Research On Morphology Controlled Synthesis Of Several Transition Metal Oxides And Their Capacitance Performances

Global warming and the depletion of fossil fuels have been alarming a bell to the sustainable development of humankind.Supercapacitors have received much attention,electrode material is the key to the supercapacitor performance,thus developing a new type of low cost,high energy density and high stability of the electrode material is the focus of the present study.Transition metal oxides are considered to be very promising electrode materials,but the cycle life and rate performance of these materials are not ideal,however unique morphology of transition metal oxides can significantly improve the electrochemical performance.This paper aims to explore simple approaches to prepare transition metal oxides with unique morphologies.Systematically study the relationship between micro-nano structure and electrochemical performance of transition metal oxides to make transition metal oxides can play a better role in the application of energy storage.The main contents are list below:?1?Research on morphology controlled synthesis and capacitance performance of V₂O₅.Various V₂O₅ three-dimensional nanostructures were synthesized by controlling the solution at a proper concentration using a hydrothermal method.By studying the supercapacitors performance of different morphologies V₂O₅,the relationship between V₂O₅ pore diameters,Brunauer-Emmett-Teller?BET?surface area and electrochemical performance were analyzed,so as to obtain the optimal reaction concentration.The asymmetric supercapacitor?ASC?was constructed with V₂ and ODCSC with 90.6%specific capacity retention after 2000 cycle at 3.0 A g^-1.The prepared ASC could easily light the LED indicator brightly,further demonstrating the prepared materials have great potential in developing high-performance supercapacitors.?2?Research on preparation of chestnut shell-like Li₄Ti₅O₁₂2 hollow sphere and flower-shaped Li₄Ti₅O₁₂-Gr nanocomposites and their capacitance performance.At present,it is highly desirable for three-dimensional?3D?metal oxides materials to further enhance the electrochemical performance of supercapacitors,as hierarchical structure gives it broader internal space and easy access of electrolyte ion.3D chestnut shell-like Li₄Ti₅O₁₂2 hollow sphere and flower-shaped Li₄Ti₅O₁₂-Gr nanocomposites were fabricated by using a simple hydrothermal strategy.Owing to the unique structural feature and the desirable chemical composition,Li₄Ti₅O₁₂2 hollow sphere displayed a remarkable capacitance.Furthermore,one aqueous asymmetric supercapacitor?ASC?based on Li₄Ti₅O₁₂2 and N-doped graphene oxide?NGO?was assembled.NGO was prepared by a facile burning method.The Li₄Ti₅O₁₂//NGO ASC showed a high energy density.This strategy may offer a versatile idea of tailoring new type of 3D metal oxides hollow materials.Subsequently,the 3D flower-shaped Li₄Ti₅O₁₂-Gr displayed a high specific capacitance of 706.5 F g^-11 at 1.0 A g^-1.The prepared pine needles derived carbon nanopores?PNDCN?also exhibited high specific capacitance of 314.5 F g^-11 at 1.0 A g^-1.An asymmetric supercapacitor utilizing Li₄Ti₅O₁₂-Gr as positive electrode and PNDCN as negative electrode was fabricated,and it delivered a high energy density and outstanding cycling stability.The fabrication process presented in this work was facile,cost-effective,and environmentally benign,offering a feasible solution for manufacturing next-generation high-performance supercapacitor.?3?Research on preparation of Gr-WO₃ hybrids and its capacitance performance.We synthesized Gr-WO₃ hybrids using a simple hydrothermal method.The WO₃nanoparticles dispersed well on the Gr.The results of electrochemical tests showed that the Gr-WO₃ hybrid electrode behaved with remarkable capacitive properties and stability.The Gr-WO₃ hybrids exhibited excellent long cycle life.The enhancement in supercapacitor performance of Gr-WO₃ was not only attributed to its large specific surface area,but also its excellent electro-conductivity,which facilitated efficient charge transport and promotes electrolyte diffusion.The synthesis method could be extended to prepare other transition metal oxides/graphene-based composites.