High capacity supercaps using new polymers developed by researchers at the Universities of Surrey and Bristol together with Superdielectrics Ltd based in the UK could soon be challenging the dominance of lithium batteries for energy storage.
It’s always been an intriguing question whether technological advances in supercap design would one day result in an energy storage component with so much capacity that it could be used to power electric motors etc. A significant advantage of a supercap is its ability to be recharged much quicker than a lithium battery.  Only last year new polymer materials were announced having dielectric properties 1,000 to 10,000 times better than existing electrolytes.

The most recent results however are astonishing; conventional supercaps achieve around 0.3 F/cm2 using relatively complex extended surface-area electrodes. Using just simple smooth-surface electrodes the researchers were able to achieve practical capacitance values up to 4F/cm2 with the new polymers and with optimized stainless steel electrodes, specific capacities of up to 20 F / cm² have been achieved!

Should it be possible to replicate these laboratory results in a mass-produced component, it would have an energy density up to 180 wh/kg, which exceeds the performance of lithium ion batteries. These would not be supercaps, more like hypercaps.

Compared to rechargeable batteries that rely on chemical processes, supercaps offer much higher charge and discharge currents, thereby achieving significantly shorter charge times and potentially a higher number of charge cycles. So far, however, the energy density is not sufficient for practical use beyond an energy buffer function.

Based on the impressive results, Superdielectrics Ltd are planning to setup a research and low-volume production facility. If all goes to plan, the supercaps could one day be used as a battery for mobile devices, energy storage for recharging stations and even to power electric vehicles.