Sodium-conducting ionic liquid electrolytes: electrochemical stability investigation

Sodium-conducting electrolytes, based on the EMIFSI, EMITFSI, N1114FSI, N1114TFSI, N1114IM14, PIP13TFSI and PIP14TFSI ionic liquids, were investigated in terms of electrochemical stability through voltammetry techniques with the aim of evaluating their feasibility in Na-ion devices. Both the anodic and cathodic sides were studied. The effect of contaminants, such as water and/or molecular oxygen, on the electrochemical robustness of the electrolytes was also investigated. Preliminary cyclic voltammetry and charge-discharge tests were carried out in Na/hard carbon and Na/α-NaMnO2 half cells using selected ionic liquid electrolytes. The results are presented and discussed in the present paper.