posted on 2024-01-03, 19:35authored byPrincess
Stephanie Llanos, Zahra Ahaliabadeh, Ville Miikkulainen, Jouko Lahtinen, Lide Yao, Hua Jiang, Timo Kankaanpää, Tanja M. Kallio
The development of
LiNi0.8Mn0.1Co0.1O2 (NMC811)
as a cathode material for high-energy-density
lithium–ion batteries (LIBs) intends to address the driving
limitations of electric vehicles. However, the commercialization of
this technology has been hindered by poor cycling stability at high
cutoff voltages. The potential instability and drastic capacity fade
stem from irreversible parasitic side reactions at the electrode–electrolyte
interface. To address these issues, a stable nanoscale lithium fluoride
(LiF) coating is deposited on the NMC811 electrode via atomic layer
deposition. The nanoscale LiF coating diminishes the direct contact
between NMC811 and the electrolyte, suppressing the detrimental parasitic
reactions. LiF-NMC811 delivers cycling stability superior to uncoated
NMC811 with high cutoff voltage for half-cell (3.0–4.6 V vs
Li/Li+) and full-cell (2.8–4.5 V vs graphite) configurations.
The structural, morphological, and chemical analyses of the electrodes
after cycling show that capacity decline fundamentally arises from
the electrode–electrolyte interface growth, irreversible phase
transformation, transition metal dissolution and crossover, and particle
cracking. Overall, this work demonstrates that LiF is an effective
electrode coating for high-voltage cycling without compromising rate
performance, even at high discharge rates. The findings of this work
highlight the need to stabilize the electrode–electrolyte interface
to fully utilize the high-capacity performance of NMC811.