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 (NCH_F) 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 NCH_F-1.38 ∼ 1.4 exhibits an excellent lithium-storage performance. The assembled Li//NCH_F-1.38 ∼ 1.4 half cell displays a high specific capacity, rate performance and cycle performance. Its initial discharge capacity and initial Coulomb efficiency 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 NCH_F-1.38 ∼ 1.4 is a potential anode material for LIBs.