Importance of microstructure and interface in designing metal oxide nanocomposites for supercapacitor electrodes

Abstract

In this work, we demonstrate that designing metal oxide nanocomposite with an optimized nanocarbon to metal oxide ratio is required to realize the best electrochemical performance. Using carbon nano-onion (CNO) and TiO2 composite as a model system, it is evidenced that the formation of interfacial structure and the existence of electrical percolation networks are essential to enhance electrical performance of the composite. When the aforementioned conditions are satisfied, CNO/TiO2 hybrid nanocomposites (CTHNs) with only 11wt% TiO2 loading exhibits excellent electrochemical performance. The maximum specific capacitance obtained for this composite electrode is 386Fg−1 at a scan rate of 5mVs−1, which is the highest reported value till date in a TiO2 composite electrode measured in a two electrode cell configuration. At this composition, excellent electrochemical stability is obtained with only 5% capacitance degradation over 2000cycles. As the TiO2 loading increases the electrochemical performance decreases.