Litian Dong

Controllable oxygenic functional groups of metal-free cathodes for high performance lithium ion batteries

The poriferous reduced graphene oxide (rGO) with abundant oxygen-containing functional groups synthesized by a one-step hydrothermal method was successfully employed as a high performance cathode in lithium-ion batteries. The electrochemical results show that the rGO exhibits a remarkable lithium storage capacity (up to 270 mA h g−1 after 100 cycles). Further analysis shows that the rGO can exhibit a significantly high rate capacity, good reversibility, and excellent cycling stability, which clearly reveals the potential use of the rGO as the cathode material to boost both energy and power densities of LIBs. Furthermore, by controlling the oxygenic functional groups of the rGO, it was demonstrated that the capacity of rGO increased with the increase of the number of oxygenic functional groups, which illustrates that the excellent electrochemical performance of rGO could be attributed to its specific poriferous structure and the oxygen-containing functional groups.

PVP-derived carbon nanofibers harvesting enhanced anode performance for lithium ion batteries

Co-embedded carbon nanofibers were synthesized using electrospinning with polyvinylpyrrolidone (PVP) instead of high cost polyacrylonitrile (PAN). The obtained composite nanofibers as an anode material for lithium ion batteries deliver a reversible capacity of 542.6 mA h g−1 in the 100th cycle at a current density of 100 mA g−1. Moreover, the anode material shows better cycle performance and rate capability in comparison to the resultant product without Co additive. It is believed that the significant improvement is attributed to the nanofiber morphology with high surface-to-volume ratio as well as the existence of Co nanoparticles that enhance the electrical conductivity of the nanocomposites.

Design of a flower-like CuS nanostructure via a facile hydrothermal route

For the first time, a flower-like nanostructured CuS material was synthesised through a facile hydrothermal route using copper foil and brenstone as Cu and S sources, respectively. The obtained CuS was characterised by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy and transmission electron microscopy. The effects of the concentrations of the brenstone, reaction time, reaction temperature and NH4F additive on the morphologies of CuS nanostructures were studied in detail. It was found that morphological adjustment of the samples could be easily realised by optimising the amount of NH4F. However, the thickness of the CuS nanoplates highly depends on the combination of reaction time, reaction temperature and the concentrations of the brenstone and NH4F.