Rencheng Jin

Mesocrystal Co9S8 hollow sphere anodes for high performance lithium ion batteries

Mesocrystal Co9S8 hollow spheres with high capacity and good cycle stability (254.9 mA h g−1 after 100 cycles at the current density of 100 mA g−1) were prepared through a solvothermal method in the presence of hexamethylenetetramine.

Hierarchical worm-like CoS2 composed of ultrathin nanosheets as an anode material for lithium-ion batteries

Hierarchical worm-like CoS2 assembled by ultrathin nanosheets with an average thickness of 2.1 nm were synthesized by a simple solvothermal process without any surfactant or template. Such hierarchical nanostructures exhibited a high specific capacity and excellent rate capability.

Solvothermal synthesis and excellent electrochemical performance of polycrystalline rose-like Co9S8 hierarchical architectures

Polycrystalline rose-like Co9S8 hierarchical architectures were fabricated by a facile solvothermal route in a binary solution of diethylenetriamine and ethylene glycol. The influencing factors, including the reaction time and volume ratio of diethylenetriamine to ethylene glycol, were systematically investigated. Based on field emission scanning electron microscope (FESEM) observations, a self-assembly process was proposed in order to explain the formation of the rose-like Co9S8 hierarchical architectures. Moreover, the electrochemical properties of the rose-like Co9S8 were measured. The rose-like Co9S8 architectures possessed high discharge capacities and good cycling performances as cathode materials for application in lithium-ion batteries.

Hierarchical NiCo2S4 hollow spheres as a high performance anode for lithium ion batteries

Hierarchical NiCo2S4 hollow spheres are successfully fabricated by a facile hydrothermal method accompanied by a high-temperature annealing and anion exchange process. By using NiCo2S4 hollow spheres as an anode material for lithium ion batteries, a high specific capacity of 696 mA h g−1 can be obtained after 100 cycles at a current density of 200 mA g−1. Even at a current density of 2000 mA g−1, the specific capacity still remains at 411 mA h g−1 after 50 cycles. The good electrochemical performance can be attributed to the unique porous features and void spaces within the surface of the hollow spheres, which provide large contact areas between the electrolyte and active materials for electrolyte diffusion and alleviate the volume change during the lithium-ion insertion/extraction process.

Self-decorated Cu2−xSe nanosheets as anode materials for Li ion batteries and electrochemical hydrogen storage

Hierarchical self-decorated Cu2−xSe nanosheets were synthesized through a facile solvothermal route in a binary solution of ethylene glycol and distilled water in the absence of a template. The X-ray diffraction (XRD), scanning electron microscope (SEM), and high-resolution transmission electron microscopy (HRTEM) analyses identified that the as-prepared Cu2−xSe nanosheets were single-crystalline decorated by Cu2−xSe nanodots. Based on the time-dependence experiment, the reaction and growth process was discussed in detail. Furthermore, the electrochemistry Li and hydrogen storage properties of the hierarchical self-decorated Cu2−xSe nanosheets were measured. This hierarchical self-decorated Cu2−xSe nanosheet showed a good cycle and rate performance, indicating its potential application as an anode material for lithium ion batteries. The good cycle and rate performance may be attributed to the unique hierarchical morphology which can buffer the volume change to some degree during the discharging/charging process.

Hierarchical Bi2Se3–xSx microarchitectures assembled from ultrathin polycrystalline nanosheets: solvothermal synthesis and good electrochemical performance

A simple solvothermal route in a binary solution of ethylene glycol and diethylenetriamine has been applied to synthesize hierarchical flower like Bi2Se3−xSx. Through SEM and TEM observations, the flower like Bi2Se3−xSx is assembled from poly-crystalline nanosheets with average thicknesses of 18 nm. It is found that the volume of thioglycolic acid, the reaction temperature and the volume ratio of ethylene glycol to diethylenetriamine play important roles in the formation of flower like Bi2Se3−xSx. Based on the experimental results, the mechanism for the formation of the flower like Bi2Se3−xSx is discussed. Meanwhile, electrochemical measurements reveal that the as-prepared flower like Bi2Se3−xSx delivers a high discharge capacity and good cycle stability in electrochemical hydrogen storage.

Microwave-assisted synthesis of Bi2Se3 ultrathin nanosheets and its electrical conductivities

Ultrathin Bi2Se3 nanosheets have been successfully fabricated through a microwave-assisted approach in the presence of ethylene glycol (EG) under 1 kW microwave power for 1 minute. The structure and morphology of the obtained products were characterized by powder X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), selected-area electron diffraction (SAED) and Raman spectroscopy techniques. Based on the control experiments, a possible growth mechanism of Bi2Se3 ultrathin nanosheets was proposed. Furthermore, the thermoelectric transport properties of the nanosheets were investigated by measuring the electrical conductivity and the Seebeck coefficient at temperatures ranging from 298 to 523 K. The maximum power factor can reach up to 157 μW m−1 K−2 at 523 K due to the ultrathin nature of the as-prepared sample, indicating that this promising approach can be extended to the synthesis of other thermoelectrical materials.

Molten salt synthesis of fluorine-doped Mn3O4 nanobelts as anode materials for Li-ion batteries

Uniform F-doped Mn3O4 nanobelts have been synthesized by the molten salt method using NaF as the fluorine source and morphology stabilizer. The as-prepared materials are characterized by field emission scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy techniques. Based on the experimental results, a possible formation mechanism of the F-doped Mn3O4 nanobelts is proposed. The electrochemical measurement indicates that the F-doped Mn3O4 nanobelts exhibit a reversible electrochemical lithium storage capacity as high as 615 mA h g−1 at 100 mA g−1 after 100 cycles, and an excellent rate capability of 412 mA h g−1 at a high current density of 1000 mA g−1.

Ni2+ ion assisted synthesis of hexagonal α-Fe2O3 nanoplates as anode materials for lithium-ion batteries

Fe2O3 hexagonal nanoplates have been successfully synthesized via a molten salt procedure with the assistance of Ni2+ ions. The resulting Fe2O3 is characterized by X-ray powder diffraction (XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). According to the microscopy observations, the morphology and size of the sample can be tailored by the foreign ions (Ni2+). Moreover, galvanostatic cell cycling is employed to evaluate the electrochemical performance of the obtained Fe2O3. The results show that the Fe2O3 hexagonal nanoplate electrodes have stable cycling performance with a reversible capacity of over 711 mA h g−1 after 100 cycles at a current density of 100 mA g−1. The sample with optimized structure shows the best rate performance with a high capacity of 418 mA h g−1 (40th cycle) even at a current density of 1000 mA g−1.

Sb Nanoparticles Anchored on Nitrogen-Doped Amorphous Carbon-Coated Ultrathin CoSx Nanosheets for Excellent Performance in Lithium-Ion Batteries

Compared to single-component materials, hybrid materials with various components display superior electrochemical performance. In this work, two-dimensional CoSx@NC@Sb nanosheets assembled by ultrathin CoSx nanosheets (∼4 nm) and a thin layer of N-doped amorphous carbon (NC) combined with colloidlike Sb nanoparticles are designed and synthesized via a solvothermal route accompanied by a carbonization and Sb deposition procedure. If applied in lithium-ion batteries (LIBs), the hybrids exhibit a specific capacity of 960 mA h g-1 at the 100th cycle at 0.1 A g-1. Moreover, the reversible capacity still maintains at 494 mA h g-1 after 500 cycles at a high rate of 10 A g-1. All enhanced electrochemical properties of the hybrids are attributed to the synergistic effect of the two components and their unique structural features, which can effectively increase the electrical conductivity, shorten the pathway of Li+ diffusion, accommodate the volume variation, and inhibit the aggregation and pulverization of the electrode. We believe that the current work can provide a new strategy for designing and fabricating high-performance anode materials for LIBs.