Observation of combination displacement/intercalation reaction in aqueous zinc-ion battery

Rechargeable aqueous Zinc-ion batteries (ZIBs) are regarded as the promising battery chemistry in stationary grid energy storage applications. Exploration of new zinc storage mechanism concepts is a feasible way to achieve high energy/power density. Herein, for the first time, we demonstrate the combination displacement/intercalation (CDI) reaction mechanism in aqueous ZIBs, as an example in Zn/Ag0.4V2O5 system. Unlike the classical intercalation/deintercalation storage mechanism, the CDI reaction mechanism enables more Zn2+ ions insertion into the host structure in two different sites, i.e. most of Ag+ in Ag0.4V2O5 replaced by Zn2+, and classical intercalation of Zn2+ in Ag0.4V2O5 and Zn2(V3O8)2. Importantly, the in-situ generation of highly conductive Ag0 matrix within the electrode provides high electronic conductivity. As a result, the Ag0.4V2O5 cathode performs excellent rate capability as well as long-term cycling performance (stable capacity of 144 mA h g−1 after 4000 cycles at 20 A g−1).