Preparation and characterization of novel thermoset polyimide and polyimide-peo doped with LiCF3SO3

UV-Cured polypropylene mesh-reinforced composite polymer electrolyte membranes

In this study, a polypropylene (PP) mesh was used to prepare proton- and Li+ conducting composite membranes for fuel cells and lithium rechargeable batteries, respectively. For the preparation of Li+ conducting membrane, polypropylene mesh was first immersed in an electrolyte solution, which was composed of LiBF4 and ethylene carbonate. Then the swollen membrane was immersed in an acetone solution of polyethylene glycol diacrylate (PEGDA), polyvinylidenefluoride-co-hexafluoro-propylene and photoinitiator. Finally, PP fabric was taken out from the solution and exposed to UV irradiation. Furthermore, proton conducting membranes were prepared by immersing the PP mesh into a mixture of vinyl phosphonic acid, PEGDA and photoinitiator. Afterwards, samples were cured under UV light. PP-reinforced membranes designed for fuel cell applications exhibited a room temperature conductivity of 3.3×10-3 mS/cm, while UV-cured electrolyte for Li batteries showed ionic conductivities in the range of 1.61×10-3–5.4×10-3 S/cm with respect to temperature. In addition, for lithium-doped composite polymer electrolyte (CPE), the electrochemical stability window was negligible below 4.75 V vs. Li/Li+. It is concluded that lithium-doped CPE has suitable electrochemical stability to allow the use of high-voltage electrode couples.

Synthesis by UV-curing and characterisation of polyurethane acrylate-lithium salts-based polymer electrolytes in lithium batteries

UV-cured caprolactone-based polyurethane acrylate (PUA) polymer blend electrolytes were prepared and characterised. To develop polymer electrolytes suited to ambient temperature, an ionically-conductive and reliable polymer electrolyte based on urethane acrylate resins synthesised from a fluorine-containing di-functional oligomer 6F ethoxylated diacrylate, a di-functional reactive diluent 1,6-hexanediol diacrylate for adjusting the viscosity, and a radical photo-initiator doped with a mixture of lithium salts were used. Free-standing flexible electrolyte films were prepared by UV-curing via free-radical photopolymerisation. The performance of the lithium polymer cell system (Li/PE(F4)/LiCoO2) was determined by electrochemical impedance spectroscopy, cyclic voltammetry, a galvanostatic recurrent differential pulse, chronocoulometry and chronoamperometry. The electrolyte with optimal amounts of fluorine-containing oligomer and optimal salt mixture content exhibited enhanced conductivity, showing a conductivity of 1.00 × 10−4 S cm−1 at ambient temperature. The specific capacity, specific energy and specific power of a Li/PE(F4)/LiCoO2 cell were also determined.