Zinc Microcapacitors Are the Best of Both Worlds

Summary

As electronics shrink, they require smaller components—including for energy storage. Batteries store a lot of energy but deliver power more slowly, whereas supercapacitors can rapidly charge and discharge but don’t hold much energy. This is the case not only for larger bulk batteries and supercapacitors, but also at much smaller scales, with both microbatteries and microsupercapacitors having the same limitations as their bigger counterparts.Now researchers from University College London (UCL) have developed a hybrid energy-storage option that offers a better balance between storage capacity and discharge rates. The component, called a zinc-ion micro-capacitor (ZIMC), could one day find its way into compact devices, such as wearables, medical implants, and IoT devices.“It wasn’t our aim to outperform microbatteries and microsupercapacitors in every way,” says Buddha Deka Boruah, a lecturer in energy storage at UCL, “but to create a middle-ground device that balances energy and power in a small footprint.” The researchers published their results in March in ACS Nano.Mixing the Best of Microcapacitors and MicrobatteriesThe device combines aspects of microcapacitors and microbatteries in a small, on-chip format. The researchers developed porous, three-dimensional interdigitated electrodes (IDEs) out of gold as current collectors using dynamic bubbling electrodeposition, which creates a porous structure with a relativelylarge surface area. Current collectors are thin metallic layers that transport the electrons between the electrodes and the external circuit (both ways to and from the electrode). Reducing the thickness of current collectors is one of the key ways of reducing the size of energy storage devices.A microplotter fabrication technique loaded the porous current collectors with different materials to create the two electrodes. The researchers added zinc ions to the IDE to form a battery-like anode and activated carbon coated with a conductive polymer called PED...