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Title: Cathodic behaviour of NiO-coated Li(Ni1/2Mn1/2)O 2
Authors: Reddy, M.V. 
Rao, G.V.S.
Chowdari, B.V.R. 
Keywords: Cathode material: Li-ion batteries
NiO coating
Issue Date: 30-May-2005
Citation: Reddy, M.V., Rao, G.V.S., Chowdari, B.V.R. (2005-05-30). Cathodic behaviour of NiO-coated Li(Ni1/2Mn1/2)O 2. Electrochimica Acta 50 (16-17) : 3375-3382. ScholarBank@NUS Repository.
Abstract: The compound, Li(Ni1/2Mn1/2)O2 was prepared by the mixed hydroxide method at 950 °C in air. It was coated with 3 and 6 wt.% NiO by the solution method and heat treated at 450 °C in air. The compounds were characterized by X-ray diffraction, SEM, TEM, BET surface area and density. Cyclic voltammmetry of the bare and NiO-coated compounds showed redox processes at 3.69-3.95 V corresponding to the couple Ni 2+/3+/4+. Galvanostatic charge-discharge cycling was carried out at 30 mA g-1 up to 70 cycles in the voltage ranges, 2.5-4.3 and 2.5-4.5 V versus Li at room temperature. The 10th cycle discharge capacities for the bare and NiO-coated compounds are 140 ± 3 mAh g-1 which are stable up to 20-30 cycles after which capacity-fading occurs. The 6% NiO-coated compound performs better with only 11% capacity loss at the 70th cycle. In the range 2.5-4.5 V, the third cycle capacities are 175 ± 5 mAh g -1 for the bare and 3% NiO-coated compounds, but capacity-fading starts from fifth cycle onwards. The 6% NiO-coated Li(Ni1/2Mn 1/2)O2 showed a stable discharge capacity of 165 ± 3 mAh g-1 during 3-30 cycles after which it degraded, by ∼9%, at the 70th cycle. Thus, NiO-coating suppresses capacity-fading but not eliminates it in Li(Ni1/2Mn1/2)O2. The coulombic efficiency in all cases was >98%. DSC on the cathodes in the charged-state (4.3 V) show that the exothermic decomposition for the bare and 6% NiO-compound occurs at 300 and 307 (±2) °C, respectively. © Published by Elsevier Ltd.
Source Title: Electrochimica Acta
ISSN: 00134686
DOI: 10.1016/j.electacta.2004.12.011
Appears in Collections:Staff Publications

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