2026-09-20T08:49:05Z https://www.ideals.illinois.edu/oai-pmh

oai:www.ideals.illinois.edu:2142/101111 2023-07-11 col_2142_5131 col_2142_14787 com_2142_5130 com_2142_9630 com_2142_234

Aluru, Narayana R. Ma, Linjian 2018-09-04T20:33:47Z 2018-09-04T20:33:47Z 2020-09-05T09:15:20Z 2018-01-25 2018-05 Solid oxide cells (SOCs) are high-efficiency energy conversion devices under high temperature. However, the key reaction mechanisms governing the overall performance of SOCs are not well understood. Here, we develop a multiscale model combining density functional theory calculations, transition state theory and continuum modeling to elucidate the essential reaction steps and predict the performance of the device. Density functional theory calculations are used to obtain the free energy barriers for different reaction steps, transition state theory is used to predict the reaction rate constants for each step based on the free energy barriers, and the continuum theory utilizes the reaction rate constants to obtain the voltage loss-current density relations. We apply the methodology to both the oxide ion-conducting SOCs as well as the proton-conducting SOCs. The proposed multiscale model yields quantitative agreement with the voltage loss-current density data from experiments. The results indicate that as to the oxygen electrode reactions in the Lanthanum Strontium Cobalt Ferrite (La_{1-x}Sr_{x}Co_{1-y}Fe_{y} O_{3-\delta} or LSCF) based oxide ion-conducting SOCs, the reaction step involving the splitting of the surface oxygen molecules into oxide ions under SOFC mode and the combination of surface oxide ions into oxygen molecules under SOEC mode is the rate limiting reaction step, and the diffusion of oxide ions in bulk LSCF is the rate limiting diffusion step. As to the Pt/Y-doped BaZrO_3/Ag based proton-conducting SOFC, the cathode reactions are rate-limiting steps. Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2020-05-01 The student, Linjian Ma, accepted the attached license on 2018-01-23 at 19:27. The student, Linjian Ma, submitted this Thesis for approval on 2018-01-23 at 19:53. This Thesis was approved for publication on 2018-01-25 at 15:34. DSpace SAF Submission Ingestion Package generated from Vireo submission #12019 on 2018-08-31 at 17:17:01 Made available in DSpace on 2018-09-04T20:33:47Z (GMT). No. of bitstreams: 2 MA-THESIS-2018.pdf: 13555149 bytes, checksum: 7f99f230741b0bc2399b094be5b68625 (MD5) LICENSE.txt: 4207 bytes, checksum: ad5f4a7eef3e19adac7348e5f000ef26 (MD5) Previous issue date: 2018-01-25 Embargo set by: Seth Robbins for item 107194 Lift date: 2020-09-04T20:34:13Z Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD system Embargo set by: Seth Robbins for item 107194 Lift date: 2020-09-04T20:37:00Z Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD system Embargo set by: Seth Robbins for item 107194 Lift date: 2020-09-04T20:42:08Z Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD system U of I Only Restriction Lifted for Item 107194 on 2020-09-05T09:15:20Z. application/pdf http://hdl.handle.net/2142/101111 en Copyright 2018 Linjian Ma multiscale modeling, continuum modeling, transition state theory, density functional theory, solid oxide cells A multiscale model for the oxide ion conducting and proton conducting solid oxide cells text text Mechanical Sci & Engineering Mechanical Engineering University of Illinois at Urbana-Champaign Thesis M.S.