A Scalable and Effective Strategy for Boosting the Initial Coulombic Efficiency of Silicon Suboxide Anode

Silicon suboxide (SiO_x) is one of the most attractive candidates for anode materials for high-energy-density lithium-ion batteries due to its high specific capacity and its relatively lower volume expansion than that of Si. However, its low initial Coulombic efficiency (ICE) seriously affects its practical applications. In this work, we demonstrate a scalable and effective strategy to enable a high ICE of the SiO_x electrode through a MnO-assisted disproportionation reaction. The obtained Mn₂SiO₄–Si–SiO_x@C (MSS@C) material shows a reduced lithium irreversible consumption in the first cycle. The Mn₂SiO₄ phase can store lithium through a conversion reaction with a smaller volume change (33%) than SiO_x, which helps to maintain the structural stability of MSS@C during cycling. Meanwhile, the metallic Mn nanoparticles generated from Mn₂SiO₄ during the lithiation process facilitate electron conduction, thus improving the electrode reaction kinetics. Owing to the synergetic effects, the MSS@C material exhibits a higher ICE (79.51%) compared to 60.91% of pure SiO_x, and a superior cyclic performance (832 mAh g⁻¹ at 0.5 A g⁻¹ after 350 cycles with a capacity retention of 90.4%). This work offers a new approach to increase the ICE while improving the electrode reaction kinetics and cycling stability of SiO_x-based materials.