--- _id: '12065' abstract: - lang: eng text: Capacity, rate performance, and cycle life of aprotic Li–O2 batteries critically depend on reversible electrodeposition of Li2O2. Current understanding states surface-adsorbed versus solvated LiO2 controls Li2O2 growth as surface film or as large particles. Herein, we show that Li2O2 forms across a wide range of electrolytes, carbons, and current densities as particles via solution-mediated LiO2 disproportionation, bringing into question the prevalence of any surface growth under practical conditions. We describe a unified O2 reduction mechanism, which can explain all found capacity relations and Li2O2 morphologies with exclusive solution discharge. Determining particle morphology and achievable capacities are species mobilities, true areal rate, and the degree of LiO2 association in solution. Capacity is conclusively limited by mass transport through the tortuous Li2O2 rather than electron transport through a passivating Li2O2 film. Provided that species mobilities and surface growth are high, high capacities are also achieved with weakly solvating electrolytes, which were previously considered prototypical for low capacity via surface growth. acknowledged_ssus: - _id: EM-Fac - _id: M-Shop acknowledgement: S.A.F. and C.P. are indebted to the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (Grant Agreement No. 636069). This project has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie Grant NanoEvolution, Grant Agreement No. 894042. S.A.F. and S.M. are indebted to Institute of Science and Technology Austria (ISTA) for support. This research was supported by the Scientific Service Units of ISTA through resources provided by the Electron Microscopy Facility and the Miba Machine Shop. C.P. thanks Vanessa Wood (ETH Zürich) for her continuing support. article_processing_charge: Yes (via OA deal) article_type: original author: - first_name: Christian full_name: Prehal, Christian last_name: Prehal - first_name: Soumyadip full_name: Mondal, Soumyadip id: d25d21ef-dc8d-11ea-abe3-ec4576307f48 last_name: Mondal - first_name: Ludek full_name: Lovicar, Ludek id: 36DB3A20-F248-11E8-B48F-1D18A9856A87 last_name: Lovicar - 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: Prehal C, Mondal S, Lovicar L, Freunberger SA. Exclusive solution discharge in Li-O₂ batteries? ACS Energy Letters. 2022;7(9):3112-3119. doi:10.1021/acsenergylett.2c01711 apa: Prehal, C., Mondal, S., Lovicar, L., & Freunberger, S. A. (2022). Exclusive solution discharge in Li-O₂ batteries? ACS Energy Letters. American Chemical Society. https://doi.org/10.1021/acsenergylett.2c01711 chicago: Prehal, Christian, Soumyadip Mondal, Ludek Lovicar, and Stefan Alexander Freunberger. “Exclusive Solution Discharge in Li-O₂ Batteries?” ACS Energy Letters. American Chemical Society, 2022. https://doi.org/10.1021/acsenergylett.2c01711. ieee: C. Prehal, S. Mondal, L. Lovicar, and S. A. Freunberger, “Exclusive solution discharge in Li-O₂ batteries?,” ACS Energy Letters, vol. 7, no. 9. American Chemical Society, pp. 3112–3119, 2022. ista: Prehal C, Mondal S, Lovicar L, Freunberger SA. 2022. Exclusive solution discharge in Li-O₂ batteries? ACS Energy Letters. 7(9), 3112–3119. mla: Prehal, Christian, et al. “Exclusive Solution Discharge in Li-O₂ Batteries?” ACS Energy Letters, vol. 7, no. 9, American Chemical Society, 2022, pp. 3112–19, doi:10.1021/acsenergylett.2c01711. short: C. Prehal, S. Mondal, L. Lovicar, S.A. Freunberger, ACS Energy Letters 7 (2022) 3112–3119. date_created: 2022-09-08T09:51:09Z date_published: 2022-08-29T00:00:00Z date_updated: 2023-08-03T13:47:56Z day: '29' ddc: - '540' department: - _id: StFr - _id: EM-Fac doi: 10.1021/acsenergylett.2c01711 external_id: isi: - '000860787000001' file: - access_level: open_access checksum: cf0bed3a2535c11d27244cd029dbc1d0 content_type: application/pdf creator: dernst date_created: 2023-01-20T08:43:51Z date_updated: 2023-01-20T08:43:51Z file_id: '12319' file_name: 2022_ACSEnergyLetters_Prehal.pdf file_size: 3827583 relation: main_file success: 1 file_date_updated: 2023-01-20T08:43:51Z has_accepted_license: '1' intvolume: ' 7' isi: 1 issue: '9' language: - iso: eng month: '08' oa: 1 oa_version: Published Version page: 3112-3119 publication: ACS Energy Letters publication_identifier: eissn: - 2380-8195 publication_status: published publisher: American Chemical Society quality_controlled: '1' scopus_import: '1' status: public title: Exclusive solution discharge in Li-O₂ batteries? tmp: image: /images/cc_by.png legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0) short: CC BY (4.0) type: journal_article user_id: 4359f0d1-fa6c-11eb-b949-802e58b17ae8 volume: 7 year: '2022' ... --- _id: '9301' abstract: - lang: eng text: Electrodepositing insulating lithium peroxide (Li2O2) is the key process during discharge of aprotic Li–O2 batteries and determines rate, capacity, and reversibility. Current understanding states that the partition between surface adsorbed and dissolved lithium superoxide governs whether Li2O2 grows as a conformal surface film or larger particles, leading to low or high capacities, respectively. However, better understanding governing factors for Li2O2 packing density and capacity requires structural sensitive in situ metrologies. Here, we establish in situ small- and wide-angle X-ray scattering (SAXS/WAXS) as a suitable method to record the Li2O2 phase evolution with atomic to submicrometer resolution during cycling a custom-built in situ Li–O2 cell. Combined with sophisticated data analysis, SAXS allows retrieving rich quantitative structural information from complex multiphase systems. Surprisingly, we find that features are absent that would point at a Li2O2 surface film formed via two consecutive electron transfers, even in poorly solvating electrolytes thought to be prototypical for surface growth. All scattering data can be modeled by stacks of thin Li2O2 platelets potentially forming large toroidal particles. Li2O2 solution growth is further justified by rotating ring-disk electrode measurements and electron microscopy. Higher discharge overpotentials lead to smaller Li2O2 particles, but there is no transition to an electronically passivating, conformal Li2O2 coating. Hence, mass transport of reactive species rather than electronic transport through a Li2O2 film limits the discharge capacity. Provided that species mobilities and carbon surface areas are high, this allows for high discharge capacities even in weakly solvating electrolytes. The currently accepted Li–O2 reaction mechanism ought to be reconsidered. acknowledged_ssus: - _id: EM-Fac acknowledgement: S.A.F. and C.P. are indebted to the European Research Council under the European Union's Horizon 2020 research and innovation program (Grant Agreement No. 636069), the Austrian Federal Ministry of Science, Research and Economy, and the Austrian Research Promotion Agency (Grant No. 845364). We acknowledge A. Zankel and H. Schroettner for support with SEM measurements. C.P. thanks N. Kostoglou, C. Koczwara, M. Hartmann, and M. Burian for discussions on gas sorption analysis, C++ programming, Monte Carlo modeling, and in situ SAXS experiments, respectively. We thank S. Stadlbauer for help with Karl Fischer titration, R. Riccò for gas sorption measurements, and acknowledge Graz University of Technology for support through the Lead Project LP-03. Likewise, the use of SOMAPP Lab, a core facility supported by the Austrian Federal Ministry of Education, Science and Research, the Graz University of Technology, the University of Graz, and Anton Paar GmbH is acknowledged. S.A.F. is indebted to Institute of Science and Technology Austria (IST Austria) for support. This research was supported by the Scientific Service Units of IST Austria through resources provided by the Electron Microscopy Facility. article_number: e2021893118 article_processing_charge: No article_type: original author: - first_name: Christian full_name: Prehal, Christian last_name: Prehal - first_name: Aleksej full_name: Samojlov, Aleksej last_name: Samojlov - first_name: Manfred full_name: Nachtnebel, Manfred last_name: Nachtnebel - first_name: Ludek full_name: Lovicar, Ludek id: 36DB3A20-F248-11E8-B48F-1D18A9856A87 last_name: Lovicar orcid: 0000-0001-6206-4200 - first_name: Manfred full_name: Kriechbaum, Manfred last_name: Kriechbaum - first_name: Heinz full_name: Amenitsch, Heinz last_name: Amenitsch - 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: Prehal C, Samojlov A, Nachtnebel M, et al. In situ small-angle X-ray scattering reveals solution phase discharge of Li–O2 batteries with weakly solvating electrolytes. Proceedings of the National Academy of Sciences. 2021;118(14). doi:10.1073/pnas.2021893118 apa: Prehal, C., Samojlov, A., Nachtnebel, M., Lovicar, L., Kriechbaum, M., Amenitsch, H., & Freunberger, S. A. (2021). In situ small-angle X-ray scattering reveals solution phase discharge of Li–O2 batteries with weakly solvating electrolytes. Proceedings of the National Academy of Sciences. National Academy of Sciences. https://doi.org/10.1073/pnas.2021893118 chicago: Prehal, Christian, Aleksej Samojlov, Manfred Nachtnebel, Ludek Lovicar, Manfred Kriechbaum, Heinz Amenitsch, and Stefan Alexander Freunberger. “In Situ Small-Angle X-Ray Scattering Reveals Solution Phase Discharge of Li–O2 Batteries with Weakly Solvating Electrolytes.” Proceedings of the National Academy of Sciences. National Academy of Sciences, 2021. https://doi.org/10.1073/pnas.2021893118. ieee: C. Prehal et al., “In situ small-angle X-ray scattering reveals solution phase discharge of Li–O2 batteries with weakly solvating electrolytes,” Proceedings of the National Academy of Sciences, vol. 118, no. 14. National Academy of Sciences, 2021. ista: Prehal C, Samojlov A, Nachtnebel M, Lovicar L, Kriechbaum M, Amenitsch H, Freunberger SA. 2021. In situ small-angle X-ray scattering reveals solution phase discharge of Li–O2 batteries with weakly solvating electrolytes. Proceedings of the National Academy of Sciences. 118(14), e2021893118. mla: Prehal, Christian, et al. “In Situ Small-Angle X-Ray Scattering Reveals Solution Phase Discharge of Li–O2 Batteries with Weakly Solvating Electrolytes.” Proceedings of the National Academy of Sciences, vol. 118, no. 14, e2021893118, National Academy of Sciences, 2021, doi:10.1073/pnas.2021893118. short: C. Prehal, A. Samojlov, M. Nachtnebel, L. Lovicar, M. Kriechbaum, H. Amenitsch, S.A. Freunberger, Proceedings of the National Academy of Sciences 118 (2021). date_created: 2021-03-31T07:00:01Z date_published: 2021-04-06T00:00:00Z date_updated: 2023-09-05T13:27:18Z day: '06' department: - _id: StFr - _id: EM-Fac doi: 10.1073/pnas.2021893118 external_id: isi: - '000637398300050' intvolume: ' 118' isi: 1 issue: '14' keyword: - small-angle X-ray scattering - oxygen reduction - disproportionation - Li-air battery language: - iso: eng main_file_link: - open_access: '1' url: https://doi.org/10.26434/chemrxiv.11447775 month: '04' oa: 1 oa_version: Preprint publication: Proceedings of the National Academy of Sciences publication_identifier: eissn: - 1091-6490 issn: - 0027-8424 publication_status: published publisher: National Academy of Sciences quality_controlled: '1' status: public title: In situ small-angle X-ray scattering reveals solution phase discharge of Li–O2 batteries with weakly solvating electrolytes type: journal_article user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1 volume: 118 year: '2021' ...