Integrated lithium ion battery silicon/carbon negative electrode material and preparation method thereof

Abstract

The invention discloses an integrated lithium ion battery silicon / carbon negative electrode material and a preparation method thereof. In the integrated lithium ion battery silicon / carbon negative electrode material, silicon powder is used as a silicon source, pyrolytic carbon is used as a carbon matrix, and nanometer carbon is used as a reinforcement framework. A nanometer carbon material introduced into the structure design can form a favorable conductive network, meanwhile, the local stress brought by a volume effect of silicon during the charge-discharge process can be reduced by the nanometer carbon dispersed in the pyrolytic carbon matrix, the problems of electrode crack even pulverization is prevented, so that the integral structure is stabilized, and the novel negative electrode has relatively high specific capacity, excellent rate property and cycle performance.

Description

technical field [0001] The invention relates to an integrated lithium ion battery silicon / carbon negative electrode material and a preparation method thereof. Background technique [0002] Lithium-ion batteries have the characteristics of high energy density, convenient use, and no geographical restrictions. They have been widely used in consumer electronics such as mobile phones and computers, as well as vehicles such as electric vehicles. At present, many fields have put forward higher and higher requirements for the energy density of lithium-ion batteries, and the development of high-energy-density lithium-ion batteries urgently needs to find new negative electrode materials with high capacity, long life and safety and reliability. [0003] Silicon is a new type of lithium-ion battery anode material with great application potential, which can completely form Li with lithium at room temperature. 15 Si 4 Alloy, theoretical capacity up to 3590mA h g -1 , about ten times t...

AI Technical Summary

Problems solved by technology

However, the Li intercalation formed by the silicon anode material 15 Si 4 The phase volume expansion exceeds 300%, so repeated volume expansion and contraction will occur in the process of intercalation and delithiation, which will lead to the fragmentation of particles and the differentiation and cracking of electrodes, and cause the silicon material to lose good electrical conductivity with conductive additives and current collectors. touch

This volume effect also makes it difficult for silicon to form a stable solid electrolyte interface (SEI) film in the electrolyte.

Along with the destruction of the electrode structure, a new SEI film is continuously formed on the exposed silicon surface, resulting in the continuous thickening of the SEI film, hindering the entry and exit of ions and electrons, and exacerbating the corrosion of silicon and capacity fading

In addition, silicon is a semiconductor with poor conductivity, which also limits the direct use of pure-phase silicon as a negative electrode material for lithium-ion batteries.

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