A review of conduction phenomena in Li-ion batteries

Ceramic and polymeric solid electrolytes for lithium-ion batteries

Solid-state electrolytes provide substantial improvements to safety and electrochemical stability in lithium-ion batteries when compared with conventional liquid electrolytes, which makes them a promising alternative technology for next-generation high-energy batteries. Currently, the low mobility of lithium ions in solid electrolytes limits their practical application. The ongoing research over the past few decades on dispersing of ceramic nanoparticles into polymer matrix has been proved effective to enhance ionic conductivity although it is challenging to form the efficiency networks of ionic conduction with nanoparticles. In this work, we first report that ceramic nanowire fillers can facilitate formation of such ionic conduction networks in polymer-based solid electrolyte to enhance its ionic conductivity by three orders of magnitude. Polyacrylonitrile-LiClO4 incorporated with 15 wt % Li0.33La0.557TiO3 nanowire composite electrolyte exhibits an unprecedented ionic conductivity of 2.4 × 10–4 S cm–1 at...

Ionic Conductivity Enhancement of Polymer Electrolytes with Ceramic Nanowire Fillers

A conceptual review on polymer electrolytes and ion transport models

Chitosan–NH 4 I and chitosan–NH 4 I–EC films have been prepared by solution cast technique. The sample containing 45 wt% ammonium iodide (NH 4 I) exhibited the highest room temperature conductivity of 3.7×10 −7  S cm −1 . The conductivity of the sample increased to 7.6×10 −6  S cm −1 when 40 wt% ethylene carbonate (EC) was added to the 55 wt% chitosan-45 wt% NH 4 I sample. The conductivity–temperature relationship is Arrhenian. From dielectric loss variation with frequency, the power law exponent was obtained. The temperature dependence of the power law exponent for chitosan–NH 4 I system follows the correlated barrier hopping (CBH) model while conduction mechanism of the plasticized system can be represented by the small polaron hopping (SPH) model.

Ionic conductivity by correlated barrier hopping in NH4I doped chitosan solid electrolyte

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 (e∗), dissipation factor (tan δ) and electric modulus (M∗) of the samples.

Investigation on dielectric relaxations of PVP–NH4SCN polymer electrolyte

Polymer electrolytes based on poly ( N -vinyl pyrrolidone) (PVP) and ammonium thiocyanate (NH 4 SCN) prepared by solution cast technique have been studied using X-ray diffraction (XRD), Raman and impedance spectroscopic techniques. The XRD and Raman spectra for the electrolytes indicate that the amorphous nature of PVP increases with the increase of the concentration of ammonium thiocyanate. The spectral changes in the Raman bands of the C O and the C N stretching indicate the interaction between the salt and the polymer. The conductivity analysis shows that the 20 mol% ammonium thiocyanate doped polymer electrolyte exhibits high ionic conductivity and it has been found to be 1.7×10 −4  S cm −1 , at room temperature. The ionic coordination in the polymeric electrolytes, as determined by Raman spectroscopy, has been discussed in relation to the conductance behavior.

Vibrational and impedance spectroscopic study on PVP–NH4SCN based polymer electrolytes

Conductivity and thermal behavior of proton conducting polymer electrolyte based on poly (N-vinyl pyrrolidone)

The proton-conducting polymer electrolytes based on poly (N-vinylpyrrolidone) (PVP), doped with ammonium chloride (NH4Cl) in different molar ratios, have been prepared by solution-casting technique using distilled water as solvent. The increase in 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. A shift in glass transition temperature (T
 g) of the PVP/NH4Cl electrolytes has been observed from the DSC thermograms which indicates the interaction between the polymer and the salt. From the AC impedance spectroscopic analysis, the ionic conductivity of 15 mol% NH4Cl-doped PVP polymer complex has been found to be maximum of the order of 2.51 × 10−5 Scm−1 at room temperature. The dependence of T
 g and conductivity upon salt concentration has been discussed. The linear variation of the proton conductivity of the polymer electrolytes with increasing temperature suggests the Arrhenius type thermally activated process. The activation energy calculated from the Arrhenius plot for all compositions of PVP doped with NH4Cl has been found to vary from 0.49 to 0.92 eV. The dielectric loss curves for the sample 85 mol% PVP:15 mol% NH4Cl reveal the low-frequency β relaxation peak pronounced at high temperature, and it may be caused by side group dipoles. The relaxation parameters of the electrolytes have been obtained by the study of Tanδ as a function of frequency.

C. S. Ramya

Papers

Investigation on dielectric relaxations of PVP–NH4SCN polymer electrolyte

Vibrational and impedance spectroscopic study on PVP–NH4SCN based polymer electrolytes

Conductivity and thermal behavior of proton conducting polymer electrolyte based on poly (N-vinyl pyrrolidone)

Structural, vibrational, thermal, and conductivity studies on proton-conducting polymer electrolyte based on poly (N-vinylpyrrolidone)

Structural and ionic transport properties of Li2AlZr[PO4]3