PMMA BASED GEL POLYMER ELECTROLYTES

摘要

Gel polymer electrolytes based on PMMA and Li salts in PC have been developed for lithium electrochemistry in batteries and electrochromics (for references, see [1]). We have developed a method for their preparation by direct polymerization of PMMA with addition of Li salts in PC, and we have applied this principle to gel electrolytes containing tetraethylamonium salts or sodium salts. The influence of temperature on conductivity of the gel is important. Apparently, a marked change of properties appears at temperature in the vicinity of -25℃, which should be treated as a transition from an elastomer to a crystalline polymer. Beyond this temperature, the prevailing component of impedance is ohmic resistivity, while the gel acts as a high tg 8 dielectric below that limit. Apparent activation energy at higher temperatures ΔH*=36 kJ/mole; ΔH*=80 kJ/mole and the apparent permittivity ε=20-40 was found at lower temperatures. The hardening of the polymer is finished in 2 to 3 days and can be monitored by conductivity measurement.