Solid interfacial conversion based on fluorine-silicon reaction enables long-term cycling of full cells with silicon anode

Long-term cycling performance has been an unsolvable problem which cannot be circumvented for full cells based on Si anodes. The instability of Si surface is one of the most fundamental problems for it continuously consumes the limited active Li from the cathode. Herein, a robust, corrosion-resistant, eave-like interfacial layer is constructed via a solid interfacial conversion between cryolite (NAF) and SiOx layer on the Si surface. The rigid inorganic functional layer plays a positive role inhibiting the side reactions of electrolytes at the Si/electrolyte interface and accelerating Li+ transport. The optimized Si@NAF-C350 anode exhibits much improved electro-chemical properties. It is able to deliver a reversible capacity of 1387.4 mAh g  1 after 500 cycles. More importantly, the full cell based on this Si anode against NCM523 cathode exhibits a dramatic cycling enhancement compared to the state-of-the-art results reported in literature. A high reversible capacity 133.8 mAh g  1 is obtained after 300 cycles, showing the feasibility of the Si anode in terms of the practical application in real cells.

Automated summary

Long-term cycling performance remains a crucial challenge for Si-based full cells due to the instability of Si surface. A solid interfacial conversion between cryolite (NAF) and SiOx layer on the Si surface forms a robust and corrosion-resistant interfacial layer. The optimized Si@NAF-C350 anode demonstrates improved electro-chemical properties and delivers a reversible capacity of 1387.4 mAh g  1 after 500 cycles. The full cell based on this Si anode exhibits a significant cycling enhancement and achieves a high reversible capacity of 133.8 mAh g  1 after 300 cycles, demonstrating the feasibility of practical application.