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Edström, Kristina, ProfessorORCID iD iconorcid.org/0000-0003-4440-2952
Publications (10 of 303) Show all publications
Aktekin, B., Valvo, M., Smith, R. I., Sörby, M. H., Marzano, F. L., Zipprich, W., . . . Brant, W. (2019). Cation Ordering and Oxygen Release in LiNi0.5-xMn1.5+xO4-y (LNMO): In Situ Neutron Diffraction and Performance in Li Ion Full Cells. ACS APPLIED ENERGY MATERIALS, 2(5), 3323-3335
Open this publication in new window or tab >>Cation Ordering and Oxygen Release in LiNi0.5-xMn1.5+xO4-y (LNMO): In Situ Neutron Diffraction and Performance in Li Ion Full Cells
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2019 (English)In: ACS APPLIED ENERGY MATERIALS, ISSN 2574-0962, Vol. 2, no 5, p. 3323-3335Article in journal (Refereed) Published
Abstract [en]

Lithium ion cells utilizing LiNi0.5Mn1.5O4 (LNMO) as the positive electrode are prone to fast capacity fading, especially when operated in full cells and at elevated temperatures. The crystal structure of LNMO can adopt a P4(3)32 (cation-ordered) or Fd (3) over barm (disordered) arrangement, and the fading rate of cells is usually mitigated when samples possess the latter structure. However, synthesis conditions leading to disordering also lead to oxygen deficiencies and rock-salt impurities and as a result generate Mn3+. In this study, in situ neutron diffraction was performed on disordered and slightly Mn-rich LNMO samples to follow cation ordering-disordering transformations during heating and cooling. The study shows for the first time that there is not a direct connection between oxygen release and cation disordering, as cation disordering is observed to start prior to oxygen release when the samples are heated in a pure oxygen atmosphere. This result demonstrates that it is possible to tune disordering in LNMO without inducing oxygen deficiencies or forming the rock-salt impurity phase. In the second part of the study, electrochemical testing of samples with different degrees of ordering and oxygen content has been performed in LNMO vertical bar vertical bar LTO (Li4Ti5O12) full cells. The disordered sample exhibits better performance, as has been reported in other studies; however, we observe that all cells behave similarly during the initial period of cycling even when discharged at a 10 C rate, while differences arise only after a period of cycling. Additionally, the differences in fading rate were observed to be time-dependent rather than dependent on the number of cycles. This performance degradation is believed to be related to instabilities in LNMO at higher voltages, that is, in its lower lithiation states. Therefore, it is suggested that future studies should target the individual effects of ordering and oxygen content. It is also suggested that more emphasis during electrochemical testing should be placed on the stability of samples in their delithiated state.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2019
Keywords
high-voltage spinel, neutron diffraction, LNMO, cation ordering, oxygen deficiency
National Category
Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-387975 (URN)10.1021/acsaem.8b02217 (DOI)000469885300040 ()
Funder
Swedish Energy Agency, 42758-1Swedish Energy Agency, 39043-1StandUp
Available from: 2019-06-27 Created: 2019-06-27 Last updated: 2019-07-29Bibliographically approved
Lv, F., Wang, Z., Shi, L., Zhu, J.-F., Edström, K., Mindemark, J. & Yuan, S. (2019). Challenges and development of composite solid-state electrolytes for high-performance lithium ion batteries. Journal of Power Sources, 441, Article ID 227175.
Open this publication in new window or tab >>Challenges and development of composite solid-state electrolytes for high-performance lithium ion batteries
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2019 (English)In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 441, article id 227175Article, review/survey (Refereed) Published
Abstract [en]

The safety concerns and the pursuit of high energy density have stimulated the development of high-performance solid-state lithium ion batteries. Therefore, the key component in solid-state lithium batteries, i.e. the solid-state electrolytes, also has attracted tremendous attention due to its non-flammability and good adaptability to high-voltage cathodes/lithium metal anodes. An in-depth understanding of the existing problems of solid-state electrolytes and proposed strategies for addressing these problems is crucial for the efficient design of high-performance solid-state electrolytes. In this review, we systematically summarized the current limitations of composite solid-state electrolytes and efforts to overcome them, and gave some proposals for the future perspectives of solid-state electrolytes with the aim to provide practical guidance for the researchers in this area.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Composite solid-state electrolytes, Li+ ion transportation, Interface issues, Lithium ion batteries
National Category
Materials Chemistry Energy Engineering
Identifiers
urn:nbn:se:uu:diva-397936 (URN)10.1016/j.jpowsour.2019.227175 (DOI)000494885800014 ()
Funder
Swedish Research Council
Available from: 2019-12-05 Created: 2019-12-05 Last updated: 2019-12-05Bibliographically approved
Källquist, I., Naylor, A. J., Baur, C., Chable, J., Kullgren, J., Fichtner, M., . . . Hahlin, M. (2019). Degradation Mechanisms in Li2VO2F Li-Rich Disordered Rock-Salt Cathodes. Chemistry of Materials, 31(16), 6084-6096
Open this publication in new window or tab >>Degradation Mechanisms in Li2VO2F Li-Rich Disordered Rock-Salt Cathodes
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2019 (English)In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 31, no 16, p. 6084-6096Article in journal (Refereed) Published
Abstract [en]

The increased energy density in Li-ion batteries is particularly dependent on the cathode materials that so far have been limiting the overall battery performance. A new class of materials, Li-rich disordered rock salts, has recently been brought forward as promising candidates for next-generation cathodes because of their ability to reversibly cycle more than one Li-ion per transition metal. Several variants of these Li-rich cathode materials have been developed recently and show promising initial capacities, but challenges concerning capacity fade and voltage decay during cycling are yet to be overcome. Mechanisms behind the significant capacity fade of some materials must be understood to allow for the design of new materials in which detrimental reactions can be mitigated. In this study, the origin of the capacity fade in the Li-rich material Li2VO2F is investigated, and it is shown to begin with degradation of the particle surface that spreads inward with continued cycling.

National Category
Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-394265 (URN)10.1021/acs.chemmater.9b00829 (DOI)000483435400005 ()
Funder
Swedish Research Council, 2016-03545EU, Horizon 2020, 711792EU, Horizon 2020, 730872StandUpSwedish National Infrastructure for Computing (SNIC)
Available from: 2019-10-09 Created: 2019-10-09 Last updated: 2019-10-09Bibliographically approved
Naylor, A. J., Makkos, E., Maibach, J., Guerrini, N., Sobkowiak, A., Björklund, E., . . . Bruce, P. G. (2019). Depth-dependent oxygen redox activity in lithium-rich layered oxide cathodes. Journal of Materials Chemistry A, 7(44), 25355-25368
Open this publication in new window or tab >>Depth-dependent oxygen redox activity in lithium-rich layered oxide cathodes
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2019 (English)In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 7, no 44, p. 25355-25368Article in journal (Refereed) Published
Abstract [en]

Lithium-rich materials, such as Li1.2Ni0.2Mn0.6O2, exhibit capacities not limited by transition metal redox, through the reversible oxidation of oxide anions. Here we offer detailed insight into the degree of oxygen redox as a function of depth within the material as it is charged and cycled. Energy-tuned photoelectron spectroscopy is used as a powerful, yet highly sensitive technique to probe electronic states of oxygen and transition metals from the top few nanometers at the near-surface through to the bulk of the particles. Two discrete oxygen species are identified, On− and O2−, where n < 2, confirming our previous model that oxidation generates localised hole states on O upon charging. This is in contrast to the oxygen redox inactive high voltage spinel LiNi0.5Mn1.5O4, for which no On− species is detected. The depth profile results demonstrate a concentration gradient exists for On− from the surface through to the bulk, indicating a preferential surface oxidation of the layered oxide particles. This is highly consistent with the already well-established core–shell model for such materials. Ab initio calculations reaffirm the electronic structure differences observed experimentally between the surface and bulk, while modelling of delithiated structures shows good agreement between experimental and calculated binding energies for On−.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2019
National Category
Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-399616 (URN)10.1039/C9TA09019C (DOI)000498556500014 ()
Available from: 2019-12-13 Created: 2019-12-13 Last updated: 2019-12-18Bibliographically approved
Pan, R., Sun, R., Wang, Z., Lindh, J., Edström, K., Strömme, M. & Nyholm, L. (2019). Double-sided conductive separators for lithium-metal batteries. Energy Storage Materials, 21, 464-473
Open this publication in new window or tab >>Double-sided conductive separators for lithium-metal batteries
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2019 (English)In: Energy Storage Materials, ISSN 2405-8297, Vol. 21, p. 464-473Article in journal (Refereed) Published
Abstract [en]

A novel double-sided conductive (DSC) separator consisting of two 5 μm-thick carbon nanotube (CNT)/cellulose nanofiber (CNF) composite layers coated on each side of a 20 μm-thick glass-fiber (GF)/CNF composite membrane is described. In a lithium-metal battery (LMB), the DSC separator exhibits a high ionic conductivity (i.e. 1.7 mS cm−1 using an LP40 electrolyte) due to the high porosity (i.e. 66%) of the GF/CNF membrane. More stable Li anodes can also be realized by depositing Li within the porous electronically conducting CNT/CNF matrix at the DSC separator anode side due to the decreased current density. The CNT/CNF layer of the DSC separator facing the cathode, which is in direct electric contact with the current collector, decreases the overpotential for the cathode and consequently improves its capacity and rate performance significantly. A Li/Li cell containing a DSC separator showed an improved cycling stability compared to an analogous cell equipped with a commercial Celgard separator at current densities up to 5 mA cm−2 for Li deposition and stripping capacities up to 5 mAh cm−2. A proof-of-concept LMB containing a lithium iron phosphate (LFP) composite cathode and a DSC separator showed a significantly improved rate capability, yielding capacities of about 110 mAh g−1 at 5 C and 80 mAh g−1 at 10 C. The LMB cell containing a DSC separator also exhibited a capacity retention of 80% after 200 cycles at a rate of 6 C indicating that the two-sided conductive separator design has significant potential in facilitating the development of well-functioning LMBs.

Place, publisher, year, edition, pages
Elsevier, 2019
National Category
Nano Technology
Research subject
Engineering Science with specialization in Nanotechnology and Functional Materials; Engineering Science with specialization in Nanotechnology and Functional Materials
Identifiers
urn:nbn:se:uu:diva-389860 (URN)10.1016/j.ensm.2019.06.025 (DOI)000484341600043 ()
Funder
Swedish Energy Agency
Available from: 2019-07-30 Created: 2019-07-30 Last updated: 2019-10-21Bibliographically approved
Mussa, A. S., Liivat, A., Marzano, F., Klett, M., Philippe, B., Tengstedt, C., . . . Svens, P. (2019). Fast-charging effects on ageing for energy-optimized automotive LiNi1/3Mn1/3Co1/3O2/graphite prismatic lithium-ion cells. Journal of Power Sources, 422, 175-184
Open this publication in new window or tab >>Fast-charging effects on ageing for energy-optimized automotive LiNi1/3Mn1/3Co1/3O2/graphite prismatic lithium-ion cells
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2019 (English)In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 422, p. 175-184Article in journal (Refereed) Published
Abstract [en]

The reactions in energy-optimized 25 Ah prismatic NMC/graphite lithium-ion cell, as a function of fast charging (1C-4C), are more complex than earlier described. There are no clear charging rate dependent trends but rather different mechanisms dominating at the different charging rates. Ageing processes are faster at 3 and 4C charging. Cycling with 3C-charging results in accelerated lithium plating but the 4C-charging results in extensive gas evolution that contribute significantly to the large cell impedance rise. Graphite exfoliation and accelerated lithium inventory loss point to the graphite electrode as the source of the gas evolution. The results are based on careful post-mortem analyses of electrodes using: scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and electrochemical impedance spectroscopy (EIS). SEM results show particle cracking independent of the charging rate used for the cycling. XPS and EIS generally indicate thicker surface film and larger impedance, respectively, towards the edge of the jellyrolls. For the intended application of a battery electric inner-city bus using this type of cell, charging rates of 3C and above are not feasible, considering battery lifetime. However, charging rates of 2C and below are too slow from the point of view of practical charging time.

Keywords
Fast charging, Lithium-ion battery, Ageing, Energy battery, Electric vehicle
National Category
Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-384064 (URN)10.1016/j.jpowsour.2019.02.095 (DOI)000465365900021 ()
Funder
Swedish Energy Agency, P40501-1
Available from: 2019-06-20 Created: 2019-06-20 Last updated: 2019-06-20Bibliographically approved
Hernández, G., Xu, C., Abbrent, S., Kobera, L., Konefal, R., Brus, J., . . . Brandell, D. (2019). Fluoroethylene Carbonate Containing Electrolytes: Origin of Poor Shelf Life and Its Mitigation. In: : . Paper presented at International Battery Association (IBA).
Open this publication in new window or tab >>Fluoroethylene Carbonate Containing Electrolytes: Origin of Poor Shelf Life and Its Mitigation
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2019 (English)Conference paper, Poster (with or without abstract) (Other academic)
National Category
Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-401981 (URN)
Conference
International Battery Association (IBA)
Available from: 2020-01-10 Created: 2020-01-10 Last updated: 2020-01-10
Hernández, G., Xu, C., Abbrent, S., Kobera, L., Konefal, R., Brus, J., . . . Brandell, D. (2019). Fluoroethylene Carbonate Containing Electrolytes: Origin of Poor Shelf Life and Its Mitigation. In: : . Paper presented at Nordbatt.
Open this publication in new window or tab >>Fluoroethylene Carbonate Containing Electrolytes: Origin of Poor Shelf Life and Its Mitigation
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2019 (English)Conference paper, Oral presentation only (Other academic)
National Category
Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-401984 (URN)
Conference
Nordbatt
Available from: 2020-01-10 Created: 2020-01-10 Last updated: 2020-01-10
Baur, C., Källquist, I., Chable, J., Chang, J. H., Johnsen, R. E., Ruiz-Zepeda, F., . . . Fichtner, M. (2019). Improved cycling stability in high-capacity Li-rich vanadium containing disordered rock salt oxyfluoride cathodes. Journal of Materials Chemistry A, 7(37), 21244-21253
Open this publication in new window or tab >>Improved cycling stability in high-capacity Li-rich vanadium containing disordered rock salt oxyfluoride cathodes
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2019 (English)In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 7, no 37, p. 21244-21253Article in journal (Refereed) Published
Abstract [en]

Lithium-rich transition metal disordered rock salt (DRS) oxyfluorides have the potential to lessen one large bottleneck for lithium ion batteries by improving the cathode capacity. However, irreversible reactions at the electrode/electrolyte interface have so far led to fast capacity fading during electrochemical cycling. Here, we report the synthesis of two new Li-rich transition metal oxyfluorides Li2V0.5Ti0.5O2F and Li2V0.5Fe0.5O2F using the mechanochemical ball milling procedure. Both materials show substantially improved cycling stability compared to Li2VO2F. Rietveld refinements of synchrotron X-ray diffraction patterns reveal the DRS structure of the materials. Based on density functional theory (DFT) calculations, we demonstrate that substitution of V3+ with Ti3+ and Fe3+ favors disordering of the mixed metastable DRS oxyfluoride phase. Hard X-ray photoelectron spectroscopy shows that the substitution stabilizes the active material electrode particle surface and increases the reversibility of the V3+/V5+ redox couple. This work presents a strategy for stabilization of the DRS structure leading to improved electrochemical cyclability of the materials.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2019
National Category
Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-396724 (URN)10.1039/c9ta06291b (DOI)000489345300018 ()
Funder
EU, Horizon 2020, 711792EU, Horizon 2020, 730872
Available from: 2019-12-05 Created: 2019-12-05 Last updated: 2019-12-12Bibliographically approved
Björklund, E., Göttlinger, M., Edström, K., Brandell, D. & Younesi, R. (2019). Investigation of dimethyl carbonate and propylene carbonate mixtures for LiNi0.6Mn0.2Co0.2O2-Li4Ti5O12 cells. Chemelectrochem, 6(13), 3429-3436
Open this publication in new window or tab >>Investigation of dimethyl carbonate and propylene carbonate mixtures for LiNi0.6Mn0.2Co0.2O2-Li4Ti5O12 cells
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2019 (English)In: Chemelectrochem, E-ISSN 2196-0216, Vol. 6, no 13, p. 3429-3436Article in journal (Refereed) Published
Abstract [en]

It has recently been shown that ethylene carbonate (EC) experience poor stability at high potentials in lithium-ion batteries, and development of electrolytes without EC, not least using ethyl methyl carbonate (EMC), has therefore been suggested in order to improve the capacity retention. In this context, we here explore another alternative electrolyte system consisting of propylene carbonate (PC) and dimethyl carbonate (DMC) mixtures in NMC-LTO (LiNi0.6Mn0.2Co0.2O2, Li4Ti5O12) cells cycled up to 2.95 V. While PC experience wettability problems and DMC has difficulties dissolving LiPF6 salt, blends between these could possess complementary properties. The electrolyte blend showed superior cycling performance at sub-zero temperatures compared to EC-containing counterparts. At 30 degrees C, however, the PC-DMC electrolyte did not show any major improvement in electrochemical properties for the NMC-LTO cell chemistry. Photoelectron spectroscopy measurements showed that thin surface layers were detected on both NMC (622) and LTO electrodes in all investigated electrolytes. The results suggest that both PC and EC will react on the electrodes, but with EC forming thinner layers comprising more carbonates. Moreover, the electrochemical stability at high electrochemical potentials is similar for the studied electrolytes, which is surprising considering that most are free from the reactive EC component.

National Category
Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-381546 (URN)10.1002/celc.201900672 (DOI)000475512500026 ()
Funder
Swedish Energy Agency, 37725-1StandUp
Available from: 2019-04-11 Created: 2019-04-11 Last updated: 2019-08-19Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0003-4440-2952

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