N-Rich Solid Electrolyte Interface Constructed In Situ Via a Binder Strategy for Highly Stable Silicon Anode

Silicon (Si) is regarded as a promising anode material for high-energy-density lithium-ion batteries due to its high specific capacity (4200 mAh g⁻¹) and low potential (0.3 V vs Li⁺/Li). However, the large volume change (over 300%) of Si during the lithiation/delithiation process leads to severe pulverization, electrode structure destruction, and finally capacity fading, which slows down its step to practical application. Herein, a poly(vinylamine) (PVAm) binder containing amino ( NH₂) and amide ( NH CHO) is proposed to improve the stability of Si anodes from particle to electrode structure. The N-containing functional groups show strong interaction with the Si particles and form a uniform and thin layer on the surface, which would decompose and form an N-rich inorganic solid electrolyte interphase (SEI) layer during discharging. The high mechanical stability N-rich SEI helps relieve the pulverization of Si particles through stress dissipation, maintains electrode structural stability, and reduces the loss of active materials. Thus, the Si anode with PVAm binder exhibits high capacity of ≈2000 mAh g⁻¹ after 200 cycles, which is much higher than that of using Poly(vinylidene fluoride) (PVDF) binder (66 mAh g⁻¹) and Poly(vinyl alcohol) PVA binder (820 mAh g⁻¹). This facile and practical strategy provides a new perspective for the application of Si anodes in advanced batteries.