{"id":{"repo_id":"cambridge","oai_identifier":"oai:www.repository.cam.ac.uk:1810/283179"},"canonical_url":"https://search.dev.ndltd.org/etd/cambridge/oai:www.repository.cam.ac.uk:1810/283179","repository":{"repo_id":"cambridge","name":"Cambridge University","base_url":"https://api.repository.cam.ac.uk/server/oai/request"},"display":{"title":"Ab Initio Prediction of Metal Phosphide Anode Materials for Lithium and Beyond Lithium Batteries","abstract":"Identifying high capacity battery materials is critical for creating better energy storage to lower our reliance on non-renewable energy resources. While Li-ion batteries are the state-of-the-art, their graphite anodes are limited by a theoretical capacity of 372 mAh/g. Phosphorus is one alternative which has a high capacity of 2596 mAh/g and can alloy with both Li$^+$ and Na$^+$ ions, but suffers from large volume changes upon cycling. To mitigate this destructive effect, transition metals act as stabilising agents, limiting volume change and retaining high capacities. In this dissertation, I investigate two classes of transition metal phosphides (TMPs) as candidates for high capacity Li and Na-ion battery anodes. Herein, I employ a computational approach which combines density-functional theory (DFT) with structure searching methods including $Ab$ $Initio$ Random Structure Searching (AIRSS) and Genetic Algorithms (GA). I conduct an AIRSS and GA search of the Li-Cu-P system, as well as an AIRSS search of the Na-Fe-P system, and study their ground state electrochemical properties with DFT. I investigate the lithiation pathway in Cu-P, and find that LiCu may form during cycling, increasing the overall capacity of all Cu-P anodes. Additionally, I calculate the capacity of CuP$_{10}$, to be 2225 mAh/g, while the highest capacity Cu-P to date is CuP$_2$ at 1495 mAh/g. This suggests that it should be tested in future experimental work. Using AIRSS, I identify a ground state $I$mm2 Cu$_2$P structure, which has not been identified experimentally, and find it is a stable semimetal at high temperature and pressures up to 10 GPa. I also find an AIRSS identified structure of Cu$_3$P with Cu vacancies (Cu$_8$P$_3$) which has different vacancy orderings to previously identified Cu$_{3-x}$P, suggesting this structure has several possible ground state orderings. Finally, I assess the effects of pressure on Cu-P, and find that several GA-identified $P$1 structures are low in energy at high pressure, suggesting they may form during extreme conditions on the battery anode. To conduct an AIRSS search on the Fe-P system, I investigate the possible ways to introduce spin polarisation into the search, and determine that breaking the spin state on each atom can be included as a post-processing step of high-throughput searching. Furthermore, the experimental sodiation pathway for FeP$_4$ has not yet been identified, though it was considered to be a conversion anode. From the results of the ternary AIRSS search on Na-Fe-P, I propose a theoretical sodiation pathway via an insertion process for FeP$_4$ which includes an as-yet unidentified $P$m ternary compound, NaFeP which may limit the overall battery capacity by 298 mAh/g.","abstract_html":"Identifying high capacity battery materials is critical for creating better energy storage to lower our reliance on non-renewable energy resources. While Li-ion batteries are the state-of-the-art, their graphite anodes are limited by a theoretical capacity of 372 mAh/g. Phosphorus is one alternative which has a high capacity of 2596 mAh/g and can alloy with both Li<span class=\"etd-inline-math\"><sup>+</sup></span> and Na<span class=\"etd-inline-math\"><sup>+</sup></span> ions, but suffers from large volume changes upon cycling. To mitigate this destructive effect, transition metals act as stabilising agents, limiting volume change and retaining high capacities. In this dissertation, I investigate two classes of transition metal phosphides (TMPs) as candidates for high capacity Li and Na-ion battery anodes. Herein, I employ a computational approach which combines density-functional theory (DFT) with structure searching methods including $Ab$ $Initio$ Random Structure Searching (AIRSS) and Genetic Algorithms (GA). I conduct an AIRSS and GA search of the Li-Cu-P system, as well as an AIRSS search of the Na-Fe-P system, and study their ground state electrochemical properties with DFT. I investigate the lithiation pathway in Cu-P, and find that LiCu may form during cycling, increasing the overall capacity of all Cu-P anodes. Additionally, I calculate the capacity of CuP<span class=\"etd-inline-math\"><sub>10</sub></span>, to be 2225 mAh/g, while the highest capacity Cu-P to date is CuP<span class=\"etd-inline-math\"><sub>2</sub></span> at 1495 mAh/g. This suggests that it should be tested in future experimental work. Using AIRSS, I identify a ground state $I$mm2 Cu<span class=\"etd-inline-math\"><sub>2</sub></span>P structure, which has not been identified experimentally, and find it is a stable semimetal at high temperature and pressures up to 10 GPa. I also find an AIRSS identified structure of Cu<span class=\"etd-inline-math\"><sub>3</sub></span>P with Cu vacancies (Cu<span class=\"etd-inline-math\"><sub>8</sub></span>P<span class=\"etd-inline-math\"><sub>3</sub></span>) which has different vacancy orderings to previously identified Cu<span class=\"etd-inline-math\"><sub>3-x</sub></span>P, suggesting this structure has several possible ground state orderings. Finally, I assess the effects of pressure on Cu-P, and find that several GA-identified $P$1 structures are low in energy at high pressure, suggesting they may form during extreme conditions on the battery anode. To conduct an AIRSS search on the Fe-P system, I investigate the possible ways to introduce spin polarisation into the search, and determine that breaking the spin state on each atom can be included as a post-processing step of high-throughput searching. Furthermore, the experimental sodiation pathway for FeP<span class=\"etd-inline-math\"><sub>4</sub></span> has not yet been identified, though it was considered to be a conversion anode. From the results of the ternary AIRSS search on Na-Fe-P, I propose a theoretical sodiation pathway via an insertion process for FeP<span class=\"etd-inline-math\"><sub>4</sub></span> which includes an as-yet unidentified $P$m ternary compound, NaFeP which may limit the overall battery capacity by 298 mAh/g.","abstract_has_math":true,"creators":["Harper, Angela F"],"institution":"University of Cambridge","degree_name":"Master of Philosophy (MPhil)","degree_level":"Masters","degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":["Morris, Andrew J"],"committee_chairs":[],"committee_members":[],"year":2019,"date_issued":"2019-02-23","date_published":"2019-02-23","updated_at":"2026-07-22T22:24:13Z","subjects":["lithium ion batteries","condensed matter physics","computational physics","physics","materials science","density functional theory","crystal structure prediction"],"languages":["en"],"rights":["Figure 1.1 is adapted from reference [4] with permission from IEEE 2011. Figure 4.7b is adapted from reference [21] with permission from Elsevier 2016, but is unable to be reused online."],"rights_urls":["https://apollo8-f-pro.lib.cam.ac.uk/bitstreams/9999fcac-29d9-42de-9c01-5a98c21ce9ff/download","https://www.rioxx.net/licenses/all-rights-reserved/"],"identifier_entries":[{"key":"dc:creator.authoridentifier","label":"Author Identifier","values":["0000000206990450","0000000174535698"],"render_values":[{"text":"0000-0002-0699-0450","href":"https://orcid.org/0000-0002-0699-0450","code":true},{"text":"0000-0001-7453-5698","href":"https://orcid.org/0000-0001-7453-5698","code":true}]}]},"links":{"outbound_url":"https://doi.org/10.17863/CAM.30542","outbound_label":"DOI","outbound_source":"dc:identifier.doi"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Morris, Andrew J"]},{"key":"dc:contributor.sponsor","label":"Sponsor","values":["Funded by the Churchill Scholarship of America, with computing resources from HPC Midlands+"]},{"key":"dc:creator","label":"Author","values":["Harper, Angela F"]},{"key":"dc:creator.authoridentifier","label":"Author Identifier","values":["0000000206990450","0000000174535698"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.issued","label":"Date","values":["2019-02-23"]},{"key":"dc:publisher.institution","label":"Dc Publisher Institution","values":["University of Cambridge"]},{"key":"dc:relation.isreferencedby.uri","label":"Dc Relation Isreferencedby URI","values":["https://www.repository.cam.ac.uk/handle/1810/283179"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"dc:type.qualificationlevel","label":"Dc Type Qualificationlevel","values":["Masters"]},{"key":"dc:type.qualificationname","label":"Dc Type Qualificationname","values":["Master of Philosophy (MPhil)"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["lithium ion batteries","condensed matter physics","computational physics","physics","materials science","density functional theory","crystal structure prediction"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["https://apollo8-f-pro.lib.cam.ac.uk/bitstreams/9999fcac-29d9-42de-9c01-5a98c21ce9ff/download","https://www.rioxx.net/licenses/all-rights-reserved/","Figure 1.1 is adapted from reference [4] with permission from IEEE 2011. Figure 4.7b is adapted from reference [21] with permission from Elsevier 2016, but is unable to be reused online."]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.doi","label":"DOI","values":["10.17863/CAM.30542"]},{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://apollo8-f-pro.lib.cam.ac.uk/bitstreams/ea696399-42ea-4425-997c-aa8d21b8d915/download"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Identifying high capacity battery materials is critical for creating better energy storage to lower our reliance on non-renewable energy resources. While Li-ion batteries are the state-of-the-art, their graphite anodes are limited by a theoretical capacity of 372 mAh/g. Phosphorus is one alternative which has a high capacity of 2596 mAh/g and can alloy with both Li$^+$ and Na$^+$ ions, but suffers from large volume changes upon cycling. To mitigate this destructive effect, transition metals act as stabilising agents, limiting volume change and retaining high capacities. In this dissertation, I investigate two classes of transition metal phosphides (TMPs) as candidates for high capacity Li and Na-ion battery anodes. Herein, I employ a computational approach which combines density-functional theory (DFT) with structure searching methods including $Ab$ $Initio$ Random Structure Searching (AIRSS) and Genetic Algorithms (GA). I conduct an AIRSS and GA search of the Li-Cu-P system, as well as an AIRSS search of the Na-Fe-P system, and study their ground state electrochemical properties with DFT. I investigate the lithiation pathway in Cu-P, and find that LiCu may form during cycling, increasing the overall capacity of all Cu-P anodes. Additionally, I calculate the capacity of CuP$_{10}$, to be 2225 mAh/g, while the highest capacity Cu-P to date is CuP$_2$ at 1495 mAh/g. This suggests that it should be tested in future experimental work. Using AIRSS, I identify a ground state $I$mm2 Cu$_2$P structure, which has not been identified experimentally, and find it is a stable semimetal at high temperature and pressures up to 10 GPa. I also find an AIRSS identified structure of Cu$_3$P with Cu vacancies (Cu$_8$P$_3$) which has different vacancy orderings to previously identified Cu$_{3-x}$P, suggesting this structure has several possible ground state orderings. Finally, I assess the effects of pressure on Cu-P, and find that several GA-identified $P$1 structures are low in energy at high pressure, suggesting they may form during extreme conditions on the battery anode. To conduct an AIRSS search on the Fe-P system, I investigate the possible ways to introduce spin polarisation into the search, and determine that breaking the spin state on each atom can be included as a post-processing step of high-throughput searching. Furthermore, the experimental sodiation pathway for FeP$_4$ has not yet been identified, though it was considered to be a conversion anode. From the results of the ternary AIRSS search on Na-Fe-P, I propose a theoretical sodiation pathway via an insertion process for FeP$_4$ which includes an as-yet unidentified $P$m ternary compound, NaFeP which may limit the overall battery capacity by 298 mAh/g."]},{"key":"dc:format.checksum.md5","label":"Dc Format Checksum Md5","values":["f18d882438dbef004a0cd50fceea6add","87eda9de84448d1f82354d60eee3eb5f"]},{"key":"dc:title","label":"Title","values":["Ab Initio Prediction of Metal Phosphide Anode Materials for Lithium and Beyond Lithium Batteries"]}]}],"canonical_facts":{"dc:contributor.advisor":["Morris, Andrew J"],"dc:contributor.sponsor":["Funded by the Churchill Scholarship of America, with computing resources from HPC Midlands+"],"dc:creator":["Harper, Angela F"],"dc:creator.authoridentifier":["0000000206990450","0000000174535698"],"dc:date.issued":["2019-02-23"],"dc:description.abstract":["Identifying high capacity battery materials is critical for creating better energy storage to lower our reliance on non-renewable energy resources. While Li-ion batteries are the state-of-the-art, their graphite anodes are limited by a theoretical capacity of 372 mAh/g. Phosphorus is one alternative which has a high capacity of 2596 mAh/g and can alloy with both Li$^+$ and Na$^+$ ions, but suffers from large volume changes upon cycling. To mitigate this destructive effect, transition metals act as stabilising agents, limiting volume change and retaining high capacities. In this dissertation, I investigate two classes of transition metal phosphides (TMPs) as candidates for high capacity Li and Na-ion battery anodes. Herein, I employ a computational approach which combines density-functional theory (DFT) with structure searching methods including $Ab$ $Initio$ Random Structure Searching (AIRSS) and Genetic Algorithms (GA). I conduct an AIRSS and GA search of the Li-Cu-P system, as well as an AIRSS search of the Na-Fe-P system, and study their ground state electrochemical properties with DFT. I investigate the lithiation pathway in Cu-P, and find that LiCu may form during cycling, increasing the overall capacity of all Cu-P anodes. Additionally, I calculate the capacity of CuP$_{10}$, to be 2225 mAh/g, while the highest capacity Cu-P to date is CuP$_2$ at 1495 mAh/g. This suggests that it should be tested in future experimental work. Using AIRSS, I identify a ground state $I$mm2 Cu$_2$P structure, which has not been identified experimentally, and find it is a stable semimetal at high temperature and pressures up to 10 GPa. I also find an AIRSS identified structure of Cu$_3$P with Cu vacancies (Cu$_8$P$_3$) which has different vacancy orderings to previously identified Cu$_{3-x}$P, suggesting this structure has several possible ground state orderings. Finally, I assess the effects of pressure on Cu-P, and find that several GA-identified $P$1 structures are low in energy at high pressure, suggesting they may form during extreme conditions on the battery anode. To conduct an AIRSS search on the Fe-P system, I investigate the possible ways to introduce spin polarisation into the search, and determine that breaking the spin state on each atom can be included as a post-processing step of high-throughput searching. Furthermore, the experimental sodiation pathway for FeP$_4$ has not yet been identified, though it was considered to be a conversion anode. From the results of the ternary AIRSS search on Na-Fe-P, I propose a theoretical sodiation pathway via an insertion process for FeP$_4$ which includes an as-yet unidentified $P$m ternary compound, NaFeP which may limit the overall battery capacity by 298 mAh/g."],"dc:format.checksum.md5":["f18d882438dbef004a0cd50fceea6add","87eda9de84448d1f82354d60eee3eb5f"],"dc:identifier.doi":["10.17863/CAM.30542"],"dc:identifier.uri":["https://apollo8-f-pro.lib.cam.ac.uk/bitstreams/ea696399-42ea-4425-997c-aa8d21b8d915/download"],"dc:language":["en"],"dc:publisher.institution":["University of Cambridge"],"dc:relation.isreferencedby.uri":["https://www.repository.cam.ac.uk/handle/1810/283179"],"dc:rights":["https://apollo8-f-pro.lib.cam.ac.uk/bitstreams/9999fcac-29d9-42de-9c01-5a98c21ce9ff/download","https://www.rioxx.net/licenses/all-rights-reserved/","Figure 1.1 is adapted from reference [4] with permission from IEEE 2011. Figure 4.7b is adapted from reference [21] with permission from Elsevier 2016, but is unable to be reused online."],"dc:subject":["lithium ion batteries","condensed matter physics","computational physics","physics","materials science","density functional theory","crystal structure prediction"],"dc:title":["Ab Initio Prediction of Metal Phosphide Anode Materials for Lithium and Beyond Lithium Batteries"],"dc:type":["Thesis"],"dc:type.qualificationlevel":["Masters"],"dc:type.qualificationname":["Master of Philosophy (MPhil)"]},"updated_at":"2026-07-22T22:24:13Z"}