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 y O x ) microparticles with stable structural evolution against Li uptake/release. The homogeneous distribution of magnesium silicate in SiMg y O 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 y O 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 y O x ‐graphite anode and LiNi 0.8 Co 0.15 Al 0.05 O 2 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.