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Interface layer formation in solid polymer electrolyte lithium batteries: an XPS study
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
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2014 (English)In: JOURNAL OF MATERIALS CHEMISTRY A, ISSN 2050-7488, Vol. 2, no 20, 7256-7264 p.Article in journal (Refereed) Published
Abstract [en]

The first characterization studies of the interface layer formed between a Li-ion battery electrode and a solid polymer electrolyte (SPE) are presented here. SPEs are well known for their electrochemical stability and excellent safety, and thus considered good alternatives to conventional liquid/gel electrolytes in high-energy density battery devices. This work comprises studies of solid electrolyte interphase (SEI) formation in SPE-based graphite|Li cells using X-ray photoelectron spectroscopy (XPS). SPEs based on high molecular weight poly(ethylene oxide) (PEO) and lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) salt are studied. Large amounts of LiOH are observed, and the XPS results indicate a correlation with moisture contamination in the SPEs. The water contents are quantitatively determined to be in the range of hundreds of ppm in the pure PEO as well as in the polymer electrolytes, which are prepared by a conventional SPE preparation method using different batches of PEO and at different drying temperatures. Moreover, severe salt degradation is observed at the graphite-SPE interface after the 1st discharge, while the salt is found to be more stable at the Li-SPE interface or when using LiTFSI-based liquid electrolyte equivalents.

Place, publisher, year, edition, pages
2014. Vol. 2, no 20, 7256-7264 p.
National Category
Biomaterials Science Energy Engineering
URN: urn:nbn:se:uu:diva-227147DOI: 10.1039/c4ta00214hISI: 000334998400019OAI: oai:DiVA.org:uu-227147DiVA: diva2:728670
Available from: 2014-06-24 Created: 2014-06-24 Last updated: 2015-05-12Bibliographically approved
In thesis
1. Functional Polymer Electrolytes for Multidimensional All-Solid-State Lithium Batteries
Open this publication in new window or tab >>Functional Polymer Electrolytes for Multidimensional All-Solid-State Lithium Batteries
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Pressing demands for high power and high energy densities in novel electrical energy storage units have caused reconsiderations regarding both the choice of battery chemistry and design. Practical concerns originating in the conventional use of flammable liquid electrolytes have renewed the interests of using solvent-free polymer electrolytes (SPEs) as solid ionic conductors for safer batteries.

In this thesis work, SPEs developed from two polymer host structures, polyethers and polycarbonates, have been investigated for all-solid-state Li- and Li-ion battery applications. In the first part, functional polyether-based polymer electrolytes, such as poly(propylene glycol) triamine based oligomer and poly(propylene oxide)-based acrylates, were investigated for 3D-microbattery applications. The amine end-groups were favorable for forming conformal electrolyte coatings onto 3D electrodes via self-assembly. In-situ polymerization methods such as UV-initiated and electro-initiated polymerization techniques also showed potential to deposit uniform and conformal polymer coatings with thicknesses down to nano-dimensions.

Moreover, poly(trimethylene carbonate) (PTMC), an alternative to the commonly investigated polyether host materials, was synthesized for SPE applications and showed promising functionality as battery electrolyte. High-molecular-weight PTMC was first applied in LiFePO4-based batteries. By incorporating an oligomeric PTMC as an interfacial mediator, enhanced surface contacts at the electrode/SPE interfaces and obvious improvements in initial capacities were realized. In addition, room-temperature functionality of PTMC-based SPEs was explored through copolymerization of ε-caprolactone (CL) with TMC. Stable cycling performance at ambient temperatures was confirmed in P(TMC/CL)-based LiFePO4 half cells (e.g., around 80 and 150 mAh g-1 at 22 °C and 40 °C under C/20 rate, respectively). Through functionalization, hydroxyl-capped PTMC demonstrated good surface adhesion to metal oxides and was applied on non-planar electrodes. Ionic transport behavior in polycarbonate-SPEs was examined by both experimental and computational approaches. A coupling of Li ion transport with the polymer chain motions was demonstrated.

The final part of this work has been focused on exploring the key characteristics of the electrode/SPE interfacial chemistry using PEO and PTMC host materials, respectively. X-ray photoelectron spectroscopy (XPS) was used to get insights on the compositions of the interphase layers in both graphite and LiFePO4 half cells.  

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2015. 89 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1243
Polymer electrolyte, Li-battery, 3D-microbattery, Functionalization, Polyether, Polycarbonate, Copolymer
National Category
Materials Chemistry
Research subject
Chemistry with specialization in Materials Chemistry
urn:nbn:se:uu:diva-248084 (URN)978-91-554-9215-1 (ISBN)
Public defence
2015-05-22, Häggsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 09:15 (English)
Available from: 2015-04-28 Created: 2015-03-26 Last updated: 2015-07-07

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