Formicarium-Like Micron Porous Si Synergistically Adjusted by Surface Hard–Soft Nanoencapsulation as Long-Life Lithium-Ion Battery Anode

Micron porous silicon (MPSi) is a promising lithium-ion battery (LIB) anode that can provide enough space to effectively alleviate the volume expansion and large number of transmission channels to rapidly transport the Li-ions. However, a long-term stable MPSi anode at high current density is still a great challenge. Herein, a double-regulated formicarium like-MPSi composite using the surface hard-soft titanium dioxide-few layered MXene nanotemplate (FMPSi@TiO₂@FMXene) was designed and synthesized via an <i>in situ</i> assembly strategy as long-life LIB anode. Such hard-soft TiO₂-FMXene nanoencapsulation can collaboratively tune the internal/external stress, inhibit the volume expansion, reduce the interfacial reactions, and improve the electrical conductivity of MPSi, resulting in the great enhancement of structural stability and electrochemical performance in cycling even at high current density. Especially, this FMPSi@TiO₂@FMXene anode exhibits a high reversible capacity of 1254.9 and 970.4 mAh/g after 500 cycles at 0.5 and 1 A/g, respectively. Moreover, a full cell is assembled with the FMPSi@TiO₂@FMXene anode and commercial LiFePO₄ (LFP) cathode, exhibiting a high capacity retention rate of 91.6% in 100 cycles. This work provides an effective surface nanoengineering tactic to obtain the structurally stable MPSi anodes by hard-soft nanotemplate for large-scale and long-term LIB application.