Multilayered graphene endowing superior dispersibility for excellent low temperature performance in lithium-ion capacitor as both anode and cathode

Abstract Constructing all-graphene symmetric lithium-ion capacitor (LIC) with high energy and power density has recently gained widespread attention. Here, O-doping multilayered porous graphene (OMG) with micron-size served as both cathode and anode for LIC was prepared via a simple and easily large-scale air thermal treatment method. By rational controlling the reaction temperature and time in the air, the obtained OMG nano-sheets possess high specific surface areas, abundant nano-pores channels, enlarged graphene-interlayers spacing, good conductivity and superior dispersibility. As anode, OMG delivered high average capacity (247 mA h g-1 at 1.0 A g-1), excellent rate capability (138 mA h g-1 at 10 A g-1) and long-term cycling performance (83% capacity retention for 10000 cycles). As cathode, OMG showed large average capacity (196 mA h g-1 at 1.0 A g-1), superior rate performance (155 mA h g-1 at 10 A g-1) and outstanding cyclic stability (increasing capacity for 7000 cycles). The assembled all-graphene symmetric OMG//OMG LIC exhibited an excellent rate capability (70.7%), high energy density of 131.6 W h kg-1 at 2272 W kg-1 and high energy density of 87.3 W h kg-1 even at a higher power density of 21660 W kg-1 coupled with ultralong cycling stability (96.8% capacity retention for 5000 cycles). More importantly, OMG//OMG still exhibit excellent low-temperature electrochemical properties (98.5 W h kg-1 at 1130 W kg-1 and 94.2% capacity retention under -30 °C), indicating a great application prospect in the next generation energy storage devices for LIC.