| 1. |
- Celeste, Arcangelo, et al.
(författare)
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Enhancement of Functional Properties of Liquid Electrolytes for Lithium-Ion Batteries by Addition of Pyrrolidinium-Based Ionic Liquids with Long Alkyl-Chains
- 2020
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Ingår i: Batteries and Supercaps. - : Wiley. - 2566-6223. ; 3:10, s. 1059-1068
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Tidskriftsartikel (refereegranskat)abstract
- Three ionic liquid belonging to the N-alkyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl) imides (Pyr(1),nTFSI with n=4,5,8) have been added as co-solvent to two commonly used electrolytes for Li-ion cells: (a) 1 M lithium hexafluorophosphate (LiPF6) in a mixture of ethylene carbonate (EC) and linear like dimethyl carbonate (DMC) in 1 : 1 v/v and (b) 1 M lithium bis-(trifluoromethanesulfonyl)imide (LiTFSI) in EC : DMC 1 : 1 v/v. These electrolyte formulations (classified as P and T series containing LiPF6 or LiTFSI salts, respectively) have been analyzed by comparing ionic conductivities, transport numbers, viscosities, electrochemical stability as well as vibrational properties. In the case of the Pyr(1,5)TFSI and Pyr(1,8)TFSI blended formulations, this is the first ever reported detailed study of their functional properties in Li-ion cells electrolytes. Overall, P-electrolytes demonstrate enhanced properties compared to the T-ones. Among the various P electrolytes those containing Pyr(1,4)TFSI and Pyr(1,5)TFSI limit the accumulation of irreversible capacity upon cycling with satisfactory performance in lithium cells.
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| 2. |
- Munoz-Garcia, Ana Belen, et al.
(författare)
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Structural evolution of disordered LiCo(1/3)Fe(1/3)Mn(1/3)PO(4)in lithium batteries uncovered
- 2020
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Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry (RSC). - 2050-7496 .- 2050-7488. ; 8:37, s. 19641-19653
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Tidskriftsartikel (refereegranskat)abstract
- In this study we address the Li-ion de-insertion/insertion mechanisms from/into the lattice of the mixed olivine LiCo1/3Fe1/3Mn1/3PO4(LCFMP). This mechanism is driven by a subtle interplay of structural, electronic and thermodynamic features. We aim at dissecting this complex landscape that is tightly connected to the long-term electrochemical performance of this material as a positive electrode in lithium-ion cells. To this end, we report advanced structural characterization, based onex situsynchrotronradiation diffraction on samples at different lithium contents. We couple this analysis with first-principles simulations, for a directvis-a-viscomparison. Our results show that (1) the mixing of the three transition-metal (TM) cations in the olivine lattice leads to a solid solution, providing the olivine lattice with the necessary flexibility to retain its single-phase structure during cell operation; (2) the electronic features of the three TMs are responsible for the observed electrochemical performance; (3) the de-lithiation of the olivine lattice is a thermodynamically driven process. Last but not least, our integrated experimental and theoretical results reveal the subtle features behind the formation of antisite defects that selectively involve Li-Co couples. In conclusion, our study provides the necessary scientific foundations to understand the structure-property-function relationships in LCFMP olivines, paving the way for further development and optimization of this material for application in Li-ion batteries.
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