Stable Aqueous Zn-Ag And Zn-Polyoxometalate Hybrid Battery Driven By Successive Ag+ Cation And Polyoxoanion Redox Reactions

Y Hybrid batteries with multiple electrochemical reactions that integrate respective advantages and remedy intricate shortages of disparate batteries are both fundamentally interesting and practically attractive. Here, an aqueous hybrid battery combining electrochemical features of Zn-Ag battery and Zn-POM battery is for the first time proposed, which is actuated by successive Ag+ cation and polyoxoanion redox reactions in an insoluble polyoxometalate (POM)-based cathode. The unique POM-based composite material constructed from loose stacking high-nuclearity polyoxovanadate clusters and crystalline Ag nanoparticles not only provides plentiful Zn2+ storage sites but also presents fast ion / electron diffusion kinetics. Meanwhile, both the severe migration of Ag+ ions and the dissolution of POM clusters in aqueous electrolyte are effectively inhibited. The as-fabricated hybrid battery with POM-based cathode exhibits a reversible capacity of 200 mAh g(-1) at 10 A g(-1) with outstanding capacity retention (97.4% over 7000 cycles) and superior rate capability. Moreover, the stable hybrid energy storage mechanism is revealed in detail. The work presents a promising strategy for the application of POM-based electrode in aqueous batteries and provides heuristic thinking for further developing novel energy storage systems.