Enhancing Charging Efficiency with Lithium Silicate in Silicon Composite Anode Materials Through Lithiothermic Reduction Reaction Synthesis
K. Jeong, Sarwar Hossen, Md Tareq Rahman, Joon S. Shim, Dong‐Hee Lee, Hayk H. Nersisyan, Jong‐Hyeon Lee
Abstract
Abstract This study synthesizes silicon (Si) powders with lithium silicates including lithium orthosilicate (Li 4 SiO 4 ), lithium metasilicate (Li 2 SiO 3 ), and lithium disilicate (Li 2 Si 2 O 5 ), creating a composite structure of crystalline Si within a Li x Si y O z matrix through the lithiothermic reduction reaction (LTRR) process. The reduction of Li‐ion consumption of the anode is investigated by 1) initial solid electrolyte interphase (SEI) layer formation, 2) SEI layer formation in response to Si expansion‐induced damage, 3) trapping of Li ions at Si defects, and 4) side reactions during initial charge and discharge cycles. Si/Li x Si y O z electrode exhibits a specific capacity of 1522.2 mAh g −1 and an initial coulombic efficiency of 83.5%. The effect of the calendering process is observed, and a pressurization condition of 5000 kgf cm −2 or less is set, and the ICE is improved to 93.4%–96%. Si/Li x Si y O z electrodes outperform pure crystalline Si electrodes in specific capacity (7.3%), ICE (42%), and retention characteristics (17%). The integration of the Li x Si y O z matrix into Si anodes enhances Li‐ion transport and partially suppresses Si expansion. Additionally, the Si/Li x Si y O z electrode exhibits superior rate capability in the 0.2–1.6 A g −1 range.