Polyvinyl alcohol (PVA)–polyethylene glycol (PEG) based solid polymer blend electrolytes with magnesium nitrate have been prepared by the solution cast technique. Impedance spectroscopic technique has been used, to characterize these polymer electrolytes. Complex impedance analysis was used to calculate bulk resistance of the polymer electrolytes. The a.c.-impedance data reveal that the ionic conductivity of PVA–PEG–Mg(NO₃)₂ system is changed with the concentration of magnesium nitrate, maximum conductivity of 9.63 × 10^-5 S/cm at room temperature was observed for the system of PVA–PEG–Mg(NO₃)₂ (35–35–30). However, ionic conductivity of the above system increased with the increase of temperature, and the highest conductivity of 1.71 × 10^-3 S/cm was observed at 100°C. The effect of ionic conductivity of polymer blend electrolytes was measured by varying the temperature ranging from 303 to 373 K. The variation of imaginary and real parts of dielectric constant with frequency was studied.

Composite polymer electrolytes based on poly(ethylene glycol) (PEG), magnesium acetate [Mg(CH₃COO)₂], and 𝑥 wt% of cerium oxide (CeO₂) ceramic fillers (where 𝑥 = 0, 5, 10, 15 and 20, respectively) have been prepared using solution casting technique. X-ray diffraction patterns of PEG–Mg(CH₃COO)₂ with CeO₂ ceramic filler indicated the decrease in the degree of crystallinity with increasing concentration of the filler. DSC measurements of PEG–Mg(CH₃COO)₂-CeO₂ composite polymer electrolyte system showed that the melting temperature is shifted towards the lower temperature with increase of the filler concentration. The conductivity results indicate that the incorporation of ceramic filler up to a certain concentration (i.e. 15 wt%) increases the ionic conductivity and upon further addition the conductivity decreases. The transference number data indicated the dominance of ion-type charge transport in these specimens. Using this (PEG–Mg(CH₃COO)₂-CeO₂) (85-15-15) electrolyte, solid-state electrochemical cell was fabricated and their discharge profiles were studied under a constant load of 100 k𝛺.

Polyvinylidenefluoride (PVDF)-based nanocomposite polymer electrolyte (NCPE) thin films for electrochemical applications have been synthesized by solution cast technique. NCPEs have 70PVDF:30Mg(NO$_3$)$_2$ solid polymer electrolyte (SPE) with conductivity ${\sim}$7.3 9 10$^{–8}$ S cm$^{–1}$ as phase-I and various nanoparticles as phase-II, dispersed in SPE for enhancement in its conductivity. These NCPE films were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and impedance spectroscopic techniques to study the structural and electrical properties. XRD and FTIR studies of film confirms formation of complexes. From composition and temperature dependence of conductivity analysis, we have obtained an optimum conducting composition of NCPE, i.e.,70PVDF:30Mg(NO$_3$)$_2$:3ZnO with conductivity ${\sigma}$ = 3.7 9 10$^{–4}$ S cm$^{–1}$. Ionic transport number (t$_{ion}$ = 0.99) have been calculated from Wagner’s dc polarization technique. Electrochemical cell has been fabricated using cell configuration Mg|NCPE|carbon cell and various cell parameters have been calculated from their discharge characteristics.

Inorganic solid electrolyte materials have great potential to overcome the issues of conventionally used organic liquid electrolyte materials in lithium ion batteries. Garnet-structured Li$_7$La$_3$Zr$_2$O$_{12}$ based solid electrolyte materials having high ionic conductivity, good thermal and electrochemical stability and most importantly excellent stability with respect to lithium metal anode seems to be the most promising candidate to be applied in all solid-state lithium ion batteries. Garnet-structured electrolyte materials synthesized by conventional solid-state reaction method requires intermittent grinding and calcination steps along with sufficiently high temperature and long time for sintering. A significant amount of lithium is lost during this lengthy synthesis process, resulting in lower ionic conductivity and bulk density. Since these two factors play the most important role in the performance of an electrolyte, therefore, some other synthesis methods are required, which help in enhancing the performance of Li$_7$La$_3$Zr$_2$O$_{12}$ based electrolytes and also are easy to operate, ecofriendly and cost effective. Here an overview of the various synthesis methods has been provided and their feasibility for Li$_7$La$_3$Zr$_2$O$_{12}$ based solid electrolyte material preparation, in the context of their ionic conductivity enhancement and commercial applicability have been reviewed.

Cubic spinel LiMn$_2$O$_4$ (LMO) nanomaterial was synthesized by the solid-state method via double-step calcinations process, and AlPO$_4$ (AlP) nano-layer is used to modify the spinel LiMn$_2$O$_4$ (LMO) electrode material, which was manufactured using a chemical deposition solution process. The cubic spinel crystal structure of LiMn$_2$O$_4$ wrapped by the AlPO$_4$ layer was verified by structural analysis (XRD) and morphological analysis (FESEM and HRTEM). TEM result indicates that the AlPO$_4$ nano-layer does not affect the bulk structure of pristine LiMn$_2$O$_4$ material. The electrochemical results demonstrated that the AlPO$_4$-wrapped LiMn$_2$O$_4$ (AlP-LMO) cathode can still deliver its initial discharge capacity of 147.6 mAh g$^{-1}$, whereas the pristine LiMn$_2$O$_4$ cathode has an initial discharge capacity of 116.4 mAh g$^{-1}$ at 0.5 C rate. AlPO$_4$ nano coating can effectively prevent the increase of the charge transfer resistance during charge–discharge process and improve the electrochemical performance of AlP-LMO electrode due to the protective nature of AlPO$_4$ nano-layer.