Heated-to-Frozen Electrochemical Interphase Formation Strategy Enables Stable 4.5 V Li-Metal Batteries in Ether-Based Electrolyte

The formation of stable solid/cathode electrolyte interphases (SEI/CEI) is critical for high-performance alkali metal batteries. While existing research focuses on optimizing SEI/CEI chemistry through electrolyte design, this study introduces a temperature-modulated strategy to control both the chemistry and structure. By combining high-temperature precharging (accelerating Li+ coordination changes and anion decomposition kinetics) with low-temperature storage (reducing solubility of decomposition products), dense and stable interphases form on both electrodes. 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 0.5 C (1.5 mAh cm–2). The 1 Ah pouch cells with high-loading cathodes (3.5 mAh cm–2) retain 81.7% capacity after 110 cycles. This study not only offers an economical and efficient approach to enhance the cycling stability of high-voltage lithium metal batteries but also, more importantly, provides new insights into strategies for controlling the formation of SEI to improve the overall battery performance.