Ultra-Low 4.3 wt% Silicon Thermal Reducing Doped Porous Si@Moc as Highly Capable and Stable Li-Ion Battery Anode

Silicon is a promising anode material in lithium-ion batteries (LIBs) for its ultra-high theoretical capacity; however, its large volume expansion and low electrical conductivity trigger capacity degradation and poor stability. Herein, an ultra-low 4.2 wt% Si-doped porous MoC (p-Si@MoC) is constructed by a facile thermal reduction on a core-shelled precursor of ZnMo-hybrid zeolitic imidazole framework (HZIF-ZnMo) coated by tetraethyl orthosilicate (TEOS), delivering a high capacity and superior cycling stability (976.6 mAh g-1 after 250 cycles at 0.2 A g-1) in LIBs. The homogeneous distribution in the porous MoC matrix contributes to its maximum capacity utilization. Meanwhile, the porous substrate enhances Li ion transport kinetics and reduced the volume expansion of Si. The excellent electronic conductivity of p-Si@MoC is revealed by the density functional theory (DFT) calculations. The MoSi bonds formed by Si-doped in the MoC matrix are verified by X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS). Moreover, the in situ X-ray diffraction (in situ XRD) reveals the lithium storage mechanism. This work presents an excellent structural design and synthesis strategy for high-performance silicon-based anode materials. An ultra-low silicon loaded (4.3 wt%) porous MoC anode (p-Si@MoC) with porous structures is assembled, showing regulated homogeneous ion flux and enhanced Li+ transport kinetics. In p-Si@MoC, the homogeneous distribution of Si induces its maximum capacity utilization and delivers a high reversible lithium-ion storage capacity of 976.6 mAh g-1 at a current density of 0.2 A g-1 over 250 cycles.image