| Lithium-ion batteries as an efficient new green memory devices are widely used in portable electronic devices market, it also has a broad market space in the field of electric vehicles, energy storage power station and others. Therefore, people put forward higher requirements for the performance of lithium-ion batteries, such as high energy density, fast charging/discharging ability, long cycle life, safety, and so on. Based on the above background, for the purpose of improving the specific capacity, prolonging the cycling performance and the rate performance of lithium-ion batteries, this paper successfully prepared a series of high-performance anode materials via a facile one-step hydrothermal synthesis, the specific contents are as follows:① We studied the effects of different Co Mo O4 contents on the lithium storage performance of the Co MoO4NP/rGO nanocomposites. CoMo O4 nanoparticles become larger and larger with the increase of Co Mo O4 contents, destroyed the pore structure of graphene, blocked porous channels which formed during the self-assemble process, and thus hinders the lithium ions enter and exhibit poor electrochemical performance. Through comparative analysis, the final result was that when the Co Mo O4 content is 74%, Co Mo O4NP/rGO anode has a higher specific capacity and better cycle performance: the specific capacity was 920 mAh g-1 at 74 mA g-1 current density, and the specific capacity was 660 mAh g-1 at 740 mA g-1. In addition, under a high current density of 740 mA g-1, after 600 charge-discharge cycles, only 8.7% of capacity fading, is a kind of having certain applycation potential anode material for lithium ion batteries.② The Mo Se2/rGO aerogel foam was synthesized by the hydrothermal method and assisted by freeze-drying, and we studied the lithium storage mechanism. The structure of Mo Se2 in the nanocomposite was also layered film, the addition of graphene improved the specific surface area. Mo Se2/r GO nanocomposite material exhibited a superior electrochemical performance than pure Mo Se2 and r GO: the specific capacity of Mo Se2/rGO electrode is 650 mAh g-1 after 50 charge-discharge cycles at 0.1 C; and it can still up to 470 mAh g-1 after 600 cycles at 0.5 C, only about 10.9% capacity loss, the coulombic efficiency was close to 100%. Its superior electrochemical performance was due to the synergistic effects of graphene and Mo Se2: graphene in the nanocomposite can not only increase conductivity, but also contribute some capacity and effectively buffer mechanical stresses generated during the lithium ion intercalation/deintercalation; on the other hand, the Mo Se2 film as a barrier to prevent graphene sheets from agglomerating or folding.③ We successfully prepared Co Se2 nanorods on graphene film by hydrothermal method, and used a lithium-ion battery anode material. Compared with pure Co Se2, Co Se2/r GO nanocomposite exhibited a higher capacity and better cycle stability: the capacity up to 1228 mAh g-1 after 70 cycles at the current density of 0.1 C(1C = 670 mA g-1), the remaining capacity was 407 mAh g-1 after 1000 cycles at 1C, the capacity retention rate was 60.3%. About the improved performance, there maybe several reasons: graphene is similar to a conductive network in the nanocomposite to improve the conductivity, and reduce the diffusion path of lithium ions, accelerate the electrode reaction kinetics; secondly, the sample had a larger surface area after mixed with graphene, the contact area between active material and the electrolyte became larger, with a large number of Li ion reactive sites, improved the utilization of the active material.④ We studied the methods of preparing structure controlled Co NiO/TiO2 electrode, and characterization the structure and electrochemical properties of the obtained material. By controlling the hydrothermal reaction time, we successfully prepared structure controllable Co NiO nanowires on the TiO2 nanotubes of titanium sheet current collector which etched by anodic oxidation method, and obtained a free-standing integrated electrode material. The results showed that the rich space among the Co NiO nanowires in the electrode benefit the spread of the electrolyte, and accelerate the diffusion of lithium ions to the electrode surface, easing the volume expansion in the electrochemical process; the growth of Co NiO nanowires on the TiO2 nanotubes with Ti sheets is helpful to electron transport, so Co NiO/TiO2 electrode has superior integration electrode kinetics, the specific area capacity was 362 μAh cm-2, about 1097 mAh g-1(0.33 mg cm-2) at a high-current density of 0.2 mA cm-2 after 60 charge-discharge cycles. Adopted by anodic oxidation etched titanium sheet to replace the traditional metal collector, avoiding the use of PVDF binder, super-P conductive agent and NMP solution dispersion, effectively reduce the ratio of inactive material in the electrode, and improve the energy density, providing a new way for the integration of the lithium-ion battery electrode design. |
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