{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/72820"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/72820","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Structure and properties of the interdiffused phase between lithiated silicon and copper current collector","abstract":"Silicon is an important electrode material for next generation high performance lithium ion batteries due to its order of magnitude higher charge carrying capacity compared to conventional graphite electrodes. The main obstacle of using Si electrodes in commercial lithium batteries is the massive volume expansion of the Si electrode under repeated charge cycling, which leads to delamination of the Si electrode from the Cu current collector and inevitably results in capacity fade. Using first principle calculations based on density functional theory and ab-initio molecular dynamics simulations, this thesis focuses on the structure of the Cu/Si interface and aims to provide a complete picture of the intermixing at the Cu/Si interface during lithiation processes. The hypothesis, supported by existing experiments, is that the Cu/Si interface is not pristine and comprises of an interdiffused Li-Si-Cu interphase structure. To test this hypothesis, the barrier energies for Li diffusion into the assumed crystalline silicide interphase structure separating crystalline Si and Cu is studied. Results show that the barrier energies for Li ion diffusion decreases towards the interphase structure, which suggest that Li ions can diffuse into the silicide structure even during early stages of lithiation. Several interdiffused Li-Si-Cu interphase structures with varying Li to Si content are subsequently modeled using rapid heating and quenching process. The atomic structure of interdiffused Li-Si-Cu phase reconstructed from rapid heating and quenching are in good agreement with previous experiment results. The work of separation of these interdiffused phase are also examined.","abstract_html":"Silicon is an important electrode material for next generation high performance lithium ion batteries due to its order of magnitude higher charge carrying capacity compared to conventional graphite electrodes. The main obstacle of using Si electrodes in commercial lithium batteries is the massive volume expansion of the Si electrode under repeated charge cycling, which leads to delamination of the Si electrode from the Cu current collector and inevitably results in capacity fade. Using first principle calculations based on density functional theory and ab-initio molecular dynamics simulations, this thesis focuses on the structure of the Cu/Si interface and aims to provide a complete picture of the intermixing at the Cu/Si interface during lithiation processes. The hypothesis, supported by existing experiments, is that the Cu/Si interface is not pristine and comprises of an interdiffused Li-Si-Cu interphase structure. To test this hypothesis, the barrier energies for Li diffusion into the assumed crystalline silicide interphase structure separating crystalline Si and Cu is studied. Results show that the barrier energies for Li ion diffusion decreases towards the interphase structure, which suggest that Li ions can diffuse into the silicide structure even during early stages of lithiation. Several interdiffused Li-Si-Cu interphase structures with varying Li to Si content are subsequently modeled using rapid heating and quenching process. The atomic structure of interdiffused Li-Si-Cu phase reconstructed from rapid heating and quenching are in good agreement with previous experiment results. The work of separation of these interdiffused phase are also examined.","abstract_has_math":false,"creators":["Hou, Binyue"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"M.S.","degree_level":"Thesis","degree_discipline":"Aerospace Engineering","degree_department":null,"school":null,"contributors":["Chew, Huck Beng"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2015,"date_issued":"2015-01-21T19:48:31Z","date_published":"2015-01-21T19:48:31Z","updated_at":"2026-07-22T22:26:07Z","subjects":["Lithium battery","interdiffused","Si/Cu interface"],"languages":["en"],"rights":["Copyright 2014 Binyue Hou"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2142/72820","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Chew, Huck Beng"]},{"key":"dc:creator","label":"Author","values":["Hou, Binyue"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2015-01-21T19:48:31Z","2014-12","2015-01-21"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Aerospace Engineering"]},{"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":["Lithium battery","interdiffused","Si/Cu interface"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2014 Binyue Hou"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/72820"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Silicon is an important electrode material for next generation high performance lithium ion batteries due to its order of magnitude higher charge carrying capacity compared to conventional graphite electrodes. The main obstacle of using Si electrodes in commercial lithium batteries is the massive volume expansion of the Si electrode under repeated charge cycling, which leads to delamination of the Si electrode from the Cu current collector and inevitably results in capacity fade. Using first principle calculations based on density functional theory and ab-initio molecular dynamics simulations, this thesis focuses on the structure of the Cu/Si interface and aims to provide a complete picture of the intermixing at the Cu/Si interface during lithiation processes. The hypothesis, supported by existing experiments, is that the Cu/Si interface is not pristine and comprises of an interdiffused Li-Si-Cu interphase structure. To test this hypothesis, the barrier energies for Li diffusion into the assumed crystalline silicide interphase structure separating crystalline Si and Cu is studied. Results show that the barrier energies for Li ion diffusion decreases towards the interphase structure, which suggest that Li ions can diffuse into the silicide structure even during early stages of lithiation. Several interdiffused Li-Si-Cu interphase structures with varying Li to Si content are subsequently modeled using rapid heating and quenching process. The atomic structure of interdiffused Li-Si-Cu phase reconstructed from rapid heating and quenching are in good agreement with previous experiment results. The work of separation of these interdiffused phase are also examined.","Item withdrawn by Laura Spradlin (lspradl2@illinois.edu) on 2014-12-09T19:17:32Z Item was in collections: University of Illinois Theses & Dissertations (ID: 1) No. of bitstreams: 5 HOU_Binyue.docx: 6619133 bytes, checksum: cdd4d02ffcee0a46cf0deaca76a0d648 (MD5) HOU_Binyue.pdf: 1643098 bytes, checksum: d594f4537444811b4171afec013ba0f0 (MD5) HOU_Binyue.pdf: 1643098 bytes, checksum: d594f4537444811b4171afec013ba0f0 (MD5) HOU_Binyue.pdf: 1653015 bytes, checksum: ac88db1bdfb9d686bed7a5088df79a20 (MD5) HOU_Binyue.pdf: 1643098 bytes, checksum: d594f4537444811b4171afec013ba0f0 (MD5)","Made available in DSpace on 2015-01-21T19:48:31Z (GMT). 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Using first principle calculations based on density functional theory and ab-initio molecular dynamics simulations, this thesis focuses on the structure of the Cu/Si interface and aims to provide a complete picture of the intermixing at the Cu/Si interface during lithiation processes. The hypothesis, supported by existing experiments, is that the Cu/Si interface is not pristine and comprises of an interdiffused Li-Si-Cu interphase structure. To test this hypothesis, the barrier energies for Li diffusion into the assumed crystalline silicide interphase structure separating crystalline Si and Cu is studied. Results show that the barrier energies for Li ion diffusion decreases towards the interphase structure, which suggest that Li ions can diffuse into the silicide structure even during early stages of lithiation. Several interdiffused Li-Si-Cu interphase structures with varying Li to Si content are subsequently modeled using rapid heating and quenching process. The atomic structure of interdiffused Li-Si-Cu phase reconstructed from rapid heating and quenching are in good agreement with previous experiment results. The work of separation of these interdiffused phase are also examined.","Item withdrawn by Laura Spradlin (lspradl2@illinois.edu) on 2014-12-09T19:17:32Z Item was in collections: University of Illinois Theses & Dissertations (ID: 1) No. of bitstreams: 5 HOU_Binyue.docx: 6619133 bytes, checksum: cdd4d02ffcee0a46cf0deaca76a0d648 (MD5) HOU_Binyue.pdf: 1643098 bytes, checksum: d594f4537444811b4171afec013ba0f0 (MD5) HOU_Binyue.pdf: 1643098 bytes, checksum: d594f4537444811b4171afec013ba0f0 (MD5) HOU_Binyue.pdf: 1653015 bytes, checksum: ac88db1bdfb9d686bed7a5088df79a20 (MD5) HOU_Binyue.pdf: 1643098 bytes, checksum: d594f4537444811b4171afec013ba0f0 (MD5)","Made available in DSpace on 2015-01-21T19:48:31Z (GMT). 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