Self-charging organic flow batteries based on multivalent metal negative electrodes

Abstract

Self-charging batteries, which integrate energy conversion and storage within a single system, represent a promising technology for building a reliable and intelligent energy network. However, the charging rate of conventional self-charging energy systems that use solid-state electrodes is limited by slow solid-gas reaction processes at the electrode-air interface. A complete charging procedure typically requires several hours. Here we show a self-charging organic redox flow battery to address the limitations of solid-state reaction kinetics. A high charging rate is achieved, with 94% of the total capacity reached within 8 minutes, owing to the rapid kinetics of liquid-phase redox reactions. Using manganese oxide-based catalysts to reduce side reactions, the flow battery exhibits nearly 99.98% capacity retention over 1,600 cycles. Even in a harsh environment of -10 degrees C, the battery can run more than 2,500 cycles at a current density of 20 mA cm-2. The redox chemistry underlying the self-charging mechanism is investigated through computational modeling and in situ characterization, revealing that fast outer-sphere electron transfer during the enolization reaction contributes significantly to the reaction kinetics. In the proof-of-concept demonstration, we further extend the system from zinc to magnesium and aluminum as the negative electrodes, demonstrating a potential pathway for constructing sustainable energy systems.