Micrometer-Sized SiMgyOx with Stable Internal Structure Evolution for High-Performance Li-Ion Battery Anodes

Abstract

In recent years, micrometer-sized Si-based anode materials have attracted intensive attention in the pursuit of energy-storage systems with high energy and low cost. However, the significant volume variation during repeated electrochemical (de)alloying processes will seriously damage the bulk structure of SiO_x microparticles, resulting in rapid performance fade. This work proposes to address the challenge by preparing in situ magnesium-doped SiO_x (SiMg_yO_x) microparticles with stable structural evolution against Li uptake/release. The homogeneous distribution of magnesium silicate in SiMg_yO_x contributes to building a bonding network inside the particle so that it raises the modulus of lithiated state and restrains the internal cracks due to electrochemical agglomeration of nano-Si. The prepared micrometer-sized SiMg_yO_x anode shows high reversible capacities, stable cycling performance, and low electrode expansion at high areal mass loading. A 21700 cylindrical-type cell based on the SiMg_yO_x-graphite anode and LiNi_0.8Co_0.15Al_0.05O₂ cathode demonstrates a 1000-cycle operation life using industry-recognized electrochemical test procedures, which meets the practical storage requirements for consumer electronics and electric vehicles. This work provides insights on the reasonable structural design of micrometer-sized alloying anode materials toward realization of high-performance Li-ion batteries.