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Kitz, P. G., Lacey, M., Novak, P. & Berg, E. (2019). Operando EQCM-D with Simultaneous in Situ EIS: New Insights into Interphase Formation in Li Ion Batteries. Analytical Chemistry, 91(3), 2296-2303
Open this publication in new window or tab >>Operando EQCM-D with Simultaneous in Situ EIS: New Insights into Interphase Formation in Li Ion Batteries
2019 (English)In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 91, no 3, p. 2296-2303Article in journal (Refereed) Published
Abstract [en]

An operando electrochemical quartz crystal microbalance with dissipation monitoring (EQCM-D) with simultaneous in situ electrochemical impedance spectroscopy (EIS) has been developed and applied to study the solid electrolyte interphase (SEI) formation on copper current collectors in Li-ion batteries. The findings are backed by EIS simulations and complementary analytical techniques, such as online electrochemical mass spectrometry (OEMS) and X-ray photoelectron spectroscopy (XPS). The evolution of mass and the mechanical properties of the SEI are directly correlated to the electrode impedance. Electrolyte reduction at the anode carbon active material initiates dissolution, diffusion, and deposition of reaction side products throughout the cell and increases electrolyte viscosity and the ohmic cell resistance as a result. On Cu the reduction of CuOx and HF occurs at >1.5 V and forms an initial LiF-rich interphase while electrolyte solvent reduction at <0.8 V vs Li+/Li adds a second, less rigid layer on top. Both the shear storage modulus and viscosity of the SEI generally increase upon cycling but-along with the SEI Li+ diffusion coefficient-also respond reversibly to electrode potential, likely as a result of Li+/EC interfacial concentration changes. Combined EIS-EQCM-D provides unique prospects for further studies of the highly dynamic structure-function relationships of electrode interphases in Li ion batteries.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2019
National Category
Physical Chemistry Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-378386 (URN)10.1021/acs.analchem.8b04924 (DOI)000458220300090 ()30569698 (PubMedID)
Available from: 2019-03-05 Created: 2019-03-05 Last updated: 2019-03-05Bibliographically approved
Mindemark, J., Lacey, M. J., Bowden, T. & Brandell, D. (2018). Beyond PEO-Alternative host materials for Li+-conducting solid polymer electrolytes. Progress in polymer science, 81, 114-143
Open this publication in new window or tab >>Beyond PEO-Alternative host materials for Li+-conducting solid polymer electrolytes
2018 (English)In: Progress in polymer science, ISSN 0079-6700, E-ISSN 1873-1619, Vol. 81, p. 114-143Article, review/survey (Refereed) Published
Abstract [en]

The bulk of the scientific literature on Li-conducting solid (solvent-free) polymer electrolytes (SPEs) for applications such as Li-based batteries is focused on polyether-based materials, not least the archetypal poly(ethylene oxide) (PEO). A significant number of alternative polymer hosts have, however, been explored over the years, encompassing materials such as polycarbonates, polyesters, polynitriles, polyalcohols and polyamines. These display fundamentally different properties to those of polyethers, and might therefore be able to resolve the key issues restricting SPEs from realizing their full potential, for example in terms of ionic conductivity, chemical or electrochemical stability and temperature sensitivity. It is further interesting that many of these polymer materials complex Li-ions less strongly than PEO and facilitate ion transport through different mechanisms than polyethers, which is likely critical for true advancement in the area. In this review, >30 years of research on these 'alternative' Li-ion-conducting SPE host materials are summarized and discussed in the perspective of their potential application in electrochemical devices, with a clear focus on Li batteries. Key challenges and strategies forward and beyond the current PEO-based paradigm are highlighted.

Keywords
Polymer electrolyte, Solid electrolyte, Li battery, Ionic conductivity, Ion transport
National Category
Materials Chemistry Polymer Technologies
Identifiers
urn:nbn:se:uu:diva-365125 (URN)10.1016/j.progpolymsci.2017.12.004 (DOI)000433643500004 ()
Funder
Swedish Research Council, 2012-3837
Available from: 2018-11-12 Created: 2018-11-12 Last updated: 2018-11-12Bibliographically approved
Chien, Y.-C., Menon, A. S., Brant, W., Brandell, D. & Lacey, M. (2018). Development of operando XRD coin cells for lithium-sulfur batteries. In: : . Paper presented at RACIRI Summer School 2018, 25 aug - 1 sept 2018, Rügen, Germany.
Open this publication in new window or tab >>Development of operando XRD coin cells for lithium-sulfur batteries
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2018 (English)Conference paper, Poster (with or without abstract) (Other academic)
Abstract [en]

Lithium-sulfur (Li-S) batteries has been regarded as one of the promising technology for the next generation of rechargeable batteries due to its high theoretical energy density (2600 Wh/kg [1]). Several works [2–7] on operando X-ray diffraction (XRD) of the Li-S system have been published; however, their experimental setups showed one or more of the following drawbacks. First, the amount of electrolyte was often not reported or would be considered too high for a common Li-S cell, which has been demonstrated to have a significant impact on the behavior of the system [8]. Another issue is the non-uniform stack pressure and electron conductivity of the operando cell setup, whose effects were found by both experiments and simulations [9].

This work aims to tackle with the above-mentioned issues by modifying commercial coin cells and using X-ray transparent metal, beryllium, as the spacers. By doing so, the electron conductivity and stack pressure can be expected to be uniform throughout the electrodes. The amount of electrolyte can also be precisely controlled since no vacuum-sealing is required for coin cells. A preliminary diffraction pattern obtained with the cell setup can be seen in Fig. 1. With electrochemical properties similar to common Li-S cells, ‘online’ electrochemical characterization techniques, e.g. Intermittent Current Interruption (ICI) method for following cell resistance [10], will be applicable with operando XRD, revealing more information about this complex system.

Figure 1 XRD patterns of alpha-S and electrode material in the modified coin cell.

References

[1] J. Tan, et al., Nanoscale (2017) 19001–19016.

[2] J. Nelson, et al., J. Am. Chem. Soc. 134 (2012) 6337–6343.

[3] N.A. Cañas, et al., J. Power Sources 226 (2013) 313–319.

[4] S. Waluś, et al., Chem. Commun. 49 (2013) 7899.

[5] M. a. Lowe, et al., RSC Adv. 4 (2014) 18347.

[6] J. Kulisch, et al., Phys. Chem. Chem. Phys. 16 (2014) 18765–18771.

[7] J. Conder, et al., Nat. Energy 2 (2017) 1–7.

[8] M.J. Lacey, ChemElectroChem (2017) 1–9.

[9] O.J. Borkiewicz, et al., J. Phys. Chem. Lett. 6 (2015) 2081–2085.

[10] M.J. Lacey, et al., Chem. Commun. 51 (2015) 16502–16505.

Keywords
lithium-sulfur, operando X-ray diffraction, online resistance measurement
National Category
Inorganic Chemistry
Research subject
Chemistry with specialization in Inorganic Chemistry
Identifiers
urn:nbn:se:uu:diva-375406 (URN)
Conference
RACIRI Summer School 2018, 25 aug - 1 sept 2018, Rügen, Germany
Funder
Swedish Energy AgencySwedish Foundation for Strategic Research
Available from: 2019-01-29 Created: 2019-01-29 Last updated: 2019-01-31Bibliographically approved
Chien, Y.-C., Pan, R., Nyholm, L., Brandell, D. & Lacey, M. (2018). Electrochemical Analysis of Modified Separators for Li-S Batteries. In: : . Paper presented at 69th Annual Meeting of the International Society of Electrochemistry, Bologna, Italy, 2 - 7 September, 2018..
Open this publication in new window or tab >>Electrochemical Analysis of Modified Separators for Li-S Batteries
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2018 (English)Conference paper, Poster (with or without abstract) (Other academic)
Abstract [en]

The lithium-sulfur system is one of the potential energy storage technologies of the next generation due to the high theoretical specific capacity (1672 mAh/g), abundance and nontoxicity of sulfur [1]. However, there are still challenges yet to be overcome, one of which is the ‘polysulfide shuttle’ [1]. In order to address this issue, several modifications of the separators have been proposed. For example, longer cycle life, higher Coulombic efficiency and higher specific capacities have been reported with metal oxide coatings [2] and conductive interlayers [3,4] on the separators. Performance improvements in one or more of these properties have been ascribed to a suppression of polysulfide transport across the separator, even though this has not always been correlated with the difference in electrochemistry.

 

In this work, the Intermittent Current Interruption (ICI) method [5] is applied to monitor the evolution of internal resistance of Li-S cells with different separators during repeated charge and discharge. Cells with different separators exhibit significant differences in resistance as a function of state-of-charge in the initial cycles, as shown in the figure.  Complemented by self-discharge tests and impedance spectroscopy at selected states of charge, the roles of the interlayers in the system can be further interpreted electrochemically. This work aims to associate the electrochemical properties of the interlayers to their corresponding microstructural counterparts, which can in turn facilitate further development of the interlayer materials.

 

Figure: Internal resistance of cells vs specific charge for Li-S cells with different separators (Zero charge indicates the fully charged state.) for the 2nd, 5th and 10th cycles at C/10 rate.

 

References:

[1]         S. Urbonaite, T. Poux, P. Novák, Adv. Energy Mater. 5 (2015) 1–20.

[2]         Z. Zhang, Y. Lai, Z. Zhang, K. Zhang, J. Li, Electrochim. Acta 129 (2014) 55–61.

[3]         H. Yao, K. Yan, W. Li, G. Zheng, D. Kong, Z.W. Seh, V.K. Narasimhan, Z. Liang, Y. Cui, Energy Environ. Sci. 7 (2014) 3381–3390.

[4]         J. Balach, T. Jaumann, M. Klose, S. Oswald, J. Eckert, L. Giebeler, Adv. Funct. Mater. 25 (2015) 5285–5291.

[5]         M.J. Lacey, K. Edström, D. Brandell, Chem. Commun. 51 (2015) 16502–16505.

Keywords
lithium-sulfur batteries, separators, cellulose
National Category
Inorganic Chemistry
Research subject
Chemistry with specialization in Inorganic Chemistry
Identifiers
urn:nbn:se:uu:diva-374818 (URN)
Conference
69th Annual Meeting of the International Society of Electrochemistry, Bologna, Italy, 2 - 7 September, 2018.
Funder
Swedish Energy Agency
Available from: 2019-01-24 Created: 2019-01-24 Last updated: 2019-01-25Bibliographically approved
Bergfelt, A., Mogensen, R., Lacey, M., Guiomar, H., Brandell, D. & Bowden, T. (2018). Mechanically Robust and Highly Conductive Di-Block Copolymers as Solid Polymer Electrolytes for Room Temperature Li-ion Batteries. In: : . Paper presented at 16th International Symposium on Polymer Electrolytes (ISPE-16).
Open this publication in new window or tab >>Mechanically Robust and Highly Conductive Di-Block Copolymers as Solid Polymer Electrolytes for Room Temperature Li-ion Batteries
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2018 (English)Conference paper, Poster (with or without abstract) (Other academic)
Abstract [en]

Alternative solid polymer electrolytes (SPEs) hosts to the archetype poly(ethylene oxide) are gaining attention thanks to their appealing properties, such as higher cation transport number, thermal stability and electrochemical stability [1]. In addition, high mechanical stability is required in order to integrate easy-to-use materials into flexible or ‘structural’ batteries [2, 3].

 In this work, a solid polymer electrolyte (SPE) featuring high ionic conductivity and mechanical robustness at room temperature is presented. The SPE consists of a di-block copolymer, poly(benzyl methacrylate)-poly(ε-caprolactone-r-trimethylene carbonate) (BCT), mixed with different loadings of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). The highest ionic conductivity achieved for these SPEs was found with 16.7 wt% LiTFSI loading (BCT17), reaching 9.1 x 10-6 S cm-1 at 30 °C. The limited current fraction (F+) for the BCT17 electrolyte was calculated to be 0.64 with the Bruce-Vincent method. Furthermore, dynamic mechanical analysis showed a storage modulus (E’) of 0.2 GPa below 40 °C and 1 MPa above 50 °C. These results indicate that BCT with LiTFSI is a competitive electrolyte, combining high ionic conductivity and modulus at ambient temperatures.

 LiFePO4|BCT17|Li half-cells showed good cycling performance at 60 °C. At 30 °C, where the SPE possessed significantly higher modulus, decent cell performance could still be achieved after several optimization steps. These included incorporating a SPE as binder, and infiltration cast the SPE on the electrode to maximize the contact between both components, thereby improving the interfacial contact and decreasing the cell resistance and overpotential when cycling the battery device.

 References

[1] J. Mindemark, M.J. Lacey, T. Bowden, D. Brandell. Prog Polym Sci, (2018). DOI: 10.1016/j.progpolymsci.2017.12.004.

[2] J.F. Snyder, R.H. Carter, E.D. Wetzel. Chem Mater, 19 (2007) 3793-801.

[3] W.S. Young, W.F. Kuan, Thomas H. Epps. J Polym Sci, Part B: Polym Phys, 52 (2014) 1-16.

National Category
Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-374680 (URN)
Conference
16th International Symposium on Polymer Electrolytes (ISPE-16)
Available from: 2019-01-22 Created: 2019-01-22 Last updated: 2019-01-22
Aktekin, B., Lacey, M. J., Nordh, T., Younesi, R., Tengstedt, C., Zipprich, W., . . . Edström, K. (2018). Understanding the Capacity Loss in LiNi0.5Mn1.5O4-Li4Ti5O12 Lithium-Ion Cells at Ambient and Elevated Temperatures. The Journal of Physical Chemistry C, 122(21), 11234-11248
Open this publication in new window or tab >>Understanding the Capacity Loss in LiNi0.5Mn1.5O4-Li4Ti5O12 Lithium-Ion Cells at Ambient and Elevated Temperatures
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2018 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 122, no 21, p. 11234-11248Article in journal (Refereed) Published
Abstract [en]

The high-voltage spinel LiNi0.5Mn1.5O4, (LNMO) is an attractive positive electrode because of its operating voltage around 4.7 V (vs Li/Li+) and high power capability. However, problems including electrolyte decomposition at high voltage and transition metal dissolution, especially at elevated temperatures, have limited its potential use in practical full cells. In this paper, a fundamental study for LNMO parallel to Li4Ti5O12 (LTO) full cells has been performed to understand the effect of different capacity fading mechanisms contributing to overall cell failure. Electrochemical characterization of cells in different configurations (regular full cells, back-to-back pseudo-full cells, and 3-electrode full cells) combined with an intermittent current interruption technique have been performed. Capacity fade in the full cell configuration was mainly due to progressively limited lithiation of electrodes caused by a more severe degree of parasitic reactions at the LTO electrode, while the contributions from active mass loss from LNMO or increases in internal cell resistance were minor. A comparison of cell formats constructed with and without the possibility of cross-talk indicates that the parasitic reactions on LTO occur because of the transfer of reaction products from the LNMO side. The efficiency of LTO is more sensitive to temperature, causing a dramatic increase in the fading rate at 55 degrees C. These observations show how important the electrode interactions (cross-talk) can be for the overall cell behavior. Additionally, internal resistance measurements showed that the positive electrode was mainly responsible for the increase of resistance over cycling, especially at 55 degrees C. Surface characterization showed that LNMO surface layers were relatively thin when compared with the solid electrolyte interphase (SEI) on LTO. The SEI on LTO does not contribute significantly to overall internal resistance even though these films are relatively thick. X-ray absorption near-edge spectroscopy measurements showed that the Mn and Ni observed on the anode were not in the metallic state; the presence of elemental metals in the SEI is therefore not implicated in the observed fading mechanism through a simple reduction process of migrated metal cations.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2018
National Category
Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-357732 (URN)10.1021/acs.jpcc.8b02204 (DOI)000434236700007 ()
Funder
Swedish Energy Agency, 42031-1
Available from: 2018-08-31 Created: 2018-08-31 Last updated: 2019-07-29Bibliographically approved
Bergfelt, A., Lacey, M. J., Hedman, J., Sångeland, C., Brandell, D. & Bowden, T. (2018). ε-Caprolactone-based solid polymer electrolytes for lithium-ion batteries: synthesis, electrochemical characterization and mechanical stabilization by block copolymerization. RSC Advances, 8(30), 16716-16725
Open this publication in new window or tab >>ε-Caprolactone-based solid polymer electrolytes for lithium-ion batteries: synthesis, electrochemical characterization and mechanical stabilization by block copolymerization
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2018 (English)In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 8, no 30, p. 16716-16725Article in journal (Refereed) Published
Abstract [en]

In this work, three types of polymers based on epsilon-caprolactone have been synthesized: poly(epsilon-caprolactone), polystyrene-poly(epsilon-caprolactone), and polystyrene-poly(epsilon-caprolactone-r-trimethylene carbonate) (SCT), where the polystyrene block was introduced to improve the electrochemical and mechanical performance of the material. Solid polymer electrolytes (SPEs) were produced by blending the polymers with 10-40 wt% lithium bis(trifluoromethane) sulfonimide (LiTFSI). Battery devices were thereafter constructed to evaluate the cycling performance. The best performing battery half-cell utilized an SPE consisting of SCT and 17 wt% LiTFSI as both binder and electrolyte; a Li vertical bar SPE vertical bar LiFePO4 cell that cycled at 40 degrees C gave a discharge capacity of about 140 mA h g(-1) at C/5 for 100 cycles, which was superior to the other investigated electrolytes. Dynamic mechanical analysis (DMA) showed that the storage modulus E' was about 5 MPa for this electrolyte.

National Category
Polymer Chemistry
Identifiers
urn:nbn:se:uu:diva-340854 (URN)10.1039/c8ra00377g (DOI)000431814500034 ()
Funder
Swedish Energy Agency, 42031-1EU, Horizon 2020, 685716
Available from: 2018-02-04 Created: 2018-02-04 Last updated: 2018-08-27Bibliographically approved
Lacey, M., Österlund, V., Bergfelt, A., Jeschull, F., Bowden, T. & Brandell, D. (2017). A robust, water-based, functional binder framework for high energy Li-S batteries. In: : . Paper presented at Lithium Sulfur Batteries: Mechanisms, Modelling and Materials.
Open this publication in new window or tab >>A robust, water-based, functional binder framework for high energy Li-S batteries
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2017 (English)Conference paper, Oral presentation only (Other academic)
National Category
Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-338014 (URN)
Conference
Lithium Sulfur Batteries: Mechanisms, Modelling and Materials
Available from: 2018-01-06 Created: 2018-01-06 Last updated: 2018-01-06
Lacey, M., Österlund, V., Bergfelt, A., Jeschull, F., Bowden, T. & Brandell, D. (2017). A Robust, Water-Based, Functional Binder Framework for High-Energy Lithium-Sulfur Batteries. ChemSusChem, 10(13), 2758-2766
Open this publication in new window or tab >>A Robust, Water-Based, Functional Binder Framework for High-Energy Lithium-Sulfur Batteries
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2017 (English)In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 10, no 13, p. 2758-2766Article in journal (Refereed) Published
Abstract [en]

We report here a water-based functional binder framework for the lithium-sulfur battery systems, based on the general combination of a polyether and an amide-containing polymer. These binders are applied to positive electrodes optimised towards high-energy electrochemical performance based only on commercially available materials. Electrodes with up to 4 mAhcm(-2) capacity and 97-98% coulombic efficiency are achievable in electrodes with a 65% total sulfur content and a poly(ethylene oxide): poly(vinylpyrrolidone) (PEO: PVP) binder system. Exchange of either binder component for a different polymer with similar functionality preserves the high capacity and coulombic efficiency. The improvement in coulombic efficiency from the inclusion of the coordinating amide group was also observed in electrodes where pyrrolidone moieties were covalently grafted to the carbon black, indicating the role of this functionality in facilitating polysulfide adsorption to the electrode surface. The mechanical properties of the electrodes appear not to significantly influence sulfur utilisation or coulombic efficiency in the short term but rather determine retention of these properties over extended cycling. These results demonstrate the robustness of this very straightforward approach, as well as the considerable scope for designing binder materials with targeted properties.

National Category
Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-337672 (URN)10.1002/cssc.201700743 (DOI)000405080200009 ()28544635 (PubMedID)
Available from: 2018-01-03 Created: 2018-01-03 Last updated: 2018-02-01Bibliographically approved
Ebadi, M., Lacey, M., Brandell, D. & Araujo, C. M. (2017). Density Functional Theory Modeling the Interfacial Chemistry of the LiNO3 Additive for Lithium-Sulfur Batteries by Means of Simulated Photoelectron Spectroscopy. The Journal of Physical Chemistry C, 121(42), 23324-23332
Open this publication in new window or tab >>Density Functional Theory Modeling the Interfacial Chemistry of the LiNO3 Additive for Lithium-Sulfur Batteries by Means of Simulated Photoelectron Spectroscopy
2017 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 121, no 42, p. 23324-23332Article in journal (Refereed) Published
Abstract [en]

Lithium-sulfur (Li-S) batteries are considered candidates for next-generation energy storage systems due to their high theoretical specific energy. There exist, however, some shortcomings of these batteries, not least the solubility of intermediate polysulfides into the electrolyte generating a so-called "redox shuttle", which gives rise to self-discharge. LiNO3 is therefore frequently used as an electrolyte additive to help suppress this mechanism, but the exact nature of the LiNO3 functionality is still unclear. Here, density functional theory calculations are used to investigate the electronic structure of LiNO3 and a number of likely species (N-2, N2O, LiNO2, Li3N, and Li2N2O2) resulting from the reduction of this additive on the surface of Li metal anode. The N is X-ray photoelectron spectroscopy core level binding energies of these molecules on the surface are calculated in order to compare the results with experimentally reported values. The core level shifts (CLS) of the binding energies are studied to identify possible factors responsible for the position of the peaks. Moreover, solid phases of (cubic) c-Li3N and (hexagonal) alpha-Li3N on the surface of Li metal are considered. The N is binding energies for the bulk phases of Li3N and at the Li3N/Li interfaces display higher values as compared to the Li3N molecule, indicating a clear correlation between the coordination number and the CLS of the solid phases of Li3N.

National Category
Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-337669 (URN)10.1021/acs.jpcc.7b07847 (DOI)000414114800009 ()
Funder
Swedish Energy Agency, 39036-1Carl Tryggers foundation Swedish Research Council, 2014-5984; 2015-05754
Available from: 2018-01-03 Created: 2018-01-03 Last updated: 2019-08-05Bibliographically approved
Organisations
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ORCID iD: ORCID iD iconorcid.org/0000-0002-0366-7228

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