| 1. |
- Carboni, Marco, et al.
(författare)
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Analysis of the Solid Electrolyte Interphase on Hard Carbon Electrodes in Sodium-Ion Batteries
- 2019
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Ingår i: ChemElectroChem. - : Wiley. - 2196-0216. ; 6:6, s. 1745-1753
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Tidskriftsartikel (refereegranskat)abstract
- The composition, morphology, and evolution of the solid electrolyte interphase (SEI) formed on hard carbon (HC) electrodes upon cycling in sodium‐ion batteries are investigated. A microporous HC was prepared by pyrolysis of d‐(+)‐glucose at 1000 °C followed by ball‐milling. HC electrodes were galvanostatically cycled at room temperature in sodium‐ion half‐cells using an aprotic electrolyte of 1 m sodium bis(trifluoromethanesulfonyl)imide dissolved in propylene carbonate with 3 wt % fluoroethylene carbonate additive. The evolution of the electrode/electrolyte interface was studied by impedance spectroscopy upon cycling and ex situ by spectroscopy and microscopy. The irreversible capacity displayed by the HC electrodes in the first galvanostatic cycle is probably due to the accumulation of redox inactive NaxC phases and the precipitation of a porous, organic‐inorganic hybrid SEI layer over the HC electrodes. This passivation film further evolves in morphology and composition upon cycling and stabilizes after approximately ten galvanostatic cycles at low current rates.
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| 2. |
- Nicotera, Isabella, et al.
(författare)
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A Novel Li+-Nafion-Sulfonated Graphene Oxide Membrane as Single Lithium-Ion Conducting Polymer Electrolyte for Lithium Batteries
- 2019
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Ingår i: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 123:45, s. 27406-27416
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Tidskriftsartikel (refereegranskat)abstract
- Single lithium-ion conducting polymer electrolytes are an innovative concept of solid-state polymer electrolytes (SPEs) for lithium-battery technology. In this work, a lithiated Nafion nanocomposite incorporating sulfonated graphene oxide (sGO-Li+), as well as a filler-free membrane, have been synthesized and characterized. Ionic conductivities and lithium transference number, evaluated by electrochemical techniques after membrane-swelling in organic aprotic solvents (ethylene carbonate-propylene carbonate mixture), display significant values, with sigma approximate to 5 x 10(-4) S cm(-1) at 25 degrees C and t(Li+) close to unity. The absence of solvent leaching on thermal cycles is also noteworthy. The description at molecular level of the lithium transport mechanism has been carefully tackled through a systematic study by Li-7 NMR spectroscopy (pulsed field gradient-PFG and relaxation times), while the mechanical properties of the film electrolytes have been evaluated by dynamic mechanical analysis (DMA) in a wide temperature range. The electrochemical performances of the graphene-based electrolyte in Li/Li symmetric cells and in secondary cells using LiFePO4 as positive electrode show good compatibility and functionality with the Li-metal anode by forming a stable interphase, as well as displaying promising performance in galvanostatic cells.
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