PNNL

Abstract

The list of remaining challenges for the realization of rechargeable lithium (Li)-metal batteries (LMBs) is quite long, including severe safety issues, continuous electrolyte decomposition, and rapid consumption of Li. Essentially, most of these issues are related to the reactions occurring at the Li metal|liquid electrolyte interface, resulting in the formation of a passivation film (commonly referred to as solid electrolyte interphase, SEI), which determines ionic diffusion and the structural and morphological evolution of the Li metal electrode upon cycling. Herein, we provide a comprehensive overview about the spontaneous and operation-induced reactions at the Li metal|electrolyte interface, taking different perspectives. In fact, the instantaneous formation of a thin protective film of corrosion products at the Li surface that acts as a barrier to further chemical reactions with the electrolyte precedes the film reformation during subsequent electrochemical stripping/plating of Li in the course of battery operation. The intrinsic Li metal|electrolyte interface instability and the search for possible solutions to overcome the remaining challenges of LMBs are largely dominated by Li surface science, electrolyte chemistry and cell engineering, thus, highlighting the need for a highly complementary and interdisciplinary approach. Based on a summary of the most relevant parameters that determine the properties of the SEI, we conclude with a brief outlook towards the final target, the achievement of safe high-performance LMBs.