Theoretical exploration of various lithium peroxide crystal structures in a Li-air battery
We describe a series of metastable Li₂O₂ crystal structures involving different orientations and displacements of the O₂²⁻ peroxy ions based on the known Li₂O₂ crystal structure. Within the vicinity of the chemical potential ΔG ~ 0.20 eV/Li from the thermodynamic ground state of the Li₂O₂ crystal structure (i.e., Föppl structure), all of these newly found metastable Li₂O₂ crystal structures are found to be insulating and high-k materials, and they have a common unique signature of an O₂²⁻ O-O vibration mode (ω ~ 799–865 cm⁻¹), which is in the range of that commonly observed in Li-air battery experiments, regardless of the random O₂²⁻ orientations and the symmetry in the crystal lattice. From XRD patterns analysis, the commercially available Li₂O₂ powder is confirmed to be the thermodynamic ground state Föppl-like structure. However, for Li₂O₂ compounds that are grown electrochemically under the environment of Li-O₂ cells, we found that the XRD patterns alone are not sufficient for structural identification of these metastable Li₂O₂ crystalline phases due to the poor crystallinity of the sample. In addition, the commonly known Raman signal of O₂²⁻ vibration mode is also found to be insufficient to validate the possible existence of these newly predicted Li₂O₂ crystal structures, asmore »
- Argonne National Lab. (ANL), Argonne, IL (United States). Materials Science Div.
- Argonne National Lab. (ANL), Argonne, IL (United States). Chemical Sciences and Engineering Div.
- Purdue Univ., West Lafayette, IN (United States). School of Chemical Engineering.
- Publication Date:
- OSTI Identifier:
- Grant/Contract Number:
- Accepted Manuscript
- Journal Name:
- Energies (Basel)
- Additional Journal Information:
- Journal Name: Energies (Basel); Journal Volume: 8; Journal Issue: 1; Journal ID: ISSN 1996-1073
- MDPI AG
- Research Org:
- Argonne National Laboratory (ANL), Argonne, IL (United States)
- Sponsoring Org:
- USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
- Country of Publication:
- United States
- 36 MATERIALS SCIENCE; 25 ENERGY STORAGE Li-air battery; lithium peroxide; crystal structure; DFT calculation