Structurally Defined 3D Nanographene Assemblies via Bottom-Up Chemical Synthesis for Highly Efficient Lithium Storage

A series of 3D NGs (nanohgraphene) with a variety of functional groups from hydrogen, methoxyl, tert-butyl, hydroxy, bromine, to fluorine through a multistep organic synthesis route using triphenylamine as the starting material was synthesized. The result indicate that the best performing 3D NG anode exhibits a very high capacity almost three times larger than that of the conventional graphite anode with an excellent stability over 250 charge?discharge cycles. These NGs have relatively small graphene flakes, hence forming a more robust self-assembled hierarchical structures. In addition, maximum electron density on the NGs and optimal d-spacing in the 3D NG self-assemblies have led to a significantly enhanced LIB anode charge capacity and cyclic stability. Our results have clearly demonstrated a structure?property correlation between the nature of functional groups and Li storage capacity. More importantly, results obtained from substantial DFT calculations are in good agreement with our electrochemical and battery measurements, identifying the mechanism on how NG electronic and geometric structures dominate the overall battery performance.