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

Abstract

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.

Ultrahigh‐areal‐capacitance aqueous supercapacitors enabled by soft biomass‐derived porous carbon membrane

“…As indicated by the Ragone plots in Figure 6F, the PECM-800-based SC presents enhanced areal energy densities of 0.24 to 0.09 mWh cm À2 at power densities of 5.20 to 51.9 mW cm À2 in the potential window of 0 to 1.3 V, which is much higher than those obtained in the potential window of 0 to 1 V. The electrochemical performance of SC based on our PECM electrode is comparable to those of SCs based on powdery/self-supported carbon materials. [45][46][47][48][49][50][51][52][53][54][55][56] Furthermore, a "NMU" logo molded by 124 red light-emitting diodes (2.0 V) can be powered by a tandem device of two PECM-800-based SCs and maintains the lighting at least 10 seconds (Inset of Figure 6F and Video S2). This further demonstrates the superiority of PECM materials as self-supported electrodes in the applications of practical energy storage and utilization devices.…”

Promising activated carbon derived from sugarcane tip as electrode material for high-performance supercapacitors

“…Moreover, a wide peak could be observed in the voltage range of −0.8 to −0.3 V, which is due to pseudo-capacitance from the faradaic processes of the C O, N-5, and N-6 functional groups on the electrode surface. 39 Fig. 4b shows the CV curves for the ACST-2 electrode at various scan rates.…”

Diethanolamine-Assisted Preparation of Reed Flower-Derived Nitrogen-Doped Porous Carbon for Supercapacitor Electrodes

“…The resultant large SSA may increase the contact area between the electrolyte and the electrode materials, and the presence of extensive micropores may greatly benefit the charge storage, hence improving the supercapacitive performance of the carbon materials . Meanwhile, the appreciable meso/macropores facilitate electrolyte diffusion and maximize the utilization of the surface area . The assisted pore-forming characteristic of DEA is probably attributed to its good wettability that can improve the hydrophilicity of the hollow fibers .…”