Formicarium-Like\nMicron Porous Si Synergistically\nAdjusted by Surface Hard–Soft Nanoencapsulation as Long-Life\nLithium-Ion Battery Anode

Micron porous silicon (MPSi) is a promising lithium-ion\nbattery\n(LIB) anode that can provide enough space to effectively alleviate\nthe volume expansion and large number of transmission channels to\nrapidly transport the Li-ions. However, a long-term stable MPSi anode\nat high current density is still a great challenge. Herein, a double-regulated\nformicarium like-MPSi composite using the surface hard–soft\ntitanium dioxide-few layered MXene nanotemplate (FMPSi@TiO<sub>2</sub>@FMXene) was designed and synthesized via an <i>in situ</i> assembly strategy as long-life LIB anode. Such hard–soft\nTiO<sub>2</sub>–FMXene nanoencapsulation can collaboratively\ntune the internal/external stress, inhibit the volume expansion, reduce\nthe interfacial reactions, and improve the electrical conductivity\nof MPSi, resulting in the great enhancement of structural stability\nand electrochemical performance in cycling even at high current density.\nEspecially, this FMPSi@TiO<sub>2</sub>@FMXene anode exhibits a high\nreversible capacity of 1254.9 and 970.4 mAh/g after 500 cycles at\n0.5 and 1 A/g, respectively. Moreover, a full cell is assembled with\nthe FMPSi@TiO<sub>2</sub>@FMXene anode and commercial LiFePO<sub>4</sub> (LFP) cathode, exhibiting a high capacity retention rate of 91.6%\nin 100 cycles. This work provides an effective surface nanoengineering\ntactic to obtain the structurally stable MPSi anodes by hard–soft\nnanotemplate for large-scale and long-term LIB application.