Lithium ion batteries with enhanced electrochemical performance by using carbon-coated SiOx/Ag composites as anode material

Abstract

Silicon monoxide (SiOx, 0 < x < 2) is considered to be one of the most promising anode materials, due to its higher theoretical specific capacity relative to graphite and smaller volume expansion rate relative to silicon materials. However, SiOx anode material still has its own disadvantages such as poor conductivity. In view of this situation, the SiOx/Ag/C composite material was synthesized with self-selective electroless deposition and carbon-coated technology by using ball-milled SiOx. Through the synergistic effect of Ag nanoparticles and the carbon layer, the electronic conductivity and the lithium ion diffusion coefficient of the SiOx/Ag/C composite was improved and its volume expansion was inhibited. Thus the SiOx/Ag/C composite of layered structure holds an excellent cycling performance with the discharge specific capacity of 1102.7 mAh·g-1 after 150 cycles at current density of 0.5C (1C = 2.1 A g-1), which is 345.1 mAh·g-1 higher than the discharge capacity of SiOx/C, and the SiOx/Ag/C composite shows 403.2 mAh·g-1 higher capacity than that of as-ball-milled SiOx at 2 C by rate performance test.