Diglyme Based Electrolytes for Sodium-Ion Batteries
Sodium-ion batteries (SIBs) are currently being considered for large-scale energy storage. Optimization of SIB electrolytes is, however, still largely lacking. Here we exhaustively evaluate NaPF6 in diglyme as an electrolyte of choice, via both physicochemical properties and extensive electrochemica...
| Autores: | , , , , , , , , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión aceptada para publicación |
| Fecha de publicación: | 2018 |
| País: | España |
| Institución: | Consejo Superior de Investigaciones Científicas (CSIC) |
| Repositorio: | DIGITAL.CSIC. Repositorio Institucional del CSIC |
| OAI Identifier: | oai:digital.csic.es:10261/177235 |
| Acceso en línea: | http://hdl.handle.net/10261/177235 |
| Access Level: | acceso abierto |
| Palabra clave: | Batteries Degradation Electrolytes Sodium-ion Stability |
| Sumario: | Sodium-ion batteries (SIBs) are currently being considered for large-scale energy storage. Optimization of SIB electrolytes is, however, still largely lacking. Here we exhaustively evaluate NaPF6 in diglyme as an electrolyte of choice, via both physicochemical properties and extensive electrochemical tests including half as well as full cells. Fundamentally, the ionic conductivity is found to be quite comparable to carbonate based electrolytes and to obey the fractional Walden rule with viscosity. We find Na metal to work well as a reference electrode and the electrochemical stability, evaluated potentiostatically for various electrodes and corroborated by DFT calculations, to be satisfactory in the entire voltage range 0–4.4 V. Galvanostatic cycling at C/10 of half and full cells using Na3V2(PO4)3 (NVP) or Na3V2(PO4)2F3 (NVPF) as cathodes and hard carbon (HC) as anodes indicates rapid capacity fading in cells with HC anodes, possibly originating in a lack of a stable SEI or by trapping of sodium. Aiming to understand this capacity fade further, we conducted a GC/MS analysis to determine electrolyte reduction products and to propose reduction pathways, concluding that oligomer and/or alkoxide formation is possible. Overall, the promising results should warrant further investigations of diglyme based electrolytes for modern SIB development, albeit avoiding HC anodes. |
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