Cross‐Coupled Macro‐Mesoporous Carbon Network toward Record High Energy‐Power Density Supercapacitor at 4 V

Abstract

AbstractIonic liquids (ILs) electrolyte hold tremendous potentials to develop high‐energy‐density electric double layer capacitor due to their wide voltage windows, but are severely plagued by the sluggish mass diffusion from high viscosity and large ion size, particularly over micropore‐dominated carbon electrodes. Exploiting the carbon electrode possessing high compatibility with ILs electrolyte remains a great challenge. Herein, an emerging 3D cross‐coupled macro‐mesoporous carbon network with ultrahigh specific surface area (SSA, 2872.2 m2 g−1), N‐self doping, small‐sized mesopores (2–4 nm) and macropores (50–150 nm) is designed via a facile, versatile, and ecofriendly salt‐template strategy from the NaNO3‐gelatin biopolymer aerogel, which shows great adaptability toward high energy power density used in 4 V EMIBF4 ILs (92 Wh kg−1 is achieved at 1 kW kg−1, and notably a record high energy density of 39 Wh kg−1 is retained even at an ultrahigh power density of 200 kW kg−1). The large energy density is ascribed to the plentiful ion‐available mesoporous active sites (Smeso/SSA = 86.6%, Vmeso/Vtotal = 92.1%), while the extraordinary power density is attributed to the synergistic effects from the suitable macro‐mesoporous ion‐diffusion channels, continuous conductive network, low oxygen content (2.24%) as well as good affinity to ILs.