Improving the electrochemical performance of Si-based anodes by co-compositing LiF and double carbon layer composed of graphite and three-dimensional PM

Abstract

In order to improve the electrochemical performance of Si-based electrodes, Nano Si, lithium fluoride (LiF) and graphite (G) were combined with three-dimensional interconnected porous carbon nanosheets network embedded with multi-walled carbon nanotubes (PM). MWCNTs provide a good conductive path that promotes electron transport and maintains structural integrity. The three-dimensional interconnect structure of PM facilitates rapid electrical/ion transport and good electrolyte penetration. The intercalation of nano-Si in layered porous matrix effectively alleviated the serious volume expansion of Si during discharge/charge and prevent the pulverization of Si particles. The addition of LiF can compensated for the L+ consume in the formation of the SEI layers and enhanced the stability of SEI membrane. The electrochemical tests shown that the initial coulombic efficiency (ICE) of the SPM/G/7.5%LiF (SPMG-7.5%LiF) electrode reached approximately 75.2%. The capacity of the SPMG-7.5% LiF electrode hold 1057 mAh g−1 after 500 cycles with a coulombic efficiency (CE) of about 100%. The SPMG electrode exhibited a good rate performance and cycle performance.