Made to Measure…Supercapacitors

Who are you?: Richard Fields
What is your role?: PhD Researcher
What is your work about?: Manufacturing and Characterising Supercapicitors
I beg your pardon?: High(ish) energy and power storage density materials that can release their stored energy quickly (but safely). I’ve been looking at both manufacturing (scaling up) and new materials (composite structure that contained some electrodes with high power density and some with high energy density). The ability to select the ratio during manufacturing means cells can be tailor made to specific applications where a certain ratio of energy to power is required.
OK. Why?: Energy storage is a fundamental requirement for having a truly high tech society, where energy production is decoupled from immediate energy consumption. Therefore, storage is an absolute necessity for utilising clean but intermittent renewable resources; maintaining a resilient power grid and powering a multitude of portable electric devices. At its simplest four aspects need to be considered: energy density, power density, cycle life and cost (Figure 1). Batteries and traditional capacitors are shown to be opposite in their properties, batteries are good at storing lots of energy but are slow to deliver it while capacitors are good at delivering energy rapidly but only store a tiny amount of it. Supercapacitors sit in the middle. They can store a small yet significant amount of energy and have the capability of delivering it fast. The best property is that they can be cycled millions of times with minimal degradation, a battery can only handle thousands of cycles before it must be replaced.

Supercap

Figure 1: Graph of Energy and Power storage densities, indicating where typical devices sit.
And?: My work looks at increasing the energy density (Wh/kg) and power density (kW/kg) of supercapacitors. This is necessary in order to make supercapacitors more desirable as consumer grade products, currently their energy density is about a quarter of what is required to see widespread adaption.
So what?: An example of good use would be in an electric vehicles, supercapacitors can deal with short but intense activities such as breaking and acceleration while batteries can provide a constant supply during cruise. This would reduce the stress on battery systems and thus increase their usable life.
Final Thought: I hope to see widespread adoption of supercapacitors as part of hybridised systems, the technology could greatly improve the efficiency and lifespan of electrical systems if implemented effectively.