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

Abstract

Inspired by the metallurgical process of aluminum production, a controllable and cost-effective Al 2 O 3 coating strategy is introduced to improve the surface stability of LiNi 0.8 Co 0.1 Mn 0.1 O 2 . The CO 2 is introduced to NaAlO 2 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 0.8 Co 0.1 Mn 0.1 (OH) 2 precursor. The electrochemical performance of Al 2 O 3 -coated LiNi 0.8 Co 0.1 Mn 0.1 O 2 is improved at both ordinary cutoff voltage of 4.3 V and elevated cutoff voltage of 4.5 V. With the optimized Al 2 O 3 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 Al 2 O 3 -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 Al 2 O 3 -coated LiNi 0.8 Co 0.1 Mn 0.1 O 2 are due to the Al 2 O 3 coating layer building up a favorable interface, preventing the direct contact between the active material and electrolyte and promoting Li + transmission at the interface.