Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
6470826 | Electrochimica Acta | 2017 | 9 Pages |
Bis(carboxytrifluoroborate lithium) salts [R(CH2COOBF3Li)2] with oxyethylene groups R of oligomeric molar masses [R = O(CH2CH2O)n, where n = 3 or 11, BCB3 and BCB11, respectively] were synthesized via reaction of carboxylates salts with boron fluoride. The new salts were characterized by spectroscopic analysis. The physical properties of the salts were determined by oxyethylene chain length. For n = 3 the salt was crystalline with mp = 197 °C and for n = 11 it showed properties of an ionic liquid at ambient temperature. Their thermal stability was at least 250 °C. The values of lithium-ion transference numbers (T+) of the solutions in polar aprotic solvents, determined by a well established steady-state technique, were in the range of 0.2-0.6. Electrochemical impedance spectroscopy analysis of solid polymer electrolytes (SPEs) based on PEO and studied salts with different concentration (from 24 to 94 wt %) was carried out. The ionic conductivity of SPEs was in the order of 10â8-10â7 S cmâ1 at room temperature and 10â4 S cmâ1 at 80 °C. A distinguishing feature of SPEs with the studied new salts is the high immobilization of anions, which causes almost a monoconducting character of charge transport. Lithium transference numbers (T+) exceed 0.9.