Effect of Aqueous Electrolytes on LiCoO2 Surfaces: Role of Proton Adsorption on Oxygen Vacancy Formation
(2021) The Journal of Physical Chemistry C — Vol. 126, n° 1, p. 110-119 (2021)
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- Authors
Posada Pérez, Sergio 
- Abstract
- Aqueous electrolytes are a safer, greener, and cheaper solution for energy storage applications. However, aqueous Li-ion batteries (ALIBs) suffer from faster degradation and poorer cyclability. The presence of H+ and O loss have often been claimed to deteriorate electrode materials in aqueous electrolytes. Understanding the surface reactivity of the commercial LiCoO2 cathode with respect to aqueous electrolytes and O loss is essential for designing cathode materials in such aqueous electrochemical cells. In this work, we use density functional theory calculations to investigate the stability and structure of several low-index surfaces of layered Li1−xCoO2 (0 ≤ x ≤ 0.5) before and after H+ adsorption. We compute the binding energies of H+ from low to full coverage regimes. By employing ab initio atomistic thermodynamics, we determine the stability of O vacancies on protonated and nonprotonated layered LiCoO2 surfaces. Our computations demonstrate that O loss is energetically favorable on the lowest energy surfaces, i.e., on the most exposed surface terminations. We suggest that the O vacancy formation is directly related to the transition metal (Co) coordination. Finally, the role of H+ on O loss is investigated, showing that H+ can facilitate the generation of O vacancies in some surface terminations.
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Citations
Posada Pérez, S., Hautier, G., & Rignanese, G.-M. (2021). Effect of Aqueous Electrolytes on LiCoO2 Surfaces: Role of Proton Adsorption on Oxygen Vacancy Formation. The Journal of Physical Chemistry C, 126(1), 110-119. https://doi.org/10.1021/acs.jpcc.1c09348 (Original work published 2021)