Dalian Chemical Institute has developed a high-energy density manganese-based hybrid single-flow battery

Recently, Li Xianxian, a researcher at the Energy Storage Technology Research Department of Dalian Institute of Chemical Physics, Chinese Academy of Sciences, developed a hybrid flow battery based on ^Br-assisted _MnO2 discharge, which has the advantages of
high energy density and high reversibility.

Flow batteries (FBs) have the advantages of high safety, long life and high efficiency, and have received widespread attention
in the field of large-scale energy storage.
At present, the energy density of flow batteries is low, and further development is hindered
.
Mn²+/Mn³⁺ has the advantages of high electrode potential, high solubility, good electrochemical kinetics and low cost, and has a good application prospect
in high energy density flow batteries.
However, the disproportionation side reaction of the oxidized state Mn³⁺ can easily lead to the accumulation of "dead manganese", which affects the energy density, reversibility and cycle stability
of the battery.

The research team introduced Br^-
into the acidic electrolyte of Mn²⁺.
During charging, two electrochemical processes, Br^-/_{Br 2} (1.
08V vs.
SHE) and Mn 2+/Mn 3+ (1.
56V vs.
SHE), occur sequentially on the electrode, accompanied by a disproportionation side reaction
from ^{Mn 3+} to_MnO2.
During discharge, the undismutated Mn3+ and part of_MnO2 are reduced to^Mn2+
on the electrode surface.
Subsequently, part of Br 2 is reduced to Br- and can chemically react with the remaining_MnO2 on the electrode to generate_{Br 2} to continue to participate in the discharge, and the reversibility of the charge-discharge process is improved by ^{chemical-electrochemical} discharge.

Based on the above design, the whole battery (BMFB) assembled with Cd/^{Cd 2+} as the negative electrode can run stably for more than 500 times at 80mA/cm², and the energy density of the battery exceeds 360Wh/L; Batteries assembled with silicotungstic acid (SWO) as the negative electrode can operate stably for more than 2,000 cycles
.
This study provides theoretical guidance and technical support
for the development of manganese-based battery systems with high energy density and long life.

The research was published in Angewandte Chemie
, Germany, under the title Bromine Assisted MnO₂Dissolution Chemistry: Toward a Hybrid Flow Battery with Energy Density of over 300 Wh ^L-1 。 The research work has been supported
by the National Natural Science Foundation of China, the Engineering Laboratory of Electrochemical Energy Storage Technology of the Chinese Academy of Sciences, and the strategic leading science and technology project of the Chinese Academy of Sciences "Key Technologies and Demonstration of Transformative Clean Energy".

Dalian Chemical Institute has developed a high-energy density manganese-based hybrid single-flow battery