The effect of cobalt doping on the morphology and electrochemical performance of high-voltage spinel LiNi0.5Mn1.5O4 cathode material

• At 15 C rate, the LCoNMO delivers 86.2% capacity relative to C/5, while this value for LNMO is 77.0%.
• The DLi values of LCoNMO are 1–2 times higher than that of LNMO in most SOC region.
• After 1000 cycles at 1 C, the LCoNMO still delivers 94.1% capacity.
• The coulombic efficiency and energy efficiency of LCoNMO keep at 99.84% and over 97.3%.

To reveal the effects of Co-doping on the electrochemical performance of micro-sized LiNi0.5Mn1.5O4 (LNMO), undoped LNMO and Co-doped LiCo0.1Ni0.45Mn1.45O4 (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 LizNi1-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 DLi + 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.