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Boosting Electrolytic MnO 2 -Zn Batteries by a Bromine Mediator.

Authors :: Zheng X
Wang Y
Xu Y
Ahmad T
Yuan Y
Sun J
Luo R
Wang M
Chuai M
Chen N
Jiang T
Liu S
Chen W
Source :: Nano letters [Nano Lett] 2021 Oct 27; Vol. 21 (20), pp. 8863-8871. Date of Electronic Publication: 2021 Oct 11.
Publication Year :: 2021
Abstract: An aqueous electrolytic MnO <subscript>2</subscript> -Zn battery with eye-catching Mn <superscript>2+</superscript> /MnO <subscript>2</subscript> cathode chemistry has been attracting immense interest for next-generation energy storage devices due to its irreplaceable advantages. However, the limited MnO <subscript>2</subscript> conductivity restricts its long service life at high areal capacities. Here, we report a high-performance electrolytic MnO <subscript>2</subscript> -Zn battery via a bromine redox mediator, to enhance its electrochemical performance. The MnO <subscript>2</subscript> /Br <subscript>2</subscript> -Zn battery displays a high discharge voltage of 1.98 V with a capacity of ∼5.8 mAh cm <superscript>-2</superscript> . It also shows an excellent rate performance of 20 C with a long-term stability of over 600 cycles. Furthermore, the scaled-up MnO <subscript>2</subscript> /Br <subscript>2</subscript> -Zn battery with a capacity of ∼950 mAh exhibits a stable 100 cycles with a practical cell energy density of ∼32.4 Wh kg <superscript>-1</superscript> and an attractively low energy cost of below 15 US$ kWh <superscript>-1</superscript> . The design approach can be generalized to other electrodes and battery systems, thus opening up new possibilities for large-scale energy storage.