Chestnut shell derived porous carbon sphere nano-diamond composite material, preparation method thereof and application of lithium ion battery negative electrode material

Abstract

The invention provides a chestnut shell derived porous carbon sphere nano-diamond composite material, a preparation method thereof and application of a lithium ion battery negative electrode material, belongs to the technical field of lithium ion battery negative electrode materials, and aims to solve the problems of low capacity, poor cycling stability and the like of a biomass carbon material. According to the present invention, the nanometer diamond is added during the hydrothermal process, the potassium chloride is adopted as the activating agent to synthesize the composite material of the porous carbon spheres derived from the Chinese chestnuts and the nanometer diamond, the material has advantages of high specific capacity, good cycle performance and other excellent performances, the preparation method is simple, the environmental protection is achieved, the compatibility is good, and the large industrial production value is provided.

Description

Technical Field

[0001] The invention belongs to the technical field of negative electrode materials for lithium ion batteries. Background Art

[0002] Lithium-ion batteries have become a mainstream energy storage technology due to their high energy density, long cycle life, and low self-discharge rate. Anode materials play a vital role in determining the electrochemical performance of lithium-ion batteries. Among various anode materials, carbon-based materials have been widely used due to their cost-effectiveness, excellent conductivity, and outstanding stability. For example, graphite is widely used as a LIB anode due to its low price, good thermal conductivity, and good chemical stability. However, its limited theoretical capacity (372 mA h g -1 ) and fragile structure hinder its further development. Graphene and single-walled / multi-walled carbon nanotubes as promising anode materials can overcome the low capacity of graphite, but their cost is still too high. Therefore, it is imperative to develop new carbon-based anode materials with high capacity, better rate performance and cost-effectiveness.

[0003] Biomass-derived carbon materials, with their tunable porosity, high surface area, and excellent electrochemical performance, are versatile and sustainable solutions for a range of energy production and storage applications. With the growing demand for renewable energy technologies, biomass-derived carbon materials have emerged as promising candidates for supercapacitors, batteries, fuel cells, and catalytic applications. These materials, derived from abundant renewable biomass sources such as agricultural waste, forestry residues, and municipal solid waste, are a cost-effective and environmentally friendly alternative to traditional fossil fuel-based carbon materials. Key synthetic methods, including pyrolysis, hydrothermal carbonization, and chemical activation, have enabled the development of carbon materials with tailored structures and chemical properties. In addition, advances in activation processes, heteroatom doping, and surface modification techniques have further improved the electrochemical performance of biomass-derived carbon materials, making them suitable for high-performance energy devices. The synthesis techniques, structural adjustment strategies, and emerging trends of biomass-derived carbon materials are presented, with a focus on their impact on energy storage and power generation systems. By utilizing biomass-derived materials, this research paves the way for environmentally friendly and sustainable energy solutions to meet the growing global energy demand. However, problems such as low capacity and poor cycling stability of pure biomass carbon need to be urgently addressed. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the background technology, introduce a specific synthetic porous carbon sphere material with easy-to-control morphology by combining nanodiamond with biomass carbon material, and successfully apply it to the negative electrode material of lithium ion battery. The present invention provides a biomass lithium ion battery negative electrode material with high capacity, long cycle stability and high safety performance and a preparation method thereof.

[0005] The technical solution adopted by the present invention is specifically as follows: A chestnut shell-derived porous carbon sphere nanodiamond composite material, which is a composite structure of porous carbon spheres and nanodiamonds. The nanodiamonds are distributed on the surface of the porous carbon spheres. The particle size of the composite structure is 4-5 µm, and the particle size of the nanodiamonds is 5-10 nm.

[0006] The preparation method of the chestnut shell-derived porous carbon sphere nano-diamond composite material of the present invention comprises the following specific steps: 1) The biomass precursor is chestnut shell, which is washed and dried, crushed by a grinder to obtain chestnut shell powder, and sieved to obtain chestnut shell powder with a particle size of 100 mesh; 2) Adding nano-diamond powder (ND) with a particle size of 5-10 nm to chestnut shell powder at a weight ratio of 0.1-2.0% by mass, and grinding and mixing, to obtain nano-diamond / biomass mixed powder; 3) Take 2-4 g of the nanodiamond / biomass mixed powder in step 2) and soak it in 40-70 ml of deionized water, and put it into a polytetrafluoroethylene-lined autoclave, heat it at 120-240°C for 4-24 hours, and after the autoclave cools down naturally, take out and dry the sample; 4) Mix potassium chloride with the sample in a ratio of (1-5) : 1, disperse in active deionized water for 4-12 hours using a magnetic stirrer for activation, and then transfer to an oven and dry at 80°C; 5) High temperature carbonization in an argon protective atmosphere, heating to 700-900°C at a heating rate of 5°C / min, and cooling to room temperature under argon flow to obtain a nanodiamond and chestnut shell-derived carbon composite material; 6) Immersing the composite material in a 1.0-5.0 M HCl solution for 3-6 h to remove inorganic impurities, then washing with deionized water until the solution becomes neutral, drying and grinding at 60-100 °C to obtain the chestnut shell-derived porous carbon sphere nanodiamond composite material.

[0007] The size of the porous carbon sphere / nano-diamond negative electrode material is about 5 μm.

[0008] The chestnut-derived porous carbon sphere / nano-diamond negative electrode material prepared by the present invention has good electrochemical performance, long cycle stability and high capacity performance. Among them, the battery prepared by using the chestnut-derived porous carbon sphere / nano-diamond negative electrode material can reach 600-700 mA hg after 100 cycles at a current density of 0.2 C. -1 At a current density of 5 C, after 3000 cycles, it can reach 200~300 mA h g -1The present invention applies nanodiamonds to synthesize biomass porous carbon ball negative electrode materials. The preparation method thereof has the advantages of simple process, easy implementation, and easy scale-up, and is expected to be mass-produced in the future. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 The scanning electron microscope image (a), transmission electron microscope image (b) and high-resolution transmission electron microscope image (c) of sample #CPCS-ND prepared in Example 1.

[0010] Figure 2 SEM images (a), TEM images (b) and HRTEM images (c) of comparison sample #CCS-ND.

[0011] Figure 3 SEM (a), TEM (b) and HRTEM (c) images of comparison sample #CCS.

[0012] Figure 4 Voltage-to-capacity curves of lithium-ion batteries using sample #CPCS-ND (a), comparative sample #CCS-ND (b) and comparative sample #CCS (c) at 0.2 C.

[0013] Figure 5 The charge and discharge cycle curves of sample #CPCS-ND, comparison sample #CCS-ND and comparison sample #CCS applied to lithium-ion batteries at constant rates of 0.2 C and 5 C.

[0014] Figure 6 The charge and discharge cycle curves of sample #CPCS-ND, comparison sample #CCS-ND and comparison sample #CCS applied to lithium-ion batteries at variable rates.

[0015] Figure 7 Impedance diagrams of lithium-ion batteries using sample #CPCS-ND, comparative sample #CCS-ND, and comparative sample #CCS. DETAILED DESCRIPTION

[0016] The present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be pointed out that the embodiments described below are intended to facilitate the understanding of the present application and do not have any limiting effect thereon.

[0017] Example 1: Preparation of porous carbon sphere / nanodiamond negative electrode material 1) The biomass precursor is chestnut shell, which is cleaned and dried, and then crushed by a grinder to obtain chestnut shell powder of about 100 meshes, and then passed through a 100-mesh sieve to obtain fine chestnut shell powder; 2) Adding nanodiamond powder (ND) with a particle size of 5-10 nm to the chestnut shell powder at a ratio of 0.5% by mass of the chestnut shell powder, grinding and mixing, to obtain nanodiamond / biomass mixed powder; 3) Soak 2 g of the nanodiamond / biomass mixed powder in step 2) in 60 ml of deionized water, and place it in a polytetrafluoroethylene-lined autoclave, heat it at 160°C for 12 h, and after the autoclave cools down naturally, take out and dry the sample; 4) Potassium chloride was mixed with the sample in a mass ratio of 3:1, dispersed in active deionized water by a magnetic stirrer for 6 h, and then transferred to an oven and dried at 80 °C; 5) High temperature carbonization in an argon protective atmosphere (99.99% argon, passing through the chamber at 50 sccm), heating to 700-900°C at a heating rate of 5°C / min, and cooling to room temperature under argon flow to obtain a nanodiamond and chestnut shell-derived carbon composite material; 6) The composite material was immersed in 1.0-5.0 M HCl solution for 3-6 h to remove inorganic impurities, then washed with deionized water until the solution became neutral, dried and ground at 60-100 °C to obtain a chestnut shell-derived porous carbon sphere nanodiamond composite material, recorded as sample #CPCS-ND.

[0018] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that step 4) is omitted, that is, potassium chloride activation is not used, and the obtained material is recorded as comparative sample #CCS-ND.

[0019] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that step 2) to step 4) are omitted, that is, potassium chloride activation is not used and no nano-diamond carbon material is added during the hydrothermal process, which is recorded as comparative sample #CCS.

[0020] Effect verification: The scanning electron microscope (SEM) image of the sample #CPCS-ND obtained in Example 1 is shown in Figure 1 Transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) are shown in Figure 1 , we can see that the sample is a composite structure of porous carbon spheres and nanodiamonds. The nanodiamonds are distributed on the surface of the porous carbon spheres. The particle size of the composite in sample #CPCS-ND is 4~5 µm.

[0021] SEM, TEM and HRTEM of the comparative sample #CCS-ND obtained in Comparative Example 1 are shown in Figure 2 The surface of the carbon spheres in the sample is smooth and non-porous.

[0022] SEM, TEM and HRTEM of the comparative sample #CCS obtained in Comparative Example 2 are shown in Figure 3 The carbon spheres in the sample are relatively small, only 0.8~1.0µm in size, and have a smooth surface without pores.

[0023] Example 2: Preparation of lithium-ion battery components using carbon negative electrode and porous carbon sphere / nanodiamond negative electrode material The negative electrode of the lithium-ion battery is composed of 80 wt% active material (i.e., sample #CPCS-ND), 10 wt% binder (polyvinylidene fluoride, PVDF) and 10 wt% conductive agent carbon black. The three are mixed and ground for 30 minutes and then placed in a container. A certain amount of 1-methyl-2-pyrrolidone (NMP) solvent is added to the container, and then placed on a magnetic stirrer and stirred at a constant speed for 4 to 8 hours until the mixture is a viscous fluid. Copper foil is used as the current collector, and the above mixed viscous material is applied to the copper foil. The coating density must be uniform. The temperature of the vacuum drying oven is set at 120°C, and the above copper foil coating is placed in the drying oven. After 12 hours of timing, it is taken out for use. The prepared copper foil coating is cut into several electrode discs with a special cutting die, and then the active material on the electrode is compacted with a tablet press to make it fully contact with the current collector to prevent material removal. The mass of the electrode sheet is weighed before assembly to prepare for the calculation of subsequent specific capacity parameters.

[0024] Example 3: Fabrication and performance of lithium-ion batteries The lithium-ion battery assembled during the test is a CR-2025 button battery. The prepared biochar and nano-diamond composite material is used as the negative electrode, the lithium sheet is used as the reference electrode, and the matching battery positive and negative electrode shells, gaskets, shrapnel, diaphragms and electrolytes are operated according to the lithium-ion battery production regulations. The battery is encapsulated in an anhydrous and oxygen-free environment, and then the battery electrochemical performance is tested in the blue power test system.

[0025] 1) Charge and discharge performance test The battery prepared in Example 5 was tested in a blue-electric test system at 25°C and discharged to 0.01V at a certain current density; after the discharge, the battery was allowed to stand for 3 minutes: then charged to 3V at a certain current density, after the charging was completed, the battery was allowed to stand for 3 minutes and then discharged to 0.01V at the same constant current density; after the battery was discharged, it was allowed to stand for 3 minutes and then charged under the same conditions.

[0026] At a current density of 0.2 C, the half-cell with sample #CPCS-ND as the negative electrode was charged and discharged. The results are as follows Figure 4 As shown, at a current density of 0.2 C, the battery capacity of sample #CPCS-ND is higher than that of pure biocarbon lithium-ion batteries.

[0027] The cycling performance of the half-cell with sample #CPCS-ND as the negative electrode was tested at current densities of 0.2 C and 5 C. The results are shown in Figure 5As shown in Figure 2, at a current density of 0.2 C, after 100 cycles, the battery capacity of sample #CPCS-ND reaches 625 mA h g as the structure gradually activates. -1 The high reversible capacity of the sample #CPCS-ND is higher than that of the half-cell battery with the control group using the comparison sample #CCS and the comparison sample #CCS-ND as the negative electrode. After 3000 cycles at a current density of 5 C, the reversible capacity of the sample #CPCS-ND is 254 mA h g -1 , which is higher than the capacity of the comparison sample #CCS and the comparison sample #CCS-ND biocarbon lithium-ion batteries.

[0028] The variable rate discharge was set to 0.2C, 0.5C, 1C, 2C, 5C and 10C in sequence, and the reversible specific capacity of the nanodiamond / carbon negative electrode battery was tested. Figure 7 As shown in Figure 2, it exhibits a more excellent rate performance, with the capacities at 0.2C, 0.5C, 1C, 2C, 5C and 10C rates being 665, 487, 364, 269, 170 and 114 mA h g -1 , and the capacity at each rate test stage is higher than that of the non-diamond battery. When the current density returns to 0.2 C, its capacity remains at 633 mA h g -1 Higher than CCS and CCS-ND biocarbon negative electrode materials. This shows that chestnut shell derived porous carbon sphere nanodiamond composite battery has high capacity and high stability.

[0029] 2) Electrochemical impedance spectroscopy The impedance spectra of the batteries prepared with the comparison sample #CCS, comparison sample #CCS-ND and sample #CPCS-ND as negative electrode materials are as follows Figure 7 As shown, the voltage range is 0-3 V. Obviously, the impedance of the chestnut shell derived porous carbon sphere nanodiamond composite material is smaller than that of the pure biomass carbon material negative electrode, which indicates that the introduction of ND increases the ionic conductivity and improves the cycling performance of lithium-ion batteries.

Claims

1. A chestnut shell-derived porous carbon sphere nanodiamond composite material, characterized in that: The composite material is a composite structure of porous carbon spheres and nano-diamonds. The nano-diamonds are distributed on the surface of the porous carbon spheres. The particle size of the composite structure is 4-5 µm, and the particle size of the nano-diamonds is 5-10 nm.

2. The method for preparing the chestnut shell-derived porous carbon sphere nanodiamond composite material according to claim 1, characterized in that: The steps of this method are as follows: 1) Wash and dry the chestnut shells, grind them into chestnut shell powder using a grinder, and sieve them to obtain chestnut shell powder with a particle size of 100 mesh; 2) Adding nano-diamond powder with a particle size of 5-10 nm to chestnut shell powder at a weight ratio of 0.1-2.0% by mass, and grinding and mixing, to obtain nano-diamond / biomass mixed powder; 3) Take 2-4 g of the nanodiamond / biomass mixed powder in step 2) and soak it in 40-70 ml of deionized water, and put it into a polytetrafluoroethylene-lined autoclave, heat it at 120-240°C for 4-24 hours, and after the autoclave cools down naturally, take out and dry the sample; 4) Mix potassium chloride with the sample in a ratio of (1-5) : 1, disperse in active deionized water for 4-12 hours using a magnetic stirrer for activation, and then transfer to an oven and dry at 80°C; 5) High temperature carbonization in an argon protective atmosphere, heating to 700-900°C at a heating rate of 5°C / min, and cooling to room temperature under argon flow to obtain a nanodiamond and chestnut shell-derived carbon composite material; 6) After removing inorganic impurities in the composite material, the chestnut shell-derived porous carbon sphere nanodiamond composite material is obtained.

3. The method for preparing the chestnut shell-derived porous carbon sphere nano-diamond composite material according to claim 2, characterized in that: In step 2), 0.5% by weight of chestnut shell powder is added to the chestnut shell powder and ground and mixed.

4. The method for preparing the chestnut shell-derived porous carbon sphere nano-diamond composite material according to claim 2, characterized in that: Step 3) The high pressure reactor was heated at 160°C for 12 h.

5. The method for preparing the chestnut shell-derived porous carbon sphere nano-diamond composite material according to claim 2, characterized in that: In step 4), the mass ratio of potassium chloride to sample is 3:

1.

6. The method for preparing the chestnut shell-derived porous carbon sphere nano-diamond composite material according to claim 2, characterized in that: The method used to remove inorganic impurities in step 6) is to immerse the composite material obtained in step 5) in a 1.0~5.0 M HCl solution for 3~6 hours, then wash it with deionized water until the solution becomes neutral, and dry and grind it at 60~100°C.

7. Use of the chestnut shell-derived porous carbon sphere nanodiamond composite material according to claim 1 for lithium ion battery negative electrode.

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