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As an emerging energy storage device, zinc ion hybrid supercapacitors (ZHSCs) have attracted wide interest because of their intrinsic safety, high energy/power densities, and long cycle life. However, problems of liquid leakage and zinc dendrite growth seriously hinder its widespread application. To solve the above problems, a gelatin/polyacrylamide/agarose/Zn(CF3SO3)2 hydrogel electrolyte (G/PAAm/AG/Zn(CF3SO3)2) was designed by constructing a multi-crosslinked network of physically crosslinked gelatin and agarose coupled with chemically crosslinked polyacrylamide. The tested results show that G/PAAm/AG/Zn(CF3SO3)2 can effectively prevent electrolyte leakage and inhibit zinc dendrite growth. Moreover, G/PAAm/AG/Zn(CF3SO3)2 possesses high ionic conductivity (2.64 S m−1), high tensile strength (72.4 kPa at 489.2%), and high compressive strength (164.5 kPa at 80%). Additionally, a highly connected porous carbon material (denoted as HSSPC) with high specific surface area (2930.9 m2 g−1) was synthesized, which exhibits a reversible capacity of 183.5 mA h g−1 and good cycling stability (the capacity remains at 96.6% after 10 000 cycles). More importantly, the quasi-solid-state ZHSC based on G/PAAm/AG/Zn(CF3SO3)2 and HSSPC delivers a high specific capacity (122.8 mA h g−1, 0.25 A g−1), high energy/power densities (96.1 Wh kg−1/14.4 kW kg−1), and good cycling stability (capacity retention can be maintained at 114.0% of the initial capacity after 14 000 cycles). [ABSTRACT FROM AUTHOR]

The rechargeable zinc ion hybrid supercapacitors (ZHSCs) are critically hindered by the low Coulombic efficiency and poor lifespan due to the continuous water‐induced side reactions and uncontrolled dendrite growth of the Zn anode. Herein, a zincophilic anionic hydrogel electrolyte (PSCA/Zn(OTf)2) is constructed by incorporating the dodecyl sulfate anions ((OSO3R)−) micelles to manipulate the solvation structures of Zn2+ cations via the moderate ion–ion coordination interactions for manipulating the Zn deposition behavior and interfacial chemistry on Zn electrode. Joint experimental and theoretical results show that the constructed solvated Zn2+ cations with the ionized (OSO3R)− electron donor significantly restrict the occurrence of adverse reactions (hydrogen evolution reactions). Concomitantly, the newly involved (OSO3R)− anions influence the adsorption configurations of solvated Zn2+ ions, which alter the electrocrystallization patterns for dendrite‐free growth and induce the oriented deposition for rapid reaction kinetics of Zn electrodes. As a proof of concept, the Zn||Zn symmetric cells with PSCA/Zn(OTf)2 exhibit high reversibility for deposition/stripping behavior with an extended long cycle span. Significantly, benefiting from the synergy of the modulatory electrolyte environment and the regulated adsorption configurations, a quasi‐solid‐state Zn||PSCA/Zn(OTf)2||N‐doped porous carbon material (NPC) ZHSC exhibits exceptional cycling stability for over 40 000 cycles with a low capacity decay (0.00027% per cycle). [ABSTRACT FROM AUTHOR]

[Display omitted] The lack of cathode materials with satisfactory Zn2+ storage capability substantially hinders the realization of high-performance aqueous zinc-ion hybrid capacitors (ZHCs). Herein, we propose a facile KMnO 4 template-assisted KOH activation strategy to prepare a novel oxygen-enriched hierarchically porous carbon (HPC-1-4). This strategy efficiently converts coal tar pitch (CTP) into a well-tuned carbon material with a large specific surface area of 3019 m2 g−1 and a high oxygen content of 9.20 at%, which is conducive to providing rich active sites, rapid charge transport, and appreciable pseudocapacitance for Zn-ion storage. Thus, the as-fabricated HPC-1-4-based aqueous ZHC exhibits prominent performance, including a high gravimetric capacity (206.7 mAh g−1 at 0.25 A g−1), a remarkable energy density (153.4 Wh kg−1 at 184.2 W kg−1), and an impressive power output (15240 W kg−1 at 63.5 Wh kg−1). In-depth ex-situ characterizations indicate that the excellent electrochemical properties of ZHCs are due to the synergistic effect of the Zn2+ adsorption mechanism and reversible chemisorption. In addition, the assembled quasi-solid-state device demonstrates excellent electrochemical stability of up to 100% capacity retention over 50000 cycles, accompanied with a desirable energy density of 115.6 Wh kg−1. The facile preparation method of converting CTP into carbonaceous functional materials has advanced the development of efficient and eco-friendly energy storage technologies. [ABSTRACT FROM AUTHOR]

Cathode materials with limited active sites to accommodate Zn2+ ions substantially hamper the development of high-performance aqueous Zn-ion hybrid capacitors (ZHCs). Thus, the dedicated design of cathode materials is pivotal for preparing high power/energy density ZHCs. Here, a hierarchically porous coal tar pitch-derived carbon (NPC) cathode with abundant N/O doping (8.7 and 2.4 at.%) was prepared via a template strategy combined with chemical activation. The engineered hierarchically porous framework with optimal pore size distribution facilitates rapid Zn2+ ion transport, provides numerous active sites, and guarantees high adsorption-site accessibility. Moreover, the N/O doping further improves the transmission kinetics and adsorption capability of Zn2+ ions. Therefore, the aqueous ZHCs assembled with the NPC cathode show a high capacity of 158.2 mAh g−1 at 0.25 A g−1 and remarkable rate performance with a capacity of 73.5 mAh g−1 at 15 A g−1. Impressively, the NPC-based flexible device exhibits significant cycling durability with a capacity retention rate of up to 96.8 % over 10000 cycles at 10 A g−1 and a preeminent energy density of up to 112.1 Wh kg−1 at 203.0 W kg−1. This work provides new insights to design advanced coal tar pitch-based carbon materials for superior ZHCs. [Display omitted] • A porous coal tar pitch-derived carbon (NPC) is prepared by a template strategy combined with chemical activation. • The well-modulated porosity and N/O co-doping in NPC promotes the adsorption/desorption process of Zn2+ ions. • Flexible NPC-based devices show excellent Zn-ion storage performance. [ABSTRACT FROM AUTHOR]