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Publications (9 of 9) Show all publications
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
Åkerlund, L., Emanuelsson, R., Hernández, G., Ruipérez, F., Casado, N., Brandell, D., . . . Sjödin, M. (2019). In situ Investigations of a Proton Trap Material: A PEDOT-Based Copolymer with Hydroquinone and Pyridine Side Groups Having Robust Cyclability in Organic Electrolytes and Ionic Liquids. ACS Applied Energy Materials, 2(6), 4486-4495
Open this publication in new window or tab >>In situ Investigations of a Proton Trap Material: A PEDOT-Based Copolymer with Hydroquinone and Pyridine Side Groups Having Robust Cyclability in Organic Electrolytes and Ionic Liquids
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2019 (English)In: ACS Applied Energy Materials, ISSN 2574-0962, Vol. 2, no 6, p. 4486-4495Article in journal (Refereed) Published
Abstract [en]

A conducting redox polymer based on PEDOT with hydroquinone and pyridine pendant groups is reported and characterized as a proton trap material. The proton trap functionality, where protons are transferred from the hydroquinone to the pyridine sites, allows for utilization of the inherently high redox potential of the hydroquinone pendant group (3.3 V versus Li0/+) and sustains this reaction by trapping the protons within the polymer, resulting in proton cycling in an aprotic electrolyte. By disconnecting the cycling ion of the anode from the cathode, the choice of anode and electrolyte can be extensively varied and the proton trap copolymer can be used as cathode material for all-organic or metal-organic batteries. In this study, a stable and nonvolatile ionic liquid was introduced as electrolyte media, leading to enhanced cycling stability of the proton trap compared to cycling in acetonitrile, which is attributed to the decreased basicity of the solvent. Various in situ methods allowed for in-depth characterization of the polymer’s properties based on its electronic transitions (UV–vis), temperature-dependent conductivity (bipotentiostatic CV-measurements), and mass change (EQCM) during the redox cycle. Furthermore, FTIR combined with quantum chemical calculations indicate that hydrogen bonding interactions are present for all the hydroquinone and quinone states, explaining the reversible behavior of the copolymer in aprotic electrolytes, both in three-electrode setup and in battery devices. These results demonstrate the proton trap concept as an interesting strategy for high potential organic energy storage materials.

Keywords
conducting redox polymer, organic electronics, renewable energy storage, proton trap, quinone, in situ
National Category
Nano Technology
Research subject
Engineering Science with specialization in Nanotechnology and Functional Materials
Identifiers
urn:nbn:se:uu:diva-389514 (URN)10.1021/acsaem.9b00735 (DOI)000473116600063 ()
Funder
SweGRIDS - Swedish Centre for Smart Grids and Energy StorageSwedish Energy AgencyCarl Tryggers foundation , CTS 17:414Stiftelsen Olle Engkvist ByggmästareSwedish Research Council Formas, 2018-00744Swedish Research Council Formas, 2016-00838
Available from: 2019-07-16 Created: 2019-07-16 Last updated: 2019-09-13Bibliographically approved
Hernández, G., Naylor, A. J., Mindemark, J., Brandell, D. & Edström, K. (2019). Non-Fluorinated Electrolytes for Si-based Li-ion Battery Anodes. In: : . Paper presented at Spring Meeting European Materials Research Society (E-MRS).
Open this publication in new window or tab >>Non-Fluorinated Electrolytes for Si-based Li-ion Battery Anodes
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2019 (English)Conference paper, Oral presentation only (Other academic)
National Category
Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-401983 (URN)
Conference
Spring Meeting European Materials Research Society (E-MRS)
Available from: 2020-01-10 Created: 2020-01-10 Last updated: 2020-01-10
Phadatare, M., Patil, R., Blomquist, N., Forsberg, S., Örtegren, J., Hummelgård, M., . . . Olin, H. (2019). Silicon-Nanographite Aerogel-Based Anodes for High Performance Lithium Ion Batteries. Scientific Reports, 9, Article ID 14621.
Open this publication in new window or tab >>Silicon-Nanographite Aerogel-Based Anodes for High Performance Lithium Ion Batteries
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2019 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, article id 14621Article in journal (Refereed) Published
Abstract [en]

To increase the energy storage density of lithium-ion batteries, silicon anodes have been explored due to their high capacity. One of the main challenges for silicon anodes are large volume variations during the lithiation processes. Recently, several high-performance schemes have been demonstrated with increased life cycles utilizing nanomaterials such as nanoparticles, nanowires, and thin films. However, a method that allows the large-scale production of silicon anodes remains to be demonstrated. Herein, we address this question by suggesting new scalable nanomaterial-based anodes. Si nanoparticles were grown on nanographite flakes by aerogel fabrication route from Si powder and nanographite mixture using polyvinyl alcohol (PVA). This silicon-nanographite aerogel electrode has stable specific capacity even at high current rates and exhibit good cyclic stability. The specific capacity is 455 mAh g(-1) for 200th cycles with a coulombic efficiency of 97% at a current density 100 mA g(-1).

Place, publisher, year, edition, pages
NATURE PUBLISHING GROUP, 2019
National Category
Materials Chemistry Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-396718 (URN)10.1038/s41598-019-51087-y (DOI)000489555900015 ()31601920 (PubMedID)
Funder
Swedish Energy Agency, 2014-001912Swedish Energy Agency, 40466-1Knowledge FoundationThe Swedish Foundation for International Cooperation in Research and Higher Education (STINT), IB-2018 7535Vinnova, 2017-03616
Available from: 2019-11-08 Created: 2019-11-08 Last updated: 2019-11-08Bibliographically approved
Åkerlund, L., Emanuelsson, R., Hernández, G., Ruipérez, F., Casado, N., Brandell, D., . . . Sjödin, M. (2019). The proton trap - a new route to organic energy storage. In: Organic Battery Days 2019: . Paper presented at Organic Battery Days 2019. Jena 3-5/6 2019.
Open this publication in new window or tab >>The proton trap - a new route to organic energy storage
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2019 (English)In: Organic Battery Days 2019, 2019Conference paper, Poster (with or without abstract) (Refereed)
National Category
Nano Technology
Research subject
Engineering Science with specialization in Nanotechnology and Functional Materials
Identifiers
urn:nbn:se:uu:diva-389538 (URN)
Conference
Organic Battery Days 2019. Jena 3-5/6 2019
Available from: 2019-07-17 Created: 2019-07-17 Last updated: 2019-12-10
Xu, C., Hernández, G., Abbrent, S., Kober, L., Konefal, R., Brus, J., . . . Mindemark, J. (2019). Unraveling and Mitigating the Storage Instability of Fluoroethylene Carbonate-Containing LiPF6 Electrolytes To Stabilize Lithium Metal Anodes for High-Temperature Rechargeable Batteries. ACS APPLIED ENERGY MATERIALS, 2(7), 4925-4935
Open this publication in new window or tab >>Unraveling and Mitigating the Storage Instability of Fluoroethylene Carbonate-Containing LiPF6 Electrolytes To Stabilize Lithium Metal Anodes for High-Temperature Rechargeable Batteries
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2019 (English)In: ACS APPLIED ENERGY MATERIALS, ISSN 2574-0962, Vol. 2, no 7, p. 4925-4935Article in journal (Refereed) Published
Abstract [en]

Implementing Li metal anodes provides the potential of substantially boosting the energy density of current Li-ion battery technology. However, it suffers greatly from fast performance fading largely due to substantial volume change during cycling and the poor stability of the solid electrolyte interphase (SEI). Fluoroethylene carbonate (FEC) is widely acknowledged as an effective electrolyte additive for improving the cycling performance of batteries consisting of electrode materials that undergo large volume changes during cycling such as Li metal. In this study, we report that while FEC can form a robust SEI on the electrode, it also deteriorates the shelf life of electrolytes containing LiPF6. The degradation mechanism of LiPF6 in FEC solutions is unraveled by liquid-and solid-state NMR. Specifically, traces of water residues induce the hydrolysis of LiPF6, releasing HF and PF5 which further trigger ring-opening of FEC and its subsequent polymerization. These reactions are significantly accelerated at elevated temperatures leading to the formation of a three-dimensional fluorinated solid polymer network. Moisture scavenger additives, such as lithium 4,5-dicyano-2-(trifluoromethyl)imidazole (LiTDI), can delay the degradation reaction as well as improve the cycling stability of LiNi1/3Mn1/3Co1/3O2/Li metal batteries at 55 degrees C. This work highlights the poor shelf life of electrolytes containing FEC in combination with LiPF6 and thereby the great importance of developing proper storage methods as well as optimizing the content of FEC in practical cells.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2019
Keywords
lithium metal batteries, thermal instability, electrolyte storage instability, fluoroethylene carbonate, moisture scavenger, lithium 4, 5-dicyano-2-(trifluoromethyl)imidazole (LiTDI)
National Category
Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-391950 (URN)10.1021/acsaem.9b00607 (DOI)000477074700040 ()
Funder
Swedish Energy Agency, 40466-1Swedish Energy Agency, 39043-1EU, Horizon 2020, 685716
Available from: 2019-08-29 Created: 2019-08-29 Last updated: 2019-12-11Bibliographically approved
Hernández, G., Naylor, A. J., Mindemark, J., Brandell, D. & Edström, K. (2018). Non-Fluorinated Electrolytes for Si-based Li-ion Battery Anodes. In: : . Paper presented at Circular Economy of Battery Production and Recycling (CEB).
Open this publication in new window or tab >>Non-Fluorinated Electrolytes for Si-based Li-ion Battery Anodes
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2018 (English)Conference paper, Poster (with or without abstract) (Other academic)
Abstract [en]

Although the performance of lithium-ion batteries has been improved to some extent since the initial commercialization,1 cycling stability, safety and sustainability still present some challenges and concerns. In this regard, the battery electrolyte plays an important role. State-of-the-art electrolytes contain the electrolyte salt LiPF6, susceptible to undergo defluorination reactions and form toxic and corrosive compounds, such as HF. Yet, fluorine-containing electrolytes are often considered necessary for enhanced battery performance. On the other hand, replacing LiPF6 with fluorine-free salts would reduce cost, increase safety and decrease toxicity, both in the manufacturing and recycling processes. Among the available fluorine-free salts, lithium bis(oxalato)borate (LiBOB) is a viable candidate due to its enhanced thermal stability.2 Furthermore, additives in the electrolyte are another common source of fluorine, not least fluoroethylene carbonate (FEC) which can form a stable solid electrolyte interface (SEI).3

Herein, we compare the cell performance of fluorinated and non-fluorinated electrolytes in NMC/Si-Graphite full cells. Three electrolytes are tested: (1) LP57 (1 M LiPF6 in ethylene carbonate (EC):ethyl methyl carbonate (EMC) 3:7 vol/vol); (2) LP57 with 10 wt% FEC and 2 wt%  vinylene carbonate (VC); and (3) 0.7 M LiBOB in EC:EMC 3:7 vol/vol and 2 wt% VC.

The cells containing the conventional electrolyte, LP57, feature a rapid capacity fade and continuous decrease in coulombic efficiency. The cell performance is improved when adding SEI-forming additives to the electrolyte (LP57 with FEC and VC). In addition, stable cycling for over 200 cycles are obtained for both the fluorinated (LP57 with FEC and VC) and non-fluorinated (LiBOB with VC) electrolytes.

Characterisation by X-ray photoelectron spectroscopy (XPS) of the anode surface showed higher amounts of carbonate species and a thicker SEI layer with the non-fluorinated electrolyte compared to the fluorinated one.

1 J. Electrochem. Soc. 2017, 164, A5019-A5025.

2 ChemSusChem 2017, 10, 2431-2448.

3 J. Electrochem. Soc. 2014, 161, A1933-A1938.

National Category
Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-374682 (URN)
Conference
Circular Economy of Battery Production and Recycling (CEB)
Available from: 2019-01-22 Created: 2019-01-22 Last updated: 2019-01-22
Hernández, G., Lago, N., Shanmukaraj, D., Armand, M. & Mecerreyes, D. (2017). Polyimide-polyether bindersediminishing the carbon content in lithium-sulfur batteries. MATERIALS TODAY ENERGY, 6, 264-270
Open this publication in new window or tab >>Polyimide-polyether bindersediminishing the carbon content in lithium-sulfur batteries
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2017 (English)In: MATERIALS TODAY ENERGY, ISSN 2468-6069, Vol. 6, p. 264-270Article in journal (Refereed) Published
Abstract [en]

Lithium-sulfur batteries are on the run to become the next generation energy storage technology. First of all due to its high theoretical energy density but also for its sustainability and low cost. However, there are still several challenges to take into account such as reducing the shuttle effect, decreasing the amount of conductive carbon to increase the energy density or enhancing the sulfur utilization. Herein, redox-active binders based on polyimide-polyether copolymers have been proposed as a solution to those drawbacks. These multiblock copolymers combine the ability of poly (ethylene oxide) to act as polysulfide trap and the properties of the imide groups to redox mediate the charge-discharge of sulfur. Thus, poly (ethylene oxide) block helps with the shuttle effect and mass transport in the electrode whereas the polyimide part enhances the charge transfer promoting the sulfur utilization. Sulfur cathodes containing pyromellitic, naphthalene or perylene polyimide-polyether binders featured improved cell performance in comparison with pure PEO binder. Among them, the electrode with naphthalene polyimide-PEO binder showed the best results with an initial capacity of 1300 mA h g(-1) at C/5, low polarization and 70% capacity retention after 30 cycles. Reducing the amount of carbon black in the cathode to 5 wt%, the cell with the redox-active binder was able to deliver 500 mA h g(-1) at C/5 with 78% capacity retention after 20 cycles. Our results demonstrate the possibility to reduce the amount of carbon by introducing polyimide-polyether copolymers as redox-active binders, increasing the sulfur utilization, redox kinetics and stability of the cell. (C) 2017 Elsevier Ltd. All rights reserved.

Keywords
Lithium-sulfur batteries, Polyimides, Redox mediators, Redox-active binders, Diminishing carbon
National Category
Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-359811 (URN)10.1016/j.mtener.2017.11.001 (DOI)000439097500026 ()
Funder
EU, European Research Council, 306250
Available from: 2018-09-14 Created: 2018-09-14 Last updated: 2018-09-14Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-2004-5869

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