Even as our electronic devices become ever more sophisticated and versatile, battery technology remains a stubborn bottleneck, preventing the full realization of promising applications such as electric vehicles and power-grid solar energy storage. Among the limitations of current materials are poor ionic and electron transport qualities. While strategies exist to improve these properties, and hence reduce charging times and enhance storage capacity, they are often expensive, difficult to implement on a large scale, and of only limited effectiveness. An alternative solution is the search for new materials with the desired atomic structures and characteristics. This is the strategy of a group of researchers who, utilizing ultra-bright x-rays from the U.S. Department of Energy’s Advanced Photon Source (APS), identified and characterized two niobium tungsten oxide materials that demonstrate much faster charging rates and power output than conventional lithium electrodes. Their work appeared in the journal Nature.
Currently, the usual approach for wringing extra capacity and performance from lithium-ion batteries involves the creation of electrode materials with nanoscale structures, which reduces the diffusion distances for lithium ions. However, this also tends to increase the practical volume of the material and can introduce unwanted additional chemical reactions. Further, when graphite electrodes are pushed to achieve high charging rates, irregular dendrites of lithium can form and grow, leading to short circuits, overheating, and even fires. Measures to prevent these dendrites generally cause a decrease in energy density. These issues seriously limit the use of graphite electrodes for high-rate applications.
Image: Artist’s impression of rapidly flowing lithium through the niobium tungsten oxide structure. This is a detail of the image, please see here for the entire art work.
Credit: Ella Maru Studio