A nitrogen-incorporated nanocarbon hybrid with high lithium-storage performances using density-graded anthracite as a starting material

Abstract As the anode material of lithium-ion batteries (LIBs), traditional graphite can no longer meet the current demands. Here, a series of nitrogen-incorporated nanocarbon hybrids (NCHF) assembled by graphene and plentiful carbon nanotubes (CNTs) are successfully prepared using anthracite fractions based graphene oxide-Co-melamine precursors via a facile pyrolysis process. Therein, anthracite fractions are separated into four parts by ZnCl2 heavy solutions with various densities. Owing to the nanocarbon assembly structure including graphene and CNTs with abundant wall holes and cracks, well-matched hierarchical porous structure, and suitable nitrogen incorporation, the optimal NCHF-1.38~1.4 exhibits an excellent lithium-storage performance. The assembled Li//NCHF-1.38~1.4 half cell displays a high specific capacity, rate performance and cycle performance. Its initial discharge capacity and initial Coulomb efficiency (ICE) reach 1111.7 mAh g-1 and 66.9% at a current density of 0.03 A g-1, respectively. And the average discharge capacity from 2nd cycle to 10th cycle attains 761.2 mAh g-1. After 500 cycles at 1 A g-1, its discharge capacity and Coulomb efficiency remain at 392.6 mAh g-1 and 99.5%, respectively. This work confirms the necessity of anthracite grading for its high value-added applications and the NCHF-1.38~1.4 is a potential anode material for LIBs.