Novel waterborne polyurethane based electrolytes for lithium batteries - (II) the effect of adding LiCF₃SO₃-PC

New type electrolytes with the addition of LiCF₃SO₃-PC into polymer films of waterborne polyurethane (WPU) prepared from our modified acetone process are investigated by using alternating current (AC) impedance and cyclic voltammetry (CV) for their ionic conductivities and interfacial characteristics. The conductivities calculated from the results of AC impedance obey an Arrhenius law. The conductivity and the charge transfer resistance of WPU based electrolytes increases and decreases, respectively, with increasing addition of LiCF₃SO₃-PC. The room temperature conductivities of WPU electrolytes are improved from 10^-5 ∼ 10^-6 S cm^-1 to ∼ 10^-3 S cm^-1 by adding LiCF₃SO₃-PC from 10 wt% to 70 wt%. However, the CV results of WPU electrolyte with 70 wt% of LiCF₃SO₃-PC in a Li/WPU electrolyte/Li cell exhibit unstable voltammetric behaviour at 65°C, which is attributable to its unstable dimension at high temperature.