Show simple item record

dc.contributor.advisorRao, G Mohan
dc.contributor.authorNimisha, C S
dc.date.accessioned2013-07-03T05:42:27Z
dc.date.accessioned2018-07-31T06:04:29Z
dc.date.available2013-07-03T05:42:27Z
dc.date.available2018-07-31T06:04:29Z
dc.date.issued2013-07-03
dc.date.submitted2011
dc.identifier.urihttps://etd.iisc.ac.in/handle/2005/2099
dc.identifier.abstracthttp://etd.iisc.ac.in/static/etd/abstracts/2700/G24794-Abs.pdfen_US
dc.description.abstractThe magnificent development of on-board solutions for electronics has resulted in the race towards scaling down of autonomous micro-power sources. In order to maintain the reliability of miniaturized devices and to reduce the power dissipation in high density memories like CMOS RAM, localized power for such systems is highly desirable. Therefore these micro-power sources need to be integrated in to the electronic chip level, which paved the way for the research and development of rechargeable thin film batteries (TFB). A Thin film battery is defined as a solid-state electrochemical source fabricated on the same scale as and using the same type of processing techniques used in microelectronics. Various aspects of deposition and characterization of LiCoO2/LiPON/Sn thin film battery are investigated in this thesis. Prior to the fabrication of thin film battery, individual thin film layers of cathode-LiCoO2, electrolyte-LiPON and anode-Sn were optimized separately for their best electrochemical performance. Studies performed on cathode layer include theoretical and experimental aspects of deposition of electrochemically active LiCoO2 thin films. Mathematical simulation and experimental validation of process kinetics involved in sputtering of a LiCoO2 compound target have been performed to analyze the effect of process kinetics on film stoichiometry. Studies on the conditioning of a new LiCoO2 sputtering target for various durations of pre-sputtering time were performed with the help of real time monitoring of glow discharge plasma by OES and also by analysing surface composition, and morphology of the deposited films. Films deposited from a conditioned target, under suitable deposition conditions were electrochemically tested for CV and charge/discharge, which showed an initial discharge capacity of 64 µAh/cm2/µm. Studies done on the deposition and characterization of solid electrolyte layer-LiPON have shown that, sputtering from powder target can be useful for certain compounds like Li3PO4 in which breaking of ceramic target and loss of material are severe problems. An ionic conductivity of 1.1 x10-6 S/cm was obtained for an Nt/Nd ratio of 1.42 for a RF power density of 3 W/cm2 and N2 flow of 30 sccm. Also the reasons for reduction in ionic conductivity of LiPON thin films on exposure to air have been analyzed by means of change in surface morphology and surface chemistry. Ionic conductivity of 2.8 x10-6 S/cm for the freshly deposited film has dropped down to 9.9 x10-10 S/cm due to the reaction with moisture, oxygen and carbon content of exposed air. Interest towards a Li-free thin film battery has prompted to choose Sn as the anode layer due to its relatively good electrochemical capacity compared with other metallic thin films and ease of processing. By controlling the rate of deposition of Sn, thin films of different surface morphology, roughness and crystallinity can be obtained with different electrochemical performance. The reasons for excessive volume changes during lithiation/delithiation of a porous Sn thin film have been analyzed with the aid of physicochemical characterization techniques. The results suggest that the films become progressively pulverized resulting in increased roughness with an increase in lithiation. Electrochemical impedance data suggest that the kinetics of charging becomes sluggish with an increase in the quantity of Li in Sn-Li alloy. Thin film batteries with configuraion LiCoO2/LiPON/Sn were fabricated by sequential sputter deposition on to Pt/Si substartes. Pt/Cu strips were used as the current collector leads with a polymer packaging. Electrochemical charge/discharge studies revealed discharge capacities in the range 6-15 µAh/cm2/µm with hundreds of repeated cycles. TFB with a higher capacity of 35 µAh/cm2/µm suffered capacity fade out after 7 cycles, for which reasons were analyzed. The surface and cross-sectional micrographs of cycled TFB showed formation of bubble like features on anode layer reducing integrity of electrolyte-anode interface. The irreversible Li insertion along with apparent surface morphology changes are most likely the main reasons for the capacity fade of the LiCoO2/LiPON/Sn TFB.en_US
dc.language.isoen_USen_US
dc.relation.ispartofseriesG24794en_US
dc.subjectFuel Cellsen_US
dc.subjectBatteriesen_US
dc.subjectElectrodes (Chemistry)en_US
dc.subjectThin Film Batteriesen_US
dc.subjectElectrolytes (Chemistry)en_US
dc.subjectLithium Ion Batteriesen_US
dc.subjectThin Films - Depositionen_US
dc.subjectLi-ion Batteryen_US
dc.subjectThin Film Battery (TFB)en_US
dc.subjectLiCoO2 Filmsen_US
dc.subjectLiPON Thin Filmsen_US
dc.subjectSn Thin Filmsen_US
dc.subject.classificationElectrochemistryen_US
dc.titleInvestigations On Electrodes And Electrolyte Layers For Thin Film Batteryen_US
dc.typeThesisen_US
dc.degree.namePhDen_US
dc.degree.levelDoctoralen_US
dc.degree.disciplineFaculty of Engineeringen_US


Files in this item

This item appears in the following Collection(s)

Show simple item record