Mitigating Ring-Opening to Develop Stable TEMPO Catholytes for pH-Neutral All-organic Redox Flow Batteries

Authors：Fan, Hao; Wu, Wenda; Ravivarma, Mahalingam; Li, Hongbin; Hu, Bo; Lei, Jiafeng; Feng, Yangyang; Sun, Xiaohua; Song, Jiangxuan^*; Liu, Tianbiao Leo^*

Source：Advanced Functional Materials, 2022, 32(33): 2203032.

DOI：10.1002/adfm.202203032

• energy storage
• nitroxyl radicals
• organic catholytes
• redox flow batteries

Redox-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.

• Institution
  西安交通大学