Building optimal SEI through control of morphology and chemical composition for high-performance lithium-ion batteries

Abstract

Recently, SiOx has attracted much attention as a promising anode material for high energy density lithium-ion batteries due to its high specific capacity. However, their long-term durability and storage performance is comparatively poor because of the continuous solid-electrolyte-interphase (SEI) growth. Until now, strategies to effectively improve cycling performance and rate capability by tailored SEIs remain largely unclear, especially in SiOx anodes. Here, we propose an optimal SEI with a unique morphology and chemical composition that are favorable to facilitate the transport of Li ions during the cycles. At first, we fabricated a pillar-type SEI using nanodiamond (ND) additives on the Ti-doped SiOx@C (Ti-SiOx@C) electrode, and the results demonstrated a significant improvement in the capacity retention in the full cell. Meanwhile, we prepared inorganic Li-N and LiF-rich SEIs with high ionic conductivity using octadecylamine (ODA) additives. Based on these results, we constructed the nanoscale pillar structure and inorganic Li-N and LiF-rich SEI with stable and superior ionic conductivity on the Ti-SiOx@C electrode using ND and ODA additives. As a result, the NCM-811||Ti-SiOx@C full cell with ND and ODA additives exhibits superior capacity retention of 91.0% at 1C after 500 cycles compared to the full cell with the baseline electrolyte (58.4%).