Hui Shan

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.

Superior Cathode Performance of Nitrogen-Doped Graphene Frameworks for Lithium Ion Batteries

Development of alternative cathode materials is of highly desirable for sustainable and cost-efficient lithium-ion batteries (LIBs) in energy storage fields. In this study, for the first time, we report tunable nitrogen-doped graphene with active functional groups for cathode utilization of LIBs. When employed as cathode materials, the functionalized graphene frameworks with a nitrogen content of 9.26 at% retain a reversible capacity of 344 mAh g-1 after 200 cycles at a current density of 50 mA g-1. More surprisingly, when conducted at a high current density of 1 A g-1, this cathode delivers a high reversible capacity of 146 mAh g-1 after 1000 cycles. Our current research demonstrates the effective significance of nitrogen doping on enhancing cathode performance of functionalized graphene for LIBs.

An optimized Al2O3 layer for enhancing the anode performance of NiCo2O4 nanosheets for sodium-ion batteries

Herein, an ultrathin Al2O3 layer was coated onto NiCo2O4 nanosheets via an atomic layer deposition (ALD) method, and the NiCo2O4 coated with an ALD-derived Al2O3 material was successfully used as an anode material for sodium-ion batteries (SIBs). This kind of electrode exhibited enhanced cycling performance with a reversible capacity of 395 mA h g−1 after 50 cycles, and good rate capability with the discharge capacities of 350, 320, and 294 mA h g−1 at the various current densities of 100, 200, and 400 mA g−1, respectively. Interestingly, remarkable prevention of the reactions between the electrode and electrolyte was observed. The performance improvement is due to the protection of the NiCo2O4 coated with an ALD-derived Al2O3 layer from the electrochemical active materials. These results demonstrate the great potential of NiCo2O4 coated with an ALD-derived Al2O3 material as anodes in SIBs.

Carbon nanotubes cross-linked Zn2SnO4 nanoparticles/graphene networks as high capacities, long life anode materials for lithium ion batteries

Abstract By shielding zinc stannate (ZTO, viz., Zn2SnO4) nanoparticles with reduced graphene oxide (RGO) as well as multi-wall carbon nanotubes (MWCNTs), we have successfully created ZTO/RGO/MWCNTs composites via a facile hydrothermal process. In the designed hybrid nanostructure, acting as the strut and bridge to open the graphene sheets, 3D RGO/MWCNT nets not only tackle the problem of volume expansion and the aggregation of ZTO nanoparticles, but also maintain the integration of anode materials for high electrochemical performance. As a result, the resultant anode material shows high reversible capacity, superior rate capacity and long-running cycle performance for lithium ion batteries (LIBs). For instance, a excellent reversible capacity of 915.9 mAhxa0g−1 was obtained at the current density of 100xa0mAxa0g−1 after 340 cycles. Our study demonstrates significant potential of ZTO/RGO/MWCNTs as anode materials for LIBs.Graphical Abstract

Metal–Organic Frameworks-Derived Co2P@N-C@rGO with Dual Protection Layers for Improved Sodium Storage

The Co2P nanoparticles hybridized with unique N-doping carbon matrices have been successfully designed employing ZIF-67 as the precursor via a facile two-step procedure. The Co2P nanostructures are shielded with reduced graphene oxide (rGO) to enhance electrical conductivity and mitigate volume expansion/shrinkage during sodium storage. As anode materials for sodium-ion batteries (SIBs), the novel architectures of Co2P@N-C@rGO exhibited excellent sodium storage performance with a high reversible capacity of 225 mA h g-1 at 50 mA g-1 after 100 cycles. Our study demonstrates the significant potential of Co2P@N-C@rGO as anode materials for SIBs.

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.