeated circulation to realize deposition. According to the method, the high-molecular polyurea coating is uniformly deposited on the hard carbon material by adopting an atomic layer deposition method, so that the interface side reaction between the hard carbon surface and the electrolyte is effectively inhibited.

Description

Technical Field

[0001] The present invention belongs to the technical field of sodium ion battery negative electrode materials, and particularly relates to a method for preparing a sodium ion battery hard carbon negative electrode material coated with a polymer polyurea coating, and also relates to a negative electrode material prepared by the preparation method. Background Art

[0002] As the global energy structure shifts toward a low-carbon economy, lithium-ion batteries, owing to their high energy density and mature technology systems, have become dominant in electric vehicles, consumer electronics, and energy storage. However, the uneven global distribution of lithium resources, limited reserves, and price fluctuations have led to rising costs and supply chain risks in their large-scale application. In addition, the potential for thermal runaway and insufficient low-temperature performance of lithium-ion batteries under extreme operating conditions further restrict their promotion in certain scenarios. Against this backdrop, sodium-ion batteries, with their abundant sodium resource reserves, low cost, and superior safety, have become an important supplement to lithium-ion batteries, showing broad prospects in large-scale energy storage and low-speed electric vehicles.

[0003] As a core candidate material for the negative electrode of sodium-ion batteries, hard carbon can achieve efficient reversible insertion / extraction of sodium ions due to its unique disordered carbon layer structure and abundant nanopores, and has high specific capacity and excellent cycle stability. At the same time, hard carbon raw materials are widely available and have good economic efficiency. However, hard carbon negative electrodes still have problems such as low coulombic efficiency in the first cycle, particle pulverization due to volume expansion in long cycles, and unstable surface solid electrolyte interface film, which restricts the further improvement of its practical application performance. Researchers generally use carbon coating, metal oxide coating and other means to improve interface stability, but traditional coating layers often have problems such as uneven thickness, weak bonding with the hard carbon matrix, or the introduction of additional impedance. Therefore, finding a uniform and controllable molecular layer deposition coating to optimize the performance of hard carbon negative electrode materials for sodium-ion batteries is an important problem that needs to be solved urgently. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for preparing a hard carbon negative electrode material for sodium ion batteries coated with a polymer polyurea coating, which solves the problem of particle pulverization caused by volume expansion during long cycles of hard carbon negative electrodes in the prior art.

[0005] Another object of the present invention is to provide a negative electrode material prepared by a method for preparing a sodium ion battery hard carbon negative electrode material coated with a polymer polyurea coating.

[0006] The technical solution adopted by the present invention is a method for preparing a hard carbon negative electrode material for a sodium ion battery coated with a polymer polyurea coating, which is specifically implemented according to the following steps: Step 1: acid-washing the coal powder, then washing and drying it; Step 2: pre-carbonize the pulverized coal treated in step 1 under an argon atmosphere and then further carbonize it. After cooling to room temperature, filter the obtained hard carbon powder with a metal mesh. Step 3: Spread the hard carbon powder that has been sieved to a uniform consistency on a stainless steel tray, place it in an atomic layer deposition chamber, and heat it to the same temperature as the chamber; Step 4: adding an isocyanate precursor and an amine precursor, and preheating them to the target temperature set for the precursors; In step 5, the isocyanate precursor and the amine precursor are sequentially introduced into the reaction chamber in a pulse-purge sequence for repeated cycles to achieve deposition, thereby obtaining a sodium ion battery hard carbon negative electrode material coated with a polymer polyurea coating.

[0007] The present invention is also characterized in that: In step 1, the acid selected for the pickling process is one or more of hydrochloric acid, nitric acid, and hydrofluoric acid, and the temperature of the pickling treatment is 40° C. to 70° C.

[0008] In step 2, the temperature of the pre-carbonization treatment is 400°C~700°C, the pre-carbonization time is 1h~3h, the pre-carbonization heating rate is 1°C / min~5°C / min, the temperature of the carbonization treatment is 800°C~1400°C, the carbonization time is 2h~4h, the carbonization heating rate is 1°C / min~5°C / min, and the final cooling rate is 1°C / min~5°C / min.

[0009] In step 3, the cavity temperature is set to 50°C~200°C.

[0010] In step 4, the isocyanate precursor includes one or more of 1,4-butyl diisocyanate and phenylene diisocyanate, and the amine precursor includes one or more of ethylenediamine, p-phenylenediamine, diethylenetriamine, triethylenetetramine, and tris(2-aminoethyl)amine.

[0011] In step 4, the preheating temperature of the isocyanate precursor is 70°C to 110°C, and the preheating temperature of the amine precursor is 20°C to 60°C.

[0012] In step 5, the pulse time of the isocyanate precursor is 0.1s~1s, the purge time is 30s~60s, the pulse time of the amine precursor is 0.1s~1s, the purge time is 30s~60s, and the number of deposition cycles is set to 5~150 cycles.

[0013] Another technical solution adopted by the present invention is a method for preparing a sodium ion battery hard carbon negative electrode material coated with a polymer polyurea coating, and a sodium ion battery hard carbon negative electrode material coated with a polymer polyurea coating.

[0014] The beneficial effects of the present invention are: 1) During the preparation process of the negative electrode material of the present invention, an atomic layer deposition method is used to uniformly deposit a polymer polyurea coating on the hard carbon material, effectively suppressing the interface side reaction between the hard carbon surface and the electrolyte.

[0015] 2) The polymer polyurea coating of the present invention can maintain the integrity of the hard carbon particles during the cycle by virtue of its good flexibility and mechanical stability, and promote the formation of a stable interface.

[0016] 3) The preparation method of the present invention is simple, precisely controllable, and has good reproducibility. It can obtain hard carbon anode materials for sodium ion batteries with high capacity and outstanding rate performance, which has high application value and significance. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a scanning electron microscope image of a sodium ion battery hard carbon negative electrode material coated with a polymer polyurea coating prepared in Example 1 of the present invention; Figure 2 This is an X-ray diffraction pattern of a sodium ion battery hard carbon negative electrode material coated with a polymer polyurea coating prepared in Comparative Example 1 of the present invention; Figure 3 The sodium ion battery hard carbon negative electrode material coated with a polymer polyurea coating prepared in Example 1 of the present invention is 0.1 Ag -1 Cycling performance diagram at different current densities. DETAILED DESCRIPTION

[0018] The present invention will be described in detail below with reference to specific embodiments and accompanying drawings.

[0019] The preparation method of the hard carbon negative electrode material for sodium ion batteries coated with a polymer polyurea coating of the present invention is specifically implemented according to the following steps: Step 1: acid-washing the coal powder, then washing and drying it; In step 1, the acid selected for the pickling process is one or more of hydrochloric acid, nitric acid, and hydrofluoric acid, and the temperature of the pickling treatment is 40° C. to 70° C.; Step 2: pre-carbonize the pulverized coal treated in step 1 under an argon atmosphere and then further carbonize it. After cooling to room temperature, filter the obtained hard carbon powder with a metal mesh. In step 2, the temperature of the pre-carbonization treatment is 400°C to 700°C, the pre-carbonization time is 1h to 3h, the pre-carbonization heating rate is 1°C / min to 5°C / min, the temperature of the carbonization treatment is 800°C to 1400°C, the carbonization time is 2h to 4h, the carbonization heating rate is 1°C / min to 5°C / min, and the final cooling rate is 1°C / min to 5°C / min; Step 3: Spread the hard carbon powder that has been sieved to a uniform consistency on a stainless steel tray, place it in an atomic layer deposition chamber, and heat it to the same temperature as the chamber; In step 3, the cavity temperature is set to 50°C~200°C; Step 4: adding an isocyanate precursor and an amine precursor, and preheating them to the target temperature set for the precursors; In step 4, the isocyanate precursor includes one or more of 1,4-butyl diisocyanate and phenylenediisocyanate, and the amine precursor includes one or more of ethylenediamine, p-phenylenediamine, diethylenetriamine, triethylenetetramine, and tris(2-aminoethyl)amine. The preheating temperature of the isocyanate precursor is 70°C to 110°C, and the preheating temperature of the amine precursor is 20°C to 60°C. Step 5: sequentially introducing an isocyanate precursor and an amine precursor into a reaction chamber in a pulse-purge sequence for repeated cycles to achieve deposition, thereby obtaining a sodium ion battery hard carbon negative electrode material coated with a polymer polyurea coating; In step 5, the pulse time of the isocyanate precursor is 0.1s~1s, the purge time is 30s~60s, the pulse time of the amine precursor is 0.1s~1s, the purge time is 30s~60s, and the number of deposition cycles is set to 5~150 cycles.

[0020] Example 1 The preparation method of the hard carbon negative electrode material for sodium ion batteries coated with a polymer polyurea coating of the present invention is specifically implemented according to the following steps: Step 1: Remove impurities from the coal powder in hydrochloric acid and hydrofluoric acid respectively, with the temperature controlled at 60°C, and then wash and dry; Step 2: The treated pulverized coal is heated to 500°C at a rate of 2°C / min under an argon atmosphere for low-temperature pre-carbonization. After holding the temperature for 2 hours, the temperature is further raised to 1200°C at a rate of 2°C / min for high-temperature carbonization. The temperature is held for 3 hours and then cooled to room temperature at a rate of 2°C / min. The obtained hard carbon powder is filtered through a 400-mesh metal sieve. Step 3: Spread the sieved hard carbon powder evenly on a stainless steel tray, place it in an atomic layer deposition chamber, and heat it to 65°C, the same temperature as the chamber. Step 4, adding phenylene diisocyanate precursor and ethylenediamine precursor, and preheating to 90° C. and 30° C. respectively; Step 5: First, introduce phenylene diisocyanate precursor into the cavity, set the pulse time to 0.5s, the purge time to 60s, then introduce ethylenediamine precursor, set the pulse time to 0.5s, the purge time to 60s, and repeat this cycle 20 times to achieve deposition, thus obtaining a sodium ion battery hard carbon negative electrode material coated with a polymer polyurea coating. The scanning electron microscope image and X-ray diffraction pattern are shown in FIG. Figure 1 and Figure 2 As shown, it is 0.1 Ag -1 The cycling performance diagram under current density is shown in Figure 2. Figure 3 shown.

[0021] Example 2 The preparation method of the hard carbon negative electrode material for sodium ion batteries coated with a polymer polyurea coating of the present invention is specifically implemented according to the following steps: Step 1: Remove impurities from the coal powder in hydrochloric acid and hydrofluoric acid respectively, with the temperature controlled at 60°C, and then wash and dry; Step 2: The treated pulverized coal is heated to 500°C at a rate of 2°C / min under an argon atmosphere for low-temperature pre-carbonization. After holding the temperature for 2 hours, the temperature is further raised to 1200°C at a rate of 2°C / min for high-temperature carbonization. The temperature is held for 3 hours and then cooled to room temperature at a rate of 2°C / min. The obtained hard carbon powder is filtered through a 400-mesh metal sieve. Step 3: Spread the sieved hard carbon powder evenly on a stainless steel tray, place it in an atomic layer deposition chamber, and heat it to 65°C, the same temperature as the chamber. Step 4, adding phenylene diisocyanate precursor and ethylenediamine precursor, and preheating to 90° C. and 30° C. respectively; In step 5, first, introduce a phenylene diisocyanate precursor into the cavity, set the pulse time to 0.7s and the purge time to 60s, then introduce an ethylenediamine precursor, set the pulse time to 0.7s and the purge time to 60s, and repeat this cycle 50 times to achieve deposition, thereby obtaining a sodium ion battery hard carbon negative electrode material coated with a polymer polyurea coating.

[0022] Example 3 The preparation method of the hard carbon negative electrode material for sodium ion batteries coated with a polymer polyurea coating of the present invention is specifically implemented according to the following steps: Step 1: Remove impurities from the coal powder in hydrochloric acid and hydrofluoric acid respectively, with the temperature controlled at 60°C, and then wash and dry; Step 2: The treated pulverized coal is heated to 500°C at a rate of 2°C / min under an argon atmosphere for low-temperature pre-carbonization. After holding the temperature for 2 hours, the temperature is further raised to 1200°C at a rate of 2°C / min for high-temperature carbonization. The temperature is held for 3 hours and then cooled to room temperature at a rate of 2°C / min. The obtained hard carbon powder is filtered through a 400-mesh metal sieve. Step 3: Spread the sieved hard carbon powder evenly on a stainless steel tray, place it in an atomic layer deposition chamber, and heat it to 65°C, the same temperature as the chamber. Step 4: Add 1,4-diisocyanate butyl ester precursor and diethylenetriamine precursor, and preheat to 95° C. and 30° C. respectively; In step 5, first, a 1,4-diisocyanate butyl ester precursor is introduced into the cavity, the pulse time is set to 0.5s, and the purge time is 60s. Then, a diethylenetriamine precursor is introduced, the pulse time is set to 0.5s, and the purge time is 60s. This sequence is repeated 20 times to achieve deposition, thereby obtaining a sodium ion battery hard carbon negative electrode material coated with a polymer polyurea coating.

[0023] Example 4 The preparation method of the hard carbon negative electrode material for sodium ion batteries coated with a polymer polyurea coating of the present invention is specifically implemented according to the following steps: Step 1: Remove impurities from the coal powder in hydrochloric acid and hydrofluoric acid respectively, with the temperature controlled at 60°C, and then wash and dry; Step 2: The treated pulverized coal is heated to 600°C at a rate of 2°C / min under an argon atmosphere for low-temperature pre-carbonization. After holding the temperature for 2 hours, the temperature is further raised to 1400°C at a rate of 2°C / min for high-temperature carbonization. The temperature is held for 3 hours and then cooled to room temperature at a rate of 2°C / min. The obtained hard carbon powder is filtered through a 400-mesh metal sieve. Step 3: Spread the sieved hard carbon powder evenly on a stainless steel tray, place it in an atomic layer deposition chamber, and heat it to 70°C, the same temperature as the chamber. Step 4, adding phenylene diisocyanate and ethylenediamine precursors and preheating to 90°C and 30°C respectively; In step 5, first, introduce a phenylene diisocyanate precursor into the cavity, set the pulse time to 0.5s and the purge time to 60s, then introduce an ethylenediamine precursor, set the pulse time to 0.5s and the purge time to 60s, and repeat this cycle 20 times to achieve deposition, thereby obtaining a sodium ion battery hard carbon negative electrode material coated with a polymer polyurea coating.

[0024] Example 5 The preparation method of the hard carbon negative electrode material for sodium ion batteries coated with a polymer polyurea coating of the present invention is specifically implemented according to the following steps: Step 1: Remove impurities from the coal powder in hydrochloric acid and hydrofluoric acid respectively, with the temperature controlled at 60°C, and then wash and dry; Step 2: The treated pulverized coal is heated to 500°C at a rate of 2°C / min under an argon atmosphere for low-temperature pre-carbonization. After holding the temperature for 2 hours, the temperature is further raised to 1200°C at a rate of 2°C / min for high-temperature carbonization. The temperature is held for 3 hours and then cooled to room temperature at a rate of 2°C / min. The obtained hard carbon powder is filtered through a 400-mesh metal sieve. Step 3: Spread the sieved hard carbon powder evenly on a stainless steel tray, place it in an atomic layer deposition chamber, and heat it to 65°C, the same temperature as the chamber. Step 4, adding phenylene diisocyanate precursor and ethylenediamine precursor, and preheating to 90° C. and 30° C. respectively; In step 5, first, introduce a phenylene diisocyanate precursor into the cavity, set the pulse time to 0.5s and the purge time to 60s, then introduce an ethylenediamine precursor, set the pulse time to 0.5s and the purge time to 60s, and repeat this cycle 50 times to achieve deposition, thereby obtaining a sodium ion battery hard carbon negative electrode material coated with a polymer polyurea coating.

[0025] Example 6 The preparation method of the hard carbon negative electrode material for sodium ion batteries coated with a polymer polyurea coating of the present invention is specifically implemented according to the following steps: Step 1: Remove impurities from the coal powder in hydrochloric acid and hydrofluoric acid respectively, with the temperature controlled at 60°C, and then wash and dry; Step 2: The treated pulverized coal is heated to 500°C at a rate of 2°C / min under an argon atmosphere for low-temperature pre-carbonization. After holding the temperature for 2 hours, the temperature is further raised to 1200°C at a rate of 2°C / min for high-temperature carbonization. The temperature is held for 3 hours and then cooled to room temperature at a rate of 2°C / min. The obtained hard carbon powder is filtered through a 400-mesh metal sieve. Step 3: Spread the sieved hard carbon powder evenly on a stainless steel tray, place it in an atomic layer deposition chamber, and heat it to 65°C, the same temperature as the chamber. Step 4, adding phenylene diisocyanate precursor and ethylenediamine precursor, and preheating to 100° C. and 30° C. respectively; In step 5, first, introduce a phenylene diisocyanate precursor into the cavity, set the pulse time to 0.7s and the purge time to 60s, then introduce an ethylenediamine precursor, set the pulse time to 0.7s and the purge time to 60s, and repeat this cycle 50 times to achieve deposition, thereby obtaining a sodium ion battery hard carbon negative electrode material coated with a polymer polyurea coating.

[0026] Example 7 The preparation method of the hard carbon negative electrode material for sodium ion batteries coated with a polymer polyurea coating of the present invention is specifically implemented according to the following steps: Step 1: The pulverized coal is treated in nitric acid and hydrofluoric acid to remove impurities at a temperature of 70°C, and then washed and dried; Step 2: The treated pulverized coal is heated to 700°C at a rate of 5°C / min under an argon atmosphere for low-temperature pre-carbonization. After holding the temperature for 3 hours, the temperature is further raised to 1400°C at a rate of 5°C / min for high-temperature carbonization. The temperature is held for 4 hours and then cooled to room temperature at a rate of 5°C / min. The obtained hard carbon powder is filtered through a 400-mesh metal sieve. Step 3: Spread the hard carbon powder that has been sieved to a uniform consistency on a stainless steel tray, place it in an atomic layer deposition chamber, and heat it to 200°C, the same temperature as the chamber. Step 4: adding 1,4-diisocyanate butyl ester precursor and p-phenylenediamine precursor, and preheating to 110° C. and 60° C. respectively; In step 5, first, a 1,4-diisocyanate butyl ester precursor is introduced into the cavity, the pulse time is set to 1s, and the purge time is 30s. Then, a p-phenylenediamine precursor is introduced, the pulse time is set to 1s, and the purge time is 30s. This sequence is repeated 150 times to achieve deposition, thereby obtaining a sodium ion battery hard carbon negative electrode material coated with a polymer polyurea coating.

[0027] Comparative Example 1 The preparation method of the hard carbon negative electrode material for sodium ion batteries coated with a polymer polyurea coating is specifically implemented according to the following steps: Step 1: Remove impurities from the coal powder in hydrochloric acid and hydrofluoric acid respectively, with the temperature controlled at 60°C, and then wash and dry; Step 2: The treated pulverized coal is heated to 500°C at a rate of 2°C / min under an argon atmosphere for low-temperature pre-carbonization treatment. After keeping the temperature for 2 hours, the temperature is further raised to 1200°C at a rate of 2°C / min for high-temperature carbonization. The holding time is 3 hours, and the cooling rate is 2°C / min. The obtained hard carbon powder is filtered with a 400-mesh metal sieve to obtain an uncoated hard carbon negative electrode material for sodium ion batteries.

[0028] The high molecular weight polyurea coating of the present invention can maintain the integrity of the hard carbon particles during the cycle by virtue of its good flexibility and mechanical stability, and promote the formation of a stable interface.

Claims

1. A method for preparing a sodium ion battery hard carbon negative electrode material coated with a polymer polyurea coating, characterized in that: Please follow the steps below to implement: Step 1: acid-washing the coal powder, then washing and drying it; Step 2: pre-carbonize the pulverized coal treated in step 1 under an argon atmosphere and then further carbonize it. After cooling to room temperature, filter the obtained hard carbon powder with a metal mesh. Step 3: Spread the hard carbon powder that has been sieved to a uniform consistency on a stainless steel tray, place it in an atomic layer deposition chamber, and heat it to the same temperature as the chamber. Step 4: adding an isocyanate precursor and an amine precursor, and preheating them to the target temperature set for the precursors; In step 5, the isocyanate precursor and the amine precursor are sequentially introduced into the reaction chamber in a pulse-purge sequence for repeated cycles to achieve deposition, thereby obtaining a sodium ion battery hard carbon negative electrode material coated with a polymer polyurea coating.

2. The method for preparing a sodium ion battery hard carbon negative electrode material coated with a polymer polyurea coating according to claim 1, characterized in that: In step 1, the acid selected for the pickling process is one or more of hydrochloric acid, nitric acid, and hydrofluoric acid, and the temperature of the pickling treatment is 40° C. to 70° C.

3. The method for preparing a sodium ion battery hard carbon negative electrode material coated with a polymer polyurea coating according to claim 1, characterized in that: In the step 2, the temperature of the pre-carbonization treatment is 400°C to 700°C, the pre-carbonization time is 1h to 3h, the pre-carbonization heating rate is 1°C / min to 5°C / min, the temperature of the carbonization treatment is 800°C to 1400°C, the carbonization time is 2h to 4h, the carbonization heating rate is 1°C / min to 5°C / min, and the final cooling rate is 1°C / min to 5°C / min.

4. The method for preparing a sodium ion battery hard carbon negative electrode material coated with a polymer polyurea coating according to claim 1, characterized in that: In step 3, the cavity temperature is set to 50°C to 200°C.

5. The method for preparing a sodium ion battery hard carbon negative electrode material coated with a polymer polyurea coating according to claim 1, characterized in that: In step 4, the isocyanate precursor includes one or more of 1,4-butyl diisocyanate and phenylenediisocyanate, and the amine precursor includes one or more of ethylenediamine, p-phenylenediamine, diethylenetriamine, triethylenetetramine, and tris(2-aminoethyl)amine.

6. The method for preparing a sodium ion battery hard carbon negative electrode material coated with a polymer polyurea coating according to claim 1, characterized in that: In step 4, the preheating temperature of the isocyanate precursor is 70° C. to 110° C., and the preheating temperature of the amine precursor is 20° C. to 60° C.

7. The method for preparing a sodium ion battery hard carbon negative electrode material coated with a polymer polyurea coating according to claim 1, characterized in that: In step 5, the pulse time of the isocyanate precursor is 0.1s~1s, the purge time is 30s~60s, the pulse time of the amine precursor is 0.1s~1s, the purge time is 30s~60s, and the number of deposition cycles is set to 5~150 cycles.

8. A hard carbon negative electrode material for sodium ion batteries coated with a polymer polyurea coating, prepared according to the method for preparing a hard carbon negative electrode material for sodium ion batteries coated with a polymer polyurea coating according to any one of claims 1 to 7.

Images