Effect of Cr dopant on the cathodic behavior of LiCoO2 |
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Authors: | S MadhaviG.V Subba Rao B.V.R Chowdari S.F.Y Li |
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Affiliation: | a Department of Chemistry, National University of Singapore, Singapore 119260, Singapore b Department of Physics, National University of Singapore, Singapore 119260, Singapore |
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Abstract: | Compounds of the formula LiCo1−yCryO2 (0.0≤y≤0.20 and y=1.0) have been synthesized by high temperature solid-state reaction and were characterized by XRD and FT-IR. Hexagonal a and c lattice parameters increase with increasing y as expected from ionic size effects. Cyclic voltammograms reveal that the phase transformation occurring at x=0.5 in Li1−x(Co1−yCry)O2 is suppressed for y=0.05 and 0.10. Low-current (0.01 C; 1 C=140 mA g−1) galvanostatic charging curves show that the deintercalation voltage for y=0.05 and 0.10 decrease for a given x as compared to LiCoO2. Galvanostatic charge-discharge cycling of the Li(Co1−yCry)O2 cathodes at 0.14 C and 2.7-4.3 V (vs. Li) show that increasing amount of chromium content in the LiCoO2 lattice drastically reduces the amount of Li that can be reversibly cycled. Ex-situ XRD of the cycled cathodes show that slight cation-mixing occurs in the layered structure for y=0.05 and 0.10 and could be the reason for their poor electrochemical performance. Reversible Li intercalation/deintercalation is not possible in LiCrO2 in the voltage range 2.7-4.3 V. |
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Keywords: | LiCoO2 LiCrO2 Doping Cathodes Lithium ion batteries |
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