Spiral Graphene Coupling Hierarchically Porous Carbon Advances Dual-Carbon Lithium Ion Capacitor

Abstract

For the first time, novel spiral graphene (SGs), which are fabricated by an ultra-facile and robust catalytic graphitization strategy, are reported as a promising negative electrode material for lithium ion capacitors (LICs). The unique spiral graphene features a special helical structure, high graphitization and porous framework, resulting in high plateau capacity (222 mAh g−1 below 0.2 V at 0.05 A g−1) and outstanding rate capability (59 mAh g−1 at 5 A g−1). The formation mechanism of SGs is proposed by understanding the precipitation behaviour of carbon and moving trail of catalyst. The hierarchically porous carbon (HPC) derived from same source is also prepared and shows N, O co-doping property, large surface area of 1878 m2 g−1, high total pore volume of 2.11 cm3 g−1 with 86% of mesopores, making it an ideal capacitive material. More remarkably, by virtue of structural advantages, the optimized SG//HPC LICs with a mass loading of ~2.5 mg cm−2 for positive side deliver a high-energy density of 57 Wh kg−1 at a high-power density of 6323 W kg−1 and long-term cyclic stability (89.1% after 10000 cycles at 5 A g−1) in 2.0~4.2 V, outperforming advanced dual-carbon and non-dual-carbon LICs. The current work advances the design and fabrication of electrode materials for high-performance lithium ion capacitors and other energy storage devices.