High-conductivity silicon-oxygen negative electrode material and application thereof

Abstract

The invention provides a high-conductivity silicon-oxygen negative electrode material which comprises a silicon-based inner core and a coating layer formed on a surface of the silicon-based inner core. The coating layer comprises carbon and a fast ion conductor, and the fast ion conductor forms a complete ion transmission channel on the coating layer, is directly connected with the silicon-based inner core and extends to the surface of the coating layer. The fast ion conductor forms the complete ion channel in the coating layer so that the silicon-oxygen negative electrode material can give consideration to both electron conductivity and ion conductivity, meanwhile, an SEI film is stabilized, and a capacity and electrochemical performance of the material are effectively improved.

Description

technical field [0001] The invention belongs to the field of battery electrode materials, and in particular relates to a high-conductivity silicon-oxygen negative electrode material and its application. Background technique [0002] With the gradual increase in power consumption of consumer electronics such as mobile phones, and the requirements of electric vehicles for cruising range, lithium-ion batteries are forced to pursue higher energy density. At present, the commercialized anode materials are mainly graphite materials, whose specific capacity is close to the theoretical value (372mAh / g), and there is an urgent need for anode materials with higher specific capacity. Silicon-based anode materials have become recognized as the next-generation anode materials because of their extremely high specific capacity (3580mAh / g), low potential for lithium extraction and extraction, abundant reserves, and non-toxic and harmless. However, the large volume expansion (over 300%), un...

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Problems solved by technology

However, since the fast ion conductor is located in the inner layer, it is difficult to achieve the above effect

Patent application CN109119617A also adopts double-layer coating, the first coating layer includes a two-dimensional quinone aldehyde covalent organic framework material, and the second coating layer includes a fast-conducting ion material to improve the electronic and ion conduction of the coating layer effect and alleviate the volume expansion, but the fast ion conductor layer is located in the outer layer, which still cannot solve the problem of lithium ion conduction in the silicon-based inner layer

Patent application CN108493428A forms a dense and uniform coating layer on the surface of silicon-carbon materials by designing fast-ion lithium salt coating, which not only effectively reduces the side reactions on the surface of silicon-carbon materials, but also effectively inhibits the expansion of silicon-carbon materials At the same time, the rate performance of the material is improved, but the dense coating leads to poor electronic conductivity, thereby reducing the performance of the material

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