Abstract The widespread deployment of electrochemical capacitors in energy-intensive technologies is fundamentally limited by their low energy density and severe self-discharge. The search of high-voltage supercapacitors has the appeal of an effective solution to increase the energy density, but suffers from risk of electrolyte decomposition and self-discharge. We herein address this challenge through a synergistic electrode/electrolyte co-design that integrates a lignin-derived porous carbon electrode with a tailored Li + -based weakly solvating electrolyte containing a functional fluorinated diluent. The porous carbon features sub-nanometer pores that are geometrically matched to the weakly solvated Li + ions, enabling stable operation at an unprecedented 4.0 V with a high energy density of 77.4 Wh kg⁻ 1 and over 90% capacitance retention after 10,000 cycles. Mechanistic analysis reveals that the sub-nanometer pores precisely accommodate solvated ions to facilitate high capacitance, while the fluorinated diluent suppresses electrolyte degradation and mitigates parasitic reactions under elevated potentials. Graphical Abstract
Zhang et al. (Wed,) studied this question.