Ammonium vanadate doped by hydrated manganese divalent ions for high-performance zinc-ion batteries

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Vanadium-based materials are considered as promising cathode materials in aqueous zinc-ion (Zn 2+ ) batteries (AZIBs) because of their abundant valence states and adjustable ion diffusion channels. However, the slow kinetics of the Zn 2+ intercalation and the instability of the layered structure during long cycle are the bottlenecks restricting their further development. In this paper, the hydrated manganese divalent ions (Mn 2+ ) are introduced into ammonium vanadate (NH 4 V 4 O 10 ) to partly replace the NH 4 + ions to prepare a high-performance AZIB cathode. After doping hydrated Mn 2+ , the interlayer spacing of NH 4 V 4 O 10 is enlarged, providing a broadened channel for the diffusion of Zn 2+ accordingly. The results reveal that the electrode with the optimal doping quantity has a very high discharge capacity (539.4 mAh g −1 at 0.2 A g −1 ) and excellent cyclic stability (85.3% retention of the initial capacity after 3000 cycles at 5 A g −1 ). A highly competitive energy density of 378 Wh kg −1 at 362 W kg −1 is delivered by the corresponding AZIB. Moreover, this method is a general and effective strategy for developing high-performance AZIB cathode materials, as demonstrated by the consistent crystal structure and stable cycling properties for NH 4 V 4 O 10 doped with other transition bivalent metal cations.