Improving the high-voltage performance of LiNi0.6Co0.2Mn0.2O2 by co-doping of zirconium and erbium

Using traditional co-precipitation method accompanied by the subsequent calcination treatment, spherical pristine LiNi0.6Co0.2Mn0.2O2 (P-LNCM), and LiNi0.6Co0.2Mn0.2O2 co-doped with Zr and Er (EZ-LNCM) cathode materials are successfully synthesized. Powder X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and X-ray photoelectron spectrometry (XPS) reveal that EZ-LNCM material exhibits some better potential crystal structural feature than P-LNCM material, mainly including the decreased Li+/Ni2+ disorder, the enlarged migration tunnel of Li+, the reduced content of Ni2+ in the surface and lower residual impurities. Within the voltage range of 2.8–4.5 V, the initial discharge capacity of EZ-LNCM at 0.1C is 208 mAh g−1, and the cycle retention at 1C after 200 cycles for EZ-LNCM electrodes maintains 90.03%, which are higher than those of P-LNCM. Results based on cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) measurements, morphology and structure of cathode material reveal that co-doping can alleviate irreversible phase transformation and stabilize structural integrity, which benefits rapid speed for Li+ transfer and reduces impedance rise for the better electrochemical properties of EZ-LNCM.