A first-order Mott transition in LixCoO2.
Despite many years of experimental searches for a first-order Mott transition in crystalline-doped semiconductors, none have been found. Extensive experimental work has characterized a first-order metal-insulator transition in Li(x)CoO(2), the classic material for rechargeable Li batteries, with a metallic state for x < 0.75 and insulating for x > 0.95. Using density functional theory calculations on large supercells, we identify the mechanism of this hereto anomalous metal-insulator transition as a Mott transition of impurities. Density functional theory demonstrates that for dilute Li-vacancy concentrations, the vacancy binds a hole and forms impurity states yielding a Mott insulator. The unique feature of Li(x)CoO(2) as compared with traditional doped semiconductors, such as Si:P, is the high mobility of the Li vacancies, which allows them to rearrange into two distinct phases at the temperature of the metal-insulator transition.
Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
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Marianetti
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Kotliar
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Ceder
D003035:Cobalt / Q000032:analysis* / Q000737:chemistry*; D004553:Electric Conductivity; D004563:Electrochemistry / Q000379:methods*; D046911:Macromolecular Substances; D008422:Materials Testing / Q000379:methods*; D008968:Molecular Conformation; D036103:Nanotechnology / Q000379:methods*; D010087:Oxides / Q000032:analysis* / Q000737:chemistry*; D012666:Semiconductors
D046911:Macromolecular Substances; D010087:Oxides; C491691:lithium cobalt oxide; D003035:Cobalt