Effect of Ce incorporation into carbon layer on the performance of silicon-carbon composite as anode for LIBs

Abstract

Volume expansion of silicon during lithiation limits its use as a commercial anode material. Carbon coating on silicon surfaces can buffer the phase change stress of silicon and enhance conductivity. In this work, the effect of the incorporation of rare earth element Ce in the carbon layer on the electrochemical properties of silicon-carbon composites was investigated. After mixing according to a particular procedure, cerium nitrate, micron silicon, and sodium alginate (SA) were calcined to obtain the silicon-carbon composite coated carbon layer incorporation Ce. The tests found that the incorporation of Ce into the carbon layer had the following effects on the performance of LIBs anode: (1) enhanced the toughness of the carbon layer and improved the cycle performance, (2) reduced the formation of SEI film and increased the first Coulombe efficiency (ICE), (3) boosted the lithium-ion conductivity of silicon-carbon composite and improved the rate capability. As a result, the electrochemical properties of Ce incorporated silicon-carbon composites (Si@C/CeO2) are significantly improved. The initial specific capacity of Si@C/CeO2 was 1848.6 mAh g-1, even micro silicon engendered strong phase change stress, still maintained 502.2 mAh g-1 after 180 cycles, and the ICE was higher than most of the silicon-carbon composites reported.