Electrical properties of fluorinated gel electrolytes using conducting solution and its application to secondary battery

The lithium ionic electrolytes of fluorinated gel materials have been found to show high ionic conductivity. We proposed the application to a lithium ion 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, or 2-glucosyloxyyethyl methacrylate (GEMA) oligomer containing fluoroalkylated end-capped units {[-RF-(AMPS)q]p-}. Three kinds of lithium salts [LiBF₆, LiCF₃SO₃, and LiN(CF₃-SO₂)₂] were used for ionic electrolyte of fluorinated gel materials. The ionic conductivity of gel electrolytes depended on the oligomer materials, the lithium salts and its concentration. The conductivity of fluoroalkylated gel electrolyte using GEMA oligomer was larger than AMPS oligomer. When the lithium salts were LiN(CF₃SO₂)₂ and concentration of 5.3 mmol/g in the case of GEMA gel electrolytes, the conductivity was 4.5 × 10^-3 S/cm. However, the highest conductivity was obtained for AMPS gel electrolyte produced by ionic solution. The conductivity was 1.2 × 10^-2 S/cm, We also measured the charge and discharge characteristics of the lithium ion secondary batteries that were fabricated by a constitution of carbon negative electrode, fluorinated gel electrolyte with LiN(CF₃SO₂)₂ and positive electrode of LiCoO₂.