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The aging towards the ionic conductivity have been studied using of different lithium salts namely, lithium bis(oxalate)borate (LiBOB), lithium difluoro(oxalato)borate (LiDFOB), lithium fluoroalkylphosphate (LiFAP) and LiPF6 in polyvinylidenefluoride–hexafluoropropylene (PVdF–HFP) matrix. The crystallization behavior of LiBOB and LiDFOB has been noticed for the first time during storage of such membranes within the texture of PVdF–HFP matrix. At the same time, such behavior has not been observed in the case of LiFAP and LiPF6 based membranes. The growth of such crystallites would certainly hinder the mobility mechanism of Li+ ions and it has been confirmed by ionic conductivity measurements. The formation of such crystals has been validated through scanning electron microscopic studies.

Carbon-coated LiFeBO3 has been successfully synthesized by solid state reaction method at 750 °C under Ar atmosphere. Adipic acid was chosen for the source material for carbon during synthesis process. X-ray diffraction pattern confirms the formation of phase with monoclinic structure. Scanning electron microscopic study vindicates the particulate nature of the synthesized LiFeBO3 with weak agglomeration. Electrochemical impedance spectroscopy parallels the enhanced conducting properties of carbon-coated LiFeBO3 rather pristine LiFeBO3. The Li/carbon-coated LiFeBO3 and LiFeBO3 cells presented the initial discharge capacities 93 and 47 mAh/g, respectively. After few cycles, the carbon-coated LiFeBO3 exhibited stable discharge behavior (~53 mAh/g), whereas bare LiFeBO3 is concerned because poor electrochemical performance has resulted. Accepted version

This paper describes preparation and characterization of polyvinyl chloride and polyethylene glycol 2000 blend polymer electrolytes with LiX (X=ClO4−, BF4−, and CF3SO3−) salt by solution casting technique. Ethylene carbonate and propylene carbonate mixture was used as the plasticizers. LiClO4-based electrolytes exhibited better ionic conduction behavior than other salts. The thermal profiles ascertain the stability of the membranes up to 120°C by differential scanning calorimetry. Complexation and crystallinity were studied through X-ray diffraction measurements. Phase morphological study reveals the porous nature of the polymer electrolyte membranes.

Polyvinylidenefluoride-hexafluoropropylene-ba- sed (PVdF-HFP-based) gel and composite microporous membranes (GPMs and CPMs) were prepared by phase- inversion technique in the presence 10 wt% of AlO(OH)n nanoparticles. The prepared membranes were gelled with 0.5-M LiPF3(CF2CF3)3 (lithium fluoroalkylphosphate, Li- FAP) in EC:DEC (1 : 1v /v) and subjected to various char- acterizations; the AC impedance study shows that CPMs ex- hibit higher conductivity than GPMs. Mechanical stability measurements on these systems reveal that CPMs exhibit Young's modulus higher than that of bare and GPMs and addition of nanoparticles drastically improves the elonga- tion break was also noted. Transition of the host from α to β phase after the loading of nanosized filler was confirmed by XRD and Raman studies. Physico-chemical properties, like liquid uptake, porosity, surface area, and activation energy, of the membranes were calculated and results are summa- rized. Cycling performance of Li/CPM/LiFePO4 coin cell was fabricated and evaluated at C/10 rate and delivered a

The plasticized polymer electrolyte composed of polyvinylchloride (PVC) and polyvinylidene fluoride (PVdF) as host polymer, the mixture of ethylene carbonate and propylene carbonate as plasticizer, and LiCF3SO3 as a salt was studied. The effect of the PVC-to-PVdF blend ratio with the fixed plasticizer and salt content on the ionic conduction was investigated. The electrolyte films reveal a phase-separated morphology due to immiscibility of the PVC with plasticizer. Among the three blend ratios studied, 3:7 PVC–PVdF blend ratio has shown enhanced ionic conductivity of 1.47 × 10−5 S cm−1 at ambient temperature, i.e., the ionic conductivity decreased with increasing PVC-to-PVdF ratio and increased with increasing temperature. A temperature dependency on ionic conductivity obeys the Arrhenius behavior. The melting endotherms corresponding to vinylidene (VdF) crystalline phases are observed in thermal analysis. Thermal study reveals the different levels of uptake of plasticizer by VdF crystallites. The decrease in amorphousity with increase in PVC in X-ray diffraction studies and larger pore size appearance for higher content of PVC in scanning electron microscopy images support the ionic conductivity variations with increase in blend ratios.

The gel polymer electrolytes composed of the blend of polyvinylchloride (PVC) and polyvinylidene fluoride (PVdF) as host polymers, the mixture of ethylene carbonate (EC) and propylene carbonate (PC) as a plasticizer, and LiClO4 as a salt was studied. An attempt was made to investigate the effect of PVdF in the plasticized PVC + LiClO4 system in three blend ratios. The differential scanning calorimetry study confirms the formation of polymer–salt complex and miscibility of the PVC and PVdF. The X-ray diffraction results of plasticized PVC (S1, S2, S3) and PVdF-blended films (S4, S5, S6) were compared, in that an increase in PVC concentration decreases the degree of crystallinity for S1 and S3, respectively, but drastically increases for PVC (S2). The increase in PVC content has not accounted in the conductivity studies also noted. However, the blending effect of PVdF showed decreases in crystallinity homogeneously for (S6 > S5 > S4), which were reflected in ionic conductivity measurements. The surface morphology of the films were also studied by scanning electron microscope, and it corroborates the same.

Lithium bis(oxalato)borate (LiBOB) salt-based nanocomposite gel polymer blend electrolyte (PVdF/PVC) membranes have been prepared by solution casting technique for various concentrations of TiO2. The effect of anatase structure of nanosized titanium dioxide in the plasticized PVC/PVdF + LiBOB matrix has been observed in the 2:1 salt filler ratio in the impedance measurements that the conductivity is increased one order of magnitude higher than the filler-free electrolyte (1:0 salt:filler ratio). The phase morphology of this electrolyte membrane represents the appearance of the free volume sites for ionic migration.

In this manuscript, a dramatic increase in the energy density of ~ 69 Wh kg−1 and an extraordinary cycleability ~ 2000 cycles of the Li-ion hybrid electrochemical capacitors (Li-HEC) is achieved by employing tailored activated carbon (AC) of ~ 60% mesoporosity derived from coconut shells (CS). The AC is obtained by both physical and chemical hydrothermal carbonization activation process and compared to the commercial AC powders (CAC) in terms of the supercapacitance performance in single electrode configuration vs. Li. The Li-HEC is fabricated with commercially available Li4Ti5O12 anode and the coconut shell derived AC as cathode in non-aqueous medium. The present research provides a new routine for the development of high energy density Li-HEC that employs a mesoporous carbonaceous electrode derived from bio-mass precursors.