Building Powerful Zinc-Ion Hybrid Capacitors by an Energy Drink-Inspired Strategy

Numerous modification strategies have been proposed to enhance the performance of the Zn anode and carbon cathode in aqueous zinc-ion hybrid capacitors (ZIHCs). However, one efficient strategy to modify both the anode and cathode is still lacking. Herein, taurine (Tau), the key ingredient of energy drinks, is used as the electrolyte additive and carbon precursor for ZIHCs simultaneously. As the electrolyte additive, Tau achieves the preferential growth of Zn (002) plane by preferentially adsorbing on other crystal planes. Moreover, Tau accelerates Zn²⁺ transference kinetics by regulating the Zn²⁺ solvation structure and constructs a functional solid electrolyte interphase layer, enabling suppressed hydrogen evolution, inhibited corrosion reaction, and dendrite-free deposition. The Zn//Zn cells using the Tau-modified·ZnSO₄ electrolyte (Tau-ZSO) can stably work for 1000 h at 76.95% depth of discharge at room temperature and 5200 h at -10 °C. Meanwhile, the taurine-derived carbon (Tau-C) exhibits N, S heteroatom doping, hierarchical porous structure, and high specific surface area, which contributes to a high cathode capacity. By using the Tau-C cathode, limited Zn anode (10 µm), and the Tau-ZSO electrolyte, the assembled ZIHCs demonstrate reduced polarization and high discharge capacities (119.4 mA h g^-1 under 3 A g^-1 at room temperature and 80.0 mA h g^-1 under 1 A g^-1 at -10 °C) with high energy density of 101.1 Wh kg^-1 and long lifetime (operating stably over 2000 cycles).