| 11. |
- Jankowski, Piotr, 1990, et al.
(författare)
-
Functional ionic liquids: Cationic SEI-formers for lithium batteries
- 2019
-
Ingår i: Energy Storage Materials. - : Elsevier BV. - 2405-8297. ; 20, s. 108-117
-
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.
|
|
| 12. |
- Jankowski, Piotr, 1990, et al.
(författare)
-
Impact of Sulfur-Containing Additives on Lithium-Ion Battery Performance: From Computational Predictions to Full-Cell Assessments
- 2018
-
Ingår i: ACS Applied Energy Materials. - : American Chemical Society (ACS). - 2574-0962. ; 1, s. 2582-2591
-
Tidskriftsartikel (refereegranskat)abstract
- Electrolyte additives are pivotal for stabilization of lithium-ion batteries, by suppressing capacity loss through creation of an engineered solid-electrolyte-interphase-layer (SEI-layer) at the negative electrode and thereby increasing lifetime. Here, we compare four different sulfur-containing 5-membered-ring molecules as SEI-formers: 1,3,2-dioxathiolane-2,2-dioxide (DTD), propane-1,3-sultone (PS), sulfopropionic acid anhydride (SPA), and prop-1-ene-1,3-sultone (PES). Density functional theory calculations and electrochemical measurements both confirm appropriate reduction potentials. For a connection of the protective properties of the SEIs formed to the chemical structure of the additives, the decomposition paths are computed and compared with spectroscopic data for the negative electrode surface. The performance of full-cells cycled using a commercial electrolyte and the different additives reveals the formation of organic dianions to play a crucial beneficial role, more so for DTD and SPA than for PS and PES.
|
|
| 13. |
- Jankowski, Piotr, 1990, et al.
(författare)
-
New boron based salts for lithium-ion batteries using conjugated ligands
- 2016
-
Ingår i: Physical Chemistry Chemical Physics. - : Royal Society of Chemistry (RSC). - 1463-9084 .- 1463-9076. ; 18:24, s. 16274-16280
-
Tidskriftsartikel (refereegranskat)abstract
- A new anion design concept, based on combining a boron atom as the central atom and conjugated systems as ligands, is presented as a route for finding alternative Li-salts for lithium-ion batteries. The properties of a wide range of novel anions designed in this way have been evaluated by DFT calculations focusing on three different fundamental success factors/measures: the strength of the cation-anion interaction, ultimately determining both the solubility and the ionic conductivity, the oxidation limit, determining their possible use vs. high voltage cathodes, and the reduction stability, revealing a possible role of the anion in the SEI-formation at the anode. For a few anions superior properties vs. today's existing or suggested anions are predicted, especially the very low cation-anion interaction strengths are promising features. The design route itself is shown to be versatile in determining the correlation between different choices of ligands and the resulting overall properties - where the most striking feature is the decreased lithium cation interaction energy upon using the (1Z,3Z)-buta-1,3-diene-1,2,3,4-tetracarbonitrile ligands. This also opens avenues for the further design of novel anions beyond those with a boron central atom.
|
|
| 14. |
- Jankowski, Piotr, 1990, et al.
(författare)
-
Prospects for Improved Magnesocene-Based Magnesium Battery Electrolytes
- 2021
-
Ingår i: Batteries and Supercaps. - : Wiley. - 2566-6223. ; 4:8, s. 1335-1343
-
Tidskriftsartikel (refereegranskat)abstract
- Magnesium batteries are currently attracting a lot of interest as a next generation battery technology. One critical issue is to find a suitable electrolyte and herein we explore an electrolyte based on magnesocene (MgCp2) in tetrahydrofuran (THF), aiming for low-voltage Mg batteries, with respect to: Mg plating characteristics, electrochemical stability windows, electrolyte speciation, and electrolyte decomposition reactions; both experimentally and computationally. Overall, the electrolyte does not seem to decompose on a Mg metal anode and most likely reduced solvation of Mg2+ by the Cp- anion is important and species such as MgCp2THF2 may play an important role for Mg plating with small overpotential. The oxidation limit is largely determined by the Cp- anion and density functional theory predicted oxidation reactions point to polymerized end-products to be possible. Furthermore, in silico substitution studies enable us to establish the prospects of some Cp- anion derivatives to further improve the oxidative stability, but still the Mg2+ solvation must be monitored for ease of reduction and Mg plating.
|
|
| 15. |
- Jankowski, Piotr, 1990, et al.
(författare)
-
SEI-forming Electrolyte Additives for Lithium-ion Batteries: Development and Benchmarking of Computational Approaches
- 2017
-
Ingår i: Journal of Molecular Modeling. - : Springer Science and Business Media LLC. - 0948-5023 .- 1610-2940. ; 23:1
-
Tidskriftsartikel (refereegranskat)abstract
- SEI-forming additives play an important role in lithium-ion batteries, and the key to improving battery functionality is to determine if, how, and when these additives are reduced. Here, we tested a number of computational approaches and methods to determine the best way to predict and describe the properties of the additives. A wide selection of factors were evaluated, including the influences of the solvent and lithium cation as well as the DFT functional and basis set used. An optimized computational methodology was employed to assess the usefulness of different descriptors.
|
|
| 16. |
- Jankowski, Piotr, 1990, et al.
(författare)
-
TFSI and TDI Anions: Probes for Solvate Ionic Liquid and Disproportionation-Based Lithium Battery Electrolytes
- 2017
-
Ingår i: Journal of Physical Chemistry Letters. - : American Chemical Society (ACS). - 1948-7185. ; 8:15, s. 3678-3682
-
Tidskriftsartikel (refereegranskat)abstract
- Highly concentrated electrolytes based on Li-salts and chelating solvents, such as glymes, are promising as electrolytes for lithium batteries. This is due to their unique properties, such as higher electrochemical stabilities, compliance with high-voltage electrodes, low volatility and flammability, and inertness toward aluminum current collector corrosion. The nature of these properties originates from the molecular-level structure created in either solvate ionic liquids (Sits) or the less common ionic aggregates by disproportionation reactions. The nature of the anion plays a crucial role, and here, we present a computational study using TFSI and TDI anions as probes, revealing increasing differences upon increased salt concentration. TFSI-based electrolytes preferably form SILs, while TDI-based electrolytes form ionic aggregates. The latter lead to an unexpected creation of "free" cationic species even at (very) high salt concentrations and thus promise of ample lithium ion transport.
|
|
| 17. |
- Jankowski, Piotr, 1990, et al.
(författare)
-
Understanding of Lithium 4,5-Dicyanoimidazolate-Poly(ethylene oxide) System: Influence of the Architecture of the Solid Phase on the Conductivity
- 2016
-
Ingår i: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 120:41, s. 23358-23367
-
Tidskriftsartikel (refereegranskat)abstract
- Solid polymer electrolytes (SPEs) with high lithium conductivity are very beneficial as a safe material for lithium battery applications. Herein we present new set of a SPEs based on lithium 2-trifluoromethyl-4,5-dicyanoimidazolate (LiTDI) with wide range of ether oxygen to lithium molar ratios. The phase composition was characterized in detail with thermal, diffraction, and spectroscopic techniques, and its influence on conductivity behavior was examined. Two detected crystalline phases of LiTDI poly(ethylene oxide) (PEO) were simulated with computational methods. The obtained results allowed insight into the structure of these electrolytes and helped us to understand on the molecular level factors influencing electrochemical properties and phase behavior. It was shown that ability to form a low-melting phase can be used to lower the temperature window of operation. That made it possible to keep such SPEs amorphous at 30 degrees C during 80 days. The thermal stability of the samples was checked to prove the safety of the electrolytes.
|
|
| 18. |
- Jeschke, Steffen, 1986, et al.
(författare)
-
Catching TFSI: A Computational–Experimental Approach to β-Cyclodextrin-Based Host–Guest Systems as electrolytes for Li-Ion Batteries
- 2018
-
Ingår i: ChemSusChem. - : Wiley. - 1864-5631 .- 1864-564X. ; 11:12, s. 1942-1949
-
Tidskriftsartikel (refereegranskat)abstract
- Cyclodextrins (CDs) are pyranoside-based macromolecules with a hydrophobic cavity to encapsulate small molecules. They are used as molecular vehicles, for instance in pharmaceutical drug delivery or as solubility enhancer of monomers for their polymerization in aqueous solution. In this context, it was discovered about 10 years ago that the bis(trifluoromethylsulonyl)imide (TFSI) anion forms host–guest complexes with βCD in aqueous media. This sparked interest in using the TFSI anion in lithium-based battery electrolytes open for its encapsulation by βCD as an attractive approach to increase the contribution of the cation to the total ion conductivity. By using semi-empirical quantum mechanical (SQM) methods and the conductor-like screening model for a real solvent (COSMO-RS), a randomly methylated βCD (RMβCD) is here identified as a suitable host for TFSI when using organic solvents often used in battery technology. By combining molecular dynamics (MD) simulations with different NMR and FTIR experiments, the formation of the corresponding RMβCD–TFSI complex was investigated. Finally, the effects of the addition RMβCD to a set of electrolytes on the ion conductivity are measured and explained using three distinct scenarios.
|
|
| 19. |
- Lindberg, Simon, 1987, et al.
(författare)
-
Charge storage mechanism of α-MnO2 in protic and aprotic ionic liquid electrolytes
- 2020
-
Ingår i: Journal of Power Sources. - : Elsevier BV. - 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.
|
|
| 20. |
- Xiong, Shizhao, 1985, et al.
(författare)
-
Design of a Multifunctional Interlayer for NASCION-Based Solid-State Li Metal Batteries
- 2020
-
Ingår i: Advanced Functional Materials. - : Wiley. - 1616-3028 .- 1616-301X. ; 30:22
-
Tidskriftsartikel (refereegranskat)abstract
- NASCION-type Li conductors have great potential to bring high capacity solid-state batteries to realization, related to its properties such as high ionic conductivity, stability under ambient conditions, wide electrochemical stability window, and inexpensive production. However, their chemical and thermal instability toward metallic lithium (Li) has severely hindered attempts to utilize Li as anode material in NASCION-based battery systems. In this work, it is shown how a tailored multifunctional interlayer between the solid electrolyte and Li anode can successfully address the interfacial issues. This interlayer is designed by creating a quasi-solid-state paste in which the functionalities of LAGP (Li1.5Al0.5Ge1.5(PO4)3) nanoparticles and an ionic liquid (IL) electrolyte are combined. In a solid-sate cell, the LAGP-IL interlayer separates the Li metal from bulk LAGP and creates a chemically stable interface with low resistance (≈5 Ω cm2) and efficiently prevents thermal runaway at elevated temperatures (300 °C). Solid-state cells designed with the interlayer can be operated at high current densities, 1 mA cm−2, and enable high rate capability with high safety. Here developed strategy provides a generic path to design interlayers for solid-state Li metal batteries.
|
|
