Fig. 1: Visual color change after storage at elevated temperature. | Communications Chemistry

Fig. 1: Visual color change after storage at elevated temperature.

From: Effect of additives on the high-temperature performance of a sodium bis(oxalato)borate in triethyl phosphate electrolyte in sodium-ion batteries

Fig. 1

Digital photos of the freshly prepared electrolyte solutions and electrolyte solutions stored at 55 °C for 1 week or 4 weeks. After 1 week and 4 weeks small samples were taken from each vial for NMR spectroscopy analysis, which showed that the visible color change seen in the figure could be explained by a reaction between ethylene sulfate (DTD) and triethyl phosphate (TEP). Note that the sodium hexafluorophosphate (NaPF6) in ethylene carbonate:diethylene carbonate (EC:DEC) electrolyte solution was stored in a polypropylene plastic vial during hot storage, it was only transferred to a glass vial for the photo.

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