Lithiophilic SiO2 nanoparticle pillared MXene nanosheets for stable and dendrite-free lithium metal anodes

Abstract

Lithium metal has been recognized as a promising anode candidate for next-generation rechargeable batteries due to its low chemical potential and high specific capacity, yet it is plagued by poor cycling stability due to the uncontrolled growth of Li dendrites. Herein, we fabricate SiO₂ nanoparticle pillared MXene (Ti₃C₂T_x) composite films through a facile vacuum-assisted self-assembly method, which can serve as stable and dendrite-free Li metal anodes. The lithiophilic MXene can foster Li nucleation and growth, while the insulating SiO₂ nanoparticles acting as lithiophilic seeds further induce uniform Li nucleation and deposition. The SiO₂ nanoparticles also serve as supporting pillars between the MXene layers which facilitate Li ion transportation and minimize volume shrinkage during delithiation. Li is preferentially deposited into the interior of the MXene/SiO₂ composite film and the flat, dendrite-free, granular Li layer is formed on its surface. Under the synergistic effects of MXene and SiO₂, the MXene/SiO₂/Li anodes demonstrate low Li deposition overpotential, small voltage hysteresis, high coulombic efficiency and low charge transfer resistance. When coupled with an LiFePO₄ cathode, the full cell shows stable voltage polarization and good cyclability. Under fast charging, it retains high-rate capacity and remains stable for 320 cycles at 3C with negligible capacity decay, demonstrating its excellent rate performance.