Researchers create capacitor with dramatically increased energy density

While capacitors can store and discharge electricity rapidly, they typically have low energy density, compared to batteries or fuel cells. However, a research team at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) announced the discovery of a process that can turn a common ferroelectric material type, or relaxor ferroelectric, into a high storage density capacitor.

The ceramic material exhibits an induced piezo-electric effect which makes it a good choice for small scale capacitor applications, like the ignition button on a gas grill. However, the Berkeley Lab team needed to find a way to optimize the material to withstand rapid and repeated charge/discharge cycles to high voltages but without damaging the material.

The researchers turned to an approach that they had previously developed to “turn off” conductivity in a material. By bombarding a thin film of lead magnesium niobite-lead titanate, a typical relaxor ferroelectric, with high-energy helium ions, they were able to introduce isolated defects that trap electrons, decreasing the film’s conductivity. Measurements showed that the ion-bombarded film had more than twice the energy storage density of previously reported values and 50 percent higher efficiencies.

According to the research team, the same approach could also improve other dielectric materials to improve energy storage, and open the possibility for longer-term applications for capacitors such as in vehicles, personal computers and other electronic devices. The Berkeley Labs team work was featured in the July 2020 issue of Science.
www.lbl.gov