Length Space-confined carbonization strategy for synthesis of carbon nanosheets from glucose and coal tar pitch for high-performance lithium-ion batteries

A space-confined carbonization strategy is developed to synthesize carbon nanosheets (CNSs) from various carbon precursors such as glucose and coal tar pitch (CTP) using expanded vermiculite as template. The carbonization process of the glucose and CTP molecules occurs in the confined space in the expanded vermiculite, which leads to the formation of well-defined carbon nanosheets (G-CNSs and CTP-CNSs). These carbon nanosheets not only have acceptable specific surface area (381 and 297 m(2).g(-1)) and total pore volume (0.379 and 0.558 cm(3).g(-1)) with abundant heteroatom functional groups (e.g. O and N), but also possess lamellar structure consisting of multi-layer graphene with appreciate interlayer spacing and favorable hierarchical pore structure. Such distinctive microstructure features ensure both kinds of CNSs applied as anode materials for lithium-ion batteries to exhibit superior electrochemical behaviors. Particularly, CTP-CNSs exhibit a high initial reversible capacity (1147 mAh/g at 0.05 A/g), outstanding rate capability (510 mAh/g at a high current density of 2 A/g), and superior long-term cycling stability (623 mAh/g with a Coulombic efficiency of 99.7% at 2 A/g after 500 cycles). This result suggests such anode material outperformed many other carbon materials reported in the literature, proving the applicability of the preparation route developed in the current work.

Automated summary

A space-confined carbonization strategy is developed to synthesize carbon nanosheets with well-defined microstructure features, leading to superior electrochemical performances as anode materials for lithium-ion batteries. The carbon nanosheets exhibit high reversible capacity, outstanding rate capability, and superior long-term cycling stability, outperforming many other carbon materials reported in the literature.