Graphite negative electrode material and preparation method thereof, negative electrode plate and lithium ion battery

Abstract

The invention belongs to the technical field of lithium ion batteries and particularly relates to a graphite negative electrode material. The graphite negative electrode material comprises a natural graphite nodule base which is coated with oxide layers at a surface functional group position and a surface defect position, and the surfaces of the oxide layers and the surface, except for the oxide layer positions, of the natural graphite nodule base are coated with asphalt carbide layers or phenolic resin carbide layers. The invention further provides a preparation method of the graphite negative electrode material. The method includes steps: adopting an atomic layer deposition method for coating the surface of the natural graphite nodule base with the oxide layers, adding asphalt or phenolic resin, mixing and performing vacuum carbonizing and heat treatment. The invention further provides a negative electrode plate prepared from the graphite negative electrode material and a lithium ionbattery prepared from the negative electrode plate. The surface of the natural graphite nodule base is coated with the oxide layers only at the surface functional group position and the surface defect position, overall coating of the natural graphite surface is avoided, and ion deintercalation and electron export are less affected.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, and in particular relates to a graphite negative electrode material, a preparation method thereof, a negative pole piece and a lithium ion battery. Background technique [0002] At present, graphite is mainly used as the negative electrode material of lithium batteries, and graphite is divided into artificial graphite and natural graphite; artificial graphite has few surface functional groups and defects, so it has a good cycle life, but it is expensive and has low capacity; although natural graphite is cheap and has high capacity , but there are many surface functional groups and defects, which cause many side reactions with the organic electrolyte, so the cycle life is poor, and the battery is severely flattened, especially the cycle and storage capacity at high temperature is poor. In order to solve the problem of using natural graphite, the current main solution is to coat the s...

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Problems solved by technology

For example, the patent with the publication number CN101108918 obtains isotropic high softening point pitch by adding modification additives such as phosphorus and boron to the pitch for deep polymerization, and the graphite coated with it does not need to be pulverized, so that the natural graphite has a high Discharge capacity, coulombic efficiency and long cycle life, but the modified additives used cause a certain degree of corrosion to the equipment, requiring regular maintenance of the equipment, resulting in high production costs; the patent with the publication number CN103897714A uses cheap medium-temperature coal tar pitch Or petroleum asphalt to prepare the coating material of natural graphite, that is, high softening point isotropic asphalt, so as to achieve a high proportion of graphite coating, firstly oxidize the asphalt under vacuum negative pressure at low temperature, and then oxidize at high temperature, so as to obtain high The softening point is isotropic asphalt, the coated graphite is not bonded, and it is easy to handle; however, the coating of this method is not uniform, it is difficult to evenly cover all functional groups and defects on the graphite surface, and the coated carbon layer is not enough Dense, the electrolyte can still permeate through the coating layer to contact the graphite surface during charging and discharging, resulting in poor cycle life and high temperature performance of the battery, and severe battery gas

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