Development of silicon matrix carbon nanotube reinforced nano composite electrodes via PVD method

Key Words: PVD, silicon, carbon nanotube, nano composite anode, lithium-ion battery.Due to widespread usage of portable electronic devices and growing necessity of electrical vehicles in order to decrease carbon dioxide emission, the need of high energy density batteries is increasing. Lithium ion batteries are the most popular choice used for this purpose and most promising battery systems in terms of developments in the field of batteries.In this thesis work silicon based composite anodes were produced for lithium ion batteries. Silicon was sputtered via DC magnetron sputtering technique onto stainless steel substrates and carbon nanotube papers to obtain thin film and composite anodes. Obtained electrodes were analyzed via X-ray diffraction technique and scanning electron microscope.Carbon nanotube papers were produced with vacuum filtration technique to obtain composite electrode architecture. Before vacuum filtration process carbon nanotubes were purified and then functionalized with different chemical agents. Thermal analysis and Fourier transform infrared spectroscopy was applied to functionalized carbon nanotubes. Field emission scanning electron microscopy analysis carried out to understand morphology of carbon nanotube papers.CR2016 type coin cells were assembled for electrochemical tests in an argon filled glove box. Composite and thin film electrodes were chosen as working electrode while high purity lithium foils were chosen as reference electrode. To determine the cycle lives, batteries were subjected to galvanostatic charge/discharge tests at constant current density. Besides electrochemical impedance spectroscopy and cyclic voltammetry techniques were used for further electrochemical performance analysis.