In-orbit feasibility demonstration of supercapacitors for space applications

Electric Double-Layer Capacitors (EDLC), also known as supercapacitors or ultracapacitors, are being considered as an energy storage option in space applications because they can operate over wider temperature ranges, and have longer lifetimes and higher power densities than batteries. However, the limited number of studies concerned with the suitability of Commercial-off-the-shelf (COTS) supercapacitors to withstand the launch and space environment has hindered the practical use of supercapacitors on-board satellites. To contribute to studies that support the feasibility of using supercapacitors in small spacecraft, two goals are pursued: First, to demonstrate that a supercapacitor can survive the launch. Second, to prove that charging and discharging a supercapacitor in Low Earth Orbit (LEO) is possible. Three charge-discharge cycles of the supercapacitor in LEO have been recorded over the time-span of five months from the launch, and are compared to ground results. In addition, self-discharge over two days in orbit has been calculated as less than 2.5%. These results show that the COTS supercapacitor can withstand the launch and space environment with capacitance loss lower than 1% and, therefore, is a viable energy storage device for LEO satellites. However, degradation of the supercapacitor over longer stays in orbit and repeated cycling is yet to be characterised.