Conductivities of electrolytes based on PEI-b-PEO-b-PEI triblock copolymers with lithium and copper TFSI salts

Tri block-copolymer poly(iminoethylene)-b-poly(oxyethylene)-b-poly(iminoethylene) with a poly(oxyethylene) central block (PEI-b-PEO-b-PEI) were used as a “dual” matrix for polymer electrolytes having selectivity for hard cations (Li+/PEO) in one phase and for soft cations (Cu2+/PEI) in the other. Conductivity measurements were recorded for 20:1, 12:1 and 8:1 coordinating atom (O or/and N) to cation (Li+, Cu2+) ratios, for each of the three complexes studied: PEI-b-PEO-LiTFSI-b-PEI, PEI-Cu(TFSI)2-b-PEO-b-PEI-Cu(TFSI)2 and PEI-Cu(TFSI)2-b-PEO-LiTFSI-b-PEI-Cu(TFSI)2. For either low (20 °C) or high temperature (80 °C) the highest conductivity was given by the polymer electrolyte based on Cu(TFSI)2 with N/Cu2+ = 20:1 (10− 6, respectively 2 × 10− 4 S cm− 1). In the present paper, the conductivity evolution is discussed in relation with the polymer structure, the type and the concentration of the salt and the thermal behavior of our systems.