Solid solution Li1.2Ni0.13Co0.13Mn0.54O2 can be referred to as the homogeneous crystal phase composed of Li2MnO3 and LiNi1/3Co1/3Mn1/3O2 in equal portions. In this paper, a combination of the primary polymerization of acrylic acid (AA) monomers, the subsequent pyrolysis of PAA polymer gel at 450 °C, and the final high-temperature crystallization are used to prepare Li1.2Ni0.13Co0.13Mn0.54O2 nanoparticles for their potential application as lithium-ion battery cathodes. The obtained results show that the powdered nanoparticles have an average particle size of 173.2 ± 66.2 nm and are composed of solvent and solute single-crystalline nanodomains with a superlattice ordering. As lithium-ion battery cathodes, these nanoparticles can possess a high initial discharge capacity of 290.7 mAh g−1 and first cycle coulombic efficiency of 78.3 % at 0.08C, remain a reversible value of 182.7 mAh g−1 at 0.4C over 60 charge–discharge cycles and reach a capacity of 122.5 mAh g−1 at a high current rate of 4C. Furthermore, the charging-discharging cutoff voltage is also varied to discuss the ever-observed high electrochemical properties of the nanosized lithium-rich manganese-based solid solutions.
