Polymer Electrolyte

The polymer electrolytes comprising blend of poly(vinyl acetate) (PVAc) and poly(methylmethacrylate) (PMMA) as a host polymer and LiClO4 as a dopant are prepared by solution casting technique. The amorphous nature of the polymer–salt complex has been confirmed by XRD analysis. The DSC thermograms show two Tg's for PVAc–PMMA blend. A decrease in Tg with the LiClO4 content reveals the increase of segmental motion. Conductance spectra results are found to obey the Jonscher's power law and the maximum dc conductivity value is found to be 1.76 × 10− 3 S cm− 1 at 303 K for the blend polymer complex with 20 wt.% LiClO4, which is suitable for the Li rechargeable batteries. The conductivity–temperature plots are found to follow an Arrhenius nature. The dc conductivity is found to increase with increase of salt concentration in the blend polymer complexes.

Gel Polymer Electrolytes (GPE) based on agar and containing LiClO4 have been prepared, characterized and applied to electrochromic devices. The ionic conductivity revealed the best result of 6.5 × 10−5 S/cm for the sample with 17 wt.% of LiClO4, which increased to 5.4 × 10−4 S/cm at 72°C. The GPE have been used in electrochromic devices (ECD) with K-glass/WO3/GPE/CeO2-TiO2/K-glass configuration. The ECD changed transmittance values up to 30% between the colored and transparent states. The charge density measurements revealed an increase of 5.5 to 7.5 mC/cm2 from the first to 500th cycles and then a decrease to 4.4 mC/cm2 during the next 4500 cycles. Coloration efficiency (η) of 25 cm2/C was obtained.

Poly (N-vinyl pyrrolidone) (PVP) and ammonium thiocyanate (NH4SCN) based polymer films with different compositions have been prepared by solution casting technique. The amorphous nature of the polymer electrolytes has been confirmed by XRD analysis. The FTIR analysis confirms the complex formation of the polymer with the salt. The conductivity analysis shows that the 20 mol% ammonium thiocyanate doped polymer electrolyte has high ionic conductivity and it has been found to be 1.7 × 10−4 S cm−1, at room temperature. From the admittance plot, the activation energy has been found to be low for 20 mol% salt doped polymer electrolyte. The dielectric behavior has been analyzed using dielectric permittivity (ε∗), dissipation factor (tan δ) and electric modulus (M∗) of the samples.

The electrochemical and ion transport properties of heterogeneous electrolyte mixtures are reviewed. The review is restricted to lithium ion conducting electrolytes and to electrolytes containing at least one polymer component. Different electrolytetypes are compared, and lithium batteries based on the eletrolytes are described.

A plasticized polymer electrolyte system composed of PVDF-HFP, potassium iodide (KI), and equal weight of ethylene carbonate (EC) and propylene carbonate (PC) has been used in a dye-sensitized solar cell (DSSC). The electrolyte with the composition 40 wt. % PVDF-HFP-10wt. % KI-50 wt. % (EC + PC) exhibits the highest room temperature ionic conductivity of 1.10 x 10(-3) S cm(-1). A small amount of iodine crystal of about 10 wt. % of KI was added to the electrolyte in the liquid state to provide the redox couple for DSSC operation. The polymer electrolyte films were prepared by the solvent casting method. The DSSCs were fabricated with the electrolyte film sandwiched between a TiO(2)/dye photoelectrode and a Pt-counter electrode and characterized under 100 mW cm(-2) white light. The DSSC performance with different dyes such as Ruthenizer 535 (N3), anthocyanin, chlorophyll, and a mixture of anthocyanin and chlorophyll (v/v = 1) has been compared. The DSSC with Ruthenizer 535 (N3) dye exhibits the best performance with a short-circuit current density of 8.16 mA cm(-2), open-circuit voltage of 0.76 V, fill factor of 0.35, and photoconversion efficiency of 2.2%.

Composite electrolyte films consisting of poly(vinylchloride), poly(acrylonitrile), ethylene carbonate, LiClO4 and also TiO2 particles have been prepared by solution casting technique. The effect of inorganic filler on the conductivity of the blended polymer electrolyte was studied. A conductivity of (7.57 × 10−5 S cm−1) is achieved at room temperature for the composition PVC–PAN–LiClO4–EC (4.8–19.2–8–68), whereas it improves two orders of magnitude (4.46 × 10−3 S cm−1) upon dispersing fine particles of TiO2 as inert filler. The role of ceramic phase is to reduce the melting temperature which is ascertained from the thermogravimetric/differential thermal analysis.