--- _id: '7275' abstract: - lang: eng text: Aprotic alkali metal–oxygen batteries require reversible formation of metal superoxide or peroxide on cycling. Severe parasitic reactions cause poor rechargeability, efficiency, and cycle life and have been shown to be caused by singlet oxygen (1O2) that forms at all stages of cycling. However, its formation mechanism remains unclear. We show that disproportionation of superoxide, the product or intermediate on discharge and charge, to peroxide and oxygen is responsible for 1O2 formation. While the overall reaction is driven by the stability of peroxide and thus favored by stronger Lewis acidic cations such as Li+, the 1O2 fraction is enhanced by weak Lewis acids such as organic cations. Concurrently, the metal peroxide yield drops with increasing 1O2. The results explain a major parasitic pathway during cell cycling and the growing severity in K–, Na–, and Li–O2 cells based on the growing propensity for disproportionation. High capacities and rates with peroxides are now realized to require solution processes, which form peroxide or release O2via disproportionation. The results therefore establish the central dilemma that disproportionation is required for high capacity but also responsible for irreversible reactions. Highly reversible cell operation requires hence finding reaction routes that avoid disproportionation. article_processing_charge: No article_type: original author: - first_name: Eléonore full_name: Mourad, Eléonore last_name: Mourad - first_name: Yann K. full_name: Petit, Yann K. last_name: Petit - first_name: Riccardo full_name: Spezia, Riccardo last_name: Spezia - first_name: Aleksej full_name: Samojlov, Aleksej last_name: Samojlov - first_name: Francesco F. full_name: Summa, Francesco F. last_name: Summa - first_name: Christian full_name: Prehal, Christian last_name: Prehal - first_name: Christian full_name: Leypold, Christian last_name: Leypold - first_name: Nika full_name: Mahne, Nika last_name: Mahne - first_name: Christian full_name: Slugovc, Christian last_name: Slugovc - first_name: Olivier full_name: Fontaine, Olivier last_name: Fontaine - first_name: Sergio full_name: Brutti, Sergio last_name: Brutti - first_name: Stefan Alexander full_name: Freunberger, Stefan Alexander id: A8CA28E6-CE23-11E9-AD2D-EC27E6697425 last_name: Freunberger orcid: 0000-0003-2902-5319 citation: ama: Mourad E, Petit YK, Spezia R, et al. Singlet oxygen from cation driven superoxide disproportionation and consequences for aprotic metal–O2 batteries. Energy & Environmental Science. 2019;12(8):2559-2568. doi:10.1039/c9ee01453e apa: Mourad, E., Petit, Y. K., Spezia, R., Samojlov, A., Summa, F. F., Prehal, C., … Freunberger, S. A. (2019). Singlet oxygen from cation driven superoxide disproportionation and consequences for aprotic metal–O2 batteries. Energy & Environmental Science. RSC. https://doi.org/10.1039/c9ee01453e chicago: Mourad, Eléonore, Yann K. Petit, Riccardo Spezia, Aleksej Samojlov, Francesco F. Summa, Christian Prehal, Christian Leypold, et al. “Singlet Oxygen from Cation Driven Superoxide Disproportionation and Consequences for Aprotic Metal–O2 Batteries.” Energy & Environmental Science. RSC, 2019. https://doi.org/10.1039/c9ee01453e. ieee: E. Mourad et al., “Singlet oxygen from cation driven superoxide disproportionation and consequences for aprotic metal–O2 batteries,” Energy & Environmental Science, vol. 12, no. 8. RSC, pp. 2559–2568, 2019. ista: Mourad E, Petit YK, Spezia R, Samojlov A, Summa FF, Prehal C, Leypold C, Mahne N, Slugovc C, Fontaine O, Brutti S, Freunberger SA. 2019. Singlet oxygen from cation driven superoxide disproportionation and consequences for aprotic metal–O2 batteries. Energy & Environmental Science. 12(8), 2559–2568. mla: Mourad, Eléonore, et al. “Singlet Oxygen from Cation Driven Superoxide Disproportionation and Consequences for Aprotic Metal–O2 Batteries.” Energy & Environmental Science, vol. 12, no. 8, RSC, 2019, pp. 2559–68, doi:10.1039/c9ee01453e. short: E. Mourad, Y.K. Petit, R. Spezia, A. Samojlov, F.F. Summa, C. Prehal, C. Leypold, N. Mahne, C. Slugovc, O. Fontaine, S. Brutti, S.A. Freunberger, Energy & Environmental Science 12 (2019) 2559–2568. date_created: 2020-01-15T07:18:04Z date_published: 2019-08-01T00:00:00Z date_updated: 2021-01-12T08:12:41Z day: '01' ddc: - '530' - '541' - '540' doi: 10.1039/c9ee01453e extern: '1' file: - access_level: open_access checksum: 94d4cfb2ab0b4c90ef76a7f3cc811feb content_type: application/pdf creator: dernst date_created: 2020-01-30T16:11:05Z date_updated: 2020-07-14T12:47:55Z file_id: '7424' file_name: 2019_EnergyEnvironScienc_Mourad.pdf file_size: 2888027 relation: main_file file_date_updated: 2020-07-14T12:47:55Z has_accepted_license: '1' intvolume: ' 12' issue: '8' language: - iso: eng license: https://creativecommons.org/licenses/by-nc/4.0/ month: '08' oa: 1 oa_version: Published Version page: 2559-2568 publication: Energy & Environmental Science publication_identifier: issn: - 1754-5692 - 1754-5706 publication_status: published publisher: RSC quality_controlled: '1' status: public title: Singlet oxygen from cation driven superoxide disproportionation and consequences for aprotic metal–O2 batteries tmp: image: /images/cc_by_nc.png legal_code_url: https://creativecommons.org/licenses/by-nc/4.0/legalcode name: Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) short: CC BY-NC (4.0) type: journal_article user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87 volume: 12 year: '2019' ... --- _id: '7302' abstract: - lang: eng text: Understanding charge carrier transport in Li2O2, the storage material in the non-aqueous Li-O2 battery, is key to the development of this high-energy battery. Here, we studied ionic transport properties and Li self-diffusion in nanocrystalline Li2O2 by conductivity and temperature variable 7Li NMR spectroscopy. Nanostructured Li2O2, characterized by a mean crystallite size of less than 50 nm as estimated from X-ray diffraction peak broadening, was prepared by high-energy ball milling of microcrystalline lithium peroxide with μm sized crystallites. At room temperature the overall conductivity σ of the microcrystalline reference sample turned out to be very low (3.4 × 10−13 S cm−1) which is in agreement with results from temperature-variable 7Li NMR line shape measurements. Ball-milling, however, leads to an increase of σ by approximately two orders of magnitude (1.1 × 10−10 S cm−1); correspondingly, the activation energy decreases from 0.89 eV to 0.82 eV. The electronic contribution σeon, however, is in the order of 9 × 10−12 S cm−1 which makes less than 10% of the total value. Interestingly, 7Li NMR lines of nano-Li2O2 undergo pronounced heterogeneous motional narrowing which manifests in a two-component line shape emerging with increasing temperatures. Most likely, the enhancement in σ can be traced back to the generation of a spin reservoir with highly mobile Li ions; these are expected to reside in the nearest neighbourhood of defects generated or near the structurally disordered and defect-rich interfacial regions formed during mechanical treatment. article_processing_charge: No article_type: original author: - first_name: A. full_name: Dunst, A. last_name: Dunst - first_name: V. full_name: Epp, V. last_name: Epp - first_name: I. full_name: Hanzu, I. last_name: Hanzu - first_name: Stefan Alexander full_name: Freunberger, Stefan Alexander id: A8CA28E6-CE23-11E9-AD2D-EC27E6697425 last_name: Freunberger orcid: 0000-0003-2902-5319 - first_name: M. full_name: Wilkening, M. last_name: Wilkening citation: ama: Dunst A, Epp V, Hanzu I, Freunberger SA, Wilkening M. Short-range Li diffusion vs. long-range ionic conduction in nanocrystalline lithium peroxide Li2O2—the discharge product in lithium-air batteries. Energy & Environmental Science. 2014;7(8):2739-2752. doi:10.1039/c4ee00496e apa: Dunst, A., Epp, V., Hanzu, I., Freunberger, S. A., & Wilkening, M. (2014). Short-range Li diffusion vs. long-range ionic conduction in nanocrystalline lithium peroxide Li2O2—the discharge product in lithium-air batteries. Energy & Environmental Science. RSC. https://doi.org/10.1039/c4ee00496e chicago: Dunst, A., V. Epp, I. Hanzu, Stefan Alexander Freunberger, and M. Wilkening. “Short-Range Li Diffusion vs. Long-Range Ionic Conduction in Nanocrystalline Lithium Peroxide Li2O2—the Discharge Product in Lithium-Air Batteries.” Energy & Environmental Science. RSC, 2014. https://doi.org/10.1039/c4ee00496e. ieee: A. Dunst, V. Epp, I. Hanzu, S. A. Freunberger, and M. Wilkening, “Short-range Li diffusion vs. long-range ionic conduction in nanocrystalline lithium peroxide Li2O2—the discharge product in lithium-air batteries,” Energy & Environmental Science, vol. 7, no. 8. RSC, pp. 2739–2752, 2014. ista: Dunst A, Epp V, Hanzu I, Freunberger SA, Wilkening M. 2014. Short-range Li diffusion vs. long-range ionic conduction in nanocrystalline lithium peroxide Li2O2—the discharge product in lithium-air batteries. Energy & Environmental Science. 7(8), 2739–2752. mla: Dunst, A., et al. “Short-Range Li Diffusion vs. Long-Range Ionic Conduction in Nanocrystalline Lithium Peroxide Li2O2—the Discharge Product in Lithium-Air Batteries.” Energy & Environmental Science, vol. 7, no. 8, RSC, 2014, pp. 2739–52, doi:10.1039/c4ee00496e. short: A. Dunst, V. Epp, I. Hanzu, S.A. Freunberger, M. Wilkening, Energy & Environmental Science 7 (2014) 2739–2752. date_created: 2020-01-15T12:17:43Z date_published: 2014-08-01T00:00:00Z date_updated: 2021-01-12T08:12:53Z day: '01' doi: 10.1039/c4ee00496e extern: '1' intvolume: ' 7' issue: '8' language: - iso: eng month: '08' oa_version: Published Version page: 2739-2752 publication: Energy & Environmental Science publication_identifier: issn: - 1754-5692 - 1754-5706 publication_status: published publisher: RSC quality_controlled: '1' status: public title: Short-range Li diffusion vs. long-range ionic conduction in nanocrystalline lithium peroxide Li2O2—the discharge product in lithium-air batteries type: journal_article user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87 volume: 7 year: '2014' ...