“Shooting three birds with one stone”: Bi-conductive and robust binder enabling low-cost micro-silicon anodes for high-rate and long-cycling operation

Abstract

High-capacity micro-sized Si-based (μSi) lithium-ion batteries confront notable challenges such as unstable bulk phase structure, thick solid electrolyte interface (SEI), and sluggish ion transport kinetics. In this study, we proposed a bi-conductive and robust binder to alleviate volume expansion, suppress repeated rupture and generation of SEI, and improve the electrochemical reaction kinetics of the μSi electrode. The binder was synthesized through thermal crosslinking of “hard” polyacrylic acid (PAA), “soft” polyvinyl alcohol (PVA) and conductive graphene (denoted as PPG). Utilizing extensive chemical and material characterizations, it has been demonstrated that the electrodes prepared with PPG binder and μSi (μSi-PPG) exhibit superior electrochemical reaction kinetics, highly complete electrode structure, dense and stable SEI during electrochemical cycling. The μSi-PPG electrodes exhibit superior electrochemical performance, with the high capacity of 1913.1 mAh g⁻¹ and capacity retention of 86.7 % at 1 C after 1000 cycles. More importantly, the μSi-PPG electrode presents an ultra-high capacity of 1451 mAh g⁻¹ at 5 C. The design concept of this bi-conductive and robust binder provides a new guidance scheme for achieving long-cycling life and high rate performance in high-volume-strain electrode materials.