Metallurgy Inspired Formation of Homogeneous Al₂O₃ Coating Layer To Improve the Electrochemical Properties of LiNi_0.8Co_0.1Mn_0.1O₂ Cathode Material

Inspired by the metallurgical process of aluminum production, a controllable and cost-effective Al₂O₃ coating strategy is introduced to improve the surface stability of LiNi_0.8Co_0.1­Mn_0.1O₂. The CO₂ is introduced to NaAlO₂ aqueous solution to generate a weak basic condition that is able to decrease the deposition rate of Al­(OH)₃ and is beneficial to the uniform coating of Al­(OH)₃ on the surface of commercial Ni_0.8Co_0.1­Mn_0.1(OH)₂ precursor. The electrochemical performance of Al₂O₃-coated LiNi_0.8Co_0.1­Mn_0.1O₂ is improved at both ordinary cutoff voltage of 4.3 V and elevated cutoff voltage of 4.5 V. With the optimized Al₂O₃ coating amount (1%), the capacity retention of the material after 60 cycles increases from 90% to 99% at 2.8–4.3 V and from 86% to 99% at 2.8–4.5 V, respectively. The Al₂O₃-coated sample also delivers a better rate capability, maintaining 117 and 131 mA h g^–1 in the voltage ranges 2.8–4.3 and 2.8 V–4.5 V at the current density of 5 C, respectively. The enhanced properties of as-prepared Al₂O₃-coated LiNi_0.8Co_0.1Mn_0.1O₂ are due to the Al₂O₃ coating layer building up a favorable interface, preventing the direct contact between the active material and electrolyte and promoting Li⁺ transmission at the interface.