PNNL

Abstract

Interfacial reactions between electrode and electrolyte are known to be critical, either beneficial or detrimental, for the performance of rechargeable batteries. The general approaches of controlling interfacial reactions are either applying a coating layer on cathode or modifying the electrolyte chemistry. In this work, we demonstrate a novel approach of modification of interfacial reactions for tailoring the battery properties through dilute doping of bulk lattice in the cathode. Using atomic level imaging, spectroscopic analysis and DFT simulation, we reveal that the Al dopant in NCA is partially dissolved in the bulk lattice and partially exist as Al2O3 particles that epitaxially dressed on the cathode particle surface. The Al2O3 particles play a role of as if surface coating at the site they reside. While dramatically, the Al substitution lowers transition metal (TM) redox energy level and consequently promotes the formation of a stable cathode electrolyte interphase (CEI) layer, which prevents the dissolution of TM from cathode, and therefore eliminates the otherwise deposition of TM on anode through cross talking upon battery cycling. The present observation provides insights, and demonstrates a general principle, as how atomic level dopants in bulk lattice modify the solid-liquid interfacial reaction for leading to enhanced performance.