Surface Modification of Micro-Silicon Anode for High-performance Lithium-Ion Batteries

Advanced lithium-ion batteries are urgently needed in consumer electronic products, electric vehicles, and energy storage, while the traditional carbonaceous anode materials with relatively low specific capacity gradually become difficult to meet the practical requirements in the market. Silicon-based anodes are considered one of the most promising alternatives in LIBs with high specific energy due to their considerable theoretical specific capacities. However, the large volume variation and severe surface parasitic reactions still limit the practical application of silicon anode. In this work, to suppress the surface side reactions and great volume changes, the electrochemical inert Li3PO4 is proposed to be coated as the physical barrier between the silicon and electrolyte. The as-coated micro-silicon has been successfully prepared via a facile spray drying method with a low-temperature thermal treatment. Li3PO4 coating layer with high shear modules can not only passivate the surface but also enable to suppression of the severe volumetric expansion and shrinkage of the silicon particle, thus enhancing the initial columbic efficiency and structural integrity of the silicon materials during long-term cycling. The optimized silicon anode with the proper amount of Li3PO4 displays a superior initial columbic efficiency higher than 90% and a highly reversible capacity of 1394 mAh g-1 after charging and discharging 200 times. It is hoped this work should shed light on the modification of high-capacity anode materials.