A Design Strategy of Lithium Orthosilicate Coating on Micro-Silicon for High Performance Lithium Storage

Micron-silicon possess dense morphology and high tap density, which can improve volume and area capacity while maintaining a large specific capacity. In addition, the cost of micron silicon is low, and compared to nano silicon, it has more potential for large-scale industrialization. However, micron-silicon will suffer huge volume expansion during the charge-discharge process, which causes the active material to fall off from the fluid collector, resulting in rapid capacity degradation; In addition, the edges and corners of micro-silicon are easy to crack the surface solid-electrolyte interface (SEI), resulting in the repeated generation of SEI, which further restricts the cyclic stability of the electrode. In this work, we added a lithium source to in-situ convert the silicon oxide on the surface of micron-silicon into lithium orthosilicate (Li₄SiO₄) protective layer. The lithium orthosilicate coating can not only effectively alleviate the volume expansion of the silicon anode during the charging and discharging process, but also effectively avoid the direct contact between the micron silicon and the electrolyte as a protective layer, which can reducing the surface side reaction of the electrode. The prepared electrode displays a high reversible specific capacity of 1075.3 mAh g^-1 after 100 cycles at 0.3C.