Electrochemical properties of LiCoPO4-thin film electrodes in LiF-based electrolyte solution with anion receptors

• Electrochemical properties of LiCoPO4 thin-film electrodes were investigated.
• LiF-based electrolyte solutions containing anion receptors were used.
• Electrochemical properties of LiCoPO4 were depended on the kind of anion receptors.

Compatibility of LiF + anion receptors/propylene carbonate (PC) electrolyte solution with high potential positive electrode for lithium-ion batteries was examined by cyclic voltammetry. As anion receptors, tripropyl borate (TPB), tris(pentafluorophenyl) borane (TPFPB), and tris(hexafluoroisopropyl) borate (THFIPB) were used. LiCoPO4 thin-film electrodes were prepared by sol–gel method and used as both carbon- and binder-free model electrodes. From cyclic voltammograms, LiCoPO4 showed better cycleability in 0.1 mol dm−3 LiF + 0.1 mol dm−3 THFIPB/PC, however, other anion receptors did not give positive influence. It is indicated that the surface protecting layer from F−-THFIPB complex and made LiCoPO4 stable. Electrochemical behavior depending on anion receptors was discussed according to reaction activity of F−.