New well-defined, high molar mass (M_w = 3.8÷4.7×10⁵ g/mol) methacrylic polymeric ionic liquids with oxyethylene side chains and bis(trifluoromethylsulfonyl)imide or tetracyanoborate anions were synthesized and demonstrated high ionic conductivities up to 10^-5 S/cm (25^oC). For the first time the all-polymer-based thin-film electrochromic devices (ECDs) have been constructed using these PILs and poly(3,4-ethylenedioxythiophene) (PEDOT) as ion conductor material and electrodes, respectively. The best electrodes were obtained by utilization of vapor phase polymerization of EDOT on ITO glass in the presence of ionic monomer and polyethyleneglycol dimethacrylate, followed by radical polymerization of the latters. The advantages of assembled symmetrical ECDs are: simplicity of preparation, fast switching times (3÷5 s), high coloration efficiency (up to 430 cm²/C at 620÷630 nm), and satisfactory optical contrast up to ΔT = 28.5 %, good performance in air and in vacuum. To gain the combination of high ionic conductivity and good mechanical properties (elasticity and toughness), a new kind of solid composite materials, namely, ionic semi-interpenetrating polymer networks (semi-IPNs) was suggested. Such innovative semi-IPN materials were prepared by radical copolymerization of ionic monomer, namely (N-[2-(2-(2-(methacryloyloxy)ethoxy)ethoxy)ethyl]-N-methylpyrrolidinium bis(fluorosulfonyl)imide) with poly(ethylene glycol)(di)methacrylates in the presence of the dissolved nitrilebutadiene rubber. Based on the filled ionic semi-IPN the thin film separator for the Li batteries was created (ionic conductivity 1.3×10^-4 Scm^-1 (25°C), tensile strength - 80 kPa, elongation at break - 60%). The assembled polymer accumulators demonstrated 75 cycles of charge/discharge at 40^оС with an average specific capacity of 70 mА×h/g.