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Träfflista för sökning "WFRF:(Jankowski Piotr 1990) "

Sökning: WFRF:(Jankowski Piotr 1990)

  • Resultat 1-10 av 21
  • [1]23Nästa
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1.
  • Jankowski, Piotr, 1990, et al. (författare)
  • Designing High-Performant Lithium Battery Electrolytes by Utilizing Two Natures of Li+ Coordination: LiTDI/LiTFSI in Tetraglyme
  • 2021
  • Ingår i: BATTERIES & SUPERCAPS. - 2566-6223. ; 4:4, s. 205-213
  • 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.
  • Lindberg, S., et al. (författare)
  • Charge storage mechanism of alpha-MnO2 in protic and aprotic ionic liquid electrolytes
  • 2020
  • Ingår i: Journal of Power Sources. - : ELSEVIER. - 0378-7753 .- 1873-2755. ; 460
  • Tidskriftsartikel (refereegranskat)abstract
    • In this work we have investigated the charge storage mechanism of MnO2 electrodes in ionic liquid electrolytes. We show that by using an ionic liquid with a cation that has the ability to form hydrogen bonds with the active material (MnO2) on the surface of the electrode, a clear faradaic contribution is obtained. This situation is found for ionic liquids with cations that have a low pKa, i.e. protic ionic liquids. For a protic ionic liquid, the specific capacity at low scan rate rates can be explained by a densely packed layer of cations that are in a standing geometry, with a proton directly interacting through a hydrogen bond with the surface of the active material in the electrode. In contrast, for aprotic ionic liquids there is no interaction and only a double layer contribution to the charge storage is observed. However, by adding an alkali salt to the aprotic ionic liquid, a faradaic contribution is obtained from the insertion of Li+ into the surface of the MnO2 electrode. No effect can be observed when Li+ is added to the protic IL, suggesting that a densely packed cation layer in this case prevent Li-ions from reaching the active material surface.
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3.
  • Sun, Jinhua, 1987, et al. (författare)
  • Critical Role of Functional Groups Containing N, S, and O on Graphene Surface for Stable and Fast Charging Li‐S Batteries
  • 2021
  • Ingår i: Small. - : John Wiley & Sons. - 1613-6810 .- 1613-6829. ; , s. 2007242-
  • Tidskriftsartikel (refereegranskat)abstract
    • Lithium‐sulfur (Li‐S) batteries are considered one of the most promising energy storage technologies, possibly replacing the state‐of‐the‐art lithium‐ion (Li‐ion) batteries owing to their high energy density, low cost, and eco‐compatibility. However, the migration of high‐order lithium polysulfides (LiPs) to the lithium surface and the sluggish electrochemical kinetics pose challenges to their commercialization. The interactions between the cathode and LiPs can be enhanced by the doping of the carbon host with heteroatoms, however with relatively low doping content (<10%) in the bulk of the carbon, which can hardly interact with LiPs at the host surface. In this study, the grafting of versatile functional groups with designable properties (e.g., catalytic effects) directly on the surface of the carbon host is proposed to enhance interactions with LiPs. As model systems, benzene groups containing N/O and S/O atoms are vertically grafted and uniformly distributed on the surface of expanded reduced graphene oxide, fostering a stable interface between the cathode and LiPs. The combination of experiments and density functional theory calculations demonstrate improvements in chemical interactions between graphene and LiPs, with an enhancement in the electrochemical kinetics, power, and energy densities.
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4.
  • Westman, Kasper, 1990, et al. (författare)
  • Diglyme based electrolytes for sodium-ion batteries
  • 2018
  • Ingår i: ACS Applied Energy Materials. - 2574-0962. ; 1:6, s. 2671-2680
  • 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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5.
  • Forestier, C., et al. (författare)
  • Comparative investigation of solid electrolyte interphases created by the electrolyte additives vinyl ethylene carbonate and dicyano ketene vinyl ethylene acetal
  • 2017
  • Ingår i: Journal of Power Sources. - 0378-7753. ; 345, s. 212-220
  • 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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6.
  • Forestier, C., et al. (författare)
  • Facile reduction of pseudo-carbonates: Promoting solid electrolyte interphases with dicyanoketene alkylene acetals in lithium-ion batteries
  • 2016
  • Ingår i: Journal of Power Sources. - 0378-7753. ; 303, s. 1-9
  • 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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7.
  • Franco, Alejandro A., et al. (författare)
  • Boosting Rechargeable Batteries R&D by Multiscale Modeling: Myth or Reality?
  • 2019
  • Ingår i: Chemical Reviews. - : AMER CHEMICAL SOC. - 0009-2665 .- 1520-6890. ; 119:7, s. 4569-4627
  • 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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8.
  • Fretz, Samuel Joseph, 1987, et al. (författare)
  • Amine- and Amide-Functionalized Mesoporous Carbons: A Strategy for Improving Sulfur/Host Interactions in Li-S Batteries
  • 2020
  • Ingår i: BATTERIES & SUPERCAPS. - 2566-6223. ; 3:8, s. 757-765
  • 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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9.
  • Grugeon, S., et al. (författare)
  • Towards a better understanding of vinylene carbonate derived SEI-layers by synthesis of reduction compounds
  • 2019
  • Ingår i: Journal of Power Sources. - 0378-7753. ; 427, s. 77-84
  • 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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10.
  • Jankowski, Piotr, 1990, et al. (författare)
  • Anion amphiprotic ionic liquids as protic electrolyte matrices allowing sodium metal plating
  • 2019
  • Ingår i: Chemical Communications. - 1364-548X .- 1359-7345. ; 55:83, s. 12523-12526
  • 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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  • Resultat 1-10 av 21
  • [1]23Nästa

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