Improved electrochemical and thermal properties of nickel rich LiNi_0.6Co_0.2Mn_0.2O₂ cathode materials by SiO₂ coating

A surface coating of SiO₂ is applied to a Ni rich LiNi_0.6Co_0.2Mn_0.2O₂ cathode material in a bid to improve its electrochemical and thermal properties. A uniform coating is achieved through a wet process using nano-sized SiO₂ powder, and though the coated electrode is found to exhibit a reduced rate capability, its cycle performance at a high temperature of 60 °C is greatly enhanced. The effect of this SiO₂ coating is further investigated by electrochemical impedance spectroscopy, which confirms that it suppresses the growth of interfacial impedance during progressive cycles. The SiO₂ coating also demonstrates good HF scavenging ability, producing a subsequent reduction in the degradation of the active core material. The thermal properties of LiNi_0.6Co_0.2Mn_0.2O₂ are also improved by the SiO₂ coating due to a reduction in the direct contact between the electrode and electrolyte. On the basis of these results, SiO₂ coating is considered a viable surface modification method for improving the electrochemical and thermal properties of LiNi_0.6Co_0.2Mn_0.2O₂.