Target design towards HER inhibition for an electrolytic Mn//MnO2 aqueous battery with high discharge voltage

作者：Meng, Lijun; Ji, Xu; Li, Man; Liu, Ting; Dong, Wenju; Pan, Yunying; Huang, Longjun; Cheng, Shuang^*

来源：Surfaces and Interfaces, 2022, 29: 101782.

DOI：10.1016/j.surfin.2022.101782

• Mn/MnO2
• Electrolytic aqueous system
• HER inhibition
• Mn plating
• High voltage

As popular green energy storage devices, Zn//MnO2 batteries have attracted widespread attention. However, issues caused by Zn based anodes and rocking-chair Zn2+ mechanism on cathodes have hindered their fast development. Herein, a new electrolytic Mn//MnO2 system without initial active materials is developed, where the main challenge is the realization of Mn plating that is highly involved with the inhibition of hydrogen evolution reaction (HER) during charging. To overcome this challenge, rational design is conducted (mainly including surface design of the current collectors, and the use of "water-in-salt" electrolytes): polyaniline (PANI) loaded on heat treated carbon cloth (CC-400/PANI) and CC-400 with microspores is constructed as current collector for anode and cathode, respectively; high concentrated aqueous of 20 m LiCl + 1 m MnCl2 is used as electrolyte to reduce the activity of water and hence extend its operating In this system, HER is largely inhibited, and reversible Mn/Mn2+ reaction is realized on the anode; Mn2+/MnO2 concerned reaction is realized on the cathode; a high discharge voltage of similar to 2.3 V with a cycling life of 500 cycles is accomplished for a full cell. Coulombic efficiency (CE) is enhanced to 80-90% along cycling. Through carefully analysis, it is found that irreversible reaction of Mn2+/MnO2 on the cathode is the main cause for the unsatisfied CE. The rechargeable electrolytic Mn//MnO2 system proposed here is a promising candidate as green and efficient aqueous cell for safe and large-scale charge storage.

• 单位
  仲恺农业工程学院