A method based on impedance spectroscopy to determine transport properties of polymer electrolytes

Abstract

In this work, we introduce a method based on impedance spectroscopy and the equations developed to evaluate, with a good degree of accuracy, the number density, mobility and diffusion coefficient of mobile ions. Nyquist plots of electrolytes based on poly(acrylonitrile) or PAN and methyl cellulose (MC) incorporated with lithium bis(oxalato)borate have been established from impedance measurements. Equivalent circuits based on a resistor and "leaky capacitor(s)" have been determined and the relevant impedance equations derived. The values of the parameters required in the equation are obtained from the Nyquist plots and the parameters that cannot be obtained from the respective plots have been obtained by trial and error in order to fit the Nyquist plots. The transport parameters are calculated using the developed equations and the results have been compared with those obtained from the broadband dielectric response (BDR) method. Finally, Fourier transform infrared (FTIR) spectroscopy has been used to verify the results obtained from the two approaches at room and elevated temperatures.

Hydrogen ion conducting starch-chitosan blend based electrolyte for application in electrochemical devices

“…The C s value of EDLC using activated carbon electrodes and polyacrylonitrile (PAN)-lithium bis(oxalate) borate (LiBOB) electrolyte with ionic mobility of 7.431 Â10 À4 cm 2 V À1 s À1 (obtained using Bandara-Mellander method) is reported to be 10-22 F g À1 [54,77]. Thus, from this comparison, it can be concluded that the higher the ionic mobility, the greater the C s value.…”

Ionic conductivity and relaxation studies in PVDF-HFP:PMMA-based gel polymer blend electrolyte with LiClO4salt

“…The complex plot shows a high frequency depressed semicircle portion which corresponds to the parallel combination of resistor R b (bulk resistor) and a constant phase element CPE1 and a low frequency spike due to the accumulation of charges (double-layer formation) at the electrolyte-electrode (blocking electrode) interface represented by constant phase element CPE2. 27 Similarly, complex impedance plot for other GPEs at 303 K for different concentrations of LiClO 4 ( Fig. 5(inset)) is fitted with equivalent circuit and fitted parameters are listed in Table 3.…”

Effect of temperature on the transport property of PVdF-HFP-MPII-PC/DME gel polymer electrolytes

“…εr is the dielectric constant of the electrolyte that can be obtained from the log εr vs. frequency plots in Fig.4. The obtained values of D were tabulated in Table 2 and were then used to calculate the number, n and mobility, μ of free ions according to equations [7]. (9) where σ is the respective conductivity and e is the electronic charge.…”

“…The n and μ can be determined quantitatively by impedance spectroscopy [5][6][7][8][9][10][11]. The obtained impedance data is analyzed by fitting it to an equivalent circuit model [12].…”