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Aqueous zinc‐ion batteries (AZIBs), which are low‐cost and environmentally friendly, have been regarded feasible for large‐scale energy storage. But the widespread application of AZIBs is hindered by lack of suitable cathode materials with high capacity and long cycle life. The zinc‐storage mechanisms, especially the formation of basic zinc salt (BZS), are still unclear. Here, Ag2V4O11 is developed as a cathode material for AZIBs, which delivers a specific capacity of 213 mA h g−1 and excellent cycling performance (93% capacity retention after 6000 cycles). The reversible formation/decomposition of BZS and reduction/oxidation of metallic Ag are ascertained during the insertion/extraction of Zn(H2O)62+. Remarkably, the phase composition of BZS in Zn(CF3SO3)2‐based electrolyte is identified first. The role of in situ formed Ag nanoparticles is simulated by employing the commercial Ag nanoparticles as an additive into the V2O5‐based electrodes. The introduction of Ag significantly improves the specific capacity (at least 50% improvement) and accordingly it is proposed that the pseudo‐Zn–air reaction (oxygen reduction reaction‐like redox reaction happens on material surface in a closed system) promotes the electrochemical performance of Ag2V4O11. This work reveals the BZS rather than unknown new phases on the electrode surface and puts forward a possible way in raising electrochemical properties by utilizing the pseudo‐Zn–air reaction. [ABSTRACT FROM AUTHOR]

Abstract Rechargeable aqueous zinc-ion batteries (ZIBs) are very promising energy storage systems owing to their low cost, high reliability, and high volumetric energy density; however, the stiff challenge for the progress of ZIBs is the lack of suitable materials that permit divalent ion-intercalation/deintercalation with fast kinetics, long cycling durations, and high rate capabilities. Herein, we demonstrate V 10 O 24 ·12H 2 O dendrites with a large interlayer spacing of 1.4 nm, fabricated through a simple hydrothermal method. The unique, open, and stable structure complemented by a mixed valence enables a satisfactory battery performance: a specific capacity of 164.5 mAh g−1, long-term cycling stability of 80.1% capacity retention after 3000 cycles, and high power density of 12247.8 W kg−1 at a high energy density of 88.5 Wh kg−1. This study provides a viable and attractive cathode material for practical ZIBs. [ABSTRACT FROM AUTHOR]