Nanostructured MnO2/graphene composites for supercapacitor electrodes: the effect of morphology, crystallinity and composition

Nanostructured MnO2 with different morphologies, i.e. amorphous, lamellar and needle-like, is incorporated with tetrabutylammonium hydroxide stabilized graphene (GTR) with different mass ratios. A systematical approach has been used to investigate the morphology, structure and electrochemical performances of these materials for supercapacitor electrodes. It is found that the morphology, crystallinity and composition all play important roles in the capacitor performance. Needle-like MnO2 (N-Mn)/GTR composites with high surface area and good crystallinity show better performance compared with the other two systems. A new morphology emerges in N-Mn/GTR13; meanwhile high specific capacitances of 280 F g(-1) for the N-Mn/GTR13 composite and 631 F g(-1) for MnO2 are achieved. The inclusion of graphene significantly improves the cycling stability.