Electrical properties of lithium ionic electrolyte using fluorinated gels

The lithium ionic electrolytes of fluorinated gel materials have been found to show high ionic conductivity. We proposed an application to a secondary battery using this gel electrolyte. Non-crosslinked fluorinated gel materials were prepared by reacting fluoroalkanoyl peroxides with 2-acrylamid-2-methylpropanesulfonic acid (AMPS) oligomer containing fluoroalkylated end-capped units {[-R_F-(AMPS)q]p-}. Several kinds of lithium salts [LiPF₄ , LiBF₆, LiCF₃SO₃, and LiN(CF₃-SO₂)₂] were used for an ionic electrolyte of fluorinated gel materials. The ionic conductivity of gel electrolytes depended on the chain length of R_F, the lithium salt material and its concentration. The highest conductivity was 4.5×10^-3 S/cm under the RP chain length of C₃F₇, the lithium salt using LiN(CF₃SO ₂)₂ and concentration of 10.7 mmol/g, respectively. We also measured the charge and discharge characteristics of the secondary batteries which were fabricated by a constitution of cabon negative electrode, fluorinated gel electrolyte with LiN(CF₃ SO₂)₂ and a positive electrode of LiCoO₂