| 1. |
- Bitenc, Jan, et al.
(författare)
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Concept and electrochemical mechanism of an Al metal anode - organic cathode battery
- 2020
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Ingår i: Energy Storage Materials. - : Elsevier BV. - 2405-8297 .- 2405-8289. ; 24, s. 379-383
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Tidskriftsartikel (refereegranskat)abstract
- Aluminum (Al) batteries are fundamentally a promising future post-Li battery technology. The recently demonstrated concept of an Al-graphite battery represents some significant progress for the technology, but the cell energy density is still very modest and limited by the quantity of the AlCl3 based electrolyte, as it relies on AlCl4- intercalation. For further progress, cathode materials capable of an electrochemical reaction with Al positively charged species are needed. Here such a concept of an Al metal anode - organic cathode battery based on anthraquinone (AQ) electrochemistry with a discharge voltage of 1.1 V is demonstrated. Further improvement of both the cell capacity retention and rate capability is achieved by nano-structured and polymerized cathodes. The intricate electrochemical mechanism is proven to be that the anthraquinone groups undergo reduction of their carbonyl bonds during discharge and become coordinated by AlCl2+ species. Altogether the Al metal anode - AQ cathode cell has almost the double energy density of the state-of-the-art Al-graphite battery.
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| 2. |
- Boschin, Andrea, 1981, et al.
(författare)
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On the Feasibility of Sodium Metal as Pseudo-Reference Electrode in Solid State Electrochemical Cells
- 2017
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Ingår i: ChemElectroChem. - : Wiley. - 2196-0216. ; 4:10, s. 2717-2721
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Tidskriftsartikel (refereegranskat)abstract
- A set-up of a sodium metal anode vs. a solid polymer electrolyte (SPE) comprising poly(ethylene oxide) (PEO) and sodium bis(trifluoromethanesulfonyl)imide (NaTFSI) has been evaluated in detail for the feasibility to use sodium metal as a pseudo-reference electrode (pseudo-RE). To evaluate the stability and reproducibility, we monitored the half-wave potential (E-1/2) of added decamethylferrocene (Me(10)Fc) and the stability of the interface by electrochemical impedance spectroscopy (EIS). The sodium/SPE interface resistance (R-Na/SPE) increases with time, up to 2.8k Omega cm(-2), and causes the E-1/2 of the Me(10)Fc(+/0) reference redox couple to drift up to 15mV during 88hours. Moreover, the sodium potential is very irreproducible, even initially after cell assembling the values can differ by 60mV, likely due to extreme sensitivity of the metal surface even to an "inert and dry" glove box environment. Indeed, freshly cut sodium readily reacts with water, forming NaOH, and adsorbs impurities that can be present even in a glove box atmosphere. The oxidation layer and the amount of adsorbed impurities increase with the exposure to the glove box atmosphere, as revealed by ATR-FTIR spectroscopy. Altogether, this calls for attention when evaluating any battery materials in half-cell configurations using sodium metal as the pseudo-RE.
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| 3. |
- Forero Saboya, Juan, 1992, et al.
(författare)
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Solvent-free lithium and sodium containing electrolytes based on pseudo-delocalized anions
- 2019
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Ingår i: Chemical Communications. - 1364-548X .- 1359-7345. ; 55:5, s. 632-635
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Tidskriftsartikel (refereegranskat)abstract
- Mixing the standard battery salt LiTFSI with various Li-salts of novel pseudo-delocalized organic anions [N(CH3)2((CH2)nSO3)((CH2)mSO3)]− (MMnm11), results in super-cooled solvent-free liquid electrolytes with glass transition temperatures of ca. 50 °C. Synthesis routes and full chemical characterisation of the new pseudo-delocalized anions are presented, as well as phase and thermal stabilities. The ion conductivities and electrochemical stabilities are evaluated towards lithium and sodium battery application.
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| 4. |
- Forero Saboya, Juan, 1992, et al.
(författare)
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Water-in-Bisalt Electrolyte with Record Salt Concentration and Widened Electrochemical Stability Window
- 2019
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Ingår i: Journal of Physical Chemistry Letters. - : American Chemical Society (ACS). - 1948-7185. ; 10:17, s. 4942-4946
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Tidskriftsartikel (refereegranskat)abstract
- Water-in-salt and water-in-bisalt electrolytes have recently attracted much attention due to their expanded electrochemical stability windows. The concentration limit of such electrolytes is constrained by the solubility of the lithium salts employed, ca. 21 m (mol kg−1) for LiTFSI (lithium bis(trifluoromethanesulfonyl)imide). By adding a second lithium salt, the total salt concentration can be increased, but the hydrogen evolution keeps limiting the application of such systems in batteries with low potential anodes. Herein we report a water-in-bisalt electrolyte with a record salt concentration (31.4 m LiTFSI + 7.9 m Li[N(CH3)2((CH2)3SO3)((CH2)4SO3)]) in which the bulky anion completely prevents the crystallization, even at such low water contents. Although the hydrogen evolution reaction is not completely suppressed, the expanded electrochemical stability window allows for low potential reactions such as aluminum−lithium alloying. The high salt concentration favors the formation of a suitable passivation layer that can be further engineered by modifying the anion structure
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| 5. |
- Lindberg, Simon, 1987, et al.
(författare)
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Charge storage mechanism of α-MnO2 in protic and aprotic ionic liquid electrolytes
- 2020
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Ingår i: Journal of Power Sources. - : Elsevier BV. - 0378-7753 .- 1873-2755. ; 460
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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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| 6. |
- Paronen, M, et al.
(författare)
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The Role of Solvated Electrons in Direct Methanol Fuel Cells
- 2023
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Ingår i: ChemElectroChem. - 2196-0216. ; 10:22
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Tidskriftsartikel (refereegranskat)abstract
- Direct methanol fuel cells, DMFCs, have for long been considered as a superior alternative to rechargeable batteries for various portable applications with respect to significantly higher theoretical power densities and faster recharging by simply filling up with new liquid fuel. In reality, however, DMFCs so far have much low power densities, suffer from high fuel losses, and require extremely expensive catalysts at high loadings. Here we show that an until now not considered process at the DMFC electrodes may cause these severe losses in performance. The process is that electrons generated at nano-structured catalyst loaded electrodes become solvated into the surrounding electrolyte. Taking this new process and resulting reaction mechanism(s) fully into account, material and catalyst/electrode design should be reconsidered to realize the true potential of DMFCs.
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