An electric double-layer capacitor with high performance at −80 °C

Abstract

Electric double-layer capacitors (EDLCs) with a high energy density for ultralow-temperature use are crucial for polar and space explorations, but hindered by the lack of suitable electrolytes and electrodes. We proposed a strong–weak interaction strategy to precisely regulate the solvation structure of an ionic liquid-based electrolyte that is stable from 25 to −80 °C. Then, by using activated carbon with a mesopore-rich structure, we obtain an EDLC that can be used at −80 °C and 4.5 V and has a record energy density of 104.5 Wh kg⁻¹ with an 89.5% capacitance retention after 10 000 cycles. Furthermore, a 300 F pouch-type EDLC was assembled and it can operate stably from 25 to −80 °C, demonstrating the practical applicability. This study provides strategic guidance for constructing EDLCs with a high energy density for use under extreme conditions.