Authors: Hao Fan, Wenda Wu, Mahalingam Ravivarma, Hongbin Li, Bo Hu, Jiafeng Lei, Yangyang Feng, Xiaohua Sun, Jiangxuan Song, Tianbiao Leo Liu
Published: 2022-06-10
Source: Full article
AbstractRedox‐active organics are highly attractive in aqueous organic redox flow batteries (AORFBs). However, the lack of capacity dense, stable organic catholytes remains a challenge to develop energy‐dense, long cycle‐life AORFBs. Herein, a stable organic catholyte, 4‐[3‐(trimethylammonium)acetylamino]‐2,2,6,6‐tetramethylpiperidine‐1‐oxyl chloride (TMAAcNHTEMPO) is developed through rational molecular engineering using connective acetamido and trimethylammonium groups. Paired with bis‐(trimethylammonium) propyl viologen tetrachloride anolyte, stable AORFBs (up to 1500 cycles) with a low capacity fade rate of ca. 0.0144% h−1 are achieved. Experimental characterizations and theoretical simulations revealed that TMAAcNH‐TEMPO is largely stabilized by the reduced reactivity of the nitroxyl radical moiety that mitigates a ring‐opening side reaction.