The Optimization Of Preparation Process And Mechanism Of Ag₃SI Fast Ionic Materials

Recently,the development of electronic equipment market is very rapid.However,the insufficient production capacity of energy storage devices still restricts energy-saving,emission reductions,market expansion and product upgrades.The fast ionic conductor material,an important part of the energy storage device,has become the popular research focus due to its excellent performance,unique safety and stability.In this work,a series of Ag₃SI samples were prepared by high-energy ball milling and heat treatment processes.In order to obtain the optimized preparation process and improve the conductive performance of the samples,different ball milling parameters and heat treatment processes were explored.In addition,experiments to investigate the phase transition behavior of AgI were also conducted via changing medium around,thus revealing the phase transition mechanism of remaining AgI under different ball milling conditions.The main research results are as follows:?1?A series of Ag₃SI samples were prepared by high-energy ball milling method.As the ball milling speed and duration increased,the raw materials gradually completely reacted,forming mixed phase product,which consisted of crystal Ag₃SI,Ag₂S,AgI and some other metastable phases.At the same time,the ionic conductivity of the samples gradually enhanced.However,excessive ball milling will cause the product to decompose again,so that the ionic conductivity of the sample decreased.The performance test revealed that the sample with 10h of ball milling duration at 600rpm presented the best ionic conductivity.?2?Pure crystal Ag₃SI can be obtained via heat-treating the ball-milled powder-like products at 160?for 0.5h.After ball milling process,intrinsic energy of such powder samples was much higher.During the heat treatment,the aforementioned metastable samples tended to release internal energy and then transformed to crystal Ag3SI,which simplified the preparation process of pure crystal Ag3SI.As a result,the ionic conductivity of the sample was remarkable improved due to the formation of a large number of Ag₃SI grains.Also,the above results demonstrated that the conductive structure and stability of crystal Ag₃SI was much better.?3?The ball-milled sample was pressed and then heat treated to facilitate the fusion of grains during the crystallization and crystal growth process,so that the number of grain boundaries as well as the grain boundary resistance would decrease,thus further improving the conductivity of the sample.Note that,the solid-phase reaction and crystal growth were able to be accelerated when properly increased the heat treatment temperature,which was beneficial to the formation connected crystal structure.However,when further enhancing the temperature,product decomposition and mechanical structure damage were both observed.In this study,250?was the optimized temperature for heat treatment.?4?A series of pure crystal AgI and?1-x?AgI·xP₂S₅ powder-like samples were prepared through ball milling method with different parameters.Also,X-ray diffraction?XRD?together with differential thermal analysis?DSC?was applied to explore the phase transition behavior of crystal AgI by changing particle size as well as environmental medium.What is more,based on the analysis on physical process of AgI phase transition,the abnormal phase transition behavior of remaining AgI in Ag₃SI product was able to be revealed.