Importance of Temperature-Dependent Formation of the Solid-Electrolyte Interphase for Stable Lithium Metal Batteries with Elastomeric Electrolytes

Abstract

The construction of a robust and Li+ conductive solid electrolyte interphase (SEI) is crucial for stable cycling in lithium metal batteries (LMBs). Here, we demonstrate that a formation cycle protocol (i.e., temperature) is critical in determining the SEI properties and, thus, the performance of LMBs with elastomeric electrolytes at different operation temperatures, including low temperature conditions. The SEI generated at low temperature (0°C) significantly reduces interfacial resistance by approximately ten times compared to that formed at 25°C, facilitating efficient Li+ transport and uniform Li deposition. As a result, Li||LiNi0.8Co0.1Mn0.1O2 cells formation-cycled at 0°C retain 89.7% of their initial capacity after 100 cycles at −10°C. They also exhibit stable performance under ambient conditions (25°C). We reveal that superior LMB performance formation-cycled at 0°C is due to the fluorinated polymer-induced LiF as well as highly Li+ conductive species such as Li2CO3/Li3N, which is confirmed through combined experiments and multiscale molecular simulations. These results highlight the important roles of fluorinated elastomeric electrolytes and formation cycle protocol in producing a robust, highly Li+ conductive SEI, thereby enhancing the cycling performance of LMBs across a wide temperature range.