Solvation Engineering Enables High‐Voltage Lithium Ion and Metal Batteries Operating Under −50 and 80 °C

Abstract Extreme temperatures (<‐20 °C or >50 °C) would seriously impair the performance of lithium batteries through deteriorating bulk ion transport and electrode interfaces. Here, a rational design of weak solvent and anti‐solvent combination is presented for wide‐temperature electrolytes. The weak solvent provides accelerated desolvation kinetics of Li⁺ around the anode region, while the anti‐solvent not only functions as an antifreeze agent for smooth ion migration at low temperatures but also interacts with the weak solvent to boost the formation of ionic aggregates. The weak and anti‐solvent electrolyte (WAE) exerts excellent compatibility with both lithium metal and graphite. Under −40 °C, Li anode delivers 98.5% Coulombic efficiency and graphite outputs capacity over 230 mAh g^‐1. Lithium‐ion/metal batteries by pairing graphite anode with LiCoO₂ cathode with a negative to positive capacity ratio of 0.75 can realize steady operation at −50 °C with an average coulombic efficiency of 99.9%. Lithium metal batteries with 4.2 mAh cm^‐2 high LiCoO₂ cathode loading and 50 µm thin lithium anode deliver 73.8% capacity output at −40 °C. Besides, the cells are stable up to 80 °C with an average coulombic efficiency of 99.7%. This research demonstrates a relatively loose Li⁺ solvation environment in WAE systems and provides wide‐temperature electrolyte for high‐performance lithium ion and metal batteries.