Zincophilic Anionic Hydrogel Electrolyte with Interfacial Specific Adsorption of Solvation Structures for Durable Zinc Ion Hybrid Supercapacitors

Abstract

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).