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 SiOx microparticles, resulting in rapid performance fade. This work proposes to address the challenge by preparing in situ magnesium‐doped SiOx (SiMgyOx) microparticles with stable structural evolution against Li uptake/release. The homogeneous distribution of magnesium silicate in SiMgyOx 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 SiMgyOx 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 SiMgyOx‐graphite anode and LiNi0.8Co0.15Al0.05O2 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.

Ether solvents with superior reductive stability promise excellent interphasial stability with high‐capacity anodes while the limited oxidative resistance hinders their high‐voltage operation. Extending the intrinsic electrochemical stability of ether‐based electrolytes to construct stable‐cycling high‐energy‐density lithium‐ion batteries is challenging but rewarding. Herein, the anion‐solvent interactions were concerned as the key point to optimize the anodic stability of the ether‐based electrolytes and an optimized interphase was realized on both pure‐SiOx anodes and LiNi0.8Mn0.1Co0.1O2 cathodes. Specifically, the small‐anion‐size LiNO3 and tetrahydrofuran with high dipole moment to dielectric constant ratio realized strengthened anion‐solvent interactions, which enhance the oxidative stability of the electrolyte. The designed ether‐based electrolyte enabled a stable cycling performance over 500 cycles in pure‐SiOx||LiNi0.8Mn0.1Co0.1O2 full cell, demonstrating its superior practical prospects. This work provides new insight into the design of new electrolytes for emerging high‐energy density lithium‐ion batteries through the regulation of interactions between species in electrolytes.