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All-solid-state sodium-ion batteries (SSSIBs) prevent leakage and fire risks associated with liquid electrolytes by using non-flammable solid electrolytes and electrodes. The primary aim of this work is to develop a NASICON type ceramic electrolyte Na3Zr2Si2PO12 (NZSP) with co-doping of Mg2+ and Sc3+ to achieve high ionic conductivity. Mg2+ doping reduces the grain–grain boundary resistance by forming conducting phase NaMgPO4 across the grain boundaries. Co-substitution of a trivalent Sc3+ at the Zr4+ site compensates for Na deficiency. As a result, the Na ion mobility through grains and grain boundaries was increased with this co-doping of aliovalent Mg2+ and Sc3+. The highest grain and grain boundary ionic conductivities (σb ∼ 1.78 × 10−3 S cm−1 and σgb ∼ 0.4 × 10−3 S cm−1) and Na ion transference number (tNa+ ∼ 0.998) have been achieved for the optimized composition of Na3.3Zr1.8Mg0.10Sc0.10Si2PO12 (NZSP-0.1MS). The NZSP-0.1MS ceramic electrolyte is further employed in quasi-solid cells; a decent discharge capacity of 91 mA h g−1 at 0.1C rate was obtained for the "Zn doped (NVZP) (cathode)‖NZSP-0.1MS‖NVZP(anode)" ceramic full cell. The NZSP-0.1MS ceramic electrolyte filler is further incorporated into the polymer–salt matrix to develop the PEO–NaTFSI/NZSP-0.1MS composite electrolyte. The all-solid-state cell comprised of composite electrode (NVZP/NZSP-0.1MS/PVDF-NaTFSI/C) and composite electrolyte PEO–NaTFSI/NZSP-0.1MS delivered a maximum discharge capacity of 105 mA h g−1 at 0.1C, at 60 °C with good rate performance and cyclic stability retaining 85% capacity over 80 cycles. The specific capacity of the catholyte‖PEO–NaTFSI/NZSP-0.1MS‖anolyte full cell has further decreased to 78 mA h g−1 with a subsequent increase in the C-rate from 0.1 to 1C. Interestingly, the capacity was restored to 97 mA h g−1 after returning to 0.1C, which suggests a better electrochemical stability of the cell components. This study presents an all solid-state sodium-ion cell exhibiting superior electrochemical performances comparable to those of NVP-based liquid electrolyte full cells, providing an avenue for developing a high-performance and safe sodium-ion battery technology. [ABSTRACT FROM AUTHOR]

Lead-free (1 − x)K0.5Na0.5NbO3–xLaScO3 (abbreviated as KNN–LSO) ceramic with (x = 0–0.10) was prepared via the solid-state synthesis route. The changes in the microstructure, crystal structure, dielectric, piezoelectric, and ferroelectric properties were analyzed for all compositions. The Rietveld refinement of powder x-ray diffraction suggested the variation in the crystal structure from orthorhombic for pure KNN to a mixed phase of tetragonal and orthorhombic for x ≥ 0.03. Temperature-dependent dielectric measurements also confirmed the change in the crystal structure with the increase in the LSO content, and the tetragonal to cubic TT-C phase transition temperature was found to shift toward room temperature. Interestingly, the temperature of the orthorhombic to tetragonal (TO-T) phase transition remained almost invariant in the LSO-doped sample (x ≥ 0.02), and a frequency dispersion in TO-T, typical for a relaxor ferroelectric, was observed. The frequency variation of temperature of the dielectric maximum Tm (∼426 K at 10 kHz and ∼444 K at 1 MHz) for x = 0.05 sample was fitted using the Vogel–Fulcher relation. This was further corroborated by the appearance of a slim hysteresis in the polarization–electric field plot. The impedance studies suggested that non-Debye relaxation and conduction mechanisms were associated with the thermal activation of oxygen vacancy that was rationalized by similar values of activation energy obtained from Arrhenius fitting for all samples. Current–voltage (I–V) measurements illustrate the reduction in room temperature DC conductivity with the increase in LSO doping. The highest room temperature piezoelectric charge coefficient (d33) value of 130 pC/N was observed for the composition corresponding to x = 0.01. [ABSTRACT FROM AUTHOR]

Quoting the abundance and cost of sodium reserve and robustly safe and high‐energy solid electrolytes, sodium solid‐state batteries (SSBs) exhibit huge promise for future energy storage applications compared to battery systems using organic liquid electrolytes and Li counterparts. However, the progress and application are still in infancy, experiencing numerous challenges for sodium SSBs due to inherent properties, interface complications, and fabrication. These are recently receiving unprecedented research attention by understanding and steadily resolving the issues associated with sodium SSBs. In this review, the governing bulk and interfacial issues and dynamics, background research correlations from Li counterparts, and strategies to address them are investigated for various ceramic‐, polymer‐, and ceramic–polymer composite based solid electrolytes. Particular attention is devoted to issues with ceramic electrolytes (such as interfacial stability, brittleness, porosity, and grain–grain boundary resistance) and polymer electrolytes (like dendrite formation, passivation layer, electrochemical instability, and ionic conductivity), and finally, robustness in overall performance and a few drawbacks (such as filler agglomeration, interface dynamics, and crack propagation) on the composited state‐of‐the‐art ceramic–polymer electrolytes are highlighted. To end with, crucial inferences and future research perspectives are condensed on the development of enhanced solid electrolytes for sodium SSBs overcoming the shortcomings illustrated for different electrolytes. [ABSTRACT FROM AUTHOR]

The present study reveals the effect of LaScO3 content on the structural, dielectric, and piezoelectric properties of perovskite structured (1 − x)(K0.5Bi0.5)TiO3–xLaScO3 (named as KBT–LSO) (x = 0–0.40) ceramics. A decrease in tetragonality and an increase in cubic phase fraction with LaScO3 doping were observed in Rietveld refinement of synchrotron X-ray diffraction (SXRD) data. Room temperature dielectric constant (εr) was found to improve in KBT–LSO solid solution. A continuous decrement in temperature of dielectric maxima (Tm) from 360 °C for x = 0.00 to 87 °C for x = 0.40 of LSO-doped KBT sample (at 1 MHz) was noticed. Highly diffuse dielectric anomaly and increasing relaxor behavior were observed with increased LSO doping content. The greater value of depolarization temperature (Td ~ 310 °C) compared to normal to relaxor ferroelectric transition (TF-R ~ 255 °C) for a 2% LSO-doped sample signifies a nonergodic relaxor state in the system. The impedance spectroscopy suggested improved DC resistivity with LSO incorporation in KBT lattice. The activation energies were obtained in the ranges 0.98 ± 0.03 eV to 1.50 ± 0.02 eV using Arrhenius equations which signifies the reduction in oxygen vacancies due to LSO doping. The current (I)–voltage (V) plot confirmed the decrement in room temperature DC conductivity (σDC) with LSO doping concentration. [ABSTRACT FROM AUTHOR]

In this work, fabrication and electrochemical behavior of polymer-in-ceramic composite electrolytes based on lithium-ion conducting triclinic LiSn2(PO4)3 (LSP) for all-solid-state batteries are reported. The composite ceramic electrolyte (CCE) was fabricated using polymeric salt (PEO+LiClO4) as a filler to the ceramic compound LSP using a simple hot-press technique. The x-ray diffraction and Fourier transform infrared spectroscopy (FTIR) studies were performed to determine the structure of the composite electrolyte. Composite electrolyte containing 30 wt.% PEO+LiClO4 exhibit the highest conductivity of ~ 3.48 × 10−5 Scm−1 at 27 °C, which improves to ~ 1.18 × 10−4 Scm−1 at 60 °C. The low activation energy calculated to be ~ 0.34 eV results from additional mobile lithium-ion in a composite electrolyte. The field emission scanning electron microscopy (FESEM) and energy-dispersive x-ray spectroscopy (EDX) reveals the Li+ diffusion route along with the 3D inter-connected LSP-(PEO+LiClO4) interfaces and distribution of polymeric salt to LSP. The ionic and Li+ transference numbers calculated by a combination of ac signal and dc polarization were found to be ~ 0.99 and ~ 0.39, respectively. The electrochemical performance of the CCE was tested using the cyclic voltammetry (CV) and galvanostatic charging-discharging (GCD) in symmetric cell employing lithium metal as the electrode. Composite electrolyte exhibited highly reversible lithium stripping/plating behavior at low current density. All-solid-state cells fabricated using LiMn2O4 as the cathode, Li metal as the anode, and the LSP-30 (PEO+LiClO4) as the solid electrolyte deliver a high specific discharge capacity of ~ 103.3 mAhg−1 at a current density of 100 μAcm−2. [ABSTRACT FROM AUTHOR]

Polycrystalline ceramics in (1 − x)K1/2Na1/2NbO3 − xCaZn1/3Ta2/3O3 (abbreviated as KNN-CZT) solid solution have been fabricated by using conventional solid-state synthesis route and the effect of CZT addition on the crystal structure, dielectric, and piezoelectric behaviour of KNN has been studied. Rietveld refinement of the room temperature X-ray diffraction data confirmed the crystal structure to be a pure perovskite phase for the compositions in the range x = 0 − 0.10. Further, the crystal structure gradually changed from orthorhombic to cubic via the formation of rhombohedral and tetragonal mixed phases with the increase in x. Raman spectroscopy suggested damping of phonon modes and a strong anharmonicity in the crystal arising due to the increased disorder in the structure as a consequence of multivalent cations occupying the A and B sites in CZT substituted compositions. Dielectric behaviour indicated the shifting of both tetragonal-cubic and orthorhombic–tetragonal phase transitions towards room temperature. The temperature dependent dielectric constant was modelled by Lorentz quadratic law, and the fitted value of diffuseness parameters confirmed an increase in diffuseness of phase transition with increasing substitution. Sample with the composition corresponding to x = 0.02 showed an improved piezoelectric coefficient d33 ~ 125 pC/N and electromechanical coupling coefficient kp ~ 30% at room temperature and d33 ~ 61 pC/N and kp ~ 24% at 300 °C which make this material a potential candidate for high-temperature piezoelectric applications. Variation of voltage coefficient (g33) with the change in compositions are also reported. Improvement in the piezoelectric properties is attributed to the reduced oxygen vacancies. [ABSTRACT FROM AUTHOR]

Lead-free ceramics based on the (1 - x )K 0.5 Na 0.5 NbO 3 - x Bi(Zn 0.5 Ti 0.5 )O 3 (KNN-BZT) system obtained via the conventional solid-state processing technique were characterized for their crystal structure, microstructure, and electrical properties. Rietveld analysis of X-ray diffraction data confirmed the formation of a stable perovskite phase for Bi(Zn 0.5 Ti 0.5 )O 3 substitutions up to 30 mol%. The crystal structure was found to transform from orthorhombic Amm 2 to cubic Pm 3̄ m through mixed rhombohedral and tetragonal phases with the increase in Bi(Zn 0.5 Ti 0.5 )O 3 content. Temperature-dependent dielectric behavior indicated an increase in diffuseness of both orthorhombic to tetragonal and tetragonal to cubic phase transitions as well as a gradual shift towards room temperature. The sample with x ≈ 0.02 exhibited a mixed rhombohedral and orthorhombic phase at room temperature. A high-temperature X-ray diffraction study confirmed the strong temperature dependence of the phase coexistence. The sample with the composition 0.98(K 0.5 Na 0.5 NbO 3 )-0.02(BiZn 0.5 Ti 0.5 O 3 ) showed an improved room temperature piezoelectric coefficient d 33 = 109 pC/N and a high Curie temperature T C = 383 °C., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)