VTT Technical Research Centre of Finland has developed a small, extremely efficient micro-supercapacitor that can be integrated directly inside a silicon microcircuit chip.

The technology opens new possibilities for integrated mobile devices and zero-power autonomous devices required for the Internet of Things (IoT). Supercapacitors resemble electrochemical batteries in that they are typically discrete energy storage devices that can power a large variety of applications, from small electronic gadgets to electrical vehicles. However, unlike phone lithium-ion batteries, which utilize chemical reactions to store energy, supercapacitors store mainly electrostatic energy that is bound at the interface between liquid and solid electrodes.

The silicon-based micro-supercapacitor is integrated directly inside a silicon chip. Image credit: VTT.The silicon-based micro-supercapacitor is integrated directly inside a silicon chip. Image credit: VTT.The energy and power density of a supercapacitor depends on the surface area and conductivity of the solid electrodes. VTT's research group has developed a hybrid nanomaterial electrode consisting of porous silicon coated, via atomic layer deposition, with a several-nanometers-thick titanium nitride layer.

This approach, VTT says, has led to an extremely large conductive surface contained in a small volume. Inclusion of ionic liquid in a micro channel formed in between two hybrid electrodes allows for extremely small and efficient energy storage.

The resulting silicon-based micro-supercapacitor is able to compete with carbon- and graphene-based devices in power, energy and durability, VTT says.

Micro-supercapacitors can be integrated directly into microelectronic devices to store electrical energy generated by thermal, light and vibration energy harvesters and to supply the electrical energy when needed. This functionality is important for autonomous sensor networks, wearable electronics and mobile electronics of the IoT.

The in-chip supercapacitor technology enables energy storage of as much as 0.2 joule and power generation of 2 watts on a one-square-centimeter silicon chip, VTT says, while leaving the surface of the chip available for active integrated microcircuits and sensors.

VTT is currently seeking a party interested in commercializing the technology.

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