Structure and electrochemical applications of boron-doped graphitized carbon nanofibers

Abstract

Boron-doped graphitized carbon nanofibers (CNFs) were prepared by optimizing CNFs preparation, surface treatment, graphitization and boron-added graphitization. The interlayer spacing (d₀₀₂) of the boron-doped graphitized CNFs reached 3.356 Å, similar to that of single-crystal graphite. Special platelet CNFs (PCNFs), for which d₀₀₂ is less than 3.400 Å, were selected for further heat treatment. The first heat treatment of PCNFs at 2800 °C yielded a d₀₀₂ between 3.357 and 3.365 Å. Successive nitric acid treatment and a second heat treatment with boric acid reduced d₀₀₂ to 3.356 Å. The resulting boron-doped PCNFs exhibited a high discharge capacity of 338 mAh g⁻¹ between 0 and 0.5 V versus Li/Li⁺ and 368 mAh g⁻¹ between 0 and 1.5 V versus Li/Li⁺. The first-cycle Coulombic efficiency was also enhanced to 71-80%. Such capacity is comparable to that of natural graphite under the same charge/discharge conditions. The boron-doped PCNFs also exhibited improved rate performance with twice the capacity of boron-doped natural graphite at a discharge rate of 5 C.

A review of nanofibrous structures in lithium ion batteries

“…The size of the diamond grains affected the formation of the passivation layer: smaller grain sizes corresponded to more efficient passivation layers and better electrochemical performances. B in graphitized CNF with boric acid provided a more amorphous structure, increasing the amount of non-flattened hexagonal edges and shortening the Li þ diffusion path during the charge/discharge process [224].…”

Key issues facing electrospun carbon nanofibers in energy applications: on-going approaches and challenges

“…For example, boron is one of the canonical candidates, which can substitute a fraction of carbon atoms in the carbon networks and form a B 2 O 3 layer at high doping concentrations, thereby accelerating the graphitization of carbonaceous materials. 46,47 Indeed, boron-doped CNFs have been widely explored as supercapacitor electrodes in recent years, whereas, considerable attention is paid to the porous structure and extra pseudocapacitance of CNFs contributed by boron doping. More discussions on heteroatom doping will be presented in section 4.…”

Enhancement of the rate performance of plasma-treated platelet carbon nanofiber anodes in lithium-ion batteries

“…Crystallographic analyses were performed according to a JSPS method (Gakushinho). 22 Calibration was done by mixing standard silicon powder (200 mesh, 99.99%, Soekawa Chemical Co., Japan) with each sample at 10 wt% concentration. The interlayer spacing (d 002 ) and stacking height (Lc 002 ) were calculated.…”