Nano silicon/carbon composite material, preparation method and lithium ion battery containing nano silicon/carbon composite material as negative electrode material

Abstract

The invention discloses a nano silicon / carbon composite material, a preparation method and a lithium ion battery comprising the same as a negative electrode material. The method comprises: 1) mixing nano silicon, a coupling agent, a conjugated diene, and an olefin monomer; 2) mixing the resulting mixture with water, an emulsifier, an initiator, and a co-surfactant, using a microemulsification method to prepare microemulsion, and using a microemulsion polymerization method to form a crosslinked polymer wrapping material on the surface of the nano silicon; and 3) performing demulsification and carbonization to obtain the nano silicon / carbon composite material. In the nano silicon / carbon composite material, a nano-silicon core and an amorphous conductive carbon layer are very tight and stableto combine, the disadvantages that a general carbon layer and a silicon material are not uniformly wrapped and not tightly combined are solved, the volume expansion of the silicon material during thecycle is suppressed, and the battery prepared from the composite material has excellent cycle performance, and has excellent rate performance and low volume expansion effect.

Description

Technical field [0001] The invention belongs to the application field of lithium ion battery negative electrode materials, and relates to a nano silicon-based composite material, a preparation method and application, and in particular to a nano silicon / carbon composite material, a preparation method and a lithium ion battery containing it as a negative electrode material. Background technique [0002] Lithium-ion batteries have been widely used in mobile terminals, digital products and portable mobile devices, electric vehicles and energy storage power stations because of their outstanding advantages such as high voltage, long cycle life, good safety performance, and fast charging. However, as the requirements for environmental protection and energy conservation have become more stringent, the new energy vehicle market has developed rapidly. At present, it is difficult for lithium-ion batteries to meet the long-term endurance requirements of new energy vehicles. Therefore, the dev...

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Problems solved by technology

Conventional solid-phase method, liquid-phase method, and impregnation method to form carbon coating can reduce the side reaction between silicon and electrolyte to a certain extent, and at the same time inhibit volume expansion, but there is uneven coating of carbon coating silicon, and the combination of materials The problem of poor force, which leads to poor long-term cycle performance of composite materials, excessive expansion, etc.

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