Cross-Talk in Si Full-Cell with Various Cathodes

Abstract

Crosstalk between cathode and anode in Li-ion batteries (LIBs) has been increasingly recognized in recent years as having a great impact on performance, safety and cycle life time. However, systemic understanding of crosstalk behavior in Si full cell with various cathode materials has not been studied. In this project, we investigated crosstalk behavior of a Si anode coupled with one of the following cathodes, LiCoO2 (LCO), LiNi0.5Mn0.3Co0.2 (NMC532), or LiFePO4 (LFP), in a full cell. For each system, we compared electrolyte decomposition products, solid electrolyte interface (SEI) chemistry, and degradation mechanisms of cells during cycling. From a very early stage of cycling, each system showed different crosstalk behavior, showing different electrolyte decomposition products and SEI chemistry on Si anodes. Especially, the SEI of the aged Si showed that decomposition of LiPF6 was more severe in the LCO/Si or the NMC532/Si cells than those containing LFP/Si. This can lead to an unstable SEI on Si anode, which can result in rapid degradation, such as significant Si pulverization and Li loss, in LCO/Si or NMC/Si system. Acknowledgment We gratefully acknowledge support from Brian Cunningham at the U. S. Department of Energy (DOE), Vehicle Technologies Office. The submitted manuscript has been created at Argonne National Laboratory. Argonne National Laboratory is operated for the DOE Office of Science by UChicago Argonne, LLC, under contract number DE-AC02-06CH11357.