李广超博士论文"Graphitic Nanorings for Super-Long Lifespan Lithium-ion Capacitors"被Nano Research接收发表
发布时间：2020-04-25
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Porous graphitic carbon nanorings (PGCNs) are proposed by smart catalytic graphitization of nano-sized graphene quantum dots (GQDs). The as-prepared PGCNs show unique ring-like morphology with diameter around 10 nm, and demonstrate extraordinary mesoporous structure, controllable graphitization degree and highly defective nature. The mechanism from GQDs to PGCNs is proven to be a dissolution-precipitation process, undergoing the procedure of amorphous carbon, intermediate phase, graphitic carbon nanorings and graphitic carbon nanosheets. Further, the relationship between particles size of GQDs precursor and graphitization degree of PGCNs products is revealed. The unique microstructure implies PGCNs a broad prospect for energy storage application. When applied as anode materials in dual-carbon lithium-ion capacitors, high energy density (77.6 Wh kg-1) and super long lifespan (89.5% retention after 40000 cycles at 5.0 A g-1) are obtained. The energy density still maintains at 24.5 Wh kg-1 even at the power density of 14.1 kW kg-1, demonstrating excellent rate capability. The distinct microstructure of PGCNs as well as the strategy for catalytic conversion from nanocarbon precursors to carbon nanorings open a new window for carbon materials in electrochemical energy storage.
