Combustion synthesis and characterization of Li1.2Mn0.52Ni0.20Co0.08O2 cathodes for Li-Ion battery: Effect of fuel mixture and annealing temperature

Abstract

The effect of fuel mixture and annealing temperature on the structural properties and electrochemical performance of Li1.20Mn0.52Ni0.20Co0.08O2 powders prepared by the combustion synthesis were studied. Different combinations of citric acid fuel and ammonium acetate along with post-temperature treatments could be used to control the product characteristics. Simultaneous thermal analyses and thermodynamic modelling were used to describe the combustion processes. The analysis of the XRD data and other reports showed that the synthesis method and chemical compositions of lithium-rich layered oxides (LLO) could influence their description either as a solid solution or a ‘composite’ structure. The annealing temperature greatly influenced the lattice parameters, unit cell volumes, crystallite sizes, and cationic disorder of the samples whilst the use of fuel mixture had little effect. Furthermore, the electrochemical performances of the cathode materials were studied and the relationship with the structural properties of the powder samples were analysed. The Li1.20Mn0.52Ni0.20Co0.08O2 powders synthesized with only citric acid fuel (100-T) displayed the best electrochemical performance compared with those produced using the fuel mixtures. The enhanced electrochemical performance of the 100-T cathodes was shown to be an integrative property of the highest values reported for their structural properties. The results show that citric acid assisted combustion and annealing temperature (mostly with pre-annealing) could be used to optimize the electrochemical performance of LLO cathode materials.