Effect of (Al,Mg) substitution in LiNiO2 electrode for lithium batteries

Stabilized lithium nickelate is receiving increased attention as a low-cost alternative to the LiCoO₂ cathode now used in rechargeable lithium batteries. Layered LiNi_1?x?yM_xM_yO₂ samples (M_x = Al³⁺ and M_y = Mg²⁺, where x = 0.05, 0.10 and y = 0.02, 0.05) are prepared by the refluxing method using acetic acid at 750 °C under an oxygen stream, and are subsequently subjected to powder X-ray diffraction analysis and coin-cell tests. The co-doped LiNi_1?x?yAl_xMg_yO₂ samples show good structural stability and electrochemical performance. The LiNiAl_0.05Mg_0.05O₂, cathode material exhibits a reversible capacity of 180 mA h g^?1 after extended cycling. These results suggest that the threshold concentration for aluminum and magnesium substitution is of the order of 5%. The co-substitution of magnesium and aluminium into lithium nickelate is considered to yield a promising cathode material.