Synthesis and electrochemical properties of LiNi_0.5-xCu _xMn_1.5-yAl_yO₄ (x = 0, 0.05, y = 0, 0.05) as 5 v spinel materials

The LiNi_0.5-xCu_xMn_1.5-yAl _yO₄ (x = 0, 0.05, y = 0, 0.05) powders are synthesized by liquid co-precipitation and wet-milling. The doping effect on LiNi _0.5Mn_1.5O₄ by Al³⁺, Cu²⁺, and Al³⁺/Cu²⁺ co-doping are investigated and compared in relation to physical and electrochemical characterization, namely, through X-ray diffraction, scanning electron microscopy, electronic conductivity, cyclic voltammetry and cycle tests. Results suggest that both Al³⁺ and Cu²⁺ doping effectively improve electrochemical performance of LiNi_0.5Mn_1.5O₄, although the effect is different between the two cations. All doped samples exceed 95% capacity retention after 100 cycles at room temperature compared to 92% retention for the undoped sample. Moreover, co-doped LiNi_0.45Cu_0.05Mn _1.45Al_0.05O₄ exhibits the best cyclic performance with slight superiority.