New types of energy storage are needed in conjunction with the deployment of solar, wind, and other volatile renewable energy sources and their integration with the electrical grid. No existing energy storage technology can provide the power, cycle life, and energy efficiency needed to respond to the costly short-term transients that arise from renewables and other aspects of grid operation. We are currently working on a new family of insertion electrodes based on the Prussian Blue open-framework crystal structure. This structure is fundamentally different from other insertion electrode materials because of its large channels and interstices. It is composed of a face-centered cubic framework of transition metal cations where each cation is octahedrally coordinated to hexacyanometallate groups and has wide channels between the A sites, allowing rapid insertion and removal of sodium, potassium and other ions. In addition, there is little lattice strain during cycling because the A sites are larger than the ions that are inserted and removed from them. The result is an extremely stable electrode: over 40,000 deep discharge cycles were demonstrated in the case of the copper hexacyanoferrate cathode. #
The student will work on synthesizing new open-framework materials, perform an in-depth structural characterization at the Diamond Light Source and evaluate their electrochemical properties.