{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/44162"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/44162","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Structural evolution of α-Fe2O3 nanowires during lithiation/delithiation and electrochemical property improvement","abstract":"Hematite Fe2O3 exhibits great potential in lithium ion battery area as anode material, due to high capacity, elemental abundance, low cost and biocompatibility. Its reaction with lithium ion is accepted as conversion reaction. In this paper, single crystal α-Fe2O3 nanowires were prepared by an electrical resistive heating method under ambient conditions. Transmission electron microscopy characterized the anode material at various stages of lithiation and delithiation. The phase and morphological evolution demonstrate the conversion reaction process in α-Fe2O3. The process was initiated through the reduction of Fe2O3 to Fe3O4 nanocrystals, which form 4-nm-nanoparticles within the nanowire. Further lithiation converted all of the iron oxides to BCC Fe nanocrystals with the significant growth up to 21 nm. During delithiation, the reactions proceeded in the reverse order, Fe0-Fe2+-Fe3+. However, the initial single crystalline α-Fe2O3 nanowires were replaced by nanocrystalline ones after first cycle. The delithiated electrode maintains the nanowire geometry over many cycles due to the nature of the short-range cation diffusion that facilitates the process. Besides, nanowires covered with continuous carbon film exhibited much better electrochemical properties, such as cycle capacity, stability and conductivity, than the uncoated ones. The intrinsic conductivity improvement from α-Fe2O3 to Fe3O4 can further enhance the electrochemical performance.","abstract_html":"Hematite Fe2O3 exhibits great potential in lithium ion battery area as anode material, due to high capacity, elemental abundance, low cost and biocompatibility. Its reaction with lithium ion is accepted as conversion reaction. In this paper, single crystal α-Fe2O3 nanowires were prepared by an electrical resistive heating method under ambient conditions. Transmission electron microscopy characterized the anode material at various stages of lithiation and delithiation. The phase and morphological evolution demonstrate the conversion reaction process in α-Fe2O3. The process was initiated through the reduction of Fe2O3 to Fe3O4 nanocrystals, which form 4-nm-nanoparticles within the nanowire. Further lithiation converted all of the iron oxides to BCC Fe nanocrystals with the significant growth up to 21 nm. During delithiation, the reactions proceeded in the reverse order, Fe0-Fe2+-Fe3+. However, the initial single crystalline α-Fe2O3 nanowires were replaced by nanocrystalline ones after first cycle. The delithiated electrode maintains the nanowire geometry over many cycles due to the nature of the short-range cation diffusion that facilitates the process. Besides, nanowires covered with continuous carbon film exhibited much better electrochemical properties, such as cycle capacity, stability and conductivity, than the uncoated ones. The intrinsic conductivity improvement from α-Fe2O3 to Fe3O4 can further enhance the electrochemical performance.","abstract_has_math":false,"creators":["Huang, Bo"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"M.S.","degree_level":"Thesis","degree_discipline":"Materials Science & Engr","degree_department":null,"school":null,"contributors":["Dillon, Shen J."],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2013,"date_issued":"2013-05-24T21:53:03Z","date_published":"2013-05-24T21:53:03Z","updated_at":"2026-07-22T22:25:33Z","subjects":["Conversion Reaction","Mechanism","Lithium Ion Battery","Nanowires"],"languages":["en"],"rights":["Copyright 2013 Bo Huang"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2142/44162","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Dillon, Shen J."]},{"key":"dc:creator","label":"Author","values":["Huang, Bo"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2013-05-24T21:53:03Z","2013-05"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Materials Science & Engr"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Thesis"]},{"key":"thesis:degree_name","label":"Degree Name","values":["M.S."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Conversion Reaction","Mechanism","Lithium Ion Battery","Nanowires"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2013 Bo Huang"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/44162"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Hematite Fe2O3 exhibits great potential in lithium ion battery area as anode material, due to high capacity, elemental abundance, low cost and biocompatibility. Its reaction with lithium ion is accepted as conversion reaction. In this paper, single crystal α-Fe2O3 nanowires were prepared by an electrical resistive heating method under ambient conditions. Transmission electron microscopy characterized the anode material at various stages of lithiation and delithiation. The phase and morphological evolution demonstrate the conversion reaction process in α-Fe2O3. The process was initiated through the reduction of Fe2O3 to Fe3O4 nanocrystals, which form 4-nm-nanoparticles within the nanowire. Further lithiation converted all of the iron oxides to BCC Fe nanocrystals with the significant growth up to 21 nm. During delithiation, the reactions proceeded in the reverse order, Fe0-Fe2+-Fe3+. However, the initial single crystalline α-Fe2O3 nanowires were replaced by nanocrystalline ones after first cycle. The delithiated electrode maintains the nanowire geometry over many cycles due to the nature of the short-range cation diffusion that facilitates the process. Besides, nanowires covered with continuous carbon film exhibited much better electrochemical properties, such as cycle capacity, stability and conductivity, than the uncoated ones. The intrinsic conductivity improvement from α-Fe2O3 to Fe3O4 can further enhance the electrochemical performance.","Item withdrawn by Mark Zulauf (zulauf@illinois.edu) on 2013-04-23T13:50:06Z Item was in collections: University of Illinois Theses & Dissertations (ID: 1) No. of bitstreams: 1 Huang_Bo.pdf: 2273892 bytes, checksum: b97e0e8edb474fda53fdac9654e129c3 (MD5)","Made available in DSpace on 2013-05-24T21:53:03Z (GMT). No. of bitstreams: 2 Bo_Huang.pdf: 2274084 bytes, checksum: 3f3ed4cd0383d0eede6f7388c991ed43 (MD5) license.txt: 4058 bytes, checksum: b7d8215f78ac545e577ef6556563958c (MD5)"]},{"key":"dc:title","label":"Title","values":["Structural evolution of α-Fe2O3 nanowires during lithiation/delithiation and electrochemical property improvement"]}]}],"canonical_facts":{"dc:contributor":["Dillon, Shen J."],"dc:creator":["Huang, Bo"],"dc:date":["2013-05-24T21:53:03Z","2013-05"],"dc:description":["Hematite Fe2O3 exhibits great potential in lithium ion battery area as anode material, due to high capacity, elemental abundance, low cost and biocompatibility. Its reaction with lithium ion is accepted as conversion reaction. In this paper, single crystal α-Fe2O3 nanowires were prepared by an electrical resistive heating method under ambient conditions. Transmission electron microscopy characterized the anode material at various stages of lithiation and delithiation. The phase and morphological evolution demonstrate the conversion reaction process in α-Fe2O3. The process was initiated through the reduction of Fe2O3 to Fe3O4 nanocrystals, which form 4-nm-nanoparticles within the nanowire. Further lithiation converted all of the iron oxides to BCC Fe nanocrystals with the significant growth up to 21 nm. During delithiation, the reactions proceeded in the reverse order, Fe0-Fe2+-Fe3+. However, the initial single crystalline α-Fe2O3 nanowires were replaced by nanocrystalline ones after first cycle. The delithiated electrode maintains the nanowire geometry over many cycles due to the nature of the short-range cation diffusion that facilitates the process. Besides, nanowires covered with continuous carbon film exhibited much better electrochemical properties, such as cycle capacity, stability and conductivity, than the uncoated ones. The intrinsic conductivity improvement from α-Fe2O3 to Fe3O4 can further enhance the electrochemical performance.","Item withdrawn by Mark Zulauf (zulauf@illinois.edu) on 2013-04-23T13:50:06Z Item was in collections: University of Illinois Theses & Dissertations (ID: 1) No. of bitstreams: 1 Huang_Bo.pdf: 2273892 bytes, checksum: b97e0e8edb474fda53fdac9654e129c3 (MD5)","Made available in DSpace on 2013-05-24T21:53:03Z (GMT). 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