Negative electrode material and preparation method and application thereof

Abstract

The invention provides a negative electrode material and a preparation method and application thereof. The negative electrode material comprises a silicon-based material core and a carbon coating layer located on the surface of the silicon-based material core, and the carbon coating layer is a porous carbon coating layer. The preparation method comprises the following steps: (1) carrying out dry mixing on a silicon-based material and peach gum to obtain a mixture; and (2) mixing the mixture with a pore forming agent, and sintering in a mixed atmosphere of protective gas and hydrogen gas to obtain the negative electrode material. The peach gum and the silicon-based material are mixed, subjected to pore forming and carbonized, a porous carbon layer is formed on the surface of the silicon-based material, volume expansion of the silicon-based material is relieved, the conductivity of the silicon-based material is improved, meanwhile, a porous structure in the carbon layer provides a channel for transmission of lithium ions, the cycle performance of the battery at low temperature and normal temperature is improved, and the service life of the battery is prolonged. In addition, peach gum belongs to biomass and contains multiple elements such as P and S, and the cycle performance can be improved.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, and relates to a negative electrode material and a preparation method and application thereof. Background technique [0002] In recent years, with the rise of portable electronic communication equipment and new energy vehicles, the research and development of high-performance and high-capacity lithium-ion batteries is imminent. Compared with traditional graphite anode materials, silicon-based anode materials have extremely high theoretical specific capacity (4200mAh / g), occupying a great market advantage. [0003] However, a series of shortcomings such as volume expansion effect and poor conductivity of silicon-based anode materials limit their practical applications. At the same time, the poor intrinsic conductivity of the silicon-based material itself limits the diffusion rate of lithium ions, which affects the charge and discharge rate of the battery. [0004] CN106025243A A li...

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Problems solved by technology

However, the method of the above-mentioned literature only has a simple conductive polymer coating, and there is no pre-carbon coating layer, and no corresponding conductive additives are mixed in the polymer coating process. Although the conductive polymer has a certain ability to transport electrons, However, compared with traditional carbon-coated materials, the electron transport capability of conductive polymers is limited, which cannot meet the needs of high-rate charge and discharge of lithium-ion batteries. The expansion problem of the battery has been alleviated to a certain extent, and the stability and safety during the charging and discharging process have been improved. However, the conductive polymer mentioned in the patent has limited ability to transport lithium ions, and it is impossible to realize lithium ions in this type of battery. Fast transport in polymers, thereby affecting capacity development and rate performance of batteries

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