Nanostructured Cathode for Magnesium Ion Batteries

A rechargeable magnesium battery would be a promising candidate for high-energy-density generation due to the natural abundance of magnesium compared to lithium, the relatively low price of its raw materials, and the higher safety of metallic magnesium compared to lithium. The only deterrent to the development of magnesium-based rechargeable batteries has been the sluggish Mg2+ insertion into ion-transfer hosts, owing to the strong polarization effect of the small and divalent Mg2+ ion compared to Li+ or Na+. Therefore, it is necessary to develop practical cathode materials that exhibit fast Mg2+ mobility, in addition to other requirements such as electronic conductivity. This project will develop a nanostructured cathode, which will have high magnesium insertion and release, for use in magnesium ion cells. In particular, nanostructured phospho-olivines will be investigated, as they exhibit the potential for high specific capacity (> 150 mAhg-1) with good magnesium intercalation/transport properties for magnesium ion batteries. Unfortunately, the electrochemical properties of this material are dependent on composition and morphology. Thus, an optimum composition must be chosen from the wide range of compositions possible. In Phase I, a high-throughput combinatorial technique will be used to rapidly screen a wide range of compositions of phosopho-olivines. The cathode material with best capacity and potential will be chosen for the fabrication of prototype magnesium batteries, and detailed testing will be conducted in Phase II. Commercial Applications and other Benefits as described by the awardee: Magnesium battery systems would be a safe and environmentally friendly substitute for environmentally problematic Ni¿Cd and lead acid battery systems, and would be a cheap alternative to lithium ion cells. Magnesium batteries should find use in applications that currently use Ni-Cd and lead acid batteries, and that cannot be replaced by lithium ion batteries due to their high cost. Magnesium battery technology is also well suited for heavy-load applications such as power tools and drills, and for load-leveling systems at power grid substations.