The effect of cobalt doping on the morphology and electrochemical performance of high-voltage spinel LiNi_0.5Mn_1.5O₄cathode material

To reveal the effects of Co-doping on the electrochemical performance of micro-sized LiNi_0.5Mn_1.5O₄ (LNMO), undoped LNMO and Co-doped LiCo_0.1Ni_0.45Mn_1.45O₄ (LCoNMO) are synthesized via a PVP-combustion method and calcined at 1000 °C for 6 h. SEM and XRD analyses suggest that Co-doping decreases the particle size and the Li_zNi_1-zO₂ impurity at the calcination temperature of 1000 °C. LCoNMO has much better rate capability while its specific capacity at C/5 is 10% lower than that of LNMO. At 15 C rate, their specific capacities are closed, and the LCoNMO delivers 86.2% capacity relative to C/5, and this value for LNMO is only 77.0%. The D_Li + values determined by potential intermittent titration technique (PITT) test of LCoNMO are 1–2 times higher than that of LNMO in most SOC region. The LCoNMO shows very excellent cycling performance, which is the best value compared with literatures. After 1000 cycles, the LCoNMO still delivers 94.1% capacity. Moreover, its coulombic efficiency and energy efficiency keep at 99.84% and over 97.3% during 1 C cycling, respectively.