Abstract
An ion-conducting neutral pH polymer electrolyte based on LiNO3 and poly(vinyl alcohol) (PVA) was developed for solid electrochemical double layer capacitors (EDLCs). Structural characterizations of LiNO3-PVA electrolytes revealed amorphous structure with well-hydrated ions. The polymer electrolytes are functional over a wide range of temperatures even at −40 °C. Although increasing the concentration of ions can improve the ionic conductivity at and above ambient, it imposes adverse effects at lower temperatures likely due to the freezing of water surrounding the hygroscopic nitrate ions. The optimal electrolyte with relatively high ionic conductivity (ca. 40 mS cm−1 at ambient) and good temperature performance was applied for solid EDLC devices with multi-walled carbon nanotube electrodes. The solid EDLC showed comparable performance to its liquid baseline with excellent rate capability and wide voltage window of 1.6 V. It outperformed the liquid counterpart with lower leakage current and retained capacitive behaviour at −40 °C.
Published Version
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