Highly flexible and free-standing carbon nanotube/hollow carbon nanocage hybrid films for high-performance supercapacitors

Carbon nanotubes (CNTs) have been considered as promising electrode materials for energy storage devices, especially flexible electronics owing to their excellent electrical, physicochemical and mechanical properties. However, the severe aggregation between CNTs significantly reduces the electrochemically active surface areas and thus degrades the electrochemical properties. In this study, we demonstrate a facile layer-by-layer strategy toward preparing a CNT/hollow carbon nanocage (HCNC) hybrid film. Through electrochemically removing the impurities in CNT films and optimizing the concentrations of HCNC, the hybrid film exhibits a high specific capacitance of 183.7 F g(−1) at 10 mV s(−1) and good cycling stability of 85% retention after 5000 cycles at 1 A g(−1). Our study provides potential scale-up synthesis of free-standing CNT electrode materials for high-performance supercapacitors.