Electrochemical performance enhancement of porous Si lithium-ion battery anode by integrating with optimized carbonaceous materials

Abstract

Silicon (Si) is regarded as a promising negative material for Li-ion batteries (LIBs), but the poor cyclic performance limits its practical applications. Herein, we used several different carbonaceous materials as carbon sources to form Si/C composites, which was formed by etched Fe–Si alloys followed by mechanical ball mill mixing with carbon. It is found that the artificial graphite as the carbonaceous material can form a well-distributed mixture during the ball milling, and then uniformly coated with amorphous carbon pyrolyzed by the phenolic resin. The pore structure of Si particles can provide rapid diffusion for lithium ions, resulting in improving the electrochemical properties. The well-coated carbon layer promotes the formation of stable SEI layer on the composites surface, which is advantageous for the long cycle performance. The carbonaceous materials (artificial graphite, flake graphite and soft carbon) have remarkable influence on the electrochemical performance of Si/C composites. The silicon/graphite-artificial graphite (Si/C-AG) exhibits the best performance among these three Si/C composites. It delivers a specific capacity of 445 mAh g-1 at 0.5 A g−1 with a retention of 94% after 200 cycles. This work would be helpful with choosing suitable carbonaceous materials for the Si/C composites.