The Study On Zinc-iodide Battery With Graphite Felt Electrode Modified By Carbon Dots

As a new type of nanomaterial,carbon dots(CDs)can be widely used in industrial production and biomedical fields.The excellent fluorescence performances of carbon dots make it widely used in ion detection and fluorescence imaging.As much,carbon dots have good electrocatalytic properties.However,compared with extensive research and application in other fields,there is still a lot of research space for the application of carbon dots in electrochemistry.As a new type of energy storage device,zinc-iodine battery is still in the early stage of research.Zinc iodine battery theoretically has higher energy density than vanadium batteries,and it has higher safety than lithium battery which has spontaneous combustion and explosions.The electrolyte in zinc-iodine batteries is neutral and environmentally friendly.At present,the research of zinc-iodine batteries mainly focuses on electrodes,electrolytes,structures,ion-conducting membranes and the like.In this paper,the electrochemical properties of carbon dots were present,and the graphite felt electrode modified with carbon dots was prepared and applied to improve the performance of zinc-iodine battery.The research work is as follows:First,the organic cleaning method and the three-step cleaning method were used to etch a groove on the carbon fiber of the graphite felt,and then o-phenylenediamine and alcohol as precursor was placed,stirred for 30 minutes,and ultrasonicated for 30 minutes to make it more uniform.The precursor and the cleaned graphite felt were placed in the hydrothermal reactor,and the carbon dots were hydrothermally synthesized at 180 ° C in a vacuum drying oven.In order to study the effect of the hydrothermal time on the fabricated of the carbon dots,6 hours,7 hours,8 hours and9 hours were set as variable.A series of characterization tests such as field emission scanning electron microscopy(FE-SEM),transmission electron microscopy(TEM),Raman spectroscopy and X-ray photoelectron spectroscopy(XPS)were used to study the effect of graphite felt modified by carbon dots with different hydrothermal time.Secondly,compared with results of the graphite felt electrode without carbon dots(GF),the graphite felt electrode modified by carbon dots(GF/CD)was tested through cyclic voltammetry,charge-discharge curve,electrochemical impedance spectroscopy and the like.It demonstrated that the carbon dots fabricated with 8 hours and 9 hours were relatively better.The performance of the 9-hour hydrothermal electrode has the longest discharge time of 14.5s at the current density of 20mA/cm,with a maximum specific capacity of 3.93F/cm,and a minimum reaction resistance of 25.91? cm.Increasing the hydrothermal time makes little sense for the electrochemical performance improvement.The Zinc-iodine battery structure with a release channel was designed by using industrial design software,and the graphite felt electrode without carbon dots and the graphite felt electrode modified by carbon dots were both assembled into the zinc iodine batteries.The battery performance was tested under the LANHE battery testing system.Under the charge and discharge current of 200 mA,the battery of the graphite felt electrode modified by carbon dots has higher cell voltage than the graphite felt electrode,and the highest discharge capacity can reach 283.5 mA?h at 200 mA.With a large discharge energy,the discharge energy can reach 295mW?h.Under 50 cycles,the zinc-iodine battery of the graphite felt electrode modified by carbon dots can still maintain high coulombic efficiency,indicating that the cycle stability is improved.