Ice template induced assembly strategy for preparation of 3D porous carbon frameworks from low-cost carbon quantum dots for high-performance lithium-ion batteries

Consider the natural similarities between the structures of coal tar pitch and carbon quantum dots (CQDs), the mass-production of low-cost zero-dimensional (0D) CQDs was achieved by using the mild oxidation with hydrogen peroxide (H2O2). The as-obtained CQDs possesses a uniformly distributed size with a diameter of 4.16 ± 0.46 nm, many oxygen-containing functional groups, distinct crystallinity nature and a production yield of ∼18 wt%. Subsequently, ice-template induced assembly coupled with carbonization strategy reveals a transition from 0D CQDs to 3D porous carbon frameworks. Differing from the well-defined porous carbon, the obtained porous carbon frameworks consist of cross-linked and twisted nanosheets, achieving a well-developed hierarchical porous structure with a reasonable specific surface area and a gradient distribution of meso/micropores. LIBs based on porous carbon frameworks as anode materials show excellent long-cycle performance, as evidenced by reversible capacity of up to 273 mAh·g−1 after 1000 charge-discharge cycles at 2000 mA·g−1. The research emphasizes a green method of preparing CQDs from representative low-value coal tar pitch and the directional transition from 0D CQDs to 3D porous carbon frameworks, providing a promising idea to prepare functional carbon materials and endow them opportunities for LIBs anode.