Nanocomposite electrode materials for high energy density rechargeable lithium batteries

Abstract

The manganese and chromium oxide nanocomposite electrode materials were synthesized by redox reactions using transition metal powders in solutions. The layered Li[CrxLi(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[CrxLi(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[CrxLi(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.