Reversible High-Temperature Lithium–Chalcogenide Batteries Enabled by a Nonflammable Sulfonamide Deep Eutectic Electrolyte

Significant efforts have recently been dedicated to enhancing reversibility and safety of high-temperature lithium–chalcogenide batteries (LCBs) to address performance-limiting issues. However, bottlenecks in electrolyte design that severely constrain the utilization of active material and reversibility of a lithium anode at elevated temperatures have received little attention. Herein, we report a nonflammable sulfonamide deep eutectic electrolyte (SDEE) composed of N,N-dimethylmethanesulfonamide and lithium bis(trifluoromethanesulfonyl)imide for high-temperature LCBs. The SDEE exhibits good thermal stability, high lithium-ion transference number, and a wide electrochemical window. Additionally, SDEE facilitates the formation of a compact and uniform lithium deposition, leading to a much mitigated shuttle effect and improved reversibility of the lithium anode compared to an ether-based electrolyte. LCBs with an SDEE exhibit a low overcharging degree at 60 °C (8.4%) and a high specific capacity (∼1107 mAh g–1) at 328.2 mA g–1. This work offers a viable electrolyte design concept for safe batteries targeting elevated temperatures using high-capacity electrodes.