A Study On Synthesis And Characterization Of Thin Polymer/Ceramic Hybrid Film Separators And Metal Oxide Coated Electrodes For Lithium Ion Batteries
Atluri, Sri Dithya
The search for new electrode and membrane materials for lithium-ion batteries (LIBs) has been under investigation to satisfy the ever-growing demands for better performance with higher energy density, improved safety and longer cycle life. In this study, electrospraying has been used to produce mesoporous thin films for the application as Li-ion battery separators. Electrospraying is a film formation technique that utilizes electrical rather than mechanical forces to form uniformly sprayed films. Polyacrylonitrile (PAN) was used to produce these thin membranes of thickness ranging between 20 and 25 microns. In this system, Polyethylene Oxide was incorporated as a sacrificial polymer. An ideal separator for LIB must be permeable and must have pore sizes ranging from 30 to 100 nm to facilitate good ion transport. In addition, a low thickness is required for high energy and power densities. Using this approach, we were able to achieve thinner and more porous membranes with pore sizes ranging from 0.1 microns to 0.3 microns. Silica precursors like PSSQ(Poly(silsesquioxane)) and OPSZ (Organopolysilazane) were incorporated into the film to increase the ionic conductivity of the membranes and thermal stability thereby increasing the battery performance. Results from SEM, BET, DSC, FTIR, Impedance Spectroscopy, Capillary Flow Analysis, Dynamic Mechanical Analysis of resulting mesoporous polymer/ceramic will be discussed. The battery tests reveal that mesoporous polymeric/ceramic film separators exhibit higher capacity and better capacity retention than polymeric/ceramic nanofiber separators. Meanwhile, metal oxides can prevent the corrosion of the electrode under harsh electrochemical conditions and thus they are regarded as promising electrode coating materials for highperformance Lithium Ion Batteries (LIBs). Zirconium metal oxide was studied as a potential anode coating material to further improve the cycle stability and performance of the LIBs. The Zirconium metal oxide was electrosprayed onto the silicon (Si)/reduced graphene ocide (RGO) anodes. Si/RGO anodes have been prepared by gas-assisted electrospraying the mixture of Si and Graphene Oxide (GO), followed by thermal treatment. Results from SEM, Impedance Spectroscopy, battery testing will be discussed.
M.S., Chemical Engineering
Master of Science
dissertation or thesis