A Discovery of an Unexpected Metal Dissolution of Thin-Coated Cathode Particles: Its Theoretical and Experimental Explanations

Abstract

The degree of metal dissolution of cathode materials is a critical parameter in determining Li-ion battery performance. Ultra-thin coated LiMn2O4 (LMO) cathode particles via Atomic Layer Deposition (ALD) exhibit superior battery performance over bare LMO particles. However, we have observed that ultra-thin CeO2 coating intensifies Mn dissolution of LMO during cycling of lithium-ion battery, whereas ultra-thin Al2O3 coating tends to inhibit Mn dissolution. A detailed study of Density Functional Theory (DFT) has been carried out to illustrate the experimental observations. First, the manganese vacancy formation energy is calculated, along with the bonding strengths of Mn-O of uncoated, Al2O3 coated, and CeO2 coated particles via Crystal Orbital Overlap Population (COOP) calculations. Further, the projected density of state calculation of Mn is used to confirm the electronic occupancy of Mn atom for each case. Surprisingly, the atomic analysis is consistent with the experimental observations. This is the first report that coatings can accelerate metal dissolution, which can show new insights into ALD coatings and their impact on metal dissolution in cathode materials.