Structural,electrical, and transport number studies of AgI-doped silver borotellurite fast ion conducting glass system

Silver ion conducting glass system composed of xAgI–(100???x)[0.444 Ag₂SO₄–0.555 (0.4TeO₂–0.6B₂O₃)] has been prepared by melt quenching method for x?=?0 to 80 in step of 10. XRD, DSC, FTIR, and SEM were carried out to understand some structural properties of prepared samples. XRD and DSC studies of the samples with x?≤?60 show predominantly glassy nature. Electrical parameters and activation energies of all the samples were evaluated by complex impedance analysis and Arrhenius plots of DC conductivity, respectively. Carrier concentration, mobility, inter-ionic distance, and ionic conductivity of samples were measured and discussed. It is observed that the conductivity varies with increasing the temperature and composition. The highest conductivity (1.8?×?10^?1 S cm^?1) and ionic current (8.33 μA) is observed for =?50 sample at room temperature; hence, it can be used as best electrolyte material for solid-state battery application.     

Synthesis,refinement of the structure,and AC conductivity behavior of sodium lithium orthonavadates

The Na _x Li_1-x CdVO₄ (x = 0.5, 1) orthovanadates were prepared using a solid-state reaction method. The x-ray diffraction patterns (XRDP) of both materials reveal the formation of the Na₂CrO₄ structure. Vibrational study confirms the existence of [VO₄]^3? group. Electrical measurements of our compounds have been investigated using complex impedance spectroscopy (CIS) in the frequency and temperature range 209 Hz–1 MHz and 589–703 K, respectively. Nyquist plots reveal the presence of tow contributions, an equivalent circuit was proposed. DC conductivity shows electrical conduction in the material as a thermally activated process. The AC conductivity is explained using the non-overlapping small polaron tunneling (NSPT) conduction mechanism. A relationship between crystal structure and ionic conductivity was established and discussed.     

Transport phenomena in superionic Na<Subscript><Emphasis Type="Italic">х</Emphasis></Subscript>Cu<Subscript>2 − <Emphasis Type="Italic">х</Emphasis></Subscript>S (<Emphasis Type="Italic">х</Emphasis> = 0.05; 0.1; 0.15; 0.2) compounds

The electronic and ionic conductivity, the electronic and ionic Seebeck coefficients, and the thermal conductivity of Na _x Cu_2 ? x S (x = 0.05, 0.1, 0.15, 0.2) compounds were measured in the temperature range of 20–450 °С. The total cationic conductivity of Na_0.2Cu_1.8S is about 2 S/cm at 400 °С (the activation energy ≈ 0.21 eV). Over the studied compounds, the composition Na_0.2Cu_1.8S has the highest electronic conductivity (500–800 S/cm) in the temperature range from 20 to 300 °С, and the highest electronic Seebeck coefficient (about 0.2 mV/K) in the same temperature range is observed for Na_0.15Cu_1.85S composition; the electronic Seebeck coefficient increases abruptly above 300 °С for all compounds. The thermal conductivity of superionic Na_0.2Cu_1.8S is low, which causes high values of the dimensionless thermoelectric figure of merit ZT from 0.4 to 1 at temperatures from 150 to 340 °С.     

Properties of a gel polymer electrolyte based on lithium salt with poly(vinyl butyral)

Poly(vinyl butyral) (PVB) is of particular interest because of its low cost, extremely wide temperature work range (? 20 to 120 °C), and efficient chemical stability. In this study, a gel polymer electrolyte (GPE) containing Li⁺ ions was fabricated by using dimethylacetylamine (DMA), lithium perchlorate (LiClO₄), and PVB. The experimental results indicated that a highly transparent GPE with a high ionic conductivity (σ) could be obtained by mixing glue (DMA with a PVB content of 10 wt%) with a LiClO₄ content of 6 wt%. It was found that the ionic conductivity (σ) of the GPE depended on the LiClO₄ content, and the GPE with a LiClO₄ content of 6 wt% exhibited a maximum σ of 7.73 mS cm^?1, a viscosity coefficient of 3360 mPa s, and a transmittance greater than 89% (visible region) at room temperature. Furthermore, PVB improved the electrolyte solution leakage, and the LiClO₄ was used as an ion supply source for the high σ of the GPE.     

Effect of chromium and tellurium impurities on the thermoelectric parameters of galena

Concentration dependences of the Seebeck coefficient, resistivity, and thermal conductivity of thermoelectric PbS crystals with chromium (0 < x ≤ 0.01) and tellurium (0 < y ≤ 0.03) impurities are examined in the temperature region of 300–800 K. It is shown that the introduction of chromium increases the number of free electrons in PbCr _x S _1–x crystals and reduces the Seebeck coefficient. However, an increase in the concentration of tellurium in PbCr _x S _1–x–y Te _y alloys raises the Seebeck coefficient while simultaneously reducing the thermal conductivity. As a result, the thermoelectric efficiency of PbCr _x S _1–x–y Te _y crystals increases. The reasons for the observed effects are discussed.     

Development of a perturbed hard-sphere equation of state for pure and mixture of ionic liquids

A perturbed hard-sphere equation of state (PHS EOS) was previously proposed to present the volumetric properties of ionic liquids by employing a variable parameter β being a function of acentric factor to justify the range of vdW dispersion forces (M. M. Papari, J. Moghadasi, S. M. Hosseini, F. Akbari, J. Mol. Liq. 158 (2011) 57–60). The main aim of the present study is to revise an attractive part of the preceding EOS by re-evaluating the above-mentioned variable parameter as well as the repulsive term. Two temperature-dependent parameters appearing in the revisited EOS have been determined from the corresponding states correlations using the interfacial properties of ILs, i.e., surface tension and liquid density, both at room temperature. The revisited EOS has been employed to model the volumetric properties of ionic liquids (ILs). The predictive power of the proposed model has been assessed by comparing the results obtained with 2189 experimental data points related to 24 ILs over a broad range of pressures and temperatures. The overall average absolute deviation (AAD) of the calculated densities from literature data was found to be 0.62 %. Furthermore, the revisited PHS EOS has been employed to model the volumetric properties of 23 mixtures including IL + IL and IL+ solvent over the vast range of temperatures. From 1580 data points of the binary mixtures of interest, the AAD of the correlated densities from the measurements was found to be 0.47 %.     

Enhanced Conductivity and High Thermal Stability of W-Doped SnO<Subscript>2</Subscript> Based on First-Principle Calculations

Tungsten (W)-doped SnO₂ is investigated by first-principle calculations, with a view to understand the effect of doping on the lattice structure, thermal stability, conductivity, and optical transparency. Due to the slight difference in ionic radius as well as high thermal and chemical compatibility between the native element and the heterogeneous dopant, the doped system changes a little with different deviations in the lattice constant from Vegard’s law, and good thermal stability is observed as the doping level reaches x = 0.125 in Sn_1-x W _x O₂ compounds. Nevertheless, the large disparities in electron configuration and electronegativity between W and Sn atoms will dramatically modify the electronic structure and charge distribution of W-doped SnO₂, leading to a remarkable enhancement of conductivity, electron excitation in the low energy region, and the consequent optical properties, while the visible transparency of Sn_1-x W _x O₂ is still preserved. Particularly, it is found that the optimal photoelectric properties of W-doped SnO₂ may be achieved at x = 0.03. These observations are consistent with the experimental results available on the structural, thermal, electronic, and optical properties of Sn_1-x W _x O₂, thus presenting a practical way of tailoring the physical behaviors of SnO₂ through the doping technique.     

Thermophysical properties of ionic liquids and their mixtures from a new equation of state

In our previous work, a perturbed hard-trimer-sphere equation of state (PHTS EOS) was developed for modeling the phase equilibria of pure ionic liquids (ILs) (M.M. Alavianmehr et al., Ionics 22 (2016) 2447–2459). In this work, we have successfully extended the model to the mixtures of IL + IL and IL + solvent. Two temperature-dependent parameters appearing in the EOS are correlated with two microscopic scaling constants σ, the effective hard-sphere diameter, and ε, the non-bonded interaction energy. The overall average absolute deviation (AAD) of the estimated densities from the literature data using the proposed model with and without non-additivity parameter (λ _ij) was found to be 0.44 and 0.79%, respectively. A modified Enskog equation and rough hard-sphere (RHS) theory are combined with our proposed equation of state to calculate the viscosity coefficient of ionic liquids and their mixtures. Finally, from the results obtained, a linear relation between logarithm of surface tension and viscosity property of ionic liquid was developed.     

Electrical conductivity of biphasic mixtures of molten silver iodide and lithium fluoride,chloride, and bromide

The electrical conductivity (EC) method was used for the biphasic systems of AgI with LiF, LiCl, or LiBr. The difference between the magnitudes of the conductivities for the equilibrium phases of the LiCl+AgI and LiBr+AgI melts decreases with an increase in temperature, becoming zero at 1250 and 983 K. For these temperatures, the values of critical conductivity are κ _c  = 4.70 S cm^?1 and κ _c  = 3.90 S cm^?1, respectively. The melt containing lithium fluoride exists in two phases up to a temperature of 1245 K. The temperature dependence of the differences between the conductivities for the coexisting phases is described as an exponential equation, with the critical exponent 0.89. This value is 11% less than that found for alkali halide melts. The covalent bonding between the silver and halide ions can be understood as causing the difference between the critical exponents of the alkali halide melts and those of silver iodide-containing mixtures.     

Biodegradable poly <Emphasis>(</Emphasis>ε<Emphasis>-</Emphasis>caprolactone<Emphasis>)/</Emphasis>lithium bis<Emphasis>(</Emphasis>trifluoromethanesulfonyl<Emphasis>)</Emphasis> imide as gel polymer electrolyte

Poor conductivity and toxic technological garbage of polymer electrolyte has delayed energy storage application in electric vehicles. Biodegradable gel polymer electrolytes (GPEs) based on poly (ε-caprolactone) (PCL) are prepared. PCL is used to immobilize liquid electrolyte containing lithium bis(trifluoromethanesulfonyl) imide, ethylene carbonate, and propylene carbonate. Impedance spectroscopy, X-ray diffraction, and differential scanning calorimetry are used to characterize the ionic conductivity and structural and thermal properties of GPEs, respectively. For jelly-like GPEs, it exhibits liquid-like ionic conductivity of 1.69 × 10^?3 S cm^?1 at room temperature with a composition ratio (PCL:LiTFSI:EC:PC) of (22.5:7.5:35:35) (w/w). Results show that the polymer matrix forms cross-linked network within the liquid electrolyte, acting like an adhesive to hold the high fluidity liquid molecules. In temperature dependence studies, the GPEs are observed to obey Arrhenius equation indicating that ion transport occurs via hopping mechanism. The findings in XRD and DSC are in good agreement with conductivity results.     

Experimental and theoretical study of AC electrical conduction mechanisms by NSPT model of LiNa<Subscript>3-x</Subscript>Ag<Subscript>x</Subscript>P<Subscript>2</Subscript>O<Subscript>7</Subscript> (<Emphasis Type="Italic">x</Emphasis> = 0.2 and 0.6) ceramic compounds

New pyrophosphate of ceramic compounds LiNa_3-xAg_xP₂O₇ (x = 0.2 and 0.6) is synthesized by a solid-state method. All the compounds crystallize in the orthorhombic lattice with space group C222₁. The infrared spectra of these compounds show characteristic bands due to a P₂O₇ group. The two semicircles observed in the complex impedance identify the presence of the grain interior and grain boundary contributions to the electrical response in these materials. The frequency independent conductivity of these compounds shows Arrhenius-type behavior. The activation energies have been calculated at the levels of impedance, electric modulus studies, and DC conductivity which suggest that the conductions are ionic in nature. The conductivity increases with an increase in Ag substitution. In order to determine the conduction mechanism, the AC conductivity and its frequency exponent have been analyzed in this work by a theoretical model based on quantum mechanical tunneling: the non-overlapping small polaron tunneling model (NSPT) is confirmed for x = 0.2 and x = 0.6. The conduction mechanism is studied with the help of Elliot’s theory, and the Elliot’s parameters are determined.     

Study on ionic conductivity and dielectric properties of PEO-based solid nanocomposite polymer electrolytes

The ionic conductivity and dielectric properties of the solid nanocomposite polymer electrolytes formed by dispersing a low particle-sized TiO₂ ceramic filler in a poly (ethylene oxide) (PEO)-AgNO₃ matrix are presented and discussed. The solid nanocomposite polymer electrolytes are prepared by hot press method. The optimum conducting solid polymer electrolyte of polymer PEO and salt AgNO₃ is used as host matrix and TiO₂ as filler. From the filler concentration-dependent conductivity study, the maximum ionic conductivity at room temperature is obtained for 10 wt% of TiO₂. The real part of impedance (Z′) and imaginary part of impedance (Z″) are analyzed using an LCR meter. The dielectric properties of the highest conducting solid polymer electrolyte are analyzed using dielectric permittivity (ε′), dielectric loss (ε″), loss tangent (tan δ), real part of the electric modulus (M′), and imaginary part of the electric modulus (M″). It is observed that the dielectric constant (ε′) increases sharply towards the lower frequencies due to the electrode polarization effect. The maxima of the loss tangent (tan δ) shift towards higher frequencies with increasing temperature. The peaks observed in the imaginary part of the electric modulus (M″) due to conductivity relaxation shows that the material is ionic conductor. The enhancement in ionic conductivity is observed when nanosized TiO₂ is added into the solid polymer electrolyte.     

High-temperature complex impedance and modulus spectroscopic studies of doped Na<Subscript>0.5</Subscript>Bi<Subscript>0.5</Subscript>TiO<Subscript>3</Subscript>-BaTiO<Subscript>3</Subscript> ferroelectric ceramics

Lead-free Na_0.5Bi_0.5TiO₃ (NBT) and (1 ? x)Na_0.5Bi_0.5TiO₃ + xBaTiO₃ with x = 0.1 and 0.2 (where x = 0.1 and 0.2 are named as NBT1 and NBT2, respectively), (1 ? y)Na_0.5Bi_0.5TiO₃ + yBa_0.925Nd_0.05TiO₃ with y = 0.1 and 0.2 (where y = 0.1 and 0.2 are named as NBT3 and NBT4, respectively)-based relaxor ferroelectric ceramics were prepared using the sol-gel method. The crystal structure was investigated by X-ray diffraction (XRD) at room temperature (RT). The XRD patterns confirmed the presence of the rhombohedral phase in all the samples. The electrical properties of the present NBT-based samples were investigated by complex impedance and the modulus spectroscopy technique in the temperature range of RT–600 °C. The AC conductivity was found to increase with the substitution of Ba²⁺ ions to the NBT sample whereas it significantly decreased with the addition of Nd³⁺ ions. The more anion vacancies in Ba-added samples and the lower anion vacancies in Nd-added samples were found to be responsible for higher and lower conductivities, respectively.     

Agglomeration behavior of lipid-capped gold nanoparticles

The current investigation deciphers aggregation pattern of gold nanoparticles (AuNPs) and lipid-treated AuNPs when subjected to aqueous sodium chloride solution with increasing ionic strengths (100–400 nM). AuNPs were synthesized using 0.29 mM chloroauric acid and by varying the concentrations of trisodium citrate (AuNP1 1.55 mM, AuNP2 3.1 mM) and silver nitrate (AuNP3 5.3 μM, AuNP4 10.6 μM) with characteristic LSPR peaks in the range of 525–533 nm. TEM analysis revealed AuNPs to be predominantly faceted nanocrystals with the average size of AuNP1 to be 35?±?5 nm, AuNP2 15?±?5 nm, AuNP3 30?±?5 nm, and AuNP4 30?±?5 nm and the zeta-average for AuNPs were calculated to be 31.23, 63.80, 26.08, and 28 nm respectively. Induced aggregation was observed within 10 s in all synthesized AuNPs while lipid-treated AuNP2 (AuNP2-L) was found to withstand ionic interferences at all concentration levels. However, lipid-treated AuNPs synthesized using silver nitrate and 1.55 mM trisodium citrate (AuNP3, AuNP4) showed much lower stability. The zeta potential values of lipid-treated AuNPs (AuNP1-L-1x/200, ??17.93?±?1.02 mV; AuNP2-L-1x/200, ??21.63?±?0.70; AuNP3-L-1x/200, ??14.54?±?0.90; AuNP3-L-1x/200 ??13.77?±?0.83) justified these observations. To summarize, AuNP1 and AuNP2 treated with lipid mixture 1 equals or above 1x/200 or 1x/1000 respectively showed strong resistance against ionic interferences (up to 400 mM NaCl). Use of lipid mixture 1 for obtaining highly stable AuNPs also provided functional arms of various lengths which can be used for covalent coupling.

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Graphical abstract Agglomeration behavior of gold nanoparticles before and after lipid capping

     

A novel and shortcut method to prepare ionic liquid gel polymer electrolyte membranes for lithium-ion battery

The ionic liquid polymer electrolyte (IL-PE) membrane is prepared by ultraviolet (UV) cross-linking technology with polyurethane acrylate (PUA), methyl methacrylate (MMA), ionic liquid (Py₁₃TFSI), lithium salt (LiTFSI), ethylene glycol dimethacrylate (EGDMA), and benzoyl peroxide (BPO). N-methyl-N-propyl pyrrolidinium bis(trifluoromethanesulfonyl)imide (Py₁₃TFSI) ionic liquid is synthesized by mixing N-methyl-N-propyl pyrrolidinium bromide (Py₁₃Br) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). The addition of Py₁₃TFSI to polymer electrolyte membranes leads to network structures by the chain cross-linking. The resultant electrolyte membranes display the room temperature ionic conductivity of 1.37 × 10^?3 S cm^?1 and the lithium ions transference number of 0.22. The electrochemical stability window of IL-PE is about 4.8 V (vs. Li⁺/Li), indicating sufficient electrochemical stability. The interfacial resistances between the IL-PE and the electrodes have the less change after 10 cycles than before 10 cycles. IL-PE has better compatibility with the LiFePO₄ electrode and the Li electrode after 10 cycles. The first discharge performance of Li/IL-PE/LiFePO₄ half-cell shows a capacity of 151.9 mAh g^?1 and coulombic efficiency of 87.9%. The discharge capacity is 131.9 mAh g^?1 with 95.5% coulombic efficiency after 80 cycles. Therefore, the battery using the IL-PE exhibits a good cycle and rate performance.     

Metallic-like conductivity of asymmetric <Emphasis Type="Italic">p</Emphasis>-In<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Ga<Subscript>1 − <Emphasis Type="Italic">x</Emphasis></Subscript>As quantum wells

The temperature dependence of the conductivity of the two-dimensional hole gas in an asymmetric GaAs/In _x Ga_{1 ? x} As/GaAs quantum well has been investigated. It is shown that fast spin relaxation leads to metallic-like behavior of the temperature dependence of the conductivity.     

Poly(ethylene glycol)/poly(2-acrylamido-2-methyl-1-propane sulfonic acid) gel electrolytes: a detailed investigation of their conductivity and characterization

Poly(ethylene glycol)/poly(2-acrylamido-2-methyl-1-propane sulfonic acid) (PEG/PAMPS) with a transparent appearance were prepared in the presence of ammonium persulfate (APS) as an initiator at 70 °C for 24 h. PEG/PAMPS-based polymer gel electrolytes in a motionless and uniform state were obtained by adding the required amount of liquid electrolytes to a dry PEG/PAMPS polymer. Liquid electrolytes include organic solvents with high boiling points (-1-methyl-2-pyrrolidone (NMP) and γ-butyrolactone (GBL)) and a redox couple (alkali metal iodide salt/iodine). The optimized conditions for PEG/PAMPS-based gel electrolytes based on the salt type, the concentration of alkali metal iodide salt/iodine, and solvent volume ratio were determined to be NaI, 0.4 M NaI/0.04 M I₂, and NMP:GBL (7:3, v/v), respectively. The highest ionic conductivity and the liquid electrolyte absorbency were 2.58 mS cm^?1 and 3.6 g g^?1 at 25 °C, respectively. The ion transport mechanism in both the polymer gel electrolytes and liquid electrolytes is investigated extensively, and their best fits with respect to the temperature dependence of the ionic conductivity are determined with the Arrhenius equation.     

Ion dynamics in methylcellulose–LiBOB solid polymer electrolytes

A polymer electrolyte system comprising methylcellulose (MC) as the host polymer and lithium bis(oxalato) borate (LiBOB) as the lithium ion source has been prepared via the solution cast technique. The electrolyte with the highest conductivity of 2.79 μS cm^?1 has a composition of 75 wt% MC–25 wt% LiBOB. The mobile ion concentration (n) in this sample was estimated to be 5.70?×?10²⁰ cm^?3. A good correlation between ionic conductivity, dielectric constant, and free ion concentration has been observed. The ratio of mobile ion number density (n) at a particular temperature to the concentration n ₀ of free ions at T?=?∞ (n/n ₀) and the power law exponents (s) exhibit opposite trends when varied with salt concentration.     

Polymer electrolytes based on vinyl ethers with various EO chain length and their polymer electrolytes cross-linked by electron beam irradiation

Polymer electrolytes based on vinyl ethers with various ethyleneoxy (EO) chain length (poly-1a (m?=?3), poly-1b (m?=?6), poly-1c (m?=?10), and poly-1d (m?=?23.5)) with lithium bis(trifluoromethanesulfonimide) (LiTFSI) were prepared, and effect of pendant EO chain length in the polymers on electrochemical and thermal properties was investigated. Glass transition temperature (T _g) of all polymer electrolytes increased linearly with an increase in salt concentrations. Ionic conductivities of the polymer electrolytes increased with an increase in the pendant EO chain length of the polymers at the constant [Li]/[O] ratio, but in the polymer electrolyte of the poly-1d (m?=?23.5) with the longest pendant EO chain length, ionic conductivity decreased in the low temperature range of ?20 to 10 °C due to the crystallization of the pendant EO chain. The highest ionic conductivity, 1.23?×?10^?4 S/cm at 30 °C, was obtained in the polymer electrolyte of the poly-1c (m?=?10) with pendant EO chain length of 10 at the [Li]/[O] ratio of 1/20. It was found that the cross-linking of the polymer electrolyte, composed of poly-1c (m?=?10) with LiTFSI at the [Li]/[O] ratio of 1/28, by electron beam (EB) irradiation may improve the mechanical property without affecting ionic conductivity, thermal property, and oxidation stability. Polymer electrolytes based on poly-1a (m?=?3), poly-1b (m?=?6), poly-1c (m?=?10), and poly-1d (m?=?23.5) and cross-linked polymer electrolytes were electrochemically stable until 4 V and thermally stable around 300 °C.     

The role of zirconium oxide as nano-filler on the conductivity,morphology, and thermal stability of poly(methyl methacrylate)–poly(styrene-co-acrylonitrile)-based plasticized composite solid polymer electrolytes

The plasticized composite solid polymer electrolytes (CSPE) involving polymer blends poly(methyl methacrylate)-poly(styrene-co-acrylonitrile) (PMMA-SAN), plasticizers ethylene carbonate (EC), and propylene carbonate (PC) with lithium triflate (LiCF₃SO₃) as salt and varying concentration of composite nano-filler zirconium oxide (ZrO₂) is prepared by solution casting technique using THF as solvent. The powder X-ray diffraction (XRD) studies reveal amorphous nature of the CSPE samples. Fourier transform infrared (FT-IR) spectroscopy studies reveal interaction of Li⁺ ion with plasticizers, both C=O and OCH₃ group of the PMMA, while nitrile group of SAN is inert. AC impedance and dielectric studies reveal that the ionic conductivity (σ), dielectric constant (ε’), and dielectric loss (ε”) of the prepared CSPE samples increase with increasing content of ZrO₂ nano-filler up to 6 wt% and decrease with further additions. The temperature dependence of ionic conductivity follows Arrhenius relation and indicates ion-hopping mechanism. The sample Z2 (6 wt% ZrO₂) with relaxation time τ of 8.13?×?10^–7 s possess lowest activation energy (E_a?=?0.23 eV) and highest conductivity (2.32?×?10^–4 S cm^?1) at room temperature. Thermogravimetric analysis (TGA) reveals thermal stability of highest conducting sample Z2 up to 321 °C after complete removal of residual solvent, moisture, and its impurities. Differential scanning calorimetric (DSC) studies reveal absence of glass transition temperature (T_g) corresponding to atactic PMMA for the CSPE Z2, while isotactic PMMA component shows T_g around 70 °C, which is due to increased interaction of filler with PMMA leading to change in its tacticity. Scanning electron microscopy (SEM) analysis reveals blending of PMMA/SAN polymers and lithium triflate salt. The incorporation of nano-filler ZrO₂ leads to change in surface topology of polymer matrix. Rough surface of the CSPE Z2 leads to new pathway for ionic conduction leading to maximum ionic conductivity.