Improved Silicon/Graphite Composite Anode for High-Energy Li-Ion Battery

Abstract

High-specific capacity of Silicon (~ reaching up to 3600 mAh/g corresponds to Li15Si4) and relatively higher lithiation potential (~0.4V Vs Li+; helpful in avoiding plating) makes it an ideal candidate for high-energy Li-ion batteries (LIBs). However, it is faced with severe issues like high crystallographic expansion (~320%), slow lithium diffusion, and high reactivity with electrolyte at higher SOCs. All of it leads to particle cracking, isolation, and electrode delamination resulting into poor cycle life performance. To harness the true potential of Silicon, we proposed an improvised Si/Gr composite anode balancing the high-specific capacity and cycle life. We investigated a novel binder formulation for Si-rich/Gr composite to enable high-specific capacity without compromising on life cycle. We demonstrated a robust and stable solid-electrolyte interface (SEI) formation by optimizing the electrolyte additive and formation protocol. Coupling our Si/Gr anode with high-energy Ni-rich cathode at appropriate capacity ratio (N/P) provides high-energy density (> 400 Wh/Kg) for LIBs.