The superpower behind iron oxyfluoride battery electrodes
(Phys.org) —Innovative materials chemistries continue to drive advances in lithium-ion batteries-the state-of-the-art in rechargeable energy storage. While many different battery components contribute to their performance, the largest gains may be achieved through the development of new electrode materials that can power portable electronics longer and propel electronic vehicles farther. Electrodes based on so-called "conversion chemistry" have the potential to double energy storage capacities compared to electrodes in existing rechargeable batteries. This higher energy storage capacity is achieved because each metal atom can react with several electrons in conversion systems, compared to the single electron limit of conventional electrodes. Although these new materials initially deliver higher capacities, their capacities often diminish with repeated charging and discharging. Nevertheless, unusually good long-term performances, with consistently high capacities, have been found with mixed-anion systems such as oxyfluorides. Although they combine the favorable performance characteristics of simple oxides and fluorides, the electrochemical reactions giving rise...