Preparation of polypyrrole nanocomposites for supercapacitor using spent battery powder as raw materials

•Spent battery powder has been utilized as raw materials for supercapacitor.•MnO2 in spent zinc-carbon battery was used for oxidative polymerization of pyrrole.•The electrochemical properties of the G/PPy were better than the MnO2/G/PPy.•It possessed the highest capacitance of 212.4F/g, retaining 89.5% after 1000 cycles.