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

Abstract

Ionic 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.