Enhanced electrochemical performances of cylindrical hybrid supercapacitors using activated carbon/ Li4-xMxTi5-yNyO12 (MÂ =Â Na, NÂ =Â V, Mn) electrodes

Cylindrical hybrid supercapacitors were fabricated using activated carbon as a cathode and Li4-xMxTi5-yNyO12 (M = Na, N = V, Mn) as an anode. We investigated the effect on the electrochemical performances of dopants. Although all dopants affect the electrochemical performances of hybrid supercapacitors, it is notable that the Na and V dopants not only improve the conductivity but also lower the operating voltage. Through these synergetic effects, the electrochemical performances of hybrid supercapacitors using Li4Ti4.7V0.3O12, Li3.7Na0.3Ti5O12 anodes were significantly improved. Especially the hybrid supercapacitor using Li4Ti4.7V0.3O12 anode shows the extraordinary capacitance retentions of 94.6% after 5000 cycles at a current density of 2.5 Ag−1 at 40 °C due to its low charge-transfer resistance. Therefore, the Li4Ti4.7V0.3O12 can be regarded as an anode material for optimum electrochemical performances of hybrid supercapacitors.