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  • 1.
    Blidberg, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry. Uppsala universitet.
    Iron based Li-ion insertion materials for battery applications2016Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Li-ion batteries are currently the most efficient technology available for electrochemical energy storage. The technology has revolutionized the portable electronics market and is becoming a corner stone for large scale applications, such as electric vehicles. It is therefore important to develop materials in which the energy storage relies on abundant redox active species, such as iron. In this thesis, new iron based electrode materials for positive electrodes in Li-ion batteries were investigated. Lithium iron pyrophosphate (Li2FeP2O7) and two polymorphs of lithium iron sulphate fluoride (LiFeSO4F) were studied.

    For Li2FeP2O7, preferred oxidation of iron with different coordination numbers within the crystal structure was studied, and six-coordinated iron was found to be oxidized preferentially at lower potentials compared to five‑coordinated iron. Electrochemical cycling resulted in structural changes of Li2FeP2O7 through an increased Li-Fe mixing in the compound, forming a metastable state during battery operation.

    For tavorite LiFeSO4F, the influence of the amount of a conductive polymer (poly(3,4-ethylenedioxythiophene), or PEDOT) was studied. All the different amounts of PEDOT coating reduced the polarization significantly, but the trade-off between functionality and weight added also has to be considered. Additionally, the effect of densifying the electrodes to different degrees is reported, and was found to have a significant influence on the battery performance. Also triplite LiFeSO4F was coated with PEODT, and it was found that the electrochemical performance improved, but not to the same extent as for tavorite LiFeSO4F. The faster solid state transport of Li-ions in tavorite type LiFeSO4F possibly accounts for the difference in electrochemical performance.

    Together, the results presented herein should be of importance for developing new iron based materials for Li-ion batteries.

    List of papers
    1. Structural and Electronic Changes in Li2FeP2O7 during Electrochemical Cycling
    Open this publication in new window or tab >>Structural and Electronic Changes in Li2FeP2O7 during Electrochemical Cycling
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    2015 (English)In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 27, no 11, p. 3801-3804Article in journal (Refereed) Published
    National Category
    Chemical Sciences Physical Sciences
    Identifiers
    urn:nbn:se:uu:diva-258346 (URN)10.1021/acs.chemmater.5b00440 (DOI)000356202800004 ()
    Available from: 2015-07-13 Created: 2015-07-13 Last updated: 2017-12-04Bibliographically approved
    2. Battery Performance of PEDOT Coated LiFeSO4F Cathodes with Controlled Porosity
    Open this publication in new window or tab >>Battery Performance of PEDOT Coated LiFeSO4F Cathodes with Controlled Porosity
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    (English)Manuscript (preprint) (Other academic)
    Keywords
    Li-ion battery, cathode material, Tavorite, LiFeSO4F, fluorosulfate, conductive coating, PEDOT, porosity, electrochemical performance
    National Category
    Materials Chemistry
    Research subject
    Chemistry with specialization in Inorganic Chemistry
    Identifiers
    urn:nbn:se:uu:diva-281262 (URN)
    Funder
    Swedish Foundation for Strategic Research , EM11-0028
    Available from: 2016-03-21 Created: 2016-03-21 Last updated: 2016-04-05Bibliographically approved
    3. Investigating the Electrochemical Performance of PEDOT-coated Triplite-type LiFeSO4F Cathode Material
    Open this publication in new window or tab >>Investigating the Electrochemical Performance of PEDOT-coated Triplite-type LiFeSO4F Cathode Material
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    (English)Manuscript (preprint) (Other academic)
    National Category
    Materials Chemistry
    Identifiers
    urn:nbn:se:uu:diva-262677 (URN)
    Available from: 2015-09-18 Created: 2015-09-18 Last updated: 2016-03-22
  • 2.
    Blidberg, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Iron Based Materials for Positive Electrodes in Li-ion Batteries: Electrode Dynamics, Electronic Changes, Structural Transformations2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Li-ion battery technology is currently the most efficient form of electrochemical energy storage. The commercialization of Li-ion batteries in the early 1990’s revolutionized the portable electronics market, but further improvements are necessary for applications in electric vehicles and load levelling of the electric grid. In this thesis, three new iron based electrode materials for positive electrodes in Li-ion batteries were investigated. Utilizing the redox activity of iron is beneficial over other transition metals due to its abundance in the Earth’s crust. The condensed phosphate Li2FeP2O7 together with two different LiFeSO4F crystal structures that were studied herein each have their own advantageous, challenges, and scientific questions, and the combined insights gained from the different materials expand the current understanding of Li-ion battery electrodes.

    The surface reaction kinetics of all three compounds was evaluated by coating them with a conductive polymer layer consisting of poly(3,4-ethylenedioxythiophene), PEDOT. Both LiFeSO4F polymorphs showed reduced polarization and increased charge storage capacity upon PEDOT coating, showing the importance of controlling the surface kinetics for this class of compounds. In contrast, the electrochemical performance of PEDOT coated Li2FeP2O7 was at best unchanged. The differences highlight that different rate limiting steps prevail for different Li-ion insertion materials.

    In addition to the electrochemical properties of the new iron based energy storage materials, also their underlying material properties were investigated. For tavorite LiFeSO4F, different reaction pathways were identified by in operando XRD evaluation during charge and discharge. Furthermore, ligand involvement in the redox process was evaluated, and although most of the charge compensation was centered on the iron sites, the sulfate group also played a role in the oxidation of tavorite LiFeSO4F. In triplite LiFeSO4F and Li2FeP2O7, a redistribution of lithium and iron atoms was observed in the crystal structure during electrochemical cycling. For Li2FeP2O7, and increased randomization of metal ions occurred, which is similar to what has been reported for other iron phosphates and silicates. In contrast, triplite LiFeSO4F showed an increased ordering of lithium and iron atoms. An electrochemically induced ordering has previously not been reported upon electrochemical cycling for iron based Li-ion insertion materials, and was beneficial for the charge storage capacity of the material.

    List of papers
    1. Identifying the Electrochemical Processes in LiFeSO4F Cathodes for Lithium Ion Batteries
    Open this publication in new window or tab >>Identifying the Electrochemical Processes in LiFeSO4F Cathodes for Lithium Ion Batteries
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    2017 (English)In: Chemelectrochem, Vol. 4, no 8, p. 1896-1907Article in journal (Other academic) Published
    Abstract [en]

    The electrochemical performance of tavorite LiFeSO4F can be considerably improved by coating the material with a conducting polymer (poly(3,4-ethylenedioxythiophene); PEDOT). Herein, the mechanisms behind the improved performance are studied systematically by careful electrochemical analysis. It is shown that the PEDOT coating improves the surface reaction kinetics for the Li-ion insertion into LiFeSO4F. For such coated materials no kinetic limitations remain, and a transition from solid state to solution-based diffusion control was observed at 0.6 mA cm−2 (circa C/2). Additionally, the quantity of PEDOT is optimized to balance the weight added by the polymer and the improved electrochemical function. Post mortem analysis shows excellent stability for the LiFeSO4F-PEDOT composite, and maintaining the electronic wiring is the most important factor for stable electrochemical cycling of LiFeSO4F. The insights and the methodology used to determine the rate-controlling steps are readily transferable to other ion-insertion-based electrodes, and the findings are important for the development of improved battery electrodes.

    Keywords
    Batteries; conducting polymers; electrochemistry; kinetics; lithium
    National Category
    Inorganic Chemistry
    Identifiers
    urn:nbn:se:uu:diva-317003 (URN)10.1002/celc.201700192 (DOI)000410498700015 ()
    Funder
    Swedish Foundation for Strategic Research , EM11-0028VINNOVASwedish Research Council Formas, 245-2014-668
    Available from: 2017-03-08 Created: 2017-03-08 Last updated: 2017-12-08Bibliographically approved
    2. Direct Observations of Phase Distributions in Operating Lithium Ion Batteries
    Open this publication in new window or tab >>Direct Observations of Phase Distributions in Operating Lithium Ion Batteries
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    (English)Article in journal (Other academic) Submitted
    National Category
    Inorganic Chemistry
    Identifiers
    urn:nbn:se:uu:diva-317005 (URN)
    Funder
    Swedish Foundation for Strategic Research , EM11-0028
    Available from: 2017-03-08 Created: 2017-03-08 Last updated: 2017-03-20
    3. Electronic Changes in LiFeSO4F-PEDOT Battery Cathodes upon Oxidation
    Open this publication in new window or tab >>Electronic Changes in LiFeSO4F-PEDOT Battery Cathodes upon Oxidation
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    (English)Manuscript (preprint) (Other academic)
    National Category
    Inorganic Chemistry
    Identifiers
    urn:nbn:se:uu:diva-317007 (URN)
    Funder
    Swedish Foundation for Strategic Research , EM11-0028
    Available from: 2017-03-08 Created: 2017-03-08 Last updated: 2017-03-20
    4. Structural and Electronic Changes in Li2FeP2O7 during Electrochemical Cycling
    Open this publication in new window or tab >>Structural and Electronic Changes in Li2FeP2O7 during Electrochemical Cycling
    Show others...
    2015 (English)In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 27, no 11, p. 3801-3804Article in journal (Refereed) Published
    National Category
    Chemical Sciences Physical Sciences
    Identifiers
    urn:nbn:se:uu:diva-258346 (URN)10.1021/acs.chemmater.5b00440 (DOI)000356202800004 ()
    Available from: 2015-07-13 Created: 2015-07-13 Last updated: 2017-12-04Bibliographically approved
    5. Surface Coating and Structural Changes in Triplite LiFeSO4F Cathodes
    Open this publication in new window or tab >>Surface Coating and Structural Changes in Triplite LiFeSO4F Cathodes
    Show others...
    (English)Manuscript (preprint) (Other academic)
    National Category
    Inorganic Chemistry
    Identifiers
    urn:nbn:se:uu:diva-317008 (URN)
    Funder
    Swedish Foundation for Strategic Research , EM11-0028
    Available from: 2017-03-08 Created: 2017-03-08 Last updated: 2017-03-08
  • 3.
    Blidberg, Andreas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Gustafsson, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Tengstedt, Carl
    Scania CV AB, Södertälje, Sweden.
    Björefors, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Brant, William R.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Monitoring LixFeSO4F (x = 1, 0.5, 0) Phase Distributions in Operando To Determine Reaction Homogeneity in Porous Battery Electrodes2017In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 29, no 17, p. 7159-7169Article in journal (Refereed)
    Abstract [en]

    Increasing the energy and power density simultaneously remains a major challenge for improving electrochemical energy storage devices such as Li-ion batteries. Understanding the underlying processes in operating electrodes is decisive to improve their performance. Here, an extension of an in operando X-ray diffraction technique is presented, wherein monitoring the degree of coexistence between crystalline phases in multiphase systems is used to investigate reaction homogeneity in Li-ion batteries. Thereby, a less complicated experimental setup using commercially available laboratory equipment could be employed. By making use of the intrinsic structural properties of tavorite type LiFeSO4F, a promising cathode material for Li-ion batteries, new insights into its nonequilibrium behavior are gained. Differences in the reaction mechanism upon charge and discharge are shown; the influence of adequate electronic wiring for the cycling stability is demonstrated, and the effect of solid state transport on rate performance is highlighted. The methodology is an alternative and complementary approach to the expensive and demanding techniques commonly employed for time-resolved studies of structural changes in operating battery electrodes. The multiphase behavior of LiFeSO4F is commonly observed for other insertion type electrode materials, making the methodology transferable to other new energy storage materials. By expanding the possibilities for investigating complex processes in operating batteries to a larger community, faster progress in both electrode development and fundamental material research can be realized.

  • 4.
    Blidberg, Andreas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Häggström, Lennart
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Ericsson, Tore
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Tengstedt, Carl
    Gustafsson, Torbjorn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Björefors, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Structural and Electronic Changes in Li2FeP2O7 during Electrochemical Cycling2015In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 27, no 11, p. 3801-3804Article in journal (Refereed)
  • 5.
    Blidberg, Andreas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry. Uppsala universitet.
    Sobkowiak, Adam
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Tengstedt, Carl
    Scania CV AB.
    Valvo, Mario
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Gustafsson, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Björefors, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Battery Performance of PEDOT Coated LiFeSO4F Cathodes with Controlled PorosityManuscript (preprint) (Other academic)
  • 6.
    Blidberg, Andreas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Sobkowiak, Adam
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Tengstedt, Carl
    Scania CV AB, Södertälje.
    Valvo, Mario
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Gustafsson, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Björefors, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Identifying the Electrochemical Processes in LiFeSO4F Cathodes for Lithium Ion Batteries2017In: Chemelectrochem, Vol. 4, no 8, p. 1896-1907Article in journal (Other academic)
    Abstract [en]

    The electrochemical performance of tavorite LiFeSO4F can be considerably improved by coating the material with a conducting polymer (poly(3,4-ethylenedioxythiophene); PEDOT). Herein, the mechanisms behind the improved performance are studied systematically by careful electrochemical analysis. It is shown that the PEDOT coating improves the surface reaction kinetics for the Li-ion insertion into LiFeSO4F. For such coated materials no kinetic limitations remain, and a transition from solid state to solution-based diffusion control was observed at 0.6 mA cm−2 (circa C/2). Additionally, the quantity of PEDOT is optimized to balance the weight added by the polymer and the improved electrochemical function. Post mortem analysis shows excellent stability for the LiFeSO4F-PEDOT composite, and maintaining the electronic wiring is the most important factor for stable electrochemical cycling of LiFeSO4F. The insights and the methodology used to determine the rate-controlling steps are readily transferable to other ion-insertion-based electrodes, and the findings are important for the development of improved battery electrodes.

  • 7.
    Blidberg, Andreas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Valvo, Mario
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Alfredsson, Maria
    Univ Kent, Sch Phys Sci, Canterbury CT2 7NH, Kent, England.
    Tengstedt, Carl
    Scania CV AB, SE-15187 Sodertalje, Sweden.
    Gustafsson, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Björefors, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Electronic changes in poly(3,4-ethylenedioxythiophene)-coated LiFeSO4F during electrochemical lithium extraction2019In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 418, p. 84-89Article in journal (Refereed)
    Abstract [en]

    The redox activity of tavorite LiFeSO4F coated with poly (3,4-ethylenedioxythiophene), i.e. PEDOT, is investigated by means of several spectroscopic techniques. The electronic changes and iron-ligand redox features of this LiFeSO4F-PEDOT composite are probed upon delithiation through X-ray absorption spectroscopy. The PEDOT coating, which is necessary here to obtain enough electrical conductivity for the electrochemical reactions of LiFeSO4F to occur, is electrochemically stable within the voltage window employed for cell cycling. Although the electronic configuration of PEDOT shows also some changes in correspondence of its reduced and oxidized forms after electrochemical conditioning in Li half-cells, its p-type doping is fully retained between 2.7 and 4.1 V with respect to Li+/Li during the first few cycles. An increased iron-ligand interaction is observed in LixFeSO4F during electrochemical lithium extraction, which appears to be a general trend for polyanionic insertion compounds. This finding is crucial for a deeper understanding of a series of oxidation phenomena in Li-ion battery cathode materials and helps paving the way to the exploration of new energy storage materials with improved electrochemical performances.

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