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Boosting Electrolytic MnO2-Zn Batteries by a Bromine Mediator
Xinhua Zheng1, Yongchao Wang2, Yan Xu1
1Department of Applied Chemistry, School of Chemistry and Materials Science, Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China.
Abstract:
An aqueous electrolytic MnO2-Zn battery with eye-catching Mn2+/MnO2 cathode chemistry has been attracting immense interest for next-generation energy storage devices due to its irreplaceable advantages. However, the limited MnO2 conductivity restricts its long service life at high areal capacities. Here, we report a high-performance electrolytic MnO2-Zn battery via a bromine redox mediator, to enhance its electrochemical performance. The MnO2/Br2-Zn battery displays a high discharge voltage of 1.98 V with a capacity of ∼5.8 mAh cm-2. It also shows an excellent rate performance of 20 C with a long-term stability of over 600 cycles. Furthermore, the scaled-up MnO2/Br2-Zn battery with a capacity of ∼950 mAh exhibits a stable 100 cycles with a practical cell energy density of ∼32.4 Wh kg-1 and an attractively low energy cost of below 15 US$ kWh-1. The design approach can be generalized to other electrodes and battery systems, thus opening up new possibilities for large-scale energy storage.
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