| 1. |
- Jankowski, Piotr, 1990, et al.
(författare)
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Designing High-Performant Lithium Battery Electrolytes by Utilizing Two Natures of Li+ Coordination: LiTDI/LiTFSI in Tetraglyme
- 2021
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Ingår i: Batteries and Supercaps. - : Wiley. - 2566-6223. ; 4:4, s. 205-213
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Tidskriftsartikel (refereegranskat)abstract
- Highly concentrated electrolytes (HCEs) based on glymes, such as tetraglyme (G4), are currently the focus of much battery research, primarily due to their unique properties - especially with respect to ion transport and electrochemical stability. While the LiTFSI-G4 and LiTDI-G4 systems both have been studied extensively, we here design their hybrid electrolytes to answer; will the resulting properties be averages/superpositions or will there be synergies created? We find the latter to be true and demonstrate that the most performant electrolytes are obtained by introducing a minor amount of LiTDI to an LiTFSI based electrolyte, which promotes the disproportionation and formation of "free" cations and at the same to avoid large aggregates - shown comprehensively both experimentally and by different modelling approaches and analyses combined. This electrolyte composition strategy can be generalized to other salts and solvents and thus a route towards a flora of novel battery electrolytes is here suggested.
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| 2. |
- Westman, Kasper, 1990, et al.
(författare)
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Diglyme based electrolytes for sodium-ion batteries
- 2018
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Ingår i: ACS Applied Energy Materials. - : American Chemical Society (ACS). - 2574-0962. ; 1:6, s. 2671-2680
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Tidskriftsartikel (refereegranskat)abstract
- Sodium-ion batteries (SIBs) are currently being considered for large-scale energy storage. Optimization of SIB electrolytes is, however, still largely lacking. Here we exhaustively evaluate NaPF6 in diglyme as an electrolyte of choice, via both physicochemical properties and extensive electrochemical tests including half as well as full cells. Fundamentally, the ionic conductivity is found to be quite comparable to carbonate based electrolytes and to obey the fractional Walden rule with viscosity. We find Na metal to work well as a reference electrode and the electrochemical stability, evaluated potentiostatically for various electrodes and corroborated by DFT calculations, to be satisfactory in the entire voltage range 0-4.4 V. Galvanostatic cycling at C/10 of half and full cells using Na3V2(PO4)(3) (NVP) or Na3V2(PO4)(2)F-3 (NVPF) as cathodes and hard carbon (HC) as anodes indicates rapid capacity fading in cells with HC anodes, possibly originating in a lack of a stable SEI or by trapping of sodium. Aiming to understand this capacity fade further, we conducted a GC/MS analysis to determine electrolyte reduction products and to propose reduction pathways, concluding that oligomer and/or alkoxide formation is possible. Overall, the promising results should warrant further investigations of diglyme based electrolytes for modern SIB development, albeit avoiding HC anodes.
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| 3. |
- Forestier, C., et al.
(författare)
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Comparative investigation of solid electrolyte interphases created by the electrolyte additives vinyl ethylene carbonate and dicyano ketene vinyl ethylene acetal
- 2017
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Ingår i: Journal of Power Sources. - : Elsevier BV. - 0378-7753. ; 345, s. 212-220
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Tidskriftsartikel (refereegranskat)abstract
- The effect of the replacement of the carbonyl oxygen in VEC additive by =C(CN)(2) in the analogous dicyano ketene vinyl ethylene acetal (DCKVEA) on the electrochemical reduction profile is significant. Yet, the additives were proven, through IR spectroscopy supported by DFT computations, by applying EELS techniques and performing synthesis of a reduction product, to reduce in a similar way. Interestingly, the reduction-induced capacities were found to be quite different and can be explained either by the different properties of the SEI, from lithium carbonate and its malononitrile homologue, or by the different abilities of the two additives to solvate Li+.
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| 4. |
- Forestier, C., et al.
(författare)
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Facile reduction of pseudo-carbonates: Promoting solid electrolyte interphases with dicyanoketene alkylene acetals in lithium-ion batteries
- 2016
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Ingår i: Journal of Power Sources. - : Elsevier BV. - 0378-7753. ; 303, s. 1-9
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Tidskriftsartikel (refereegranskat)abstract
- Dicyanoketene ethylene and propylene acetals, DCKEA and DCKPA respectively, have been investigated as electrolyte additives for Li-ion batteries. The purpose was to assess the changes in reduction behaviour and solid electrolyte interphase (SEI) passivation properties upon replacing the carbonyl group of ethylene carbonate (EC) and propylene carbonate (PC) solvents, respectively, by the slightly more electronegative and highly conjugated =C(CN)(2) group. The experimental reduction potentials and the IR spectroscopy characterisation efforts were further supported by density functional theory (DFT) computations. The two additives were found to, in relatively small amount (0.5 wt%), provide beneficial effects on the capacity retention of 8 mAh cells cycled at 20 and 45 degrees C. Moreover, the additives proved to enhance the thermal stability of the lithiated graphite/electrolyte interface, as deduced from DSC measurements.
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| 5. |
- Franco, Alejandro A., et al.
(författare)
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Boosting Rechargeable Batteries R&D by Multiscale Modeling: Myth or Reality?
- 2019
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Ingår i: Chemical Reviews. - : American Chemical Society (ACS). - 0009-2665 .- 1520-6890. ; 119:7, s. 4569-4627
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Tidskriftsartikel (refereegranskat)abstract
- This review addresses concepts, approaches, tools, and outcomes of multiscale modeling used to design and optimize the current and next generation rechargeable battery cells. Different kinds of multiscale models are discussed and demystified with a particular emphasis on methodological aspects. The outcome is compared both to results of other modeling strategies as well as to the vast pool of experimental data available. Finally, the main challenges remaining and future developments are discussed.
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| 6. |
- 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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| 7. |
- Grugeon, S., et al.
(författare)
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Towards a better understanding of vinylene carbonate derived SEI-layers by synthesis of reduction compounds
- 2019
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Ingår i: Journal of Power Sources. - : Elsevier BV. - 0378-7753. ; 427, s. 77-84
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Tidskriftsartikel (refereegranskat)abstract
- Here two chemical reduction pathways to synthesize the vinylene carbonate (VC)and poly(VC)reduction products are investigated, with the precise aim of further deciphering the lithium-ion battery solid electrolyte interphase (SEI)layer composition and the associated reduction mechanisms. The liquid synthesis pathway offers the opportunity of varying the concentration of Li-4,4′-Di-tert-butylbiphenyl reducing agent, whereas the dry synthesis pathway by ball milling allows to solve issues related to solvent-induced side reactions and washing procedure. As a result, the two syntheses do not unveil the same reduction mechanisms, favouring either carboxylate or carbonate salts as the major end product. The latter pathway is very efficient in terms of providing SEI-layers products resulting in well-defined IR spectra and comparisons with simulated spectra enable us to obtain IR fingerprints of the Li di-vinylene di-carbonate (LDVD)compound. Taken together the synthesis procedures provide information on conditions favouring radical polymerization and further poly(VC)reduction into Li 2 CO 3 and polyacetylene. Overall, this chemical simulation of SEI-layers formation assists in a proper characterization of the SEI-layers created on graphite surfaces by their IR spectra showing that Li 2 CO 3 , LDVD and poly(VC)are all present in different proportions dependent on the VC content in the electrolyte.
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| 8. |
- Jankowski, Piotr, 1990, et al.
(författare)
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Anion amphiprotic ionic liquids as protic electrolyte matrices allowing sodium metal plating
- 2019
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Ingår i: Chemical Communications. - : Royal Society of Chemistry (RSC). - 1364-548X .- 1359-7345. ; 55:83, s. 12523-12526
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Tidskriftsartikel (refereegranskat)abstract
- The sodium-ion battery (SIB) is proposed as a complementary technology to today's commercially dominant lithium-ion battery (LIB). While much know-how can be transferred from LIBs to SIBs, adjustments are still necessary, not the least for the electrolytes employed. Here the use of anion amphiprotic ionic liquid (AAIL) based electrolytes is proposed for SIB application. Two different AAILs, based on organic trifluoromethylsulfonylamide (TFSAm) and inorganic HSO4- anions, respectively, doped with NaTFSI salt have been studied, focusing on electrochemical stability and transport properties, complemented by studies of the ion-ion interactions, and final sodium-ion battery performance via stripping/plating vs. sodium metal electrodes.
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| 9. |
- Jankowski, Piotr, 1990, et al.
(författare)
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Chemically soft solid electrolyte interphase forming additives for lithium-ion batteries
- 2018
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Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry (RSC). - 2050-7488 .- 2050-7496. ; 6:45, s. 22609-22618
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Tidskriftsartikel (refereegranskat)abstract
- The solid electrolyte interphase (SEI) layer is a key element of lithium-ion batteries (LIBs) enabling stable operation and significantly affecting the cycling performance including life-length. Here we present the concept of chemically soft SEI-forming additives, created by introducing aromatic ring based derivatives of already well-known SEI-formers to render them chemically soft, resulting in 1,3,2-benzodioxathiole 2,2-dioxide (DTDPh), 3H-1,2-benzoxathiole 2,2-dioxide (PSPh), and 1,4,2-benzodioxathiine 2,2-dioxide (PSOPh). A computational DFT based comparison predicts promise with respect to both early and controlled reduction processes. These predictions are verified by basic electrochemical studies targeting appropriate additive reduction potentials i.e. prior to any electrolyte solvent or salt decomposition. In addition, the decomposition paths of the SEI-formers are projected and the end products compared with spectroscopic data for the SEI-layers formed in LIB cells. The SEI-layers formed finally show very good properties in terms of improved capacity retention, improved coulombic efficiency, and reduced resistance for the graphite/electrolyte/LFP full cells made, especially observed for PSOPh. That is due to the preferred C-O bond breaking mechanism, observed also for DTDPh, and supported by the S-C bond breaking mechanism, together resulting in well conductive and good adhesion properties of the SEI-layers. This is expedited by higher softness, eventuating in a formation process stabilizing some of the radicals and/or lowering the kinetic barriers. These positive effects are confirmed both when applying a commercial style electrolyte and for a new generation electrolyte based on the LiTDI salt, where suppression of the TDI anion reduction is truly crucial.
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| 10. |
- Jankowski, Piotr, 1990, et al.
(författare)
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Functional ionic liquids: Cationic SEI-formers for lithium batteries
- 2019
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Ingår i: Energy Storage Materials. - : Elsevier BV. - 2405-8297. ; 20, s. 108-117
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Tidskriftsartikel (refereegranskat)abstract
- More stable electrolytes for lithium-ion batteries are urgently needed, and apart from general improvements in thermal and electrochemical stabilities, both stability, safety and performance are connected with the formation of the solid electrolyte interphase (SEI) layer at the negative electrode. A high performant SEI-layer; thin, uniform, highly ion conducting, etc., is difficult to achieve and proper control of its formation process is therefore highly desirable. The idea presented here is based on computational screening of a wide range of modifications of wellknown ionic liquid (IL) cations towards better ability to form SEI-layers - i.e. acting as SEI-formers. Different cation chemistries and kinds of structural modifications were tested, with introduction of nitrile groups and/or double bonds resulting to be the most promising. The latter is outlined as especially beneficial, as apart from enabling an easier initiation reaction it provides a site for polymerization, resulting in polymeric SEI-products poly (IL) s (PILs), which can be expected to provide both protection of the electrode surface and fast Li thorn transport.
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