RESEARCH HIGHLIGHT - Oxygen ‘holes’ could hold the key to higher performing EV batteries
Nickel is already used in lithium-ion batteries, but increasing the proportion of nickel could significantly improve battery energy density, making them especially suitable for electric vehicles and grid-scale storage. However, practical applications for these materials have been limited by structural instability and the tendency to lose oxygen atoms, which cause battery degradation and failure.
The researchers, led by the University of Cambridge and the University of Birmingham, found that ‘oxygen hole’ formation – where an oxygen ion loses an electron – plays a crucial role in the degradation of nickel-rich battery materials. These oxygen holes accelerate the release of oxygen that can further degrade the battery’s cathode, one of its two electrodes. Their results are reported in the journal Joule. Using a set of computational techniques on UK regional supercomputers, the researchers examined the behaviour of nickel-rich cathodes as they charged. They found that during charging, the oxygen in the material undergoes changes while the nickel charge remains essentially unchanged.
"Potentially, by adding compounds that shift the electrochemical reactions from oxygen more to the transition metals, especially at the surface of the battery materials, we can prevent the formation of singlet oxygen. This will enhance the stability and longevity of these lithium-ion batteries, paving the way for more efficient and reliable energy storage systems," Dr Annalena Genreith-Schriever, Yusuf Hamied Department of Chemistry
Lithium-ion batteries are widely used for various applications because of their high energy density and rechargeability, but challenges associated with the stability of cathode materials have hindered their overall performance and lifespan.
The research was supported in part by the Faraday Institution, the UK’s flagship battery research programme.
Read the full University of Cambridge article
Annalena R Genreith-Schriever et al. ‘Oxygen Hole Formation Controls Stability in LiNiO2 Cathodes: DFT Studies of Oxygen Loss and Singlet Oxygen Formation in Li-Ion Batteries.’ Joule (2023). DOI: 10.1016/j.joule.2023.06.017
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