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

Summary A series of Al‐doping Li(Ni 1/3 Co 1/3 Mn 1/3 ) 1‐y Al y O 2 (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(Ni 1/3 Co 1/3 Mn 1/3 ) 1‐y Al y O 2 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 Li y (Ni 1/3 Co 1/3 Mn 1/3 ) 1‐y Al y O 2 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 (T onset  = 289°C; ΔH = 738 J/g).