6922

6464

كارشناسي ارشد

خوردگي و حفاظت از مواد

اصفهان: دانشگاه صنعتي اصفهان، دانشكده مهندسي مواد

1390

دوازده، 74ص.: مصور، جدول، نمودار

ص.ع. به فارسي و انگليسي

احمد ساعتچي، كيوان رئيسي

حسين توانايي، محمود منير واقفي

14/5/91

محمد ژياني، محمدحسين عنايتي

1396/09/18

كتابنامه

مواد

مهندسي مواد

ID6464

به فارسي و انگليسي: قابل رويت در نسخه ديجيتالي

Investigation of electrochemical properties of MnOx carbon nanofiber composite as an energy storage material Jafar Moazeni j moazeny@gmail com Date of Submission 2012 03 05 Department of Materials Engineering Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language FarsiSupervisor Ahmad Saatchi a saatchi@cc iut ac ir Keivan Raeissi k raeissi@cc iut ac irAdvisor Hossein Tavanai tavanai@cc iut ac ir Mahmoud Monirvaghefi vagh mah@cc iut ac irAbstract Lithium ion batteries are ideal power sources for portable electronic devices and electrical vehicles The carbon anodepresently used in commercial lithium ion batteries has a relatively low capacity It s required that the capacity of anodematerials verge on 1000 mAh g On other hand these materials must have low cast and be available Manganese oxidesmaterials are a good choice that used as anode and cathode materials in lithium ion batteries Mangense oxides materialshave high capacity and good cyclic behavior but they suffer from low conductivity and high capacity lost in first cycledue to conversion reaction with lithium To solve this problem active carbon nanofiber manganese oxide composite areused Active carbon nanofibers are produced via electrospinning from polyacrylonitril dimethylformamid solution usinga homemade electrospinning setup and then pyrolyzed in N2 atmosphere at 850 C The diameters of carbon nanofibersare varied from 150 to 250 nanometer as revealed by scanning electron microscope SEM Manganese oxides aredeposited on active carbon nanofibers surface by electroless from an aqueous permanganate solution and influence ofpermanganate solution pH and deposition time on thickness morphology and uniformity of deposited manganese oxideare surveyed It s showed that the pH plays a very important role in determining the uniformity and kinetic behavior ofdeposited manganese oxide and at nearly neutral pH the self limiting redox reaction of carbon nanofibers substrates withpermanganate produces conformal nanoscale manganese oxide deposits throughout the nanofibers network Themanganese oxide coating contributes additional capacitance to the carbon nanofibers Such bare carbon nanofibersproduce 190 mAh g capacitance at first cycle while the capacity of carbon nanofibers manganese oxide composite was850 mAh g at first cycle One of the electrode materials degradation mechanisms in lithium ion batteries is fracture ofelectrode particles due to intercalation induced stress At this research a model with the analogy to thermal stressmodeling is proposed to determine intercalation induced stress and its effect on concentration profile Intercalation induced stress is calculated within cylindrical and spherical geometry with a constant diffusion flux assumed at theparticle surface It was found that the intercalation induced stress in cylindrical geometry is less than the sphericalgeometry Simulation results show that whatever the charge discharge rate and particle size be lower the intercalationinduced stress will be lower Key words Lithium ion battery carbon nanofiber electrospinning manganese oxide electroless diffusion induced stress

احمد ساعتچي، كيوان رئيسي

حسين توانايي، محمود منير واقفي

محمد ژياني، محمدحسين عنايتي