High-energy-density aqueous zinc-based hybrid supercapacitor-battery with uniform zinc deposition achieved by multifunctional decoupled additive

Aqueous Zn-based hybrid supercapacitors (ZHSs) are promising energy storage devices, benefiting from their safety, high power density, low-cost and environmental benignity. However, the major issues of Zn dendrites low density severely hinder further rapid development. Herein, a multifunctional decoupled additive, 1-methyl-1-ethyl pyrrolidinium bromide (MEP?Br), is proposed to update traditional ZHS supercapacitor-battery (ZHSB) with higher density. Thanks merits uniform deposition induced by MEP+, reduced polarization derived alteration solvation structure Br?, increased capacity electrochemical reversible reaction Br2/Br?, fixation charged Br2-containing species in cathode realized robust complexation MEP?Br, compared ZHS, ZHSB MEP?Br demonstrates much average 383.2 W h kg?1 (265.8 mAh g?1) long-term cycling durability (over 5000 cycles) at 16.8 kW (10 A g?1). Interestingly, even an ultrahigh current 20 g?1, can still deliver specific 252.4 g?1 (about three times than that ZHS). This work provides new option for next generation technologies.