Boosting initial Coulombic efficiency and cycling stability of SiO anodes via carbon-buffered prelithiation

Carbon layer acts as a thermal/reaction buffer to regulate prelithiation kinetics. • In-situ formed LixSiOy provide mechanical support and facilitate Li+ transport. • Carbon layer and LixSiOy synergy stabilize the interface structure of SiO@C/Li. • Carbon-buffered prelithiation builds SiO@C/Li anode with high ICE and good cycling. Silicon monoxide (SiO) is regarded as a high-capacity lithium-ion battery (LIB) anode. However, the severe volume expansion and low initial Coulombic efficiency (ICE) hinder its practical deployment. Herein, we report a two-step strategy combining chemical vapor deposition (CVD) carbon coating and LiH-mediated solid-phase prelithiation to regulate the phase evolution and grain growth of SiO. Comprehensive characterizations including XRD, 29 Si NMR, and HR-TEM confirm the successful fabrication of the SiO@C/Li composite with a well-controlled microstructure. The pre-deposited uniform amorphous carbon layer not only enhances electrical conductivity and buffers volume expansion but also acts as a reaction regulator to prevent localized overheating and grain coarsening during high-temperature prelithiation. In-situ formed lithium silicate phases during prelithiation further provide structural reinforcement and fast Li + transport pathways. The uniform carbon layer and in-situ formed lithium silicate phases synergistically promote a robust, LiF-rich SEI layer, effectively lowering interfacial charge-transfer resistance. The optimized SiO@C/Li electrode delivers a reversible capacity of 1418.5 mAh g -1 with an ICE of 91.38%. When paired with a commercial NCM811 cathode in a full cell, the cell exhibits an initial discharge capacity of 193.8 mAh g -1 and retains a capacity of 102.4mAh g -1 after 150 cycles at 0.5C. This work demonstrates that the synergistic design of carbon coating and controlled prelithiation is an effective approach to advance the practical application of SiO-based anodes. Download: Download high-res image (279KB) Download: Download full-size image