Abstract. The manganese and chromium oxide nanocomposite electrode materials were synthesized by redox reactions using transition metal powders in solutions. The layered Li[Cr_xLi_{(1/3 − x/3)}Mn_{(2/3 − 2x/3)}] O₂ (x= 0.054, 0.0142, 0.147 and 0.311) materials having α-NaFeO₂ (R-3 m) structure were prepared by solid-state reactions with LiOH and the pre-prepared manganese and chromium precursors. The amount of chromium, after removing the traces of Li₂CrO₄ from the prepared samples, is found to increase with temperature. The Li[Cr_xLi_{(1/3 − x/3)}Mn_{(2/3 − 2x/3)}] O₂ material with x = 0.147 exhibits a high discharge capacity of 280 mAh g^{− 1} in the first cycle and a good reversible capacity of about 250 mAh g^{− 1} when cycled in the voltage range 2.0–4.9 V. Whereas, the Li[Cr_xLi_{(1/3 − x/3)}Mn_{(2/3 − 2x/3)}]O₂ material with x = 0.311 delivers a very low initial discharge capacity of 98 mAh g⁻¹, which is found to be increased up to a discharge capacity of about 260 mAh g^{− 1} at the 30th cycling. This drastic increase in capacity is attributed to the redox couples of Cr^{+ 4/}Cr^{+ 6} and Cr^+3/Cr⁺⁴.

PACS numbers: 82.47.Aa, 74.62.Bf, 82.45.Yz

Print publication: Issue T129 (December 2007)
Received 2 April 2007, accepted for publication 21 July 2007
Published 23 November 2007