Synthesis and characterisation of LiNi1-x-yCoxAlyO2cathodes for lithium-ion batteries by the PVA precursor method

Polycrystalline powders of LiNi1-xCoxO2 and LiNi1-x-yCoxAlyO2 were synthesized at 720 degreesC from the nitrate-PVA precursor method. The water was removed by two different processes: (i) evaporation-drying at 110 degreesC, (ii) spray-drying at 150 degreesC. In both cases a gel is obtained wherein LiNO3 crystallizes in evaporated-dried samples but not in spray-dried samples which are more amorphous. All precursors give single phase powders with micronic well-shaped grains. The best electrochemical performances are obtained from evaporated samples with a capacity remaining higher than 160 mAh/g for LiNi0.82Co0.18O2 and 140 mAh/g for LiNi0.82Co.013Al0.05O2 after 20 cycles. The lower performances of the spray-dried samples seem to be related to Li2CO3 formation with subsequent non-stoichiometry as a consequence of the improved homogeneous distribution of the constituent cations in the polymer. (C) 2003 Elsevier Ltd. All rights reserved.