High-Power and Ultralong-Life Aqueous Zinc-Ion Hybrid Capacitors Based on Pseudocapacitive Charge Storage

Rechargeable aqueous zinc-ion hybrid capacitors and zinc-ion batteries are promising safe energy storage systems. In this study, amorphous RuO(2)·H(2)O for the first time was employed to achieve fast and ultralong-life Zn(2+) storage based on a pseudocapacitive storage mechanism. In the RuO(2)·H(2)O||Zn zinc-ion hybrid capacitors with Zn(CF(3)SO(3))(2) aqueous electrolyte, the RuO(2)·H(2)O cathode can reversibly store Zn(2+) in a voltage window of 0.4–1.6 V (vs. Zn/Zn(2+)), delivering a high discharge capacity of 122 mAh g(−1). In particular, the zinc-ion hybrid capacitors can be rapidly charged/discharged within 36 s with a very high power density of 16.74 kW kg(−1) and a high energy density of 82 Wh kg(−1). Besides, the zinc-ion hybrid capacitors demonstrate an ultralong cycle life (over 10,000 charge/discharge cycles). The kinetic analysis elucidates that the ultrafast Zn(2+) storage in the RuO(2)·H(2)O cathode originates from redox pseudocapacitive reactions. This work could greatly facilitate the development of high-power and safe electrochemical energy storage. [Image: see text] ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s40820-019-0328-3) contains supplementary material, which is available to authorized users.