Investigating transition metal crosstalk on SEI stability as a function of anode chemistry

Abstract

This study explores the effects of transition metal (TM) ions—Ni, Co, Mn, and Fe—on the solid-electrolyte interphase (SEI) formation and electrochemical behavior of graphite and silicon (Si) anodes in lithium-ion batteries (LIBs). Graphite anodes accumulate significantly more TM ions due to their higher electronic conductivity, which accelerates the hydrolysis of LiPF₆ salt during SEI formation, resulting in a less stable SEI and reduced cycle life. Si anodes, on the other hand, exhibit lower TM ion deposition, but TM ions promote the formation of an organic-rich SEI in the inner layer and accelerate LiPF₆ hydrolysis in the outer layer, increasing parasitic reactions and potentially shortening calendar life. Among the TM ions, Mn—though often regarded as particularly harmful—was found to be less detrimental than Ni and Co. Overall, the study demonstrates that the influence of TM crosstalk is highly dependent on both the anode material and the specific TM ions involved. These findings underscore the importance of tailoring strategies to mitigate TM ion effects in order to improve SEI stability and enhance the electrochemical performance of LIBs, which is essential for the development of high-performance, next-generation LIBs.