Heated-to-Frozen Electrochemical Interphases Formation Strategy Enables Stable 4.5 V Li-metal Batteries in Ether-based Electrolyte

Formation of stable electrochemical interphases, including solid electrolyte interphase (SEI) and cathode electrolyte interphase (CEI) is crucial for developing high performance alkali metal batteries. The stability of SEI/CEI mainly depends on their chemistry and structure. Current studies on SEI/CEI design mainly focus on regulating their chemistry by tuning electrolyte formulations. In this work, we showcase that both the chemistry and structure of SEI/CEI could be readily regulated via a temperature modulated formation strategy. Specifically, pre-charging under heated condition was used to regulate the types and kinetics of electrolyte decomposition reactions, followed by frozen at low-temperature storage to control the deposition behavior of decomposition products on the electrode interface. Studies show that high temperatures pre-charging can affect the coordination structure of Li+ and accelerate the decomposition reaction kinetics, leading to large amount of anion decomposition. The subsequent low-temperature storage rapidly reduces the solubility of decomposition products generated at high temperatures, promoting the deposition of insoluble products on both electrodes, resulting in a dense and stable SEI/CEI. The robust SEI/CEI enables stable cycling of a 4.5 V Li||NCM811 cell in a medium-concentration ether-based electrolyte, achieving a capacity retention of 88.7% after 200 cycles at 0.5C (areal capacity 1.5 mAh cm-2). Even under practical conditions with a high NCM811 areal loading of 4.5 mAh cm-2, the battery maintained over 80% capacity retention after 130 cycles at 0.5C. This study not only offers an economical and efficient approach to enhance the cycling stability of high-voltage lithium metal batteries but, more importantly, provides new insights into strategies for controlling the formation of SEI to improve overall battery performance.