Towards flexible and wearable supercapacitors: A hierarchical approach in material design

Wearable devices requires from macroscopic mechanical properties laying in macro-scale in comparison with chemical processes that requires from material design in the nanoscale. Besides, such reactions and phenomena involves charge transfer, and therefore a charge transducer in mean scale is required. In this paper we propose a flexible and wearable supercapacitor that takes advantage of a conductive fabric current collector that is coated by electrospray with MnO2-decorated carbon nanofibers (CNF). The results point out that a high capacitance is obtained due to the pseudocapacitive reactions in MnO2; moreover, the long and conductive structure of CNF allow transferring charge to conductive fabric, keeping a low equivalent serial resistance (ESR). The results indicate a specific capacitance on fabric collector of (226.40 ± 0.3) F/g, about 10 times higher than on aluminum foil collector, with a similar ESR which indicates a suitable way to wearable devices. The proposed technique is scalable, and can be easily applied in the industry.