High temperature use, high current densities and high capacity charging or discharging are possible

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Capacitors are energy storage devices, consisting of two electrodes and an electrolyte, capable of charging and discharging rapidly due to charge adsorption and desorption properties at the electrode-electrolyte interface. Because capacitors’ energy storage does not involve chemical reactions, their storage capacity is less than that of lithium-ion batteries, but they are useful for power leveling for renewables that require repeated charging at high currents, regenerative braking energy for electric or electric trains and batteries. hybrid cars, as well as instantaneous voltage drop compensation devices that prevent equipment failure due to lightning. They should also be used to store energy for portable devices in the near future.

Most capacitors use a low boiling point liquid electrolyte, which can only be used at temperatures below 80℃. Ceramic capacitors that use solid inorganic materials as the dielectric can be used at temperatures above 80℃, but their storage capacity is much lower than that of liquid electrolyte capacitors, which limits their use to electronic circuits. To increase the energy storage of capacitors, it is necessary to have a large contact surface at the interface between the electrode and the electrolyte. Making a large surface area is difficult using solid electrolytes; thus, the creation of a capacitor with high storage capacity that can also operate at high temperatures has long been desired.

A research group led by Professor Akitoshi Hayashi from the Graduate School of Engineering of Osaka Metropolitan University has developed a highly deformable solid electrolyte, allowing it to have a large contact surface with an electrode, which has was developed for use in an all-solid-state oxide battery. In this study, they fabricated a composite using the same highly deformable solid electrolyte and carbon, and then used it to build the two electrodes of a bulk-type all-solid capacitor. This capacitor is capable of high current densities and large capacity charge and discharge at temperatures of 200 to 300°C, creating the world’s first bulk-type semiconductor capacitors. The researchers expect their capacitor to be used to improve technology for high-temperature environments, which previously could not be developed due to these technical limitations.

“The key to making this capacitor was to take the solid oxide electrolytes we developed for solid-state lithium batteries – which combine excellent deformability and lithium-ion conductivity – and apply them to capacitors,” explained Professor Hayashi. .

In the future, researchers hope to build all-solid-state hybrid capacitors with even higher energy densities, by controlling the chemical reaction between a solid electrolyte and carbon, then combining them with positive electrode materials used in lithium ion batteries.

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Materials provided by Osaka Metropolitan University. Note: Content may be edited for style and length.

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