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All-solid-state batteries with a lithium negative electrode and a ceramic electrolyte are key toward high energy density. To ensure a safe, fast, accurate, and cost-effective development of this technology, the experimental methodology must be supported by the numerical modeling approach. This work proposes and describes an electrochemical model of a Li7La3Zr2O12 (LLZO) and Ni-rich NMC-based lithium cell with a deformable lithium negative electrode. Simulations were computed using the finite element method at different operating conditions to demonstrate the scope of the modeling work. Discharge rate tests, deformation tracking, geometric defect investigation, and polarization decomposition are described. Theoretical validation of the mass balance, the stripping rate, the ohmic polarization, and the mesh deformation demonstrated the consistency of the volumetric deformation strategy. We demonstrated in this study a deformable modeling strategy, which was found to be useful for the electrostripping analysis of anodic geometry defects during discharge. Non-uniformity in the lithium stripping rate was found along the anodic interface with defects, and this non-uniformity was accentuated with a higher discharge rate. The cell's discharge potential was decomposed by considering the equilibrium potential and the polarizations of the main components of the cell. This post-processing was found to be useful for the understanding of the cell's behavior. [ABSTRACT FROM AUTHOR]

Abstract Li7-xLa3Zr2-xO12-Tax (x =0, 0.1, 0.2, 0.3) nanostructured powders were successfully synthesized using an innovative wet chemical route via spray pyrolysis technique at 800 °C for 10 seconds, followed by post heat treatment at 800 °C for 30 minutes in a muffle furnace. X-ray diffraction (XRD) analysis confirmed that Ta-doping increased the cubic phase up to 99%. Scanning Electron Microscopy (SEM) showed spherical particles with sizes ranging from slightly below 200 nm to 3 µm. The powders were then pressed at 50 MPa and sintered at 850 °C for 7 minutes using Spark Plasma Sintering, followed by post heat-treatment at 900 °C for 2 hours in a muffle furnace. XRD indicated the majority predominance of the garnet cubic phase, and SEM images showed coalescence and longitudinal growth of the particles, forming layers inside the samples. This study reports a fast synthesis and sintering method to obtain cubic garnet crystalline structure in contrast to conventional methods that are widely used and published in the literature, which require longer parameters in the synthesis stages (~24 hours) and sintering stages (over 12 hours).

Solid polymer and perovskite-type ceramic electrolytes have both shown promise in advancing solid-state lithium metal batteries. Despite their favorable interfacial stability against lithium metal, polymer electrolytes face issues due to their low ionic conductivity and poor mechanical strength. Highly conductive and mechanically robust ceramics, on the other hand, cannot physically remain in contact with redox-active particles that expand and contract during charge-discharge cycles unless excessive pressures are used. To overcome the disadvantages of each material, polymer-ceramic composites can be formed; however, depletion interactions will always lead to aggregation of the ceramic particles if a homopolymer above its melting temperature is used. In this study, we incorporate Li0.33La0.56TiO3 (LLTO) nanoparticles into a block copolymer, polystyrene-b-poly (ethylene oxide) (SEO), to develop a polymer-composite electrolyte (SEO-LLTO). TEMs of the same nanoparticles in polyethylene oxide (PEO) show highly aggregated particles whereas a significant fraction of the nanoparticles are dispersed within the PEO-rich lamellae of the SEO-LLTO electrolyte. We use synchrotron hard x-ray microtomography to study the cell failure and interfacial stability of SEO-LLTO in cycled lithium-lithium symmetric cells. Three-dimensional tomograms reveal the formation of large globular lithium structures in the vicinity of the LLTO aggregates. Encasing the SEO-LLTO between layers of SEO to form a "sandwich" electrolyte, we prevent direct contact of LLTO with lithium metal, which allows for the passage of seven-fold higher current densities without signatures of lithium deposition around LLTO. We posit that eliminating particle clustering and direct contact of LLTO and lithium metal through dry processing techniques is crucial to enabling composite electrolytes.

The need to develop safe solid-state lithium batteries has stimulated intense research efforts for Li+ solid electrolytes. However, the low conductivity limits the development of NASICON LiZr 2 (PO 4) 3 (LZP) electrolyte. Here, the doping effects of Ta on the structure, surface morphologies and electrochemical properties of Li 1- x Zr 2- x Ta x (PO 4) 3 (LZTP, x = 0, 0.01, 0.02, 0.04, 0.06 and 0.08) solid electrolyte were analyzed. LZTP was prepared using a simple solid-state reaction route, followed by sintering at 1200 °C for 12 h. A proper content of Ta5+ substitution for Zr4+ is beneficial to stabilize the high conductive rhombohedral (α) phase of LZP at room temperature. Doping Ta5+ is conducive to unblocking of Li+ at the M1 site and facilitates the occupation of Li+ at the M2 site, thereby expanding the pathway for Li+ conduction. Rietveld refinement data demonstrated that the Zr–O and P–O bond lengths (d Zr-O and d P-O) increased with a decrease in Zr–O–P bond angles (θ Zr-O-P) as x rose. The distortions in the ZrO 6 octahedron may weaken the coulomb attraction in Li+-O2-, resulting in a lower activation energy (E a) and a higher Li+ conductivity. The highest room-temperature conductivity (6.06 × 10−5 S cm−1) was obtained at x = 0.06, which reached 1.5 × 10−4 S cm−1 at 50 °C. The E a was found to decrease from 0.388 eV (x = 0) to 0.306 eV (x = 0.06). In addition, Ta doping resulted in improved connectivity and reduced pore formation, which also contributed to the decrease in resistance. The Raman spectrum demonstrated that some phonon modes of bending vibration in PO 4 were degenerate and external modes became too weak to be observed or even disappeared as Ta content increased. This change in the modes also had an impact on the Li+ conductivity. Overall, the LZTP-0.06 appears to be a promising candidate for the solid electrolyte. [ABSTRACT FROM AUTHOR]

Current Li battery technology employs graphite anode and flammable organic liquid electrolytes. Thus, the current Li battery is always facing the problems of low energy density and safety. Additionally, the sustainable supply of Li due to the scarce abundance of Li sources is another problem. An all-solid-state Mg battery is expected to solve the problems owing to non-flammable solid-state electrolytes, high capacity/safety of divalent Mg metal anode and high abundance of Mg sources; therefore, solid-state electrolytes and all-solid-state Mg batteries have been researched intensively last two decades. However, the realization of all-solid-state Mg batteries is still far off. In this article, we review the recent research progress on all-solid-state Mg batteries so that researchers can pursue recent research trends of an all-solid-state Mg battery. At first, the solid-state electrolyte research is described briefly in the categories of inorganic, organic and inorganic/organic composite electrolytes. After that, the recent research progress of all-solid-state Mg batteries is summarized and analyzed. To help readers, we tabulate electrode materials, experimental conditions and performances of an all-solid-state Mg battery so that the readers can find the necessary information at a glance. In the last, challenges to realize the all-solid-state Mg batteries are visited. [ABSTRACT FROM AUTHOR]

[Display omitted] Lithium metal solid state batteries (LMSSB) attract great interest in academia and industry due to their projected high energy density and safety. However, hard short circuits due to the penetration of lithium filaments through the solid electrolyte impede their development for practical application. Here, multi-characterization methods ranging from operando and in situ scanning electron microscopy to ex situ focused ion beam scanning electron microscopy are employed for comprehensive understanding of the cell failure. The rapid failure is attributed to coupled crack propagation and subsequent lithium filament growth during the plating process which is demonstrated in a Li 6 PS 5 Cl (lithium argyrodite) based LMSSB. Cracking initiates at current constriction spots and voids, where inhomogeneous lithium plating/stripping causes high local stress fields that trigger continuous crack propagation. Lithium filament growth finally leads to a hard short circuit. Considering the low fracture toughness of ceramic electrolytes, strengthening with Al 2 O 3 fibers is shown to be effective in significantly improving the critical current density and cycling stability. Our results clearly show that cracks can have a detrimental effect on LMSSB and we suggest focusing on strategies to improve the fracture toughness of thiophosphate electrolytes in order to suppress lithium filament growth. [ABSTRACT FROM AUTHOR]

All-solid-state batteries with a lithium negative electrode and a ceramic electrolyte are key toward high energy density. To ensure a safe, fast, accurate, and cost-effective development of this technology, the experimental methodology must be supported by the numerical modeling approach. This work proposes and describes an electrochemical model of a Li7La3Zr2O12 (LLZO) and Ni-rich NMC-based lithium cell with a deformable lithium negative electrode. Simulations were computed using the finite element method at different operating conditions to demonstrate the scope of the modeling work. Discharge rate tests, deformation tracking, geometric defect investigation, and polarization decomposition are described. Theoretical validation of the mass balance, the stripping rate, the ohmic polarization, and the mesh deformation demonstrated the consistency of the volumetric deformation strategy. We demonstrated in this study a deformable modeling strategy, which was found to be useful for the electrostripping analysis of anodic geometry defects during discharge. Non-uniformity in the lithium stripping rate was found along the anodic interface with defects, and this non-uniformity was accentuated with a higher discharge rate. The cell’s discharge potential was decomposed by considering the equilibrium potential and the polarizations of the main components of the cell. This post-processing was found to be useful for the understanding of the cell’s behavior.

Solid polymer and perovskite-type ceramic electrolytes have both shown promise in advancing solid-state lithium metal batteries. Despite their favorable interfacial stability against lithium metal, polymer electrolytes face issues due to their low ionic conductivity and poor mechanical strength. Highly conductive and mechanically robust ceramics, on the other hand, cannot physically remain in contact with redox-active particles that expand and contract during charge-discharge cycles unless excessive pressures are used. To overcome the disadvantages of each material, polymer-ceramic composites can be formed; however, depletion interactions will always lead to aggregation of the ceramic particles if a homopolymer above its melting temperature is used. In this study, we incorporate Li0.33La0.56TiO3 (LLTO) nanoparticles into a block copolymer, polystyrene-b-poly (ethylene oxide) (SEO), to develop a polymer-composite electrolyte (SEO-LLTO). TEMs of the same nanoparticles in polyethylene oxide (PEO) show highly aggregated particles whereas a significant fraction of the nanoparticles are dispersed within the PEO-rich lamellae of the SEO-LLTO electrolyte. We use synchrotron hard x-ray microtomography to study the cell failure and interfacial stability of SEO-LLTO in cycled lithium-lithium symmetric cells. Three-dimensional tomograms reveal the formation of large globular lithium structures in the vicinity of the LLTO aggregates. Encasing the SEO-LLTO between layers of SEO to form a “sandwich” electrolyte, we prevent direct contact of LLTO with lithium metal, which allows for the passage of seven-fold higher current densities without signatures of lithium deposition around LLTO. We posit that eliminating particle clustering and direct contact of LLTO and lithium metal through dry processing techniques is crucial to enabling composite electrolytes.

All-Solid-State Lithium Batteries (ASSLB) are promising candidates for next generation lithium battery systems due to their increased safety, stability, and energy density. Ceramic and solid composite electrolytes (SCE), which consist of dispersed ceramic particles within a polymeric host, are among the preferred technologies for use as electrolytes in ASSLB systems. Synergetic effects between ceramic and polymer electrolyte components are usually reported in SCE. Herein, we report a case study on the lithium conductivity of ceramic and SCE comprised of Li1.4Al0.4Ti1.6(PO4)3 (LATP), a NASICON-type ceramic. An evaluation of the impact of the processing and sintering of the ceramic on the conductive properties of the electrolyte is addressed. The study is then extended to Poly(Ethylene) Oxide (PEO)-LATP SCE. The presence of the ceramic particles conferred limited benefits to the SCE. These findings somewhat contradict commonly held assumptions on the role of ceramic additives in SCE. [ABSTRACT FROM AUTHOR]

Acceptor doped barium zirconates are known for their exceptional protonic conductivity and the challenges in their fabrication. Within this work, BaZr 0.8 Y 0.2 O 3-δ (BZY20) films were successfully deposited on a BaZr 0.7 Ce 0.2 Y 0.1 O 3-δ /Ni (BZCY72/Ni) substrate using a combination of closed-field unbalanced magnetron sputtering and various annealing techniques such as conventional furnace annealing and laser annealing. Thin films could be tempered at only 800 °C with an additional laser annealing step and exhibit a heigh density as well as a sufficient protonic conductance. The highest measured ionic conductivity was 1.11*10−3 S/cm. The provided synthesis could pave the way for employing metallic supports in protonic ceramic fuel cells by using lower sintering temperatures than normally required. • Dense BaZr 0.8 Y 0.2 O 3-δ films were synthesized by a combined magnetron sputtering and laser annealing process. • A crystalline perovskite phase was stabilized without substrate temperatures exceeding 800 °C. • BZY20 films exhibit 35 % reduced intrinsic stress compared to conventional benchmarks. • Protonic conductivities of 2.24*10−4 S/cm and 1.11 * 10−3 S/cm were measured in H 2 /Ar and air at 550 °C, respectively. [ABSTRACT FROM AUTHOR]

Current Li battery technology employs graphite anode and flammable organic liquid electrolytes. Thus, the current Li battery is always facing the problems of low energy density and safety. Additionally, the sustainable supply of Li due to the scarce abundance of Li sources is another problem. An all-solid-state Mg battery is expected to solve the problems owing to non-flammable solid-state electrolytes, high capacity/safety of divalent Mg metal anode and high abundance of Mg sources; therefore, solid-state electrolytes and all-solid-state Mg batteries have been researched intensively last two decades. However, the realization of all-solid-state Mg batteries is still far off. In this article, we review the recent research progress on all-solid-state Mg batteries so that researchers can pursue recent research trends of an all-solid-state Mg battery. At first, the solid-state electrolyte research is described briefly in the categories of inorganic, organic and inorganic/organic composite electrolytes. After that, the recent research progress of all-solid-state Mg batteries is summarized and analyzed. To help readers, we tabulate electrode materials, experimental conditions and performances of an all-solid-state Mg battery so that the readers can find the necessary information at a glance. In the last, challenges to realize the all-solid-state Mg batteries are visited.

CeY0.15Er0.05O2 nanocrystal powders prepared via sol-gel method. Phases identification have been made X-ray diffraction, SEM-EDX, FTIR, thermal and impedance analysis. XRD data show that all powders were obtained with cubic fluorite structure. With the increase of sintering temperature, the unit cell size decreased and the crystal size increased. The particle size was found to be in the range of 150 to 270 nm. It was found that the nitrates and organic species seen in the FTIR results. It was observed that organic species disappeared at sintering temperatures selected according to thermal analysis results. Impedance measurements of the pelletized sample were made. Although the crystal structure properties were good, it was found that the conductivity values were low.

BaCe0.7Zr0.1Y0.16Zn0.04O3-δ (BCZYZ) ceramic slurry has been prepared with different solid loading and the maximum solid loading of the slurry has been predicted as 25 vol.% using the Krieger-Dougherty equation. The slurry with the maximum solid loading has been formulated and applied as an electrolyte on porous NiO/BCZYZ tubular supports by the dip-coating method. Cells sintered at 1500°C for 10h have been characterised by Scanning Electron Microscopy (SEM) analysis. The 30μ thick, very dense electrolyte layer has successfully been achieved with some closed pores. [ABSTRACT FROM AUTHOR]

This work verifies the Li-ion transfer of ceramic electrolytes in ceramic-liquid hybrid electrolytes during battery cycling and also finds spontaneous Li-ion exchange between ceramic and liquid electrolytes through tracking the 6Li and 7Li substitution behavior using solid-state nuclear magnetic resonance (NMR) spectroscopy. [Display omitted] Ceramic electrolytes are important in ceramic-liquid hybrid electrolytes (CLHEs), which can effectively solve the interfacial issues between the electrolyte and electrodes in solid-state batteries and provide a highly efficient Li-ion transfer for solid–liquid Li metal batteries. Understanding the ionic transport mechanisms in CLHEs and the corresponding role of ceramic electrolytes is crucial for a rational design strategy. Herein, the Li-ion transfer in the ceramic electrolytes of CLHEs was confirmed by tracking the 6Li and 7Li substitution behavior through solid-state nuclear magnetic resonance spectroscopy. The ceramic and liquid electrolytes simultaneously participate in Li-ion transport to achieve highly efficient Li-ion transfer in CLHEs. A spontaneous Li-ion exchange was also observed between ceramic and liquid electrolytes, which serves as a bridge that connects the ceramic and liquid electrolytes, thereby greatly strengthening the continuity of Li-ion pathways in CLHEs and improving the kinetics of Li-ion transfer. The importance of an abundant solid–liquid interface for CLHEs was further verified by the enhanced electrochemical performance in LiFePO 4 /Li and LiNi 0.8 Co 0.1 Mn 0.1 O 2 /Li batteries from the generated interface. This work provides a clear understanding of the Li-ion transport pathway in CLHEs that serves as a basis to build a universal Li-ion transport model of CLHEs. [ABSTRACT FROM AUTHOR]

Solid oxide fuel cells (SOFCs) have strong potential for next-generation energy conversion systems. However, their high processing temperature due to multi-layer ceramic components has been a major challenge for commercialization. In particular, the constrained sintering effect due to the rigid substrate in the fabrication process is a main reason to increase the sintering temperature of ceramic electrolyte. Herein, we develop a bi-layer sintering method composed of a Bi 2 O 3 sintering sacrificial layer and YSZ main electrolyte layer to effectively lower the sintering temperature of the YSZ electrolyte even under the constrained sintering conditions. The Bi 2 O 3 sintering functional layer applied on the YSZ electrolyte is designed to facilitate the densification of YSZ electrolyte at the significantly lowered sintering temperature and is removed after the sintering process to prevent the detrimental effects of residual sintering aids. Subsequent sublimation of Bi 2 O 3 was confirmed after the sintering process and a dense YSZ monolayer was formed as a result of the sintering functional layer-assisted sintering process. The sintering behavior of the Bi 2 O 3 /YSZ bi-layer system was systematically analyzed, and material properties including the microstructure, crystallinity, and ionic conductivity were analyzed. The developed bi-layer sintered YSZ electrolyte was employed to fabricate anode-supported SOFCs, and a cell performance comparable to a conventional high temperature sintered (1400 °C) YSZ electrolyte was successfully demonstrated with significantly reduced sintering temperature (<1200 °C). [ABSTRACT FROM AUTHOR]

All-Solid-State Lithium Batteries (ASSLB) are promising candidates for next generation lithium battery systems due to their increased safety, stability, and energy density. Ceramic and solid composite electrolytes (SCE), which consist of dispersed ceramic particles within a polymeric host, are among the preferred technologies for use as electrolytes in ASSLB systems. Synergetic effects between ceramic and polymer electrolyte components are usually reported in SCE. Herein, we report a case study on the lithium conductivity of ceramic and SCE comprised of Li1.4Al0.4Ti1.6(PO4)3 (LATP), a NASICON-type ceramic. An evaluation of the impact of the processing and sintering of the ceramic on the conductive properties of the electrolyte is addressed. The study is then extended to Poly(Ethylene) Oxide (PEO)-LATP SCE. The presence of the ceramic particles conferred limited benefits to the SCE. These findings somewhat contradict commonly held assumptions on the role of ceramic additives in SCE.

A precipitous increase in the resistance of the Li metal/solid electrolyte interface can occur during the stripping of Li from the electrode. This electrical failure has been typically attributed to the loss of contact associated with the growth of voids in the Li anode at the electrode/electrolyte interface. We first analyse the growth of voids at the electrode/electrolyte interface using a framework that couples the power-law creep deformation of the Li electrode and the flux of L i + through a single-ion conductor solid electrolyte. We show that a modified Butler-Volmer kinetics where the local interfacial resistance decreases due to dislocations within the creeping Li predicts that voids indeed grow around interfacial sub-micron impurity particles. Consistent with observations that the increase in resistance of interface occurs earlier for thinner electrodes, we predict that the propensity of void growth increases with decreasing electrode thickness, and this is associated with the mechanical constraint imposed by the current collector. However, in contrast to the observations and rather counterintuitively, this analysis predicts that the cell voltage decreases with void growth. Consequently, we investigate an alternative mechanism of contact loss due to the deposition of insulating solute atoms within the Li electrode onto the interface. Predictions of the rising cell voltage using this analysis are in broad agreement with measurements. This leads us to hypothesize that although void growth occurs at the interface it is not the primary mechanism leading to the increase in interface resistance during stripping. • Contact loss due to void growth at the Li electrode/solid electrolyte interface is investigated. • The mechanical constraint imposed by the current collector controls the void growth. • The precipitous increase in cell voltage upon stripping is not associated with contact loss due to void growth. • Solute deposition from within the electrode onto the interface is proposed as a mechanism for the contact loss. • This model provides predictions of cell voltage that are in broad agreement with measurements. [ABSTRACT FROM AUTHOR]

Ceramic electrolytes formed by Bi (4 mol%)-doped 8YSZ, i.e., Y2O3 (8 mol%)-doped ZrO2, were synthesized by a simple co-precipitation route, using ammonia solution as precipitating agent. The amorphous as-synthesized powders convert into zirconia-based single phase with fluorite structure through a mild calcination step at 500 °C. The calcined powders were sintered at very low temperatures (i.e., 900–1100 °C) achieving in both cases very high values of relative densities (i.e., >95%); the corresponding microstructures were highly homogeneous and characterized by micrometric grains or sub-micrometric grains for sintering at 1100 °C and 900 °C, respectively. Very interesting electrochemical properties were determined by Electrochemical Impedance Spectroscopy (EIS) in the best samples. In particular, their total ionic conductivity, recorded at 650 °C, are 6.06 × 10-2S/cm and 4.44 × 10-2S/cm for Bi (4 mol%)-doped 8YSZ sintered at 1100 °C and 900 °C, respectively. Therefore, Bi was proved to be an excellent sintering aid dopant for YSZ, highly improving its densification at lower temperatures while increasing its total ionic conductivity.

Mg 0.5 (Zr 1- x Sn x) 2 (PO 4) 3 with 0.0 ≤ x ≤ 1.0 compounds were synthesized using water-based citrate sol-gel method. X-ray diffraction and its Rietveld refinement analysis for x ≤ 0.6 confirmed the formation of a monoclinic NASICON structured compound with a space group P 2 1 / n upon sintering at 800 °C for 24 h. The total conductivity value obtained for Mg 0.5 ZrSn(PO 4) 3 is 2.47 × 10-5 S cm-1 at 500 °C which is two order of magnitude higher compared to the pristine Mg 0.5 Zr 2 (PO 4) 3. The activation energy value for pristine Mg 0.5 Zr 2 (PO 4) 3 and Mg 0.5 ZrSn(PO 4) 3 are E a = 0.84 ± 0.05 eV and E a = 0.79 ± 0.04 eV respectively. Furthermore, exponent s (T) behaviour was found to increase with rising temperature and is in good agreement with the correlated barrier hopping model. It seems that Mg 0.5 ZrSn(PO 4) 3 achieved higher conductivity and lower activation energy than the pristine Mg 0.5 Zr 2 (PO 4) 3 , indicates that the Sn4+ ion substituted compound make a desirable solid electrolytes for magnesium power storage. [ABSTRACT FROM AUTHOR]

Lithium-ion batteries with single ion-conductor ceramic electrolytes short-circuit when subjected to charging currents above a critical current density. Here, we analyse the rate at which a lithium (Li) filament (sometimes referred to as a dendrite) will grow from the cathode towards the anode during charging of such batteries. The filament is modelled as a climbing edge dislocation with its growth occurring by L i + flux from the electrolyte into the filament tip at constant chemical potential. The growth rate is set by a balance between the reduction of free-energy at the filament tip and energy dissipation associated with the resistance to the flux of L i + through the filament tip. For charging currents above the critical current density, the filament growth rate increases with decreasing filament tip resistance. Imperfections, such as voids in the Li cathode along the electrolyte/cathode interface, decrease the critical current density but filament growth rates are also lower in these cases as filament growth rates scale with the charging currents. The predictions of the model are in excellent quantitative agreement with measurements and confirm that above the critical current density a filament can traverse the electrolyte in minutes or less. This suggests that initiation of filament growth is the critical step to prevent short-circuiting of the battery. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Halloysite clay was acid-treated to obtain SiO 2 nanoparticles that were used as one of the starting reagents to synthesise clay-based Na 2 ZnSiO 4 (Clay-NZS) through sol-gel method. XRD and FESEM results showed that the Clay-NZS produced a nanocrystalline structure, with grain sizes of 50–70 nm, in comparison to its synthetic counterpart (Synth-NZS) that had grain sizes of ~200 nm. BET measurements showed that Clay-NZS pellets pressed and sintered at the same condition as Synth-NZS were denser, allowing for a better grain-grain contact. Conductivity studies using EIS demonstrated superior conductivity of Clay-NZS in contrast to Synth-NZS due to the exponential reduction in grain boundary resistance, with calculated conductivity values of σ C l a y (500) = 2.95 × 10 − 5 S c m − 1 and σ S y n t h (500) = 3.25 × 10 − 6 S c m − 1 at 500 °C. Activation energy required for ionic conduction was also found to be lower in Clay-NZS, Δ E A (C l a y) = 0.67 ± 0.01 e V compared to Δ E A (S y n t h) = 0.71 ± 0.02 e V , testifying that nanostructured ionic materials (nanoionics) provided easier diffusion pathway for ionic conduction in Clay-NZS. [ABSTRACT FROM AUTHOR]

Solid electrolytes could address the increasingly urgent safety and energy density concerns of lithium-ion batteries. Among several kinds of solid electrolytes, Ta-doped Li 7 La 3 Zr 2 O 12 (Ta-LLZO) became a research hotspot because of its high Li-ion conductivity and chemical stability against Li-metal and air. However, the preparation of high quality LLZO ceramic electrolyte via conventional air ambient sintering method is still a big challenge due to the serious "Li-loss" and abnormal grain growth phenomenon during the long-time high-temperature sintering process. Herein, a new rapid ultra-high-temperature air ambient sintering method without mother powder (MP) is put forward for the preparation of high quality Ta-LLZO ceramic electrolyte. The rapid sintering strategy can effectively restrain "Li-loss". Furthermore, it is demonstrated that the none-mother-powder method is superior to traditional mother-powder method. Ta-LLZO ceramics sintered without MP via this rapid sintering method own small grain size, tight grain boundary, dense microstructure and high conductivity. Specifically, the Ta-LLZO ceramic sintered at 1360 °C for 10 min without MP exhibits high conductivity (8.5 × 10−4 S cm−1 at 25 °C) and high relative density (97%), which equate those made by hot pressing sintering method. Without MP, the sintering process can avoid a lot of material waste and simplify the operation process. Moreover, the rapid sintering process can sharply shorten sintering time and reduce energy consumption. Therefore, this low-cost high-efficient sintering strategy can be effectively used in the large-scale production of high-quality Ta-LLZO ceramic electrolyte. [ABSTRACT FROM AUTHOR]

Sodium-Ion Batteries has emerged as a potential alternative to the conventional Lithium-Ion Batteries, with current research focusing mainly on realising an all-solid-state battery system. In building a highly conducting hybrid solid electrolyte, Na 2 ZnSiO 4 was synthesised using sol-gel method and then infused with ionic liquid Py 14 TFSI. Crystal structure of Na 2 ZnSiO 4 was characterized by X-ray diffraction and refined by Rietveld method, showing phase purity at almost 100%. FTIR and FESEM-EDX measurements indicated that the infused Py 14 TFSI did not change the Na 2 ZnSiO 4 structure and fill up the pores within the crystalline pellet. Highest conductivity value obtained by Na 2 ZnSiO 4 -Py 14 TFSI hybrid solid electrolyte is 5.0 × 10−3 S cm−1 at 498 K. The activation energy values calculated for Pristine Na 2 ZnSiO 4 and Na 2 ZnSiO 4 -Py 14 TFSI hybrid solid electrolyte are Δ E (A) N Z S = 0.33 ± 0.02 eV and Δ E (A) H S E = 0.12 ± 0.03 eV respectively. By Jonscher's power law, it was found that the ionic conduction in Na 2 ZnSiO 4 -Py 14 TFSI hybrid solid electrolyte is primarily due to the diffusion of mobile ions instead of ionic hopping as per in Pristine Na 2 ZnSiO 4. [ABSTRACT FROM AUTHOR]

Developing high-performing solid electrolytes that could replace flammable organic liquid electrolytes is vital in designing safer solid-state batteries. Among the sodium-ion (Na + ) conducting solid electrolytes, Na-β″-alumina (BASE) is highly regarded for its employment in solid-state battery applications due to its high ionic conductivity and electrochemical stability. BASE has long been employed in commercial Na-NiCl 2 and Na-S batteries. However, the synthesis of highly conductive BASE is energy-intensive, involving elevated temperatures for sintering and the incorporation of stabilizing additives. Additionally, BASE is highly sensitive to humidity, which limits its applications. Hence, there is an intense search to identify suitable high-performing solid electrolytes that could replace BASE. In this context, we reinvestigated Na 5 GdSi 4 O 12 (NGS) and demonstrated that phase pure NGS could be synthesized by a simple solid-state reaction. Beyond a high ionic conductivity of 1.9 × 10 -3 S cm -1 at 30 °C (1.5 × 10 -3 S cm -1 for BASE), NGS exhibited high chemical as well as electrochemical stability, lower interfacial resistance, lower deposition and stripping potential, and higher short-circuiting current, designating NGS as a better solid electrolyte than BASE.

Abstract Metallic Li anodes are key to reaching high energy densities in next-generation solid-state batteries, however, major problems are the non-uniform deposition of Li at the interface and the penetrative power of Li metal during operation, which cause failure of the ceramic electrolyte, internal short-circuits and a premature end of battery life. In this work, we explore the anode-electrolyte interface instability of a Li metal-garnet electrolyte system during Li electrodeposition, and its implications for mechanical fracture, Li metal propagation, and electrolyte failure. The degradation mechanism was followed step-by-step during in-operando electrochemical cycling using optical and scanning electron microscopy. High amounts of Li electrodeposition in a localized zone of the interface lead to ceramic fracture followed by an electrode-to-electrode electrical connection via a conductor Li metal filament. This work enables deeper understanding of battery failure modes in all-solid-state batteries containing a ceramic electrolyte membrane. Graphical abstract Image 1 Highlights • In-operando visualization of Li metal propagation in a ceramic electrolyte. • Mechanisms of mechanical failure in a garnet electrolyte. • Li electrodeposition leading to short circuit via soft dendrite formation. • Limitation of all-solid-state batteries with a ceramic membrane. [ABSTRACT FROM AUTHOR]

It is commonly observed that voids can nucleate and grow in the lithium anode of a solid state Li-ion battery at a location adjacent to the solid electrolyte during the stripping (discharge) phase of the battery; a similar phenomenon is observed in sodium-based batteries. It is hypothesised in the current literature that the formation of these voids is due to the coalescence of vacancies that have been generated at the electrode/electrolyte interface when metal atoms are oxidized and transported into the electrolyte: the slow diffusion of the vacancies away from the electrolyte interface into the adjacent electrode results in their coalescence and the consequent growth of voids. These hypotheses are challenged in the current study by using the Onsager formalism to generate a variational principle for vacancy diffusion. Our analysis reveals that no driving force exists for the diffusion of vacancies into a homogeneous metal electrode that thins by stripping. This finding is contrary to models in the literature which have mistakenly assumed that the vanishing flux at the current collector prevents rigid body motion (drift) of the electrode which in turn prevents thinning of the electrode during stripping. Based on our analysis, we conclude that vacancy diffusion within a homogeneous electrode is not responsible for the nucleation and growth of voids at the interface between a stripping metal electrode and a solid electrolyte. [ABSTRACT FROM AUTHOR]

Addition of LiBO 2 glass which acts as sintering aid is carried in Li 3.6 Si 0.6 V 0.4 O 4 (LVSO) sample. The solid electrolyte is synthesized using conventional solid state sintering. LiBO 2 is added with an aim to enhance the ionic conductivity of LVSO system for solid state Li + ion battery applications. X-ray diffraction is studied for all samples. Addition of LiBO 2 in LVSO makes denser pellet which is revealed by SEM. Compositional analysis is done using EDS which confirms that proper stoichiometry is maintained. Conductivity of LVSO electrolyte increases with addition of lithium borate glass. It can be attributed to decrease in porosity of ceramic in glass added samples. Highest ionic conductivity of 6.4 × 10 −4  S cm −1 at 423 K is observed for 2 wt% LiBO 2 addition with lowest activation energy of 0.43 eV. Transport number measurement is carried out which confirms Li + ion conduction. IR spectra are studied to know the structural groups present in the ceramics. [ABSTRACT FROM AUTHOR]

To improve the microstructural and electrochemical properties of Gadolinium-doped ceria (GDC) electrolytes, materials co-doped ceria with bismuth oxide (1–5 mol%) have been successfully prepared in a one-step sol-gel combustion synthetic route. Sol-gel combustion facilitates molecular mixing of the precursors and substitution of the large Bi 3+ cations into the fluorite structure, considerably reducing the sintering temperature. Adding Bi 2 O 3 as a dopant increases the GDC densification to above 99.7% and reduces its traditional sintering temperature by 300 °C. Impedance analyses show that the addition of bismuth enhances the conductivity (3.1∙10 −2 −1.7∙10 −1 S·cm −1 in the temperature range 600–800 °C) and improves the performance of the solid electrolyte in intermediate-temperature solid oxide fuel cells. [ABSTRACT FROM AUTHOR]

In this study (Bi2O3)0.9-x(Tb4O7)0.1(Sm2O3)x ternary solid solutions were synthesized by solid-state synthesis techniques. The products were characterized by means of X-ray powder diffraction, differential thermal analysis/thermal gravimetry, and the four-point probe technique (4PPT). Total electrical conductivity (sT) depending on the temperature and doping concentration has been measured by 4PPT. Activation energy of the four samples are calculated by Arrhenius relation. Activation energies of the samples increases with the concentration of dopant Sm2O3. Bi2O3-based ceramic system doped with Sm2O3 and Tb4O7 showed an oxide ionic-type electrical conductivity which is increased with the increasing amount of Sm2O3. The highest conductivity value is found as 3.48 × 10-1 S cm-1 for the (Bi2O3)0.85(Tb4O7)0.1(Sm2O3)0.05 ternary system at 850°C. [ABSTRACT FROM AUTHOR]

Nanocrystalline Samarium (20 mol%)-doped ceria (SDC20) nanopowders were prepared using a combined co-precipitation/hydrothermal treatment synthesis route carried out at reduced temperature (120 °C). The amorphous precursor experiences some microstructural transformations during the hydrothermal treatment, and after 16 h a Samarium-Cerium hydroxide carbonate, characterized by a hexagonal crystalline lattice, spherical morphology and particles of about 100 nm in size, with a very low degree of agglomeration, is the only present phase in contrast to the initial amorphous state. After the calcination step, the powders which preserved this morphology are still characterized by the absence of hard agglomerates. As a consequence, these powders exhibited an excellent sintering behaviour with a microstructure characterized by regular, equiaxed and micrometric grain size. In fact, at 1500 °C a nearly perfect densified sample was obtained, but also at 1300 °C a very good sintering behaviour was observed. Finally, the electrochemical characterization carried out by EIS measurements showed a very good electrical behaviour with high ionic conductivity, i.e. at 800 °C 5.2·10 −2 S cm −1 and 4.8·10 −2 S cm −1 for pellets sintered at 1500 °C and 1300 °C respectively, making them suitable for IT-SOFCs. [ABSTRACT FROM AUTHOR]

A 500 nm thick yttria-doped barium zirconate (BZY) proton conducting electrolyte film, fabricated via a low-cost and high-throughput chemical solution deposition (CSD) technique, was sintered at a remarkably low temperature of 1000 °C, which is much lower than the typical solid state sintering temperature of minimum 1300 °C. Therefore, the detrimental issues, commonly encountered in solid state sintering, such as barium evaporation and phase separation, were not observed. Gas-tightness of the BZY film was confirmed by 8 h of stable open circuit voltage (OCV) at 1.08 V from a button fuel cell with NiO-BZY anode substrate and LSCF cathode. The application of the film is aimed at the electrolytes of intermediate to low temperature solid oxide fuel cells (SOFCs). [ABSTRACT FROM AUTHOR]

A simple model of an intergrain region of an oxide ceramic electrolyte is used for kinetic Monte Carlo (KMC) simulations of the charge and electric field distribution in the system consisted of the grain bulks and intergrain region. The activation energies of thermally activated particle transitions in the grain bulk and intergrain region alongside the medium dielectric constant were the parameters of the model. The influence of the charge distribution on the grain boundary resistance is discussed. The density gradient contribution to the free energy was taken into account; the modified Nernst–Planck–Poisson (NPP) equation was formulated and used for the analysis of the charge distribution in the vicinity of the intergrain region. The analytical solutions of the modified NPP equation are compared with the results of the KMC simulations. The parameters of yttria stabilized zirconia are used as reference values while the model is of a more general nature. [ABSTRACT FROM AUTHOR]

Stripping of metal cations from the anode of a Li- or Na-ion cell into a ceramic electrolyte results in the formation of voids on the electrolyte/electrode interface. Such voids have been observed to grow to sizes in excess of 100 μ m. Dendrites can nucleate and grow in the electrolyte from the vicinity of the voids during the plating phase of cycling of the cell, and lead to short-circuiting of the cell. Current theoretical understanding of the formation of these voids is in its infancy: the prevailing qualitative notion is that voids form within the metal anode when the stripping current density removes metal from the interface faster than it can be replenished. We review models that employ the Onsager formalism to develop a variational approach to model void growth by coupling power-law creep of the metal electrode and the flux of metal cations through a single-ion conductor solid electrolyte. These models, based on standard Butler-Volmer kinetics for the interfacial flux, predict that voids will shrink for realistic combinations of interfacial ionic resistance and electrolyte conductivity. Additional physics in the form of modified kinetics, such that the interfacial resistance is decreased by the presence of dislocations within the creeping metal electrode, are shown to give rise to initial growth of voids around impurity particles on the electrolyte/electrode interface. However, these voids ultimately collapse under the imposed stripping fluxes and no conditions have been identified for which isolated voids grow to more than 10 μ m in size. This is in contrast to the experimentally observed sizes of ∼ 100 μ m. The physical processes by which large voids form remain unclear but the current state-of-the-art understanding does provide clues of possible mechanisms that have not as yet been considered. • There exists a disconnect between observations and predictions of void formation in Li electrodes. • The mechanisms of void formation proposed are critically reviewed. • The gaps in understanding and possible avenues for future investigations are highlighted. [ABSTRACT FROM AUTHOR]

The electrochemical stability of Li6.5La3Zr1.5Nb0.5O12 (LLZNO) and Li6.5La3Zr1.5Ta0.5O12 (LLZTO) against metallic Li was studied using direct current (DC) and electrochemical impedance spectroscopy (EIS). Dense polycrystalline LLZNO (ρ=97 %) and LLZTO (ρ=92 %) were made using sol-gel synthesis and rapid induction hot-pressing at 1100 °C and 15.8 MPa. During DC cycling tests at room temperature (±0.01 mA/cm2 for 36 cycles), LLZNO exhibited an increase in Li-LLZNO interface resistance and eventually short-circuiting while the LLZTO was stable. After DC cycling, LLZNO appeared severely discolored while the LLZTO did not change in appearance. We believe the increase in Li-LLZNO interfacial resistance and discoloration are due to reduction of Nb5+ to Nb4+. The negligible change in interfacial resistance and no color change in LLZTO suggest that Ta5+ may be more stable against reduction than Nb5+ in cubic garnet versus Li during cycling.

All-solid-state Li-O 2 batteries that use ceramic electrolytes have been suggested to overcome the limitations posed by the decomposition of organic electrolytes. However, these systems show a low discharge capacity and high overpotential because the discharge product Li 2 O 2 has low electronic conductivity. In this study, all-solid-state planar-type Li-O 2 cells were constructed using a lithium anode, a Li 1·3 Al 0·3 Ti 1·7 (PO 4 ) (LATP) inorganic solid electrolyte, and an air electrode composed of a Pt grid pattern. The discharge/charge process was observed in real time in a humidified O 2 environment for the first time, which clarified both the hydration process of the discharge products and the charging process of the hydrated discharge products. The discharge product (LiOH) could be easily hydrated in water, which would facilitate ion transport, thereby increasing the discharge capacity and discharge voltage (vs Li/Li + ; from 2.96 to 3.4 V). Thus, Li-O 2 cells with a high energy density and a capacity of 3600 mAh/g cathode were achieved using a planar Pt-patterned electrode in a humidified O 2 environment. This study is the first to demonstrate the hydration of the discharge products of a Li-O 2 cell in humidified O 2 . Based on a thorough understanding of the hydration phenomenon/mechanism, our findings suggest new strategies for developing high-energy-density all-solid-state Li-O 2 batteries using a simple, easy-to-manufacture planar Pt-patterned cathode.

Organic-inorganic hybrid solid electrolytes composed of Li + -conducting lithium aluminum germanium phosphate (LAGP), poly(ethylene oxide) (PEO), lithium perchlorate and succinonitrile (SN) were prepared in the form of flexible thin film, and their electrochemical properties were investigated. The hybrid solid electrolytes showed high ionic conductivities ranging from 3.0 × 10 −5 to 1.1 × 10 −4 S cm −1 at room temperature and exhibited good electrochemical stability. A solid-state Li/LiFePO 4 cell assembled with hybrid solid electrolyte composed of 70 wt.% LAGP, 21 wt.% PEO-LiClO 4 and 9 wt.% SN delivered a high discharge capacity and exhibited good capacity retention at ambient temperature. Good cycling performance of the cell resulted from the high ionic conductivity of the solid electrolyte and its good interfacial contacts with electrodes. [ABSTRACT FROM AUTHOR]

Magnesium-based Nasicon-type compounds with formula MgZnAlZr(PO), (0.0 ≤ y ≤ 0.4) were prepared by the nitrate sol-gel method and characterized by X-ray diffraction, particle size analyser, scanning electron microscopy, energy-dispersive X-ray spectroscopy and impedance spectroscopy. The substitution of Zr by a smaller Zn and Al cations reduced the unit cell dimensions of the parent compound's structure to form a more stable framework and enhanced its conductivity by about three orders of magnitude. X-ray diffraction spectra clearly indicated the formation of single-phase compounds without any impurity. The compounds belong to the monoclinic structure with P2/ n space group. The substitution of Al and Zn in zirconium sites did not affect the formation of the single phase, and this probably due to the concentration of both Al and Zn was too low to induce structural changes. The AC conductivity analysis demonstrated that the increase in conductivity was mainly due to an increase in the number of mobile ions. The MgZnAlZr(PO) exhibited the highest conductivity in the order of 10 S cm. Graphical Abstract: [ABSTRACT FROM AUTHOR]

The sample of Mg (Zr Fe) (PO) (0.0 ≤ y ≤0.5) was synthesized using the sol-gel method. The structures of the samples were investigated using X-ray diffraction and Fourier transform infrared spectroscopy measurement. XRD studies showed that samples had a monoclinic structure which was iso-structured with the parent compound, MgZr (PO) . The complex impedance spectroscopy was carried out in the frequency range 1-6 MHz and temperature range 303 to 773 K to study the electrical properties of the electrolytes. The substitutions of Fe with Zr in the MgZr (PO) structure was introduced as an extrainterstitial Mg ion in the modified structured. The compound of Mg (Zr Fe)(PO) with y = 0.4 gives a maximum conductivity value of 1.25 × 10 S cm at room temperature and 7.18 × 10 S cm at 773 K. Charge carrier concentration, mobile ion concentration, and ion hopping rate are calculated by fitting the conductance spectra to power law variation, σ (ω) = σ + Aω . The charge carrier concentration and mobile ion concentration increases with increase of Fe inclusion. This implies the increase in conductivity of the compounds was due to extra interstitial Mg ions. [ABSTRACT FROM AUTHOR]

The growth of voids at the electrode/electrolyte interface of a solid state Li battery is analysed by establishing a framework that uses the Onsager formalism to couple the power-law creep deformation of the Li electrode and flux of L i + through a single-ion conductor solid electrolyte. For realistic combinations of the interfacial resistance and electrolyte conductivity, standard Butler-Volmer kinetics for the interfacial flux does not provide sufficient flux focussing to initiate void growth and so a modified kinetics is adopted where the interfacial resistance is decreased by the presence of dislocations within the creeping Li electrode. Micron-sized pre-existing voids shrink under stripping conditions as flux focussing on the periphery of these voids is always low. However, spatially inhomogeneous creep in the electrode around a hemispherical impurity particle reduces the interfacial resistance with consequent significant flux focussing at the periphery of the impurity. This flux focussing results in void growth with two distinct regimes of behaviour: (i) at low currents stable but small voids form while (ii) at higher currents large voids form but these ultimately collapse. No conditions are identified for which isolated voids are predicted to grow larger than 10 μ m in size suggesting that cell failure does not occur by the growth of isolated voids. We therefore propose a hypothesis for the coalescence of voids that initiate around impurity particles being deposited on the interface during stripping of the electrode. The ensuing predictions are consistent with measurements of cell failure and provide clues of the failure mechanisms due to void growth. [Display omitted] [ABSTRACT FROM AUTHOR]

The LaLiTiO ceramic with the structure of defect perovskite and high conductivity of (2-4) × 10 S cm at the room temperature is obtained. Ceramic electrolyte based on LaLiTiO is developed for a lithium-air cell with EMF of 3.1 V and high discharge stability in time. Discharge characteristics of a lithium-air cell are studied in a laboratory cell. The dependence of electrophysical properties of a lithium-air cell on the thickness of the LaLiTiO ceramic electrolyte and effect of the catalyst on its discharge characteristics are investigated. [ABSTRACT FROM AUTHOR]

In this study, eight different samples of Tb 4 O 7 and Eu 2 O 3 co-doped Bi 2 O 3 were prepared by solid-state synthesis techniques. (Bi 2 O 3 ) 1−x−y (Tb 4 O 7 ) x (Eu 2 O 3 ) y (x = 5,10; y = 5, 10, 15, 20 mol%) ternary systems were investigated by using X-ray powder diffraction (XRD), differential thermal analysis/thermal gravimetry (DTA/TG), and four-point probe techniques (4PPT). Effect of concentration of doping elements on the temperature and electrical conductivity was investigated. All samples were evaluated by calculating activation energies and average crystal sizes. XRD measurements show that five samples have a single phase (δ-phase) structure. According to electrical conductivity measurements, the conductivity increases with increasing temperature but decreases with increasing amount of Eu 2 O 3 . The highest ionic conductivity was measured as 7.28 × 10 −1 (ohm.cm) −1 for the (Bi 2 O 3 ) 0.90 (Tb 4 O 7 ) 0.05 (Eu 2 O 3 ) 0.05 sample at 850 °C and the lowest activation energy was measured as 0.64 eV for (Bi 2 O 3 ) 0.90 (Tb 4 O 7 ) 0.05 (Eu 2 O 3 ) 0.05. [ABSTRACT FROM AUTHOR]

Lisicon-type ceramic electrolytes, Li 4.11 Zn 0.04 Al 0.03 Si 0.93 O 4 and Li 4.11 Zn 0.04 Cr 0.03 Si 0.93 O 4 , were synthesized by sol gel method. X-ray diffraction was applied to investigate the phase, structure and unit cell parameters of both solid electrolytes. The information of particles size distribution was obtained by laser particle sizer. Meanwhile, energy dispersive X-ray was used for elemental composition analysis. The complex impedance spectroscopy was carried out in the frequency range 10 Hz–10 MHz and temperature range 273 K to 773 K to study the electrical properties of the electrolytes. Both compounds were indexed to the monoclinic unit cell in the space group P2 1/ m . The particle size in Cr substituted sample was smaller compared to that in the Al substituted sample. The EDX results showed that the chemical compositions for both compounds were very close to the designed compositions. The Li 4.11 Zn 0.04 Cr 0.03 Si 0.93 O 4 compound gave slightly higher total conductivity values of 3.16 × 10 −5 S cm −1 at ambient temperature and 1.78 × 10 −3 S cm −1 at 773 K compared to Li 4.11 Zn 0.04 Al 0.03 Si 0.93 O 4 which showed total conductivity values of 1.16 × 10 −5 S cm −1 at ambient temperature and 1.12 × 10 −3 S cm −1 at 773 K. The conductivity-frequency spectra were used to estimate the ionic hopping rate in the structure. The dielectric constant and dielectric loss were found to decrease with the increase of frequency but increased with the increase of temperature. Ionic transference number corresponding to Li + ion transport determined by means of Bruce and Vincent technique is 0.93 and 0.94 for Li 4.11 Zn 0.04 Al 0.03 Si 0.93 O 4 and Li 4.11 Zn 0.04 Cr 0.03 Si 0.93 O 4 respectively. Linear sweep voltammetry results demonstrated that the Li 4.11 Zn 0.04 Cr 0.03 Si 0.93 O 4 and Li 4.11 Zn 0.04 Al 0.03 Si 0.93 O 4 ceramic electrolytes was electrochemically stable up to 4.10 V and 3.5 V versus a Li/Li + reference electrode respectively. [ABSTRACT FROM AUTHOR]

Novel LiZnSiO electrolyte was synthesized by citric acid-assisted sol-gel method. The compound was studied by X-ray diffraction and complex impedance spectroscopy in the frequency range from 10 Hz to 10 MHz and temperature range from 573 to 773 K. The conductivity-frequency spectra exhibited two regions of conductivity dispersion related to Li ion transport in the bulk and grain boundaries. The activation energy of the bulk conductivity was found to be equal to the activation energy of relaxation frequency in the bulk. This indicated that the increase in conductivity with temperature was due to the increase in ion mobility while the number of charge carrier concentration was found to be constant with selected temperature range. The observation was in agreement with the calculated charge carrier concentration and ion mobility derived from conductance spectra, σ( ω) = σ + Aω. [ABSTRACT FROM AUTHOR]