Effect of low Al ³⁺ doping on the structural, electrochemical performances, and thermal stability of the LiNi ₁ / ₃ Co ₁ / ₃ Co ₁ / ₃ O ₂ electrode material for lithium‐ion batteries

A series of Al-doping Li(Ni1/3Co1/3Mn1/3)1-yAlyO2 (y = 0, 0.0001, 0.0002, 0.0003, and 0.0004) electrode materials were prepared via an optimized co-precipitation method using high-purity metal sulfates produced by Managem (Morocco), and at low-synthesis temperature of 750°C. Refinement of the X-ray diffraction patterns reveals the formation of pure layered oxides with no obvious change in the hexagonal unit-cell parameters. Li(Ni1/3Co1/3Mn1/3)1-yAlyO2 electrode materials were tested as electrode for lithium-ion batteries in the voltage range of 2.5 to 4.25 V vs Li+/Li. Discharge capacities of around 160 mAh/g were achieved with an obvious enhancement of the electrochemical performance although the rate of Al-doping is very small. 0.02% Al-doping exhibits better coulombic efficiency (98%) and a capacity retention of 98% at the 50th cycle. Safety tests were also investigated for delithiated cathode materials Liy(Ni1/3Co1/3Mn1/3)1-yAlyO2 recovered at the end of the charge process. Once again, the composition corresponding to 0.02% Al-doping shows the best safety parameters compared to the NCM(111) reference material (Tonset = 289°C; ΔH = 738 J/g).