Porous graphene as cathode material for lithium ion capacitor with high electrochemical performance

The porous reduced graphene is prepared via an ethylene glycol assisted-hydrothermal method which is green, simple and nontoxic. The ethylene glycol assisted-hydrothermal reduced graphene (EG-RGO) delivers superior power density compared to those prepared without the assistant of ethylene glycol when used as cathode materials for the lithium ion capacitors. The EG-RGO electrode shows a high capacity of 172 mAh g− 1 at 0.1 A g− 1 and without capacity loss after 3000 cycles. Furthermore, the power density of the electrodes reaches 53.5 kW kg− 1 at the current density of 20 A g− 1 with an energy density of 240 Wh kg− 1. The high electrochemical performance of EG-RGO is attributed to the high electronic conductivity of the graphene.