<br/>With global energy demands rising each year, it is projected that current state-of-the-art lithium-ion batteries (LIBs) will soon reach their limit, in terms of the amount of energy density that they can supply. Since these batteries power nearly all portable electronics and electric vehicles, much research is being conducted to develop alternative battery systems that can match or surpass lithium (Li). Among these alternatives, multi-valent systems such as the rechargeable magnesium battery (RMB) consisting of a magnesium (Mg) metal anode is a promising candidate due to its high elemental abundance, decreased reactivity (compared to Li), and environmental friendliness. In addition to its benefits over lithium, the volumetric capacity of the magnesium anode (3,832 mAh/g) is more than four times larger than that of the conventional graphite anode (777 mAh/g) used in current LIBs. However, Mg batteries suffer from slow reaction kinetics at the cathode interface due to the strong electrostatic interactions experienced by the divalent Mg-ion. In response to this, a great deal of work is currently being conducted on the development of novel cathode materials capable of efficient and reversible Mg-ion storage. Of the many different cathode materials being investigated, polyoxometalates (POMs) are being strongly considered due to their high ionic conductivity, ability to function as electron reservoirs, and unique redox mechanism which allows them to partake in multiple reversible electron-transfer reactions. Polyoxometalates are composed of cations of early transition metals linked by polyanion clusters of oxygen atoms to form a three-dimensional network. In recent years, POMs have found applications in energy storage devices ranging from supercapacitors to lithium-ion batteries but to date, no such work has been conducted to apply this redox chemistry to magnesium systems. In this work, POM nanocomposite materials have been successfully fabricated via a one-step co-electrodeposition process and studied as potential cathodes for Mg-ion storage. The electrochemistry and insertion mechanism of these cathodes has been studied in-depth using techniques such as cyclic voltammetry and constant current cycling. While cathode testing is still in the early stages, preliminary results demonstrate that the POM molecules show an affinity for Mg-ion storage as well as reversible electron-transfer reactions.

Polyoxometalate cluster molecules as cathodes for rechargeable magnesium batteries

254th National Meeting (2017)

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