Characterization of a multivalent charged electrolyte using electrochemical method and electrophoretic NMR

Understanding various transport parameters, for example conductivity, diffusion coefficient and transference member, is important for developing electrolytes for lithium ion battery applications. Theoretically, electrolytes with high transference number are predicted to prevent Li dendrite growth. In this aspect ceramic and solid polymer electrolytes have been studied. However, solid electrolytes can suffer from poor Li-interfacial contact. Additionally, solid polymer electrolytes exhibit lower conductivity at room temperature. On the other hand, liquid electrolytes with bulkier multivalent anion could potentially increase the transference number as mobility of ionic species is inversely proportional to the size of ions. In the present work, we have designed a new electrolyte of a polyanionic lithium salt containing a negative charge of -20, dissolved in ethylene carbonate/dimethyl carbonate mixed solvent. The transport properties of the electrolytes have been fully characterized using various electrochemical techniques. Furthermore, electrophoretic NMR technique was used to investigate the electric-field-induced movement of ions and solvents which in turn provided the transference number for these electrolytes. Thus, the transference number data obtained using two different techniques is compared in this study