Researchers led by Nagoya University in Japan successfully applied nanosheet technology to create a dielectric capacitor. This capacitor features the highest energy storage density ever recorded, as well as quick charging time, high output, longevity, and superior high-temperature stability. The results were featured in the journal Nano Letters.
Energy storage technology innovation is crucial for both renewable energy and the mass production of electric vehicles. Existing energy storage technology, including lithium-ion batteries, have limitations, including long charging times, electrolyte degradation, reduced lifespan, and even risks of spontaneous ignition.
Dielectric energy storage capacitors are promising. They feature a sandwich-like structure comprising two metal electrodes separated by a solid dielectric film. Their advantages include a short charging time of a few seconds, long life, and high power density. However, the energy density of current dielectrics is significantly lower than the increasing electrical energy demands.
The energy stored is linked to the amount of polarization, so a high energy density can be achieved by applying an electric field as high as possible to a high dielectric constant material. Existing materials, however, are limited.
The researchers used calcium, sodium, niobium, and oxygen nanosheets with a perovskite crystal structure. The nanosheet dielectric capacitors showed an energy density of 1-2 orders of magnitude higher than their predecessors yet maintained the same high output density. They achieved a high energy density with stability over multiple use cycles, even at temperatures up to 300°C (572°F).
Dielectric capacitors release stored energy extremely quickly and create an intense pulsed voltage or current, useful in pulsed-discharge and power electronic applications. In addition to hybrid electric vehicles, they can be used in high-power accelerators and microwave devices.