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DTSTAMP:20260404T200000Z
UID:1718285400@ist.ac.at
DTSTART:20240613T153000
DTEND:20240613T163000
DESCRIPTION:Speaker: Annalena Genreith-Schriever\nhosted by Stefan Freunber
 ger\nAbstract: Title: Singlet oxygen formation in Ni-rich cathodes for Li-
 ion batteriesAbstract:Ni-rich cathode materials achieve both high voltages
  and capacities in Li-ion batteries but are prone to structural instabilit
 ies and oxygen loss via the formation of singlet oxygen. Using ab initio m
 olecular dynamics simulations\, we observe spontaneous O2 loss from the (0
 12) surface of delithiated LiNiO2\, singlet oxygen forming in the process.
  Using density functional theory calculations and dynamical mean-field the
 ory calculations based on maximally localised Wannier functions\, we find 
 that the origin of the material’s instability lies in the pronounced oxi
 dation of O during delithiation\, i.e.\, O plays a central role in Ni-O re
 dox in LiNiO2. Predicted XAS Ni K and O K-edge spectra are in excellent ag
 reement with experimental XAS spectra\, confirming the predicted charge st
 ates. The calculations also show that a high-voltage O K-edge feature at 5
 31 eV previously assigned to lattice O-redox processes could alternatively
  arise from O-redox induced water intercalation and O–O dimer formation 
 with lattice O at high states of charge. The O2 surface loss route observe
 d here consists of 2 surface O•– radicals combining to form a peroxide
  ion\, which is oxidised to O2\, leaving behind 2 O vacancies and 2 O2– 
 ions: effectively 4 O•– radicals disproportionate to O2 and 2 O2– io
 ns. The reaction liberates ca. 3 eV per O2 molecule. Singlet oxygen format
 ion is caused by the singlet ground state of the peroxide ion\, with spin 
 conservation dictating the preferential release of 1O2\, the strongly exer
 gonic reaction providing the free energy required for the formation of 1O2
  in its excited state.
LOCATION:Moonstone / Ground floor / Seminar Room F\, ISTA
ORGANIZER:
SUMMARY:Annalena Genreith-Schriever: Chemistry Colloquium  - Singlet oxygen
  formation in Ni-rich cathodes for Li-ion batteries
URL:https://talks-calendar.ista.ac.at/events/4916
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