Energy storage mechanism, advancement, challenges, and perspectives on vivid manganese redox couples

Recently, aqueous-based redox flow batteries with the manganese (Mn2+/Mn3+) redox couple have gained significant attention due to their eco-friendliness, cost-effectiveness, non-toxicity, and abundance, providing an efficient energy storage solution for sustainable grid applications. However, the construction of manganese-based redox flow batteries remains difficult due to severe intrinsic issues, including poor cyclability and limited capacity. During the past few decades, several scientific attempts have been made to alleviate the issues fundamentally enabling a pathway for high performance redox flow batteries. Herein, various developments of manganese-based redox flow batteries are methodically understood and reviewed. Moreover, the charge storage chemical reaction mechanism of manganese redox couples under various conditions is conferred providing an excellent opportunity to design scalable, affordable and environmentally benevolent manganese-based redox flow batteries for futuristic grid applications. The remaining challenges are tabulated and the authors' perspectives are highlighted for the highly promising manganese redox couple. Manganese redox couples are a promising candidate for redox flow batteries due to their low cost, ecofriendliness, high standard reduction potential, and variable oxidation states.