Highly reversible and stable manganese(II/III)-centered polyoxometalates for neutral aqueous redox flow battery
Wenjin Li,
Peng Luo,
Zhiyong Fu,
Xianzhi Yuan,
Mingbao Huang,
Kai Wan,
Zhipeng Xiang,
Zhenxing Liang
Affiliations
Wenjin Li
Guangdong Provincial Key Laboratory of Fuel Cell Technology, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510641, PR China
Peng Luo
Guangdong Provincial Key Laboratory of Fuel Cell Technology, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510641, PR China
Zhiyong Fu
Guangdong Provincial Key Laboratory of Fuel Cell Technology, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510641, PR China
Xianzhi Yuan
Guangdong Provincial Key Laboratory of Fuel Cell Technology, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510641, PR China
Mingbao Huang
Guangdong Provincial Key Laboratory of Fuel Cell Technology, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510641, PR China
Kai Wan
Guangdong Provincial Key Laboratory of Fuel Cell Technology, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510641, PR China
Zhipeng Xiang
Corresponding authors.; Guangdong Provincial Key Laboratory of Fuel Cell Technology, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510641, PR China
Zhenxing Liang
Corresponding authors.; Guangdong Provincial Key Laboratory of Fuel Cell Technology, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510641, PR China
Manganese (Mn) is a promising positive electrode element for aqueous redox flow batteries (ARFB); however, reversible and stable Mn species are still highly desirable. Herein, an ultra-stable Mn-centered Keggin-type polyoxometalate, viz. (NH4)6[MnW12O40]·9 H2O, is designed for neutral ARFB. The polyoxometalate is extensively characterized by X-ray crystalline diffraction, ultraviolet-visible spectroscopy, X-ray photoelectron spectroscopy, and electrochemical method. It is found that for (NH4)6[MnW12O40], the rigid skeleton and cage-structural coordination yield superior stability in a symmetrical flow battery. Pairing with viologen derivative, 0.50 M (NH4)6[MnW12O40] flow battery delivers a capacity of 10.2 Ah L−1 and a capacity retention ratio of 99.994% per cycle at 20 mA cm−2 over 500 cycles (∼19 days). This work provides new insight into designing stable electroactive materials for ARFB.
