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Lookup NU author(s): Paul Oloniyo,
Emeritus Professor Keith Scott
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Manganese dioxide (MnO2) has been shown to be effective for improving the efficiency of cathodes in lithium-air cells. Different crystallographic phases including alpha-, beta-, and gamma-MnO2 nanowires, alpha-MnO2 nanospheres, and alpha-MnO2 nanowires on carbon (alpha-MnO2/C) were synthesized using the hydrothermal method. Their physical properties were examined using x-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) surface area measurements, and scanning electron microscopy (SEM) and found to be in agreement with the literature. Electrochemical properties of the synthesized catalyst particles were investigated by fabricating cathodes and testing them in a lithium-air cell with lithium hexafluorophosphate in propylene carbonate (LiPF6/PC) and tetra(ethylene glycol)dimethyl ether (LiTFSi/TEGDME) electrolytes. alpha-MnO2 had the highest discharge capacity in the LiTFSi/TEGDME electrolyte (2500 mAh/g), whilst alpha-MnO2/C in LiPF6/PC showed a significantly higher discharge capacity of 11,000 mAh/g based on total mass of the catalytic cathode. However, the latter showed poor capacity retention compared with gamma-MnO2 nanowires, which was stable for up to 30 cycles. The reported discharge capacity is higher than recorded in previous studies on lithium-air cells.
Author(s): Oloniyo O, Kumar S, Scott K
Publication type: Article
Publication status: Published
Journal: Journal of Electronic Materials
Print publication date: 05/04/2012
ISSN (print): 0361-5235
ISSN (electronic): 1543-186X
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