Acetonitrile-free organic electrolyte for textile supercapacitor applications

Textile supercapacitors are a key enabler of future, wireless, textile based smart wearables. With high power densities and long cycle lives, textile supercapacitors can be readily paired with energy harvesters to power the wearable technology. However, the energy density of these devices remains low (of the order of μWh) and work to increase this through improvements in the electrode design are requiring ever more complex materials and manufacturing processes. This work presents a novel and safe organic electrolyte that can increase the energy density of a simple symmetric activated carbon textile supercapacitor by ~ 8 times when compared to previous devices utilizing an identical substrate and set of electrodes. With a capacitance of 34.0 mF.cm-2 and an energy density of 18.9 μWh.cm-2, this device showed excellent performance. The device also underwent a rarely seen test for calendar ageing and was found to still exhibit 48% capacitance retention after two months of calendar ageing. This novel electrolyte enables the production of high energy density electric double layer textile supercapacitors without the need for pseudocapacitve or battery-like electrode materials