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Graphite material and its preparation method and application

A graphite material and graphite technology, applied in the field of graphite material and its preparation, can solve problems such as poor coating effect, peeling, shell structure cracking, etc., and achieve the effect of improving structural stability, ensuring manufacturability, and maintaining structural stability

Active Publication Date: 2022-05-24
CHINA AVIATION LITHIUM BATTERY RES INST CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The direct coating method cannot achieve effective continuous coating on the graphite surface, resulting in poor coating effect, and during the cycle, the rigid coating layer will peel off due to the volume expansion of graphite; although the core-shell void coating can Relieve the expansion of the material, but the core-shell void structure cannot achieve effective contact with the interface layer, resulting in poor electronic conductivity, and the core-shell void structure cannot relieve the uneven expansion of the graphite material, and the shell structure still occurs during the cycle the rupture

Method used

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  • Graphite material and its preparation method and application
  • Graphite material and its preparation method and application
  • Graphite material and its preparation method and application

Examples

Experimental program
Comparison scheme
Effect test

preparation example Construction

[0015] Below, combine figure 1 The production method of the present invention is explained. like figure 1 As shown, the preparation method of the graphite material includes a coating step and a heat treatment step. In the coating step, the graphite core precursor 10 is coated with the coating shell layer 20 to obtain a coating material. The graphite core precursor 10 includes graphite 11 and a solvent 12 embedded in the graphite 11 layer. After that, the clad material is heat-treated. The heat treatment step includes three heat treatment stages. The first stage heat treatment stage expands the volume of the graphite core precursor to obtain the expanded cladding material, and the second stage heat treatment stage heats the expanded cladding material to solidify the cladding shell layer 20 structure. , obtain the cured coating material, and heat the cured coating material in the third heat treatment stage to shrink the volume of the graphite core precursor to obtain the fir...

Embodiment 1

[0027] Immerse the disassembled negative pole piece in pure water, control the solid-liquid ratio to 120g / L, and after immersion for 2 hours, wash and collect the graphite core precursor after washing. The washed graphite core precursor was acid washed with 1 mol / L sulfuric acid + 5% (accounting for the mass of the graphite core precursor) hydrogen peroxide, the solid-liquid ratio was 80 g / L, reacted at 50 ° C for 1 h, and collected after the acid washing. dry. The graphite core precursor after impurity removal was mixed with 10% (accounting for the total amount of graphite core precursor and cellulose fibers) cellulose fibers, and spray-dried at a drying temperature of 150°C.

[0028] The graphite core precursor coated with cellulose fibers is heat-treated at high temperature in stages. The temperature of the first heat treatment is 200°C, keeping the air atmosphere, the heating rate is 2°C / min, and the holding time is 6h; the temperature of the second heat treatment is 600°...

Embodiment 2

[0034] The recovery, impurity removal and coating processes are the same as in Example 1.

[0035] High temperature heat treatment conditions: the temperature of the first heat treatment is 300 °C, maintaining an air atmosphere, the heating rate is 2 °C / min, and the holding time is 4 h; the temperature of the second heat treatment is 700 °C, maintaining an argon atmosphere, and the heating rate is 10 °C / min. , the holding time is 3h; the temperature of the third heat treatment is 1200°C, the heating rate is 5°C / min, and the holding time is 2h. Graphite material was prepared and used for later use.

[0036] The monolithic battery was assembled in the same manner as in Example 1, and the prepared graphite material and the assembled monolithic battery were tested in the same manner as in Example 1. The test results show that the coating layer of the graphite material prepared in this example has a double-layer structure, the graphite core is supported by the first coating layer ...

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Abstract

The invention discloses a graphite material and a preparation method and application thereof. The graphite material includes core-shell structure particles, and the core-shell structure particles include a graphite core, a first coating layer coated outside the graphite core core, and a second coating layer coated outside the first coating layer layer, the porosity of the first cladding layer is greater than the porosity of the second cladding layer. Utilizing the properties of graphite core precursors that expand and contract when heated at different temperatures, through multi-stage heat treatment, the surface of graphite core precursors is coated, forming a void ratio of the first coating layer that is greater than that of the second coating layer. graphite material. This coating method not only provides a flexible shell for the graphite core, but also uses the first coating layer with a large porosity to alleviate the volume expansion of graphite, while maintaining the structural stability of the graphite core and the second coating layer, and improving the structural stability of the graphite material. Improving the cycle performance of lithium-ion batteries also ensures the manufacturability of materials.

Description

technical field [0001] The invention belongs to the field of battery materials, and in particular relates to a graphite material and a preparation method and application thereof. Background technique [0002] The recycling of waste graphite electrode materials can realize the recycling of resources. However, after the battery is cycled for a long time, the interface of the graphite material is roughened and the SEI film is deposited. In addition, the interlayer co-intercalation of small molecular organic solvents will also lead to the degradation of graphite performance. , can not be directly reused in battery manufacturing. At present, the conventional graphite regeneration method is to first use a strong inorganic acid (H 2 SO 4 , HCl) to leaching the impurities deposited on the surface of graphite, and then carry out coating treatment to improve the interface properties of graphite. The cladding material is generally made of rigid carbon materials, and the structure is...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M4/36H01M4/583H01M10/0525
CPCH01M4/366H01M4/583H01M10/0525Y02E60/10
Inventor 刘可禄彭祖铃闫银贤
Owner CHINA AVIATION LITHIUM BATTERY RES INST CO LTD