Systematic Comparison of Al3+ Modified LiNi0.6Mn0.2Co0.2O2 Cathode Material from Recycling Process

Abstract

High-nickel cathode materials offer high specific capacity and thus high energy density; however, they suffer from low cycle life due to a less stable crystal structure. In this study, LiNi0.6Mn0.2Co0.2O2 (NMC 622) synthesized from a recycling process, and chemically modified with Al3+ via two simple methods (dry coating and wet coating), was used to demonstrate the feasibility of coating in large scale. Through XRD, STEM, and XPS, we demonstrate the difference of Al3+ distribution depth and its impact on the surface atomic structure of NMC 622 between the two coating methods. The Al-rich layer was largely concentrated on the surface of secondary particles after the dry coating process, whereas Al penetrated into the secondary particles in the wet coating process. The Al-rich layer from the dry coating process imparted improved electrochemical performance, and the capacity retention of pouch cells with dry coated NMC 622 (D-NMC) cathode increased from 83% to 91% compared to Al-free NMC 622 after 300 cycle...