Adapting a Kinetics-Enhanced Carbon Nanostructure to Li/Na Hybrid Water-in-Salt Electrolyte for High-Energy Aqueous Supercapacitors

Wide-potential supercapacitor systems are highly anticipated to put aside the low-energy roadblock caused by the finite electrolysis voltage (1.23 V). However, poor electrolyte kinetics within the popular activated carbon electrodes usually downgrades the inherent high-power supply and long-cycle tolerance. To address this issue, multimodal porous carbon nanostructures are fabricated by the spontaneous cross-coupling between tetrachloro-1,4-benzoquinone (network joint) and four aromatic amines (chain motif) with varying bond dissociation energies, followed by temperature-programmed alkali thermolysis. The representative electrode with a broad ion-accessible platform (2539 m2 g–1) stands out by virtue of substantial electrosorption spaces (<1 nm micropores) and multi-level pore highways nested in open macroporous voids, enabling an instant ion-transport kinetics response (0.40 Ω s–0.5) and remarkable rate capability (80.4% capacitance retention up to 20 A g–1) in the H2SO4 electrolyte. Moreover, a LiOTf/NaOTf hybrid water-in-salt electrolyte is developed here to shift the water-splitting potential, wherein double Li+/Na+ cations can weaken strong Coulombic interactions for low migration barrier and dense interface accumulation. Consequently, the upgraded symmetric device using such concentrated aqueous medium, displays a boosted energy capacity of 39.2 Wh kg–1@550 W kg–1, an extraordinary power response of 22 kW kg–1 under high-energy delivery up to 28.2 Wh kg–1, and a durable service lifespan (85.5% energy retention over 10 000 successive cycles). This inspiring work provides structural insights for designing carbon electrodes adaptive to safe, wide-potential but kinetically sluggish electrolytes, realizing comprehensive energy-power improvements in supercapacitors.