H.F. Liu, F. Zhou *, Z.K. Zhang, H.D. Wang, H.Q. Liu, Z.H. Ren, E.D. Yang, Z.D. Ma, T.L. Chen, P. Das, C.D. Ma, A. Leng, S.H. Liao, X. Zhang, Y.B. An, C. Lian, Y.W. Ma, H.-M. Cheng * and Z.-S. Wu *

Energy & Environmental Science, 2026, accepted.

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.