▎ 摘　　要

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 10,000 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 electro-chemical properties (98.5 W h kg(-1) at 1130 W kg(-1) and 94.2% capacity retention under -30 degrees C), indicating a great application prospect in the next generation energy storage devices for LIC.