Earth-abundant, low-cost raw micro-silicon enabled by mechanically strengthened binder for high-capacity and long-life battery electrode

Nano-structured silicon materials with high capacity, are currently being gradually commercialized and composited with graphite in high-energy batteries, although their fabrication cost is rather high. However, the low-cost micro-silicon materials are always criticized and discarded in batteries due to the severe particle-to-electrode crack and huge volume change. Herein, inspired by the human ligament, a cross-linked binder with greatly enhanced mechanical properties is designed and fabricated to stabilize micro-silicon anodes. This biomimetic polymer can not only act as flexible “fibrils” in ligament, to adapt the high-volume change of silicon anode; but also act as “proteoglycan” in ligament to firmly hold these flexible fibrils and proactively constrain stress concentration of silicon anode. The combination of “soft to hard” hierarchical structure would endow binders with excellent elasticity and toughness. The pure micro-Si (5∼10 μm) electrodes with PSB binder exhibit high initial coulombic efficiency (ICE) of 93.3 % and favorable reversible capacity of ∼1500 mAh g⁻¹ at 4000 mA g⁻¹ after 600 cycles. Furthermore, the PSB binder also enables the μSi/GR//NCM811 full cell with 91.4 % capacity retention over 200 cycles. This functional PSB binders provide inspiration for constructing μSi anodes with high-ICE, high reversible capacity, and long-cycling life.