Manufacture of non-aqueous redox flow batteries using sulfate-templated Dawson-type polyoxometalate with improved performances

• Published in: Journal of energy storage Vol. 35; p. 102281
• Main Authors: Chen, Zheng-Fan, Yang, Yu-Liang, Zhang, Chi, Liu, Su-Qin, Yan, Jun
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.03.2021
• Subjects: Electrolyte; Nano-clusters; Non-aqueous solvent; Polyoxometalates; Redox flow battery; Non-aqueous solvent; Polyoxometalates; Electrolyte; Nano-clusters; Redox flow battery
• ISSN: 2352-152X; 2352-1538
• DOI: 10.1016/j.est.2021.102281

•Two new non-aqueous redox flow batteries based on Dawson-type polyoxometalate were designed and tested.•The asymmetric redox flow battery yielded outstanding performances with higher theoretical cell voltage of 1.54 V, theoretical energy density of 8.25 Wh L−1 and coulombic efficiency more than 97%.•The mechanisms of electrode reactions in these symmetric and asymmetric redox flow batteries were both identified. The compatible redox pairs are essential to make non-aqueous redox flow batteries (NRFBs) reach their full potentials. Two novel NRFBs with polyoxometalate (POM) redox pairs were designed and investigated. [C16H36N]4[S2W18O62] used as anolyte and benzophenone(BP) severed as catholyte in an asymmetric NRFB, these two diverse active species could cooperate well with each other and achieve a high theoretical cell voltage of 1.54 V. During the charge-discharge cyclic tests, it yielded impressive results with the coulombic efficiency more than 97%, and high voltage efficiency and energy efficiency were delivered without reduction. At the current density of 0.5 mA cm−2, this reformative asymmetric battery delivered a volumetric capacity of 1.97 Ah L−1. The excellent stability of [C16H36N]4[S2W18O62] was validated by the identical 1HNMR and XRD spectra. As a comparison, the symmetric battery employed [C16H36N]4[S2W18O62] both as anolyte and catholyte, which delivered a moderate performances with the coulombic efficiency was about 90%. Also, the permeability of polyoxoanion [S2W18O62]4- cross through AMI-7001 membrane was 1.307×10−7 cm 2 min −1 and less than 1% of this active species had crossed over after 3 d stationary tests. [Display omitted]