New dielectric capacitor could make electric vehicles more efficient

Researchers in Japan have created an advanced dielectric capacitor using nanosheet technology that can store energy with unparalleled density and stability. This discovery could significantly improve the efficiency of renewable energy and electric vehicle production.

A dielectric capacitor is a device that stores energy in the form of an electric field between two metal electrodes separated by a solid dielectric. Dielectrics are materials that have the property of polarization, that is, the ability to change the distribution of charges under the influence of an external electric field. The greater the polarization of the dielectric, the more energy can be stored in the capacitor.

Dielectric capacitors have a number of advantages over other energy storage technologies such as lithium-ion batteries. They have a short charging time (only a few seconds), a long service life and high power. However, existing dielectric capacitors have a low energy density, i.e. little energy per unit volume or mass.

To increase the energy density, it is necessary to use dielectrics with high polarization and high breakdown strength, that is, the ability to withstand high voltages without destruction. Existing materials cannot simultaneously possess these qualities.

A team of researchers led by Professor Minoru Osada from the Institute of Materials and Systems for Sustainability (IMaSS) of Nagoya University, in collaboration with the National Institute of Materials Science (NIMS), solved this problem with nanosheet technology.

Nanosheets are thin layers of material a few nanometers thick (one nanometer is equal to a billionth of a meter). Using nanosheets of calcium, sodium, niobium and oxygen with a perovskite crystal structure, the researchers created a dielectric capacitor with a record energy density.

“The perovskite structure is known to be the best structure for ferroelectrics because it has excellent dielectric properties such as high polarization,” Osada explains. “We have found that by exploiting this property, it is possible to apply a high electric field to highly polarized dielectric materials and convert it into lossless electrostatic energy, achieving the highest energy density ever recorded.”

The nanosheet dielectric capacitor showed an energy density 1-2 orders of magnitude higher than its predecessors, while maintaining the same high power. In addition, the nanosheet capacitor was highly stable under repeated use and at high temperatures up to 300°C.

“This achievement provides new guidelines for the development of dielectric capacitors and is expected to be applicable to solid state energy storage devices,” concludes Osada.

The results of the study were published in magazine Nano Letters .