Cambridge team discovers material with potential for faster charging batteries

Researchers at Cambridge University have identified a group of materials that could be used to make batteries with higher power.

The team from the university's Department of Chemistry looked at niobium tungsten oxide as part of the search for materials with high rate battery performance: that is, capable of charging faster and delivering higher power output.

Niobium tungsten oxide has a complex atomic arrangement, which according to postdoctoral researcher Kent Griffith, might explain why it has so far been neglected in battery studies. However, the team has found that this unusual structure allows lithium ions to pass through it much faster than conventional materials used in battery electrodes, such as graphite.

In typical batteries, electrons are extracted from the positive electrode during the charge cycle. They then move through its crystal structure and the battery electrolyte to be stored in the negative electrode. The faster this happens, the faster the battery charges. One way that researchers try to speed this process up is to make electrodes from nanoparticles, because this should reduce the distance the ions have to travel. But this has drawbacks: nanoparticle electrodes tend to encourage unwanted chemical reactions in the electrolyte, reducing the battery lifetime, Griffith said. Moreover, as team leader Prof Clare Grey explained, nanoparticles tend to be difficult to make and to pack together efficiently.