<p>The Li-ion battery has, from its commercialisation in the early 1990's, now become the most widely used power source for portable low-power electronics: laptops, cellular phones and MP3-players are a few examples. To further develop existing and find new electrode materials for these batteries, it is vital to understand the lithium insertion/extraction mechanisms taking place during battery operation. In this thesis, single-crystal X-ray diffraction has been used to investigate lithium insertion/extraction mechanisms in the cathode materials V₆O₁₃ and LiFePO₄. A novel single-crystal electrochemical cell for <i>in situ</i> single-crystal X-ray diffraction studies has also been developed.</p><p>The phases Li₃V₆O₁₃ and Li_3+xV₆O₁₃, 0<x<1, both contain a disordered lithium ion. A low-temperature study of Li_3.24V₆O₁₃ (at 95 K) shows that this disorder is static rather than dynamic; the lithium ion is equally distributed above and below an inversion centre in the centrosymmetric V₆O₁₃ host structure. Short-range-ordering between this disordered lithium ion and the lithium ion inserted into Li₃V₆O₁₃ gives rise to solid-solution behaviour not observed earlier in the Li_xV₆O₁₃ system. A model is proposed for the lithium insertion mechanism up to the end-member composition Li₆V₆O₁₃.</p><p>Lithium has also been electrochemically extracted from LiFePO₄ single crystals. On the basis of the shapes of the LiFePO₄ and FePO₄ reflections, it is concluded that FePO₄ is formed at the crystal surface and that the LiFePO₄/FePO₄ interface propagates into the crystal. This is in agreement with an earlier proposed model for lithium extraction from LiFePO₄ particles.</p><p>Initial experiments with the newly developed single-crystal electrochemical cell for <i>in situ</i> single-crystal X-ray diffraction demonstrate that it is possible to insert lithium into a single crystal of V₆O₁₃ and then collect single-crystal X-ray diffraction data. The method needs further development but promises to become a powerful tool for studying lithium insertion/extraction mechanisms.</p>

<p>There are today clear indications that the Li-ion battery of the type currently used worldwide in mobile-phones and lap-tops is also destined to soon become the battery of choice in more energy-demanding concepts such as electric and electric hybrid vehicles (EVs and EHVs). Since the currently used cathode materials (typically of the Li(Ni,Co)O₂-type) are too expensive in large-scale applications, these new batteries will have to exploit some much cheaper transition-metal. Ideally, this should be the very cheapest - iron(Fe) - in combination with a graphite(C)-based anode. In this context, the obvious Fe-based active cathode of choice appears to be LiFePO₄. A second and in some ways even more attractive material - Li₂FeSiO₄ - has emerged during the course of this work.</p><p>An effort has here been made to understand the Li extraction/insertion mechanism on electrochemical cycling of Li₂FeSiO₄. A fascinating picture has emerged (following a complex combination of Mössbauer, X-ray diffraction and electrochemical studies) in which the material is seen to cycle between Li₂FeSiO₄ and LiFeSiO₄, but with the structure of the original Li₂FeSiO₄ transforming from a metastable short-range ordered solid-solution into a more stable long-range ordered structure during the first cycle. Density Functional Theory calculations on Li₂FeSiO₄ and the delithiated on LiFeSiO₄ structure provide an interesting insight into the experimental result.</p><p>Photoelectron spectroscopy was used to study the surface chemistry of both carbon-treated LiFePO₄ and Li₂FeSiO₄ after electrochemical cycling. The surface-layer on both materials was concluded to be very thin and with incomplete coverage, giving the promise of good long-term cycling.</p><p>LiFePO₄ and Li₂FeSiO₄ should both be seen as highly promising candidates as positive-electrode materials for large-scale Li-ion battery applications.</p>

Surface film formation at the electrode/electrolyte interface in lithium-ion batteries has a crucial impact on battery performance and safety. This thesis describes the characterisation and treatment of electrode interfaces in lithium-ion batteries. The focus is on interface modification to improve battery safety, in particular to enhance the onset temperature for thermally activated reactions, which also can have a negative influence on battery performance. Photoelectron Spectroscopy (PES) and Differential Scanning Calorimetry (DSC) are used to investigate the surface chemistry of electrodes in relation to their electrochemical performance. Surface film formation and decomposition reactions are discussed. The upper temperature limit for lithium-ion battery operation is restricted by exothermic reactions at the graphite anode; the onset temperature is shown to be governed by the composition of the surface film on the anode. Several electrolyte salts, additives and an anion receptor have been exploited to modify the surface film composition. The most promising thermal behaviour is found for graphite anodes cycled with the anion receptor, tris(pentafluorophenyl)borane, which reduces salt reactions and increases the onset temperature from ~80 °C to ~150 °C. The electrochemical performance and surface chemistry of Swedish natural graphite, carbon-treated LiFePO4 and anodes from high-power lithium-ion batteries are also investigated. Jet-milled Swedish natural graphite exhibits a high capacity and rate capability, together with a decreased susceptibility to solvent co-intercalation. Carbon-treated LiFePO4 shows promising results: no solvent reaction products are detected. The amount of salt compounds increases, with power fade occurring for anodes from high-power lithium-ion batteries; the solvent reduction products comprise mainly Li-carboxylate type compounds.

The Li-ion battery has, from its commercialisation in the early 1990's, now become the most widely used power source for portable low-power electronics: laptops, cellular phones and MP3-players are a few examples. To further develop existing and find new electrode materials for these batteries, it is vital to understand the lithium insertion/extraction mechanisms taking place during battery operation. In this thesis, single-crystal X-ray diffraction has been used to investigate lithium insertion/extraction mechanisms in the cathode materials V6O13 and LiFePO4. A novel single-crystal electrochemical cell for in situ single-crystal X-ray diffraction studies has also been developed. The phases Li3V6O13 and Li3+xV6O13, 0&lt;x&lt;1, both contain a disordered lithium ion. A low-temperature study of Li3.24V6O13 (at 95 K) shows that this disorder is static rather than dynamic; the lithium ion is equally distributed above and below an inversion centre in the centrosymmetric V6O13 host structure. Short-range-ordering between this disordered lithium ion and the lithium ion inserted into Li3V6O13 gives rise to solid-solution behaviour not observed earlier in the LixV6O13 system. A model is proposed for the lithium insertion mechanism up to the end-member composition Li6V6O13. Lithium has also been electrochemically extracted from LiFePO4 single crystals. On the basis of the shapes of the LiFePO4 and FePO4 reflections, it is concluded that FePO4 is formed at the crystal surface and that the LiFePO4/FePO4 interface propagates into the crystal. This is in agreement with an earlier proposed model for lithium extraction from LiFePO4 particles. Initial experiments with the newly developed single-crystal electrochemical cell for in situ single-crystal X-ray diffraction demonstrate that it is possible to insert lithium into a single crystal of V6O13 and then collect single-crystal X-ray diffraction data. The method needs further development but promises to become a powerful tool for studying lithium insertion/extraction mechanisms.

There are today clear indications that the Li-ion battery of the type currently used worldwide in mobile-phones and lap-tops is also destined to soon become the battery of choice in more energy-demanding concepts such as electric and electric hybrid vehicles (EVs and EHVs). Since the currently used cathode materials (typically of the Li(Ni,Co)O2-type) are too expensive in large-scale applications, these new batteries will have to exploit some much cheaper transition-metal. Ideally, this should be the very cheapest - iron(Fe) - in combination with a graphite(C)-based anode. In this context, the obvious Fe-based active cathode of choice appears to be LiFePO4. A second and in some ways even more attractive material - Li2FeSiO4 - has emerged during the course of this work. An effort has here been made to understand the Li extraction/insertion mechanism on electrochemical cycling of Li2FeSiO4. A fascinating picture has emerged (following a complex combination of Mössbauer, X-ray diffraction and electrochemical studies) in which the material is seen to cycle between Li2FeSiO4 and LiFeSiO4, but with the structure of the original Li2FeSiO4 transforming from a metastable short-range ordered solid-solution into a more stable long-range ordered structure during the first cycle. Density Functional Theory calculations on Li2FeSiO4 and the delithiated on LiFeSiO4 structure provide an interesting insight into the experimental result. Photoelectron spectroscopy was used to study the surface chemistry of both carbon-treated LiFePO4 and Li2FeSiO4 after electrochemical cycling. The surface-layer on both materials was concluded to be very thin and with incomplete coverage, giving the promise of good long-term cycling. LiFePO4 and Li2FeSiO4 should both be seen as highly promising candidates as positive-electrode materials for large-scale Li-ion battery applications.

Die vorliegende Dissertation beschäftigt sich mit der Synthese, den Li+-Transporteigenschaften und der Thermodynamik von Olivin-Typ LiFePO4. Es werden verschiedene Solvothermalsynthesen untersucht. Neben der Einstellung von Partikelgröße und Partikelmorphologie steht die Analyse der Hydrothermalsynthese aus Li3PO4 und Vivianit durch in situ Messung der elektrolytischen Leitfähigkeit im Vordergrund. Die Untersuchung des Li+-Transportes geschieht auf Basis von Redoxreaktionen. Die formalkinetische Auswertung von Lithiierungs- und Delithiierungsreaktionen und eine Nukleationsanalyse wird durch ein Modell zur Auswirkung von antisite-Defekten auf die Kapazität des Elektrodenmaterials ergänzt. Die Ramanspektroskopie wird in Verbindung mit Lösungsenthalpien zur Identifizierung reaktiver Spezies herangezogen. Schwerpunkt der thermodynamischen Charakterisierung ist die experimentelle Ermittlung der Wärmekapazität. Diese wurde unter Berücksichtigung einer magnetischen Phasenumwandlung im Bereich von 2 K bis 773 K ermittelt. Die Daten erlauben die Berechnung wichtiger thermodynamischer Funktionen.

Journal articles are the formal medium for the communication of results among scientists, and often contain valuable data. However, manually collecting article data from a large field like lithium-ion battery chemistry is tedious and time consuming, which is an obstacle when searching for statistical trends and correlations to inform research decisions. To address this a platform for the automatic retrieval and analysis of large numbers of articles is created and applied to the field of lithium-ion battery chemistry. Example data produced by the platform is presented and evaluated and sources of error limiting this type of platform are identified, with problems related to text extraction and pattern matching being especially significant. Some solutions to these problems are presented and potential future improvements are proposed.

Магистерская диссертация посвящена синтезу и исследованию структуры положительного электродного материала на основе железофосфата лития. В работе проведена работа по поиску и систематизации информации по интересующей теме, описаны методики синтеза, изучению методом спектроскопии комбинационного рассеивания света и результаты измерения структуры, как железофосфата лития, так и композитов на его основе. Изучена зависимость спектра КРС от мощности лазерного излучения. Сделано предположение о модификации поверхностного слоя частиц железофосфата лития после воздействия лазерного излучения. / The master's thesis is devoted to the synthesis and study of the structure of the positive electrode material based on lithium iron phosphate. The work was carried out to search for and systematize information on a topic of interest, describes synthesis methods, studies of Raman spectroscopy and the results of measuring the structure of both lithium iron phosphate and composites based on it. The dependence of the Raman spectrum on the power of laser radiation was studied. An assumption was made about the modification of the surface layer of lithium iron phosphate particles after exposure to laser irradiation.

Elanvändningen i Sverige förväntas fördubblas till 2045 på grund av ökad elektrifiering av det svenska samhället. För att ställa om till ett elsystem som är beroende av mer förnyelsebara elproduktionsslag föreslår Svenska kraftnät (2021) att Sverige kommer att behöva öka sin flexibilitet i elnätet. Ett sätt att göra detta på är genom ellagring, där batterisystem är ett alternativ. Någon konkret plan för hur och när detta skulle genomföras har inte gjorts av Svenska kraftnät. Därför syftade detta projekt till att ta reda på om ett litiumjärnfosfat (LFP) batterienergilagringssystem skulle vara en lönsam investering att använda för energiomställning i det svenska elmarknadsområdet SE3. Detta mål uppnåddes genom att modellera ett batterilager över ett år och extrapolera dessa resultat till en investeringskalkyl genom annuitetsmetoden. Sammanfattat så konstaterades det att det inte är en lönsam investering. Men det fullständiga svaret är mer komplicerat än så. Batteriets storlek och livslängd påverkar batteriets investeringskostnad, som vidare påverkar batteriets lönsamhet. Batteriets livslängd är beroende av egenskaper som batteriets upp och urladdningstid (s.k. C-rate) samt i vilken utsträckning batteriet laddas och laddas ur (s.k. state of charge), som i sin tur influerar totala antalet laddningscykler batteriet kan genomföra. Exakt hur mycket dessa egenskaper påverkar livslängden för LFP:erna är oklart eftersom resultaten från tidigare studier av LFP-batteriers prestanda skiljer sig något. Till exempel är det känt att state of charge för ett batteri påverkar livslängden för ett LFP-batteri, men mer exakt hur mycket varierar beroende på studie, vilket visas i detta examensarbete. Det som gör detta ännu mer komplicerat är det faktum att investeringskostnaden kommer att förändras beroende på till exempel vilken state of charge som används. Dessutom varierar uppskattningar av investeringskostnaden för LFP-batterier i olika källor. Allt detta leder till flera typer av osäkerheter för att bestämma den exakta investeringskalkylen. Det huvudsakliga bidraget denna studie kan ge är dock att den kan ge en första inblick i hur ett batterilagringssystem för kortvarig energilagring (energy shifting) skulle fungera i Sverige. Med fler studier liknande detta projekt skulle en mer konkret plan kunna göras för genomförandet av det statliga klimatmålet om netto noll utsläpp av växthusgaser till år 2045 (Naturvårdsverket, 2023). / The electricity use in Sweden is expected to double before 2045 due to increased electrification of the Swedish society. In order to transition into an electrical system that is dependent of more sustainable renewable energy sources, Svenska kraftnät (2021) is suggesting that Sweden will need to increase their flexibility in the power grid. One of the main ideas on how to do that is through energy storages, where battery systems could play an important part. However, a concrete plan of how and when this would happen was not made clear by Svenska kraftnät. Therefore, this project aimed at finding out whether a Lithium iron phosphate (LFP) battery energy storage system would be a worthwhile investment to use for energy shifting in the Swedish SE3 electricity market area. This aim was reached through modelling a battery storage over a year and extrapolating these results into an investment calculation using the annuity method. In short, it was found that it is not a profitable investment. But the full answer was found to be more complicated than that. The battery’s size and lifetime affect the battery’s investment cost, which further affects the battery’s profitability. The battery’s lifetime is dependent on battery characteristics such as the charge/discharge time of the battery (C-rate) and the extent to which the battery is charged and discharged (state of charge), which in turn influences the total amount of charge cycles a battery can perform. Further, how significant these characteristics affect cost and lifetime of the LFP’s is unclear as the results from previous studies on LFP batteries differ somewhat. For example, it is known that the state of charge range of a battery affects the lifetime of an LFP battery, but by exactly how much varies with different studies, which is explained in this master thesis. What makes this even more complicated is the fact that depending on the state of charge used, the investment cost will change. Additionally, the assessed investment cost also changes depending on the source used. Therefore, the exact cost is difficult to determine. However, the main contribution this study has is that it can give a first insight into how a battery storage system for energy shifting would work. With more case-like studies similar to this project, a more concrete plan could be made about how to realise the Swedish governmental climate goal of net zero greenhouse gas emissions by the year 2045 (Naturvårdsverket, 2023).

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