Morphology, ionic diffusion and applicability of novel polymer gel electrolytes with LiI/I₂

Abstract

Novel polymer gel electrolytes have been prepared by incorporating LiI-I(2) solutions into a polyethylene oxide matrix supported by a TiO(2) filler. The gel electrolytes, based on either acetonitrile or propylene carbonate solvents are compared with liquid standard ones and are examined by (7)Li solid state nuclear magnetic resonance relaxometry and diffusion measurements. In parallel, the triiodide apparent diffusion coefficient has been determined by linear sweep voltammetry. The results are correlated with atomic force microscopic images of the electrolytes and give insight of the dynamic properties of the ions in the constrained polymer medium. Furthermore, the dissociation of the ions is estimated by relating the ionic conductivity to the ionic diffusion. As a prime application, the polymer gel electrolytes were incorporated in dye sensitized solar cells and the measured energy conversion efficiencies were successfully correlated with their morphological, diffusive and conducting properties.

Co-existence of LiI and KI in filler-free, quasi-solid-state electrolyte for efficient and stable dye-sensitized solar cell

“…The values of the ionic conductivities are listed in Table 2. The ionic conductivities of the pure polymer and plasticized electrolyte systems are close to those reported in literature [27,33,34]. The optimized electrolyte with 14.5% KI in the PEO/I 2 /LiI matrix gives a conductivity value of 3.0 × 10 −3 S cm −1 , which is much higher than polymer and metal salt matrix electrolytes.…”

Molecular dynamics simulation of polypyrrole film in an acetonitrile solution

“…These values are in good accordance with the experimental data of 1.8 Â 10 À5 cm 2 /s obtained from conductivity measurements by Bartel et al [33] and 0.81 Â 10 À5 cm 2 /s, measured by linear sweep voltammetry and NMR, by Kontos et al [34]. In the polymer core, values of 2.18 ± 0.30 Â 10 À6 cm 2 /s and 1.60 ± 0.34 Â 10 À6 cm 2 /s were estimated for the reduced and oxidized state respectively.…”

A Thermoplastic Gel Electrolyte for Stable Quasi‐Solid‐State Dye‐Sensitized Solar Cells

“…[7] However, the potential problems caused by liquid electrolytes, such as the leakage and volatilization of the liquid, possible desorption and photodegradation of the attached dyes, and the corrosion of the Pt counter electrode, have had the effect of limiting the long-term performance and practical use of these DSSCs. Thus, solid-state and quasi-solid-state electrolytes, such as polymer gel electrolytes, [8][9][10][11][12][13][14] organic hole conductors, [2,15,16] inorganic p-type semiconductors (CuI, CuBr, CuSCN, NiO, etc. ), [17][18][19][20][21] and polymer electrolytes, [9,[22][23][24][25][26][27] have been proposed as alternatives to the liquid electrolytes.…”

“…The first quasi-solid-state DSSC was constructed by integrating polyacrylonitrile, ethylene carbonate, propylene carbonate (PC), acetonitrile, and NaI in 1995; [28] however, the photoelectric efficiency of the cell was only 4.4 %. In subsequent efforts, many different polymer gel electrolytes have been used to construct quasi-solid-state DSSCs, [8,[11][12][13][14][29][30][31][32][33][34][35][36][37][38] and Dye-sensitized solar cells (DSSCs) are receiving considerable attention as low-cost alternatives to conventional solar cells. In DSSCs based on liquid electrolytes, a photoelectric efficiency of 11 % has been achieved, but potential problems in sealing the cells and the low long-term stability of these systems have impeded their practical use.…”