Metallurgy Inspired Formation of Homogeneous Al2O3 Coating Layer to Improve the Electrochemical Properties of LiNi0.8Co0.1Mn0.1O2 Cathode Material

Abstract

Inspired by the metallurgical process of aluminum production, a controllable and cost-effective Al2O3 coating strategy is introduced to improve the surface stability of LiNi0.8Co0.1Mn0.1O2. 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 Ni0.8Co0.1Mn0.1(OH)2 precursor. The electrochemical performance of Al2O3-coated LiNi0.8Co0.1Mn0.1O2 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 LiNi0.8Co0.1Mn0.1O2 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.