CORROSION RESEARCH CENTER
Sensors and Batteries
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CORROSION RESEARCH CENTER
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Rechargeable lithium or lithium-ion batteries are the focus of intensive research and development efforts worldwide due to their potentially promising uses in portable electronic devices and electric vehicles. Transition metal oxides occupy a prominent position in rechargeable lithium battery technology. Of the three systems being actively developed as cathodes for rechargeable lithium or lithium ion batteries, namely, lithium cobalt, nickel, or manganese oxides, lithium manganese oxides are the most attractive due to their low cost and relative non-toxicity. Research on these systems reported from other institutions has so far focused on different crystalline structures, such as the spinel or layered structure. While these crystalline materials offer certain attractive features such as high voltages, intrinsic problems such as phase transitions and structural irreversibility during lithium intercalation have limited their charge capacity and therefore energy density.
We have developed a room-temperature sol-gel route to synthesize manganese dioxide of amorphous structure. The entire synthesis process was carried out at room temperature to result in an amorphous structure, which was confirmed by x- ray powder diffraction of the synthesized material. SEM images and BET analysis showed that the synthesized material has a highly porous morphology and very high internal surface area. Chemical lithiation of the material was carried out with butyllithium in hexanes. Close to two moles of lithium per mole of Mn can be inserted into the amorphous structure, giving rise to by far the highest lithium intercalation capacity among all manganese oxide materials reported. Galvanostatic cycling of composite electrodes based on the amorphous manganese dioxide also revealed an extremely high charge capacity and promising cyclability. We are currently carrying out various chemical, thermal, and electrical characterizations of the material as well as assessing its thermodynamic and kinetic performance as a cathode for rechargeable lithium batteries.
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