Polyoxometalates: Molecular Metal Oxide Clusters for Supercapacitors

Abstract The modification of conductive organic supports with polyoxometalate (POM) metal oxide clusters is a promising approach for the design of nanocomposite electrodes for energy storage. The fast and reversible electron-transfer processes of these POM molecules make them particularly well suited for supercapacitor (SC) applications. This chapter will provide a detailed overview of POM-based composite SC electrodes, including an evaluation of the most promising fabrication methods: (1) chemisorption to a carbon surface, (2) immobilization in a conductive polymer matrix, and (3) layer-by-layer self-assembly. Furthermore, the role of these POM composite materials in enhancing the performance of SC devices will also be reviewed, from pioneering work to the latest developments. This will include an analysis of how the tunability of POM redox properties can be leveraged to move from faradaic SC electrodes using only a single POM chemistry to pseudocapacitive electrodes incorporating multiple different POM molecules.