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Phenothiazine‐Based Organic Catholyte for High‐Capacity and Long‐Life Aqueous Redox Flow Batteries
Author(s) -
Zhang Changkun,
Niu Zhihui,
Peng Sangshan,
Ding Yu,
Zhang Leyuan,
Guo Xuelin,
Zhao Yu,
Yu Guihua
Publication year - 2019
Publication title -
advanced materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.707
H-Index - 527
eISSN - 1521-4095
pISSN - 0935-9648
DOI - 10.1002/adma.201901052
Subject(s) - redox , aqueous solution , materials science , anode , cathode , electrolyte , solubility , chemical engineering , capacity loss , solvent , inorganic chemistry , chemistry , organic chemistry , electrode , engineering , metallurgy
Redox‐active organic materials have been considered as one of the most promising “green” candidates for aqueous redox flow batteries (RFBs) due to the natural abundance, structural diversity, and high tailorability. However, many reported organic molecules are employed in the anode, and molecules with highly reversible capacity for the cathode are limited. Here, a class of heteroaromatic phenothiazine derivatives is reported as promising positive materials for aqueous RFBs. Among these derivatives, methylene blue (MB) possesses high reversibility with extremely fast redox kinetics (electron‐transfer rate constant of 0.32 cm s −1 ), excellent stability in both neutral and reduced states, and high solubility in an acetic‐acid–water solvent, leading to a high reversible capacity of ≈71 Ah L −1 . Symmetric RFBs based on MB electrolyte demonstrate remarkable stability with no capacity decay over 1200 cycles. Even concentrated MB catholyte (1.5 m ) is still able to deliver stable capacity over hundreds of cycles in a full cell system. The impressive cell performance validates the practicability of MB for large‐scale electrical energy storage.