Bismuth oxyformate microspheres assembled by ultrathin nanosheets as an efficient negative material for aqueous alkali battery.

A negative electrode with high capacity and rate capability is essential to match the capacity of a positive electrode and maximize the overall charge storage performance of an aqueous alkali battery (AAB). Due to the 3-electron redox reactions within a wide negative potential range, bismuth (Bi)-based compounds are recognized as efficient negative electrode materials. Herein, hierarchically structured bismuth oxyformate (BiOCOOH) assembled by ultrathin nanosheets was prepared by a solvothermal reaction for application as negative material for AAB. Given the efficient ion diffusion channels and sufficient exposure of the inner surface area, as well as the pronounced 3-electron redox activity of Bi species, the BiOCOOH electrode offered a high specific capacity (C _s , 229 ± 4 mAh g ^-1 at 1 A g ^-1 ) and superior rate capability (198 ± 6 mAh g ^-1 at 10 A g ^-1 ) within 0 ∼ -1 V. When pairing with the Ni ₃ S ₂ -MoS ₂ battery electrode, the AAB delivered a high energy density (E _cell , 217 mWh cm ^-2 at a power density (P _cell ) of 661 mW cm ^-2 ), showing the potential of such a novel BiOCOOH negative material in battery-type charge storage.
Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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