cm5b03081_si_001.pdf (1.59 MB)
Self-Terminated Artificial SEI Layer for Nickel-Rich Layered Cathode Material via Mixed Gas Chemical Vapor Deposition
journal contribution
posted on 2015-11-10, 00:00 authored by In Hyuk Son, Jong Hwan Park, Soonchul Kwon, Junyoung Mun, Jang Wook ChoiBecause of the higher specific capacity,
nickel-rich layered cathode
material has received much attention from the lithium-ion battery
community. However, its cycle life is desired to improve further for
practical applications, and unstable interface with electrolyte is
one of the main capacity fading mechanisms. Here, we report a facile
chemical vapor deposition process involving mixed gases of CO2 and CH4, which yields thin and conformal artificial
solid-electrolyte-interphase (SEI) layer consisting of alkyl lithium
carbonate (LiCO3R) and lithium carbonate (Li2CO3) on nickel-rich active cathode powder. The coating
layer protects from side reactions and improves the cycle life and
efficiency significantly. Remarkably, the coating process is self-terminated
after the thickness reaches ∼10 nm, leading to the coating
layer to account for only 0.48 wt %, because of the growing binding
energy between the gas mixture and the surface products. The self-termination
is characterized by various analytical tools and is well-explained
by density functional theory calculations. The current gas phase coating
process should be applicable to other battery materials that suffer
from continuous side reactions with electrolyte.