Hierarchical SnO2 nanoclusters wrapped functionalized carbonized cotton cloth for symmetrical supercapacitor

As an excellent free-standing carbon source, commercialized cotton cloth can be carbonized to fabricate conductive carbon cloth composed of hollow carbon microfibers. In view of the hydrophobicity of carbon cloth, a functionalized carbonized cotton cloth (FCC) is prepared by acidification treatment, and acted as a flexible substrate to grow hierarchical SnO2 nanoclusters by a solvothermal reaction and calcination process. In this SnO2 wrapped FCC (FCC@SnO2) composite, the oxygen-containing groups in carbon microfibers provide numerous anchoring sites for growing SnO2 nanoparticles, meanwhile, the carbon microfibers provide conductive channels for the fast transfer of electrons and ions. The SnO2 nanoclusters effectively contribute their pseudocapacitance. As free-standing electrodes in a symmetrical two-electrode supercapacitor, the FCC@SnO2 composite exhibits a higher capacitance of 197.7 F g−1 or 1265.3 mF cm−2 at 1 A g−1, much higher than that of FCC (100.3 F g−1 or 411.2 mF cm−2); furthermore, its capacitance remains 95.5% after cycling for 5000 cycles at 15 A g−1. The FCC@SnO2 composite is easier preparation and low cost, which can be utilized as self-supporting flexible electrodes for high performance supercapacitors.