Water-Lubricated Intercalation in V<sub>2</sub> O<sub>5</sub> ·nH<sub>2</sub> O for High-Capacity and High-Rate Aqueous Rechargeable Zinc Batteries.

Yan, Mengyu; He, Pan; Chen, Ying; Wang, Shanyu; Wei, Qiulong; Zhao, Kangning; Xu, Xu; An, Qinyou et al. · Adv Mater · 2018

basic_science · Level V

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Abstract

Low-cost, environment-friendly aqueous Zn batteries have great potential for large-scale energy storage, but the intercalation of zinc ions in the cathode materials is challenging and complex. Herein, the critical role of structural H<sub>2</sub> O on Zn<sup>2+</sup> intercalation into bilayer V<sub>2</sub> O<sub>5</sub> ·nH<sub>2</sub> O is demonstrated. The results suggest that the H<sub>2</sub> O-solvated Zn<sup>2+</sup> possesses largely reduced effective charge and thus reduced electrostatic interactions with the V<sub>2</sub> O<sub>5</sub> framework, effectively promoting its diffusion. Benefited from the "lubricating" effect, the aqueous Zn battery shows a specific energy of ≈144 Wh kg<sup>-1</sup> at 0.3 A g<sup>-1</sup> . Meanwhile, it can maintain an energy density of 90 Wh kg<sup>-1</sup> at a high power density of 6.4 kW kg<sup>-1</sup> (based on the cathode and 200% Zn anode), making it a promising candidate for high-performance, low-cost, safe, and environment-friendly energy-storage devices.