Low-Temperature and Fast-Charging Lithium Metal Batteries Enabled by Solvent-Solvent Interaction Mediated Electrolyte

Lithium metal batteries utilizing lithium metal as the anode can achieve a greater energy density. However, it remains challenging to improve low-temperature performance and fast-charging features. Herein, we introduce an electrolyte solvation chemistry strategy to regulate the properties of ethylene carbonate (EC)-based electrolytes through intermolecular interactions, utilizing weakly solvated fluoroethylene carbonate (FEC) to replace EC, and incorporating the low-melting-point solvent 1,2-difluorobenzene (2FB) as a diluent. We identified that the intermolecular interaction between 2FB and solvent can facilitate Li⁺ desolvation and lower the freezing point of the electrolyte effectively. The resulting electrolyte enables the LiNi_0.8Co_0.1Mn_0.1O₂||Li cell to operate at -30 °C for more than 100 cycles while delivering a high capacity of 154 mAh g^-1 at 5.0C. We present a solvation structure and interfacial model to analyze the behavior of the formulated electrolyte composition, establishing a relationship with cell performance and also providing insights for the electrolyte design under extreme conditions.