A new nanoscale coating could make lithium-ion batteries last much longer. It works by stopping oxygen from being released, which usually damages battery cells during charging.
Researchers at the University of Arkansas created a very thin zirconium sulfide coating. They applied it to a common cathode material called lithium nickel manganese cobalt oxide (NMC811). This material is popular for electric vehicle batteries because it stores a lot of energy and is relatively inexpensive.
However, NMC811 has a problem. When it charges and discharges many times, the cathode releases oxygen. This oxygen can react with the battery's liquid parts, creating gases and other harmful substances. These substances reduce how well the battery works and can even be a safety risk.
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Start Your News DetoxThe research team solved this by adding a tiny coating. This coating chemically traps the released oxygen, stopping it from causing bad reactions inside the battery.
Oxygen-Trapping Nanoscale Coating
The scientists put a zirconium sulfide coating, only two nanometers thick, onto existing NMC811 cathodes. They used a method called atomic layer deposition. When the cathode releases oxygen during battery use, the coating reacts with it.
This reaction changes the coating from zirconium sulfide into zirconium sulfate. Essentially, the coating acts like an oxygen catcher inside the battery cell.
By trapping the oxygen, the coating prevents it from reacting with the electrolyte and forming harmful byproducts. The new sulfate layer also helps stabilize the connection between the cathode and electrolyte. It also limits damage to the cathode's structure.
This extra protection helps reduce tiny cracks and keeps the cathode material's internal structure intact over time.
Battery Cycle Life Boost
The tests showed a big improvement in battery performance. Regular NMC811 cathodes usually only last about 200 charge-discharge cycles before they stop working well.
But with the zirconium sulfide coating, the cathodes kept working for over 1,000 cycles. The coated batteries also held about 60% of their charge capacity even after 1,300 cycles.
This idea builds on earlier work by the same research group. They had been looking into sulfide-based protective layers for battery materials.
Meng, one of the researchers, said that sulfides could be a new type of protective coating for lithium-ion batteries. He described these coatings as "robust, clean and antioxidative protective layers on battery cathodes."
So far, the team has tested several sulfide materials. These include Li2S, ZrS2, Al2S3, ZnS, and Cu2S. All of them can turn into sulfates during battery operation.
The project was led by Xiangbo “Henry” Meng, an associate professor at the University of Arkansas. Kevin Velasquez, a doctoral researcher, was the first author of the study. He tested the coated cathodes using small coin cells, like those found in watches.
Meng’s lab focuses on creating new nanomaterials for energy storage. His work involves making inorganic, organic, and hybrid nanomaterials to improve battery performance.
The US Department of Energy supports this project. Researchers from Argonne National Laboratory also helped. Meng mentioned that large technology companies are interested in testing these coatings in other battery systems.
The study was published in the journal Small.
Deep Dive & References
Oxygen-Scavenging Zirconium Sulfide Coating Enables High-Energy-Density NMC811 Cathodes to Achieve 1000 Cycles - Small, 2024
