Structural Regulation and Potassium Storage Performance of B, N Co-doped Hard Carbon Derived from Toluene-Insoluble Fractions of Coal Tar Pitch

In this work, high-temperature coal tar pitch was modified with pyridine borane as a boron–nitrogen co-dopant, and the modified TI precursor was obtained by toluene extraction, followed by carbonization at 800 °C to prepare a series of B, N-codoped TI-derived hard carbons.

The effects of pyridine borane content on the chemical structure and pyrolysis behavior of TI precursors were systematically investigated, and the microstructure, pore characteristics, heteroatom speciation and potassium storage performance of the as-prepared hard carbons were characterized. The sample with 1 wt.% pyridine borane showed a carbon interlayer spacing of 0.375 nm and the highest doping levels of active B–C–O, pyridinic N and pyrrolic N. It delivered a reversible capacity of 206.52 mAh g-1 at 0.05 A g-1, and maintained 100.92 mAh g-1 after 300 cycles at 1 A g-1.