| 1. |
- Dussauze, M., et al.
(författare)
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Lithium Ion Conducting Boron-Oxynitride Amorphous Thin Films: Synthesis and Molecular Structure by Infrared Spectroscopy and Density Functional Theory Modeling
- 2013
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Ingår i: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 117:14, s. 7202-7213
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Tidskriftsartikel (refereegranskat)abstract
- Li ion containing oxynitride amorphous thin films are promising materials for electrochemical applications due to their high ionic conductivity, mechanical stability and chemical durability. Here we report on the preparation of Li boron-oxynitride (LiBON) amorphous thin films by rf sputtering of Li-diborate and Li-pyroborate targets in nitrogen atmosphere. The materials produced were subsequently studied by infrared transmittance spectroscopy assisted by density functional theory calculations using representative Li boron-oxide and boron-oxynitride clusters. The combination of experiments and calculations allows us to propose accurate vibrational assignments and to clarify the complex infrared activity of the LiBON films. Both experimental and calculated spectra show that nitrogen incorporation induces significant structural rearrangements, manifested mainly by a change in boron coordination number from four to three, and by the formation of boron-nitrogen-boron bridges. The nature of boron-nitrogen bonding depends on the composition of the sputtering target, with an exponential relationship adequately describing the dependence of B-N stretching frequency on bond length. Besides bonding to two boron atoms by covalent bonds, the nitrogen atoms interact also with Li ions by participating in their coordination sphere together with oxygen atoms. Likely, boron-nitrogen bonding in LiBON films facilitates Li ion transport due to induced charge delocalization within the boron-nitrogen-boron bridges and reduced electrostatic interaction with the Li ions.
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| 2. |
- Fretz, Samuel Joseph, 1987, et al.
(författare)
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Amine- and Amide-Functionalized Mesoporous Carbons: A Strategy for Improving Sulfur/Host Interactions in Li-S Batteries
- 2020
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Ingår i: Batteries and Supercaps. - : Wiley. - 2566-6223. ; 3:8, s. 757-765
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Tidskriftsartikel (refereegranskat)abstract
- Lithium-sulfur (Li-S) batteries are of great interest due to their potentially high energy density, but the low electronic conductivity of both the sulfur (S-8) cathode active material and the final discharge product lithium sulfide (Li2S) require the use of a conductive host. Usually made of relatively hydrophobic carbon, such hosts are typically ill-suited to retain polar discharge products such as the intermediate lithium polysulfides (LiPs) and the final Li2S. Herein, we propose a route to increase the sulfur utilization by functionalizing the surface of ordered mesoporous carbon CMK3 with polar groups. These derivatized CMK3 materials are made using a simple two-step procedure of bromomethylation and subsequent nucleophilic substitution with amine or amide nucleophiles. We demonstrate that, compared to the unfunctionalized control, these modified CMK3 surfaces have considerably larger binding energies with LiPs and Li2S, which are proposed to aid the electrochemical conversion between S-8 and Li2S by keeping the LiPs species in close proximity to the carbon surface during Li-S battery cycling. As a result, the functionalized cathodes exhibit significantly improved specific capacities relative to their unmodified precursor.
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| 6. |
- Johansson, Patrik, 1969, et al.
(författare)
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The conductivity of pyrrolidinium and sulfonylimide based ionic liquids: A combined experimental and computational study
- 2010
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Ingår i: Journal of Power Sources. - : Elsevier BV. - 0378-7753. ; 195:7, s. 2074-2076
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Tidskriftsartikel (refereegranskat)abstract
- Ionic conductivity is a fundamental property of ionic liquids with its origin and exact nature under debate. Using a specially selected system of pyrrolidinium cations (PYR1x, x = 3,4) and sulfonylimide anions (FSI, TFSI, BETI, and IM14)-based ionic liquids we observe a simple and accurate connection between ab initio computed cation and anion volumes and measured molar ionic conductivities.
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| 7. |
- Kim, Jae-Kwang, 1978, et al.
(författare)
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2,3,6,7,10,11-Hexamethoxytriphenylene (HMTP): A new organic cathode material for lithium batteries
- 2012
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Ingår i: Electrochemistry Communications. - : Elsevier BV. - 1388-2481. ; 21:1, s. 50-53
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Tidskriftsartikel (refereegranskat)abstract
- We propose a new organic cathode material for rechargeable lithium battery applications: 2,3,6,7,10,11-hexamethoxytriphenylene (HMTP). HMTP is composed of six methoxy functional groups substituted onto a central triphenylene moiety. The cell, incorporating 40 wt.% of organic cathode material, exhibits full specific capacity at current densities up to 3 C. The main advantage of HMTP as organic cathode material lies in a stable cell performance and negligible self discharge, even though the capacity is lower, similar to 66 mAh/g, compared to other organic cathode materials. Cells with the HMTP cathode showed >95% retention of the initial discharge capacity after 50 cycles at 1 C and self-discharge was not observed during a full month of open circuit voltage measurements. The latter is due to the fact that the nature of the HMTP radical is fundamentally different from other organic cathode materials' radicals.
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| 8. |
- Kim, Jae-Kwang, 1978, et al.
(författare)
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Characterization of N-butyl-N-methyl-pyrrolidinium bis(trifluoromethanesulfonyl)imide-based polymer electrolytes for high safety lithium batteries
- 2013
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Ingår i: Journal of Power Sources. - : Elsevier BV. - 0378-7753. ; 224:15 Feb. 2013, s. 93-98
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Tidskriftsartikel (refereegranskat)abstract
- Poly(vinylidene difluoride-co-hexafluoropropylene) (PVdF-HFP) membrane was prepared by electrospinning. The membranes served as host matrices for the preparation of ionic liquid-based polymer electrolytes (ILPEs) by activation with non-volatile, highly thermally stable, and safe room temperature ionic liquid (RTIL) electrolytes; N-butyl-N-methyl-pyrrolidinium bis(trifluoromethanesulfonyl)imide (Py14TFSI) complexed with 1 M lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). In this work, the first combination of electrospun PVdF-HFP fiber polymer host and pyrrolidinium-based ionic electrolyte was employed for highly stable lithium batteries. The ILPE exhibited low Li+-TFSI coordination, low crystallinity, high thermal stability, high electrochemical stability, and high ionic conductivity with a maximum of 1.1 x 10(-4) S cm(-1) at 0 degrees C. The ILPE exhibited good compatibility with a LiFePO4 electrode on storage and good charge-discharge performance in Li/ILPE/LiFePO4!
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| 9. |
- Kim, Jae-Kwang, 1978, et al.
(författare)
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Nano-fibrous polymer films for organic rechargeable batteries
- 2013
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Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry (RSC). - 2050-7488 .- 2050-7496. ; 1:7, s. 2426-2430
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Tidskriftsartikel (refereegranskat)abstract
- We propose a nano-fibrous polymer (NFP) film, fabricated by electrospinning poly(2,2,6,6-tetramethylpiperidinyloxy-4-yl methacrylate) (PTMA), as a key component in high performance organic batteries. The new strategy with a NFP film enables extraordinary rate capability and excellent cyclability, due to its special morphology. Moreover, the NFP film enhances the flexibility of the electrode at a low cost and prevents dissolution of PTMA into the electrolyte.
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