With the development of on-board electronic systems and wireless technologies, the miniaturisation of energy storage devices has become necessary. Micro-batteries are widespread and store a large quantity of energy due to their chemical properties. However, they are affected by temperature variations and suffer from low electric power and limited lifetime. By contrast, micro-supercapacitors have high power and theoretically infinite lifetime, but only store a low amount of energy.
Micro-supercapacitors have been the subject of an increasing amount of research, but no concrete applications have come from it. Their lower energy density has meant that they were not able to power sensors or microelectronic components. The French and Canadian researchers have succeeded in removing this limitation by combining the best of micro-supercapacitors and micro-batteries.
They have developed an electrode material whose energy density is said to exceed all the systems available to date. The electrode is made of an extremely porous gold structure into which ruthenium oxide has been inserted. These expensive materials can be used in this application because the components are in the order of square millimetres.
This electrode was used to make a micro-supercapacitor with energy density 0.5J/cm², which is about 1000 times greater than existing micro-supercapacitors, and very similar to the density characteristics of current Li-ion micro-batteries.
With this energy density, their long lifetime, high power and tolerance to temperature variations, these micro-supercapacitors could finally find used in wearable, intelligent, on-board microsystems.
