Long Cycle Life Aqueous Rechargeable Battery Zn/Vanadium Hexacyanoferrate with H+/Zn2+ Coinsertion for High Capacity

Abstract Aqueous rechargeable ion batteries have drawn considerable interest owing to their high safety, low cost, and outstanding ionic conductivity. Herein, the vanadium hexacyanoferrate Prussian blue analogs (VO-PBAs) nanoparticles are prepared by a facile co-precipitation way to fully make use of the merits of VO2+/VO2+ and Fe(CN)6]4−/[Fe(CN)6]3− redox actives. Specifically, the as-fabricated Zn/VO-PBAs aqueous rechargeable battery achieves a high capacity of 209.6 mAh g−1 at 0.1 A g−1 due to the introduction of V = O bonds and obtains an excellent rate performance (129.0 mAh g−1 at 2 A g−1) due to the high proportion of pseudocapacitive contribution. Moreover, the conversion of the VO-PBAs nanoparticles to nanosheets during the initial activation process increases the electrochemical reaction active sites and promotes the fast electrolyte ions transport of the electrode materials. Meanwhile, the VO-PBAs cathode presents excellent cycle stability, which can retain 95.5% capacity after 2000 cycles at 1 A g−1. Besides, the electrochemical energy storage mechanism is involved with the co-insertion/extraction of the Zn2+/H+, and the VO-PBAs keeps the cubic phase during the charge/discharge process revealed by the in situ XRD. The synergistic effect of the Zn2+/H+ ions makes the excellent electrochemical performance of the Zn/VO-PBAs system and thus promotes the application of aqueous rechargeable ion batteries.