Control of Surface Chemistry and Electrochemical Performance of Carbon-coated Silicon Anode Using Silane-based Self-Assembly for Rechargeable Lithium Batteries

Silane-based self-assembly was employed for the surface modification of carbon-coated Si electrodes and their surface chemistry and electrochemical performance in battery electrolyte depending on the molecular structure of silanes was studied. IR spectroscopic analyses revealed that siloxane formed from silane-based self-assembly possessed Si-O-Si network on the electrode surface and high surface coverage siloxane induced the formation of a stable solid-electrolyte interphase (SEI) layer that was mainly composed of organic compounds with alkyl and carboxylate metal salt functionalities, and PF-containing inorganic species. Scanning electron microscopy imaging showed that particle cracking were effectively reduced on the carbon-coated Si when having high coverage siloxane and thickened SEI layer, delivering > 1480 mAh/g over 200 cycles with enhanced capacity retention 74% of the maximum discharge capacity, in contrast to a rapid capacity fade with low coverage siloxane.