Synthesis and characterisation of LiNi1−x−yCoxAlyO2 cathodes for lithium-ion batteries by the PVA precursor method

Polycrystalline powders of LiNi1−xCoxO2 and LiNi1−x−yCoxAlyO2 were synthesized at 720 °C from the nitrate-PVA precursor method. The water was removed by two different processes: (i) evaporation-drying at 110 °C, (ii) spray-drying at 150 °C. 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 LiNi0.82Co0.13Al0.05O2 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.