Silicon-carbon composite material, preparation method thereof and lithium ion battery

Abstract

The embodiment of the invention provides a silicon-carbon composite material, which comprises an inner core and a carbon layer coated on the surface of the inner core, wherein the inner core comprisesa graphite skeleton, amorphous carbon filled in the graphite skeleton structure, and a silicon material uniformly distributed in the amorphous carbon, the silicon-carbon composite material only has apore structure with a pore diameter of less than or equal to 50nm inside, and a pore structure with the pore diameter of greater than 50nm does not exist. The silicon-carbon composite material is small in internal pore size, the contact area of the silicon material and electrolyte can be effectively reduced, side reactions are reduced, and the service life of a battery is prolonged; and meanwhile, the silicon material is uniformly dispersed around the graphite skeleton without agglomeration, so that the volume expansion and shrinkage of the silicon material can be effectively relieved by thegraphite skeleton, and the structural stability and energy density of the composite material are improved. The embodiment of the invention also provides a preparation method of the silicon-carbon composite material and a lithium ion battery containing the silicon-carbon composite material.

Description

technical field [0001] The embodiments of the present invention relate to the technical field of lithium-ion batteries, in particular to a silicon-carbon composite material, a preparation method thereof, and a lithium-ion battery. Background technique [0002] Graphite has been the mainstream anode material for lithium-ion batteries since the early 1990s. However, the current commercial high-quality graphite has a specific capacity of 360mAh / g, which is close to its theoretical value of 372mAh / g. The energy density in full batteries has reached the ceiling, which cannot meet the needs of various consumer electronic devices, especially energy storage devices and electric vehicles. Automobile requirements for energy density. Therefore, it is urgent to find a high energy density anode material that can replace graphite. [0003] Silicon-based materials are currently one of the most researched anode materials that can replace graphite. According to different reaction depths, ...

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Problems solved by technology

[0005] In view of this, the embodiment of the present invention provides a silicon-carbon composite material, with graphite as the skeleton, and the silicon material is uniformly dispersed between the gaps of the graphite skeleton through amorphous carbon, and the pores inside the material are controlled to have no pores with a size greater than 50nm, so as to achieve a certain degree of Solve the problem of uneven dispersion of nano-silicon in the existing silicon-carbon composite materials and large internal pores, resulting in low structural stability of the composite material and prone to side reactions

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