Synthesis and Surface Modification of LiCo1/3Ni1/3Mn1/3O2 for Lithium Battery Applications

In an attempt to prepare phase-pure LiCo_1/3Mn_1/3Ni_1/3O₂ compound, the sol–gel method with precursors containing different ratios of lithium and transition-metal ions such as Li:M = 1:1, 1.05:1, 1.10:1, 1.15:1, 1.20:1, and 1.25:1 has been deployed. Properties such as phase purity, perfect layeredness, good cation ordering, and acceptable charge–discharge behavior were observed only when LiCo_1/3Ni_1/3Mn_1/3O₂ was prepared using a Li:M ratio of 1.15:1.0, leading to the recommendation of this as the optimum precursor ratio to prepare active LiCo_1/3Ni_1/3Mn_1/3O₂ cathodes for batteries. Further, with a view to suppress the capacity fade behavior of native LiCo_1/3Mn_1/3Ni_1/3O₂ cathodes observed in high-voltage (4.6 V) regions, selected HF-scavenging metal oxide (Al₂O₃) or metal hydroxide Al(OH)₃] was deployed as a surface modifier. Interestingly, LiCo_1/3Ni_1/3Mn_1/3O₂ cathode modified with Al(OH)₃ exhibited significantly improved electrochemical properties such as lower charge-transfer resistance (42 Ω), higher specific capacity (158 mAh/g), and excellent capacity retention (99%). This study demonstrates the superiority of Al(OH)₃ over Al₂O₃ in modifying the electrochemical properties of native LiCo_1/3Ni_1/3Mn_1/3O₂ cathodes, as desired for practical lithium battery applications.