Quantifying lithium loss in amorphous silicon thin-film anodes via titration-gas chromatography
Wurigumula Bao, Chengcheng Fang, Diyi Cheng, Yihui Zhang, Bingyu Lu, Darren H. S. Tan, Ryōsuke Shimizu, Bhagath Sreenarayanan, Shuang Bai, Weikang Li, Minghao Zhang, Ying Shirley Meng
Abstract
Silicon with a high theoretical capacity (3,579 mAh/g) is a promising anode candidate for lithium-ion batteries. However, commercialization is still impeded by low Coulombic efficiency, caused by solid electrolyte interphase (SEI) formation and trapped lithium (Li)-silicon (Si) alloy during repeated volume change. Quantifying capacity losses from each factor is crucial to formulate rational design strategies for further improvement. In this work, titration-gas chromatography and cryogenic transmission electron microscopy are applied to characterize the evolution of trapped Li-Si alloy and SEI growth in a silicon thin-film anode. It is found that continuous growth of the SEI is the dominant factor for lithium inventory loss during cycling, with only a marginal increase in trapped Li-Si alloy. This study offers a quantitative approach to differentiate Li in the SEI from trapped Li in Li-Si alloy through a silicon thin-film anode, providing unique insights into identifying critical bottlenecks for developing Si anodes.