Study On The Preparation And Electrochemical Performance Of V₂O₅ Nanowires Paper

Among the developed electrode materials for lithium ion batteries,V₂O₅ has been highly concerned for its high theory capacity,easy to prepare and low cost.But,V₂O₅ always suffer from its poor electronic conductivity,low diffusion coefficient of Li-ions,poor cycle performance,etc.which seriously hinder the practical application of V₂O₅ in LIBs.Usually,vanadium pentoxide nanowires prepared by hydrothermal method need long period and have low specific surface area,the conventional LIBs electrode materials always require conductive additives,binders and current collectors,those inactive ingredients significantly decreased the overall energy density,besides increasing the costs and complex process,in addition,traditional liquid electrolyte for lithium-ion batteries exists flammability,toxic and other risk.In this paper,High temperature hydrothermal process was used to synthesis V₂O₅nanowires with high quality and high specific surface area,two-step reduction?TSR?method was used to fabricate pure V₂O₅ nanowires paper and V₂O₅/rGO composite paper,finally,the electrochemical performance of lithium-ion batteries with liquid electrolyte and all-solid-state lithium-ion battery were studied,which is important for solving low energy density,poor cycle life and poor security of lithium-ion batteries.So the research is as follows.?1?V₂O₅ nanowires were obtained through hydrothermal process.The temperature and reaction time was studied on the impact of product phase and micro-structure,the V₂O₅nanowires with¹ millimetre and 100 nm in diameter was synthesised.The pure V₂O₅nanowire paper was prepared by self-assembled process,its Cyclic Voltammetry?CV?,galvanostatic charge-discharge,electrochemical impedance spectroscopy?EIS?was studied.The results show that pure V₂O₅ nanowire paper electrode just appear one redox peaks in CV and galvanostatic charge-discharge,the discharge capacity only have 0.57 mAh/cm²,the residual capacity is only 28%of the initial capacity after 1000 cycles.In the test of EIS,its ohmic resistance is 3.0?,the impedance of SEI film is 76.8?and the charge transfer resistance is 163.5?.?2?Free-standing V₂O₅/rGO composite paper was prepared by the two-step reduction?TSR?method,the product phase,micro-structure and electrochemical performance of the composite paper was studied.The results show that the V₂O₅/rGO composite paper is uniform and have 15%of r GO.Assembled into lithium-ion batteries with liquid electrolyte and the electrochemical performance tests show that there are three redox peaks in CV and galvanostatic charge-discharge,the discharge capacity has 0.885 mAh/cm²,moreover,under the current density of 0.9 mA/cm²,the residual capacity still has 70%of the initial capacity after 1000 cycle.In the test of EIS,its ohmic resistance is 2.6?,the impedance of SEI film is35.9?and the charge transfer resistance is 112?.Those results indicated that greatly improve the electronic conductivity and structure stability of V₂O₅ nanowires was greatly improved by the introducing of rGO.?3?The V₂O₅/rGO composite paper electordes was assembled into all-solid-state lithium-ion batteries with the solid polymer electrolyte work as electrolyte.Electrochemical measurements show that those redox peaks of CV match well with the curve of galvanostatic charge-discharge.Under the current density of 17 mA/g,its discharge capacity can reach up to343.5 mAh/g.The coulombic efficiency always keep above 99%in the 40 cycle tests,and the rate capability is pretty good.In the test of EIS,the impedance decreases in the charge-discharge process.In addition,the battery can drive a LED lights at 80 ^o C.Compared with the liquid Electrolyte lithium ion batteries,the all-solid-state lithium-ion batteries have greater voltage window and safety performance.