L.K. Shi, X.X. Wang, R.J. Jiao, D.W. Lan, Y. Gao, Z.M. Lang, W.X. He, G.X. Jia, Z.-S. Wu, J.L. Cui * and K. Chen *

Journal of Energy Chemistry, 2025, accepted.

C/SiOx anode with higher capacity and lower lithiation potential has been recognized as a next-generation alternative to replace graphite for high-energy-density lithium-ion batteries. However, C/SiOx suffers from low initial Coulomb efficiency (ICE), which significantly hinders its practical application. Herein, we reported a straightforward iodine redox chemistry strategy to realize highly reversible Li storage behavior and remarkably enhances ICE of high-capaity C/SiOx anode toward long-life lithium-ion batteries. Specifically, I2 is introduced into porous C/SiOx via simple fumigation to synthesize their composite (C/SiOx@I), in which I2 can effectively inhibit the irreversible lithiation reactions of SiOx through redox reaction. Further, redox reaction intermediates of LiI3 and LiIO3 can inhibit the decomposition of electrolyte and LiPF6, thereby reducing the thickness of solid-electrolyte interphase film. Consequently, the obtained C/SiOx@I exhibits a considerable capacity of 1241 mAh g-1 with an improved ICE of 88.5% at 0.1 A g-1 and impressive cyclability, showing capacity retention of 95% after 700 cycles at 5.0 A g-1. Besides, the C/SiOx@I with a 12% addition ratio can greatly enhance capacity of graphite from 352 to 454 mAh g-1, with negligible impact on its ICE. This study opens a new avenue for developing high ICE in SiOx-based anodes for high-energy-density lithium-ion batteries.