CASE STUDY – BATTERIES
Modification of Ni-Rich FCG NMC and NCA Cathodes by Atomic Layer Deposition: Preventing Surface Phase Transitions for High-Voltage Lithium-Ion Batteries
Authors: Debasish Mohanty et al.
Institution: Oak Ridge National Laboratory
Application: Batteries – Cathodes
Summary: The energy density of current lithium-ion batteries (LIBs) based on layered LiMO2 cathodes (M=Ni, Mn, Co: NMC; M=Ni, Co, Al: NCA) needs to be improved significantly to compete with internal combustion engines and allow for widespread implementation of electric vehicles (EVs). To achieve higher energy densities, LIBs can be run at higher upper cutoff voltages (greater than 4.2 V), but this often results in increased capacity fade due to degradation of unstable cathode materials and parasitic reactions with the electrolyte. In this study, Oak Ridge National Lab used atomic layer deposition (ALD) of titania (TiO2) and alumina (Al2O3) on NMC and NCA active particles to stabilize the cathode material. ALD coatings substantially improve electrochemical performance and allow for increased upper cutoff voltage (UCV) during charging, delivering significantly increased specific energy utilization. The ability to mitigate degradation mechanisms for NMC and NCA illustrated in this study provides promising insights into the enablement of high-voltage LIBs.
Key Takeaways:
- Cathodes were stabilized using Atomic Layer Deposition at an UCV as high as 4.4V
- ALD-coated NMC811 particles showed a 40% longer cycle life in a 2 Ah pouch cell cycled at 4.35V UCV (1C/1C).
- ALD-coated NCA particles exhibited 34% longer cycle life in a 2 Ah pouch cell cycled at 4.4V UCV (1C/1C).
- Repeatable results after scaling to 450 kg batch size
Read the Full Paper: https://www.nature.com/articles/srep26532
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