Basic Research On Supercritical Preparation Of V₂O₅/PRC Technology

As an important energy storage component,lithium batteries have the advantages of high voltage,high capacity,long life,and fast and safe charging and discharging.The cathode material often has a decisive influence on the electrochemical performance of lithium batteries.In the past ten years,V₂O₅has been favored by lithium battery researchers due to its wide range of raw materials and relatively large theoretical specific volume.The supercritical solvothermal method can prepare nanoparticles simply and efficiently,and has a shorter experimental period than hydrothermal/solvothermal,and it is easier to control the experimental conditions.In the future,it will become the mainstream technology for preparing micro-nano particles.The experiment mainly changes the experimental parameters,such as temperature,pressure,reaction time,and characterizes the experimental products with the help of X-ray diffraction,scanning electron microscope,nanoparticle size and Zeta potential analyzer,and investigates the composite of V₂O₅and V₂O₅/PRC(porous carbon material)The influence law of material crystallization,morphology and particle size.And the preparation conditions of 3kinds of nano-V₂O₅electrode materials(nanospheres,nanosheets,nanorods)with different morphologies were determined.Finally,the electrochemical performance of the V₂O₅nanosphere electrode sheet and the V₂O₅/PRC composite electrode material under the optimal experimental conditions were studied by cyclic voltammetry,constant current charge-discharge method and electrochemical impedance method,and found that it has better capacity retention Rate and superior rate performance,smaller impedance.However,the electrochemical performance of the V₂O₅/PRC composite electrode material is more excellent.For three different morphologies of nano-V₂O₅electrode materials,the preparation conditions of V₂O₅nanospheres are temperature 260?,pressure 13 MPa,and reaction time 8h;V₂O₅nanorods preparation conditions are temperature 260?,pressure 13 MPa,and reaction time 6 h;The preparation conditions of V₂O₅ nanosheets are temperature 280?,pressure 13 MPa,and reaction time 10 h.The electrochemical impedance method found that the V₂O₅nanospheres have a smaller impedance than the other two structures.Therefore,the electrochemical performance of the V₂O₅nanospheres was studied.The V₂O₅nanosphere electrode sheet can provide an initial specific volume of 149 m Ah g^-1,an impedance of 52?,and a capacity retention rate of 98.85%.Shows superior rate performance and reversible performance under high rate conditions.The porous carbon material(PRC)is prepared by carbonizing natural reeds at high temperature under nitrogen atmosphere.It has a specific surface area of 71.3403 m²/g as measured by BET specific surface area.It has a hierarchical pore structure and a cumulative pore volume of 0.05 ml/g.More N-containing functional groups were found by infrared spectroscopy,which provides the possibility to enhance the reactivity and conductivity of carbonaceous materials.The V₂O₅is distributed in the pores of the PRC under the action of supercritical ethanol,and a larger specific surface area is obtained,which can provide more active sites for the deintercalation of lithium ions.The V₂O₅/PRC composite electrode material under the optimal working conditions was obtained through orthogonal experiments,and it was clarified that the order of the influence of the experimental conditions on the specific surface area of the composite material was pressure>temperature>reaction time.The tested V₂O₅/PRC composite electrode material shows a high specific volume(292 m Ah g^-1),and the impedance is only 15?.At a higher current density(2.0 A/g),the capacity can be stabilized at 161m Ah g^-1.After the rate experiment,the capacity retention rate is 98.85%.Shows superior rate performance and reversible performance.Shows very good research value and application prospects.