Fabrication of a novel graphene nano-sheet electrode embedded with nano-particles of zirconium dioxide for electrochemical capacitors: Ions-redeposition on the surface of nanoporous electrode

In this paper, the effect of charge/discharge cycles on the electrode containing nano-zirconium oxide, nanoporous carbon black and graphene nanosheets in electrochemical capacitors has been described. Surface morphology and electrochemical performance of the prepared electrode have also been conducted. The electrode prepared from graphene nanosheets (GNS), nanoporous carbon black (NCB), zirconium oxide (ZrO₂), and polytetrafluoroethylene (PTFE) in molar ratio of 54:09:27:10 respectively showed a maximum specific capacitance as high as 11.84 F g^-1 in the potential range between -0.45 and 0.35 V (V vs. SCE) at a scan rate of 10 mV s^-1 in a 3 M NaCl electrolyte. The electrochemical results show the low ratio of the outer to total charge (q_O∗/q_T∗) which confirms the low current response and higher voltage reversal at the end potentials. SEM images confirms the ions re-deposit as agglomerates and accompanied by a drastic decrease in the surface area on the surface of the electrode after one charge/discharge cycle.