Preparation method of negative electrode material silicon-based material/polyaniline/graphene composite material, and product and application thereof

Abstract

The invention provides a preparation method of a negative electrode material silicon-based material / polyaniline / graphene composite material, and a product and an application thereof. The compounding of organic and inorganic materials is realized by coating a silicon-based material with conductive polymer polyaniline, the outer surface is coated with graphene oxide through polyelectrolyte modification, and then the graphene oxide is reduced by adopting hydrazine hydrate to obtain the silicon-based material / polyaniline / graphene composite material. The conductive polymer polyaniline in the intermediate layer is far superior to a carbon material in terms of mechanical toughness, and can better buffer the huge size change of silicon during charge and discharge processes. The graphene on the outer layer greatly increases the electrical conductivity of the system. The material integrates the advantages of high specific capacity of silicon, high toughness of polyaniline, good electrical conductivity of graphene and the like, has the advantages of excellent cycle and rate performance, maintains the specific capacity at 710 mAh g<-1> after 200 cycles under the current density of 500 mAh g<-1>, and can be widely used in the field of negative electrode materials for automotive power lithium batteries.

Description

technical field [0001] The invention relates to a preparation method, product and application of a negative electrode material silicon-based material / polyaniline / graphene composite material. It is mainly used in the field of silicon / carbon anode for automotive power lithium-ion batteries. Background technique [0002] As an energy storage device, lithium-ion batteries have the advantages of environmental friendliness, long life, and high energy density. They have been widely used in mobile electronic devices. At present, researchers are making every effort to increase the capacity of lithium-ion batteries to replace fuel engines. It is widely used in the field of pure electric vehicles. In order to meet the needs of pure electric vehicles on the cruising range, there is an urgent need for positive and negative electrode materials with high energy density. Silicon has a capacity of 4200 mAh g -1 Theoretical specific capacity, and abundant reserves on the earth, has become a...

AI Technical Summary

Problems solved by technology

[0003] There are three major disadvantages of silicon material alone as a negative electrode material: 1) The volume change is very drastic (up to 400% ， ), drastic changes in volume will lead to material powdering and falling off, which will lead to a sharp decline in battery capacity and shorten cycle life

2) Due to the huge volume change of Si during the cycle, the newly generated Si surface will be exposed to the electrolyte to continuously produce the SEI film, and the continuous growth and thickening of the SEI film will consume a large amount of lithium ions and electrolyte

3) Si is a semiconductor with a very low intrinsic carrier concentration and poor conductivity

These three shortcomings severely limit the application of silicon in negative electrodes. Some researchers modify silicon by carbon, that is, prepare silicon / carbon composite materials.

[0004] In actual research, it has been found that directly coating silicon materials with carbon will expand the volume of the carbon shell in the subsequent electrochemical reaction and lose the protection of the internal silicon.

Images