“Our group is looking to combine the large energy density of batteries and the fast charging times and high-power capabilities of capacitors into one energy-storage device,” said Professor Bruce Dunn. “This new materials approach shows a very promising path forward toward such a device.”
To resolve the trade-off between batteries, which last longer, and capacitors, which charge faster and hold more power, the researchers altered the atomic structure of an energy storage material by opening up atomic ‘lanes’. These allow more energy-carrying ions and electrons to travel through the material at higher rates.
Prof Dunn, together with Professor Vidvuds Ozolins and Professor Sarah Tolbert, modified the structure of molybdenum trioxide – a material which already has a large energy density. The altered structure allows power to be provided for an extended time, but also for the material to be charged in minutes.
“We improved its power capabilities by selectively removing some of the oxygen through materials processing,” said Prof Tolbert. “At the atomic level, the gaps where oxygen atoms once were provide space for ions and pathways for electrons to move more quickly through the structure. In total, we have created a material that keeps its high energy density and provides greater power with faster charging times thanks to the small changes we made to the structure to allow fast transport of ions and electrons.”