Regulating adhesion of solid-electrolyte interphase to silicon via covalent bonding strategy towards high Coulombic-efficiency anodes

Nanostructured silicon-based materials are the promising anodes for next-generation lithium-ion batteries. However, as the result of the weak adhesion of solid-electrolyte interphase (SEI) to Si, the fracture, exfoliation and subsequent regrowth of SEI layer on the expanded Si remains unsolved, leading to low initial Coulombic efficiency (ICE) (50–80%). Herein, the Ti‒Si covalent bond between nano-Si and MXene-derived artificial SEI layer is elaborately introduced, to effectively strengthen the interfacial stability and suppress the excessive interfacial side reaction. Upon the three-times expansion during first cycling, the as-obtained anodes with the ultrathin SEI still deliver a high ICE of 91.4%. Due to the stable interfacial ionic conduction, remarkable capacity retention of 90.7% after 1000 cycles at 5 A g −1 with an average Coulombic efficiency of 99.8% could be maintained. This strategy provides new insight into designing durable alloy anodes from the point of the interfacial adhesion strength .