Please use this identifier to cite or link to this item: http://scholarbank.nus.edu.sg/handle/10635/15310
Title: Studies on metal oxides as anodes for lithium ion batteries
Authors: NIDHI SHARMA
Keywords: anode materials, metal oxides, Lithium ion battery
Issue Date: 28-Apr-2006
Source: NIDHI SHARMA (2006-04-28). Studies on metal oxides as anodes for lithium ion batteries. ScholarBank@NUS Repository.
Abstract: Commercial lithium ion batteries (LIB) exhibit significant advantages in terms of operating voltage range, high volumetric and gravimetric energy density in comparison with other rechargeable batteries. The preferred cathode and anode in LIB are LiCoO2 and graphite respectively. Efforts are being made to improve battery performance by optimizing the properties of the battery components, i.e., anode, cathode and electrolyte. In the case of anode, metal oxides have been proposed as possible alternatives to the graphite. Depending upon the nature of metal, these undergo reversible reaction with Li by Li-metal alloy formation or displacive redox reaction or Li-metal-oxide-bronze formation or intercalation reaction. The key factors influencing the electrochemical response of metal oxides are: the crystal structure of the starting oxide, oxygen coordination of the compound, the nature and amount of the counter ion, the morphology and the operating voltage range. The present research work is devoted to extensive investigations on metal oxides as anodes for LIB. Mixed oxides, MSnO3, M=Ca, Sr, Ba (perovskite crystal structure), K2(M',Sn)8O16, M'=Mg, Li, Fe, Mn (hollandite crystal structure), CaFe2O4, Li0.5Ca0.5Fe1.5Sn0.5O4, NaFeSnO4 (CaFe2O4-type structure), Ca2Fe2O5, Ca2Co2O5 (brownmillerite structure), CaMoO4 (with and without carbon coating), carbon coated CaWO4 (scheelite crystal structure) were synthesized by high temperature solid-state reaction or co-precipitation or sol-gel methods and studied. These compounds contain Sn, Fe, Co, Mo and W as the a??electrochemically activea?? centre. Techniques used for physical characterization include X-ray diffraction, SEM, HR-TEM, XPS, thermogravimetric analysis and BET surface area studies. Electrochemical cycling was carried out on fabricated cells using Li-metal as counter electrode by galvanostatic cycling and cyclic-voltammetry. The reaction kinetics was studied by electrochemical impedance spectroscopy. A comparison of our results with the findings of earlier investigators available in the literature revealed that a??Caa?? acts as a good matrix element, and carbon-coating is beneficial. Promising electrochemical cycling behaviour was exhibited by CaSnO3, Ca2Co2O5, K2(Li2/3Sn22/3)O16 and carbon coated-CaMoO4.
URI: http://scholarbank.nus.edu.sg/handle/10635/15310
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