Beibei Wang

Hybrids of Mo2C nanoparticles anchored on graphene sheets as anode materials for high performance lithium-ion batteries

In this article, we demonstrate a general approach to grow Mo2C nanoparticles of 10–40 nm on a graphene (GR) support through a simple and environmentally friendly carburization process. The unique and special structural features of the Mo2C/GR hybrids including good structural robustness, small particle size and porous structure permit easy access for electrons and ions to the electrode/electrolyte, when the resulting materials are used as anode materials for lithium-ion batteries. Electrochemical tests indicate that the Mo2C/GR hybrids exhibit much better lithium storage properties than pure GR and bulk Mo2C electrodes. The enhanced electrochemical properties of the Mo2C/GR hybrids are mainly ascribed to the synergetic effects between Mo2C nanoparticles and the highly conductive GR support. The results clearly demonstrate that the Mo2C/GR hybrids have potential application as anode materials in high-performance energy storage devices.

Easy access to nitrogen-doped mesoporous interlinked carbon/NiO nanosheet for application in lithium-ion batteries and supercapacitors

We report a simple route to synthesis nitrogen-doped mesoporous interlinked carbon/NiO nanosheet that consist of carbon nanosheets and monodisperse NiO nanoparticles embedded in them homogeneously. The nitrogen-doped mesoporous interlinked carbon/NiO nanosheet with carbon content of 46% was obtained through directly low temperature heat treatment of Ni-ZIF-8 with a rapid heating rate (5 °C min−1). During the heat treatment, a large number of mesoporous were formed in the product with the evaporation (or thermal decomposition) of the organic ligand. When tested as an anode for lithium ion batteries (LIBs), the unique structure of the mesoporous carbon/NiO nanosheet not only shortened electro- and iron-transport pathways but also accommodated the volume change during Li+ intercalation and deintercalation process, resulting in a reversible capacity of 627 mA h g−1 at 0.5 A g−1 after 300 cycles. Moreover, the as-assembled carbon/NiO nanosheet supercapacitor can also exhibit an excellent cycling performance (414 F g−1 at 5 A g−1) with 92.2% specific capacitance retention after 3000 cycles by combined the pseudocapacitive behavior of the NiO nanoparticles with the electric double-layer capacitors (EDLCs) of the nitrogen-doped mesoporous carbon.

Hierarchical NiCo 2 O 4 nanosheets grown on hollow carbon microspheres composites for advanced lithium-ion half and full batteries

Hierarchical ultrathin NiCo2O4 nanosheeets grown on uniform hollow carbon microspheres (HC@NiCo2O4) are designed and fabricated by a solvothermal reaction followed with an annealing process. When evaluated as an anode for lithium ion batteries, the as-prepared HC@NiCo2O4 microspheres exhibit excellent electrochemical performance (a high reversible capacity of 1015 mA h g-1 after 100 cycles at a current density of 0.1 A g-1 and a high capacity of 805 mA h g-1 even at a high current density of 0.5 A g-1). By pairing with the LiCoO2 cathode, the HC@NiCo2O4 anode also manifests excellent performance in full cells. The outstanding electrochemical performance in half and full cells can be attributed to its unique structure, which can not only promote the contact of electrode and electrolyte during the charge and discharge processes, but also shorten the transmission path of electrons and ions. More importantly, this study inspires a better design of various metal oxide/carbon electrode materials for high performance lithium ion batteries.

Rational design of Fe3O4@C yolk-shell nanorods constituting a stable anode for high-performance Li/Na-ion batteries

In the current research project, we have prepared a novel Fe3O4@mesoporous carbon nanorod (denoted as Fe3O4@C) anode with yolk-shell structure for Li/Na-ion batteries via one-pot and surfactant-free synthesis strategy. The yolk-shell structure consists of Fe3O4 nanorod yolk completely protected by a well-conductive mesoporous carbon shell. The substantial void space in the Fe3O4@C yolk-shell nanorod can not only accommodate the full volume expansion of inner Fe3O4 nanorod, but also preserve the structural integrity of the Fe3O4@C anode and develop a stable SEI film on the outside mesoporous carbon shell during the repeated Li+/Na+ insertion/extraction processes. As for lithium storage, the Fe3O4@C electrode exhibits a high specific capacity (1247 mAh g-1), stable cycling performance (a specific capacity of 954 mAh g-1 after 200 cycles at a current density of 0.5 A g-1) and excellent rate capability (specific capabilities of 1122, 958, 783, 577, and 374 mAh g-1 at 0.5, 1, 2, 4, and 8 A g-1, respectively). As for sodium storage, the Fe3O4@C yolk-shell nanorods also maintain a reversible capacity of approximate 424 mAh g-1 at 0.1 A g-1 after 100 cycles.