Editors’ Choice—Understanding the Superior Cycling Performance of Si Anode in Highly Concentrated Phosphonium-Based Ionic Liquid Electrolyte
| Autor: | Robert Kerr, Dominique Guyomard, Khryslyn Arano, Jean Le Bideau, Patrick C. Howlett, Nicolas Dupré, Maria Forsyth, Driss Mazouzi, Bernard Lestriez |
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| Rok vydání: | 2020 |
| Předmět: |
Materials science
Renewable Energy Sustainability and the Environment 020209 energy chemistry.chemical_element 02 engineering and technology Electrolyte Condensed Matter Physics Thermal diffusivity Electrochemistry 7. Clean energy Surfaces Coatings and Films Electronic Optical and Magnetic Materials Anode chemistry.chemical_compound Chemical engineering chemistry Ionic liquid 0202 electrical engineering electronic engineering information engineering Materials Chemistry Lithium Phosphonium Cobalt |
| Zdroj: | Journal of The Electrochemical Society. 167:120520 |
| ISSN: | 1945-7111 |
| DOI: | 10.1149/1945-7111/abac84 |
| Popis: | Considerable effort has been devoted to improving the cyclability of silicon (Si) negative electrodes for lithium-ion batteries because it is a promising high specific capacity alternative to graphite. In this work, the electrochemical behaviour of Si in two ionic liquid (IL) electrolytes, triethyl(methyl)phosphonium bis(fluorosulfonyl)imide (P1222FSI) and N-propyl-N-methylpyrrolidinium-FSI (C3mpyrFSI) with high and low lithium (Li) salt content is investigated at 50 °C. Results highlight that higher capacity and better cycling stability are achieved over 50 cycles with high salt concentration, the first time for a pyrrolidinium-based electrolyte in the area of Si negative electrodes. However, the Si cycling performance was far superior in the P1222FSI-based high salt content electrolyte compared to that of the C3mpyrFSI. To understand this unexpected result, diffusivity measurements of the IL-based electrolytes were performed using PFG-NMR, while their stability was probed using MAS-NMR and XPS after long-term cycling. A higher apparent transport number for Li ions in highly concentrated ILs, combined with a significantly lower extent of electrolyte degradation explains the superior cycle life of the highly concentrated phosphonium-based system. Si/concentrated P1222FSI-LiFSI/lithium nickel cobalt aluminum oxide (NCA) full cells with more than 3 mAh cm−2 nominal capacity deliver a promising cycle life and good rate capability. |
| Databáze: | OpenAIRE |
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