A review on polyoxometalates-based materials in addressing challenges faced by electrochemical energy storage systems

Current electrochemical energy storage systems (EESSs) are insufficient to meet the escalating energy demands in grid-scale energy storage. The main deficiencies of the current EESSs include the low energy density, short durability, and inadaptability under harsh conditions. To surmount these challenges, the complex electrochemical reactions need to be rationally regulated in a desired manner. Due to their precise cluster structures and tunable reaction behaviors, polyoxometalates (POMs) have been employed to confront these obstacles. In this review, the recent advances in using POM-based materials for EESSs are summarized, with the focused attention concentrated on their essential role in elevating energy densities, extending cycling life, and promoting usability under harsh conditions. After a brief introduction of the typical routes to regulate the chemistry of POMs, the capability of POMs to address the aforementioned issues is elucidated in great detail. Then, the prospects of POMs in this rising field are highlighted by listing the recently proposed typical examples. Finally, the challenges and opportunities are provided from our viewpoint to end this review. We believe that this review will provide innovative solutions to addressing the challenges of EESSs for grid-scale energy storage, and ultimately contribute to the development of this rising field.