Improvement of the high-voltage electrochemical properties of Li[Ni0.5Co0.2Mn0.3]O2@ ZrO2 cathode materials with liquid phase modification

Li[Ni_0.5Co_0.2Mn_0.3]O₂@ZrO₂ modified materials are successfully synthesized by the method of liquid phase modification. XRD and EDS analyses illustrate that zirconium not only successfully has been doped into the interior of the crystal lattice but also uniformly distributed on the surface of the modified materials particles. The ZrO₂ coating layer can effectively prevent the harmful side reactions occurred on the surface of the electrode materials. Meanwhile, the degree of Li/Ni cation mixing is reduced and the stability of the crystal structure improved after ZrO₂ modification. And the better electrochemical performances are presented after the ZrO₂ modification for the Li[Ni_0.5Co_0.2Mn_0.3]O₂(NCM523) cathode materials. The discharge capacity (in 3.0–4.6 V at 1 C) of the Zr-10000 sample (with zirconium contents (wt%) of 10000 ppm) decays from 188.1 mAh g⁻¹ to 163.8 mAh g⁻¹ after 100 cycles, and that of the Pristine decay from 186.6 mAh g⁻¹ to 138.3 mAh g⁻¹. The Zr-10000 sample have a higher capacity retention (87.1%) compared with that of the Pristine (74.1%). The improved high-voltage electrochemical performances after the modification are ascribed to the lower degree of polarization and electrochemical resistance of the battery.