Preparation And Lithium Storage Performances Of Graphene Membrane-based Nickel Molybdate

The purpose of this paper was to improve the performance of lithium ion batteries based on the graphene membrane.Through the regulation of the morphology of nickel molybdate,the design of the thickness of the graphene membrane and the composite of three-dimensional structure,the electrochemical performance of the lithium ion battery was improved.The following three aspects were mainly studied:NiMoO4 nanorods and NiMoO4 nanoflower were prepared by controlling the morphology of the nickel molybdate.NiMoO4 nanorods were with a diameter of 100-250 nm and the surface of nanorod is smooth.NiMoO4 nanoflowers were growth on the substrate of NiMoO4 nanofilm.After 100 cycles,the capacity of NiMoO4 nanorods was higher than NiMoO4 nanoflowers.And the NiMoO4 nanoflowers features better rate performance than that of the NiMoO4 nanorods.Secondly,three kinds of thickness of free-standing r GO membranes were fabricated through the method of vacuum filtration and heat treatment.The electrochemical properties of r GO membranes with different thickness were tested,the cycle performance of r GO membrane of 10.1 ?m was better than the other two,and the rate performance of r GO membrane of 9.3 ?m was better than the other two films.Based on r GO membrane and NiMoO4 nanorods.A free-standing and flexible NiMoO4 nanorods/r GO membrane with a three-dimensional hierarchical structure was successfully synthesized by a general approach including vacuum filtration followed by thermal reduction.NiMoO4 nanorods with about 50 ? 100 nm diameter were embedded homogenously into the 3D r GO sheets and assembled with r GO to form a membrane about 10 ?m in thickness.The NiMoO4/r GO membrane could be directly evaluated as anode materials for lithium-ion batteries(LIBs)without using binder.The 3D layerstacked graphene hierarchical architecture can not only offers a continuous conducting framework for efficient diffusion and transport of ion/electron,but also accommodates the large volume expansion of NiMoO4 nanorods changes during cycling.Moreover,our results show that NiMoO4/r GO membrane exhibited excellent electrochemical performance with a high reversible capacity of 945 m Ah g-1 at a current density of 0.25 A g-1 as anode materials in LIBs.