Search Results (28)

Natrium superionic conductor (NASICON) compounds have emerged as a rising star in the field of sodium-ion batteries (SIBs) owing to their stable framework structure and high Na⁺ ionic conductivity. The NASICON-structured Na₂VTi(PO₄)₃ manifests significant potential as Na⁺ storage material, characterized by decent rate capability and cyclability. However, the low redox potential of Ti³⁺/Ti⁴⁺ and undesirable energy density limit its practical applications. We developed a NASICON-structured Na₃Co_2/3V_2/3Ti_2/3(PO₄)₃ (NCTVP) cathode material by doping an appropriate amount of cobalt into Na₂VTi(PO₄)₃. Cobalt doping introduces a Co³⁺/Co²⁺ redox couple at ~4.1 V and activates the V⁵⁺/V⁴⁺ redox at ~3.9 V, resulting in significantly increased medium discharge voltage and capacity. NCTVP demonstrates a high capacity of over 160 mAh g⁻¹ at 20 mA g⁻¹. With a medium discharge voltage of ~2.7 V, the energy density of NCTVP reaches 432.0 Wh kg⁻¹. NCTVP also demonstrates desirable cycling stability (87.4% retention for 100 cycles at 50 mA g⁻¹). In situ X-ray diffraction discloses a solid solution reaction mechanism for NCTVP, while the galvanostatic intermittent titration technique demonstrates fast Na⁺ diffusion kinetics. NCTVP also demonstrates high capacity and good cyclability in full cells. This contribution demonstrates an effective approach for the construction of NASICON materials for SIBs. Full article

Nowadays, some amorphous and microcrystalline solid-state electrolytes (SSEs) with dual anions have attained high ionic conductivity and good compatibility with electrodes in all-solid-state lithium-ion batteries (ASSLIBs). In this work, crystalline SSEs of series A (Li_1+xTaO_1+xCl_4−x, −0.70 ≤ x ≤ 0.50) and B (LiTaO_2+yCl_2−2y, −1.22 ≤ y ≤ 0), having great application potential well over ambient temperatures, were prepared at 260–460 °C for 2–10 h using Li₂O, TaCl₅, and LiTaO₃ as the raw materials. The three-phase coexisting samples attained high σ values ranging from 5.20 to 7.35 mS cm⁻¹, which are among the reported high values of amorphous co-essential SSEs and other alloplasmatic crystalline ones. It is attributed to the synergistic effect of the polyanion trans-[O₂Cl₄] and cis-[O₄Cl₂] octahedra framework. Full article

This article discusses the superionic glassy GeS₂-Sb₂S₃-AgI system with mobile silver ions as a material for creating new energy-efficient solid-state ion emitters. The effect of replacing silver iodide with germanium sulfide on the structure of the electrolyte, activation energy of diffusion, and specific ionic conductivity was studied. Electrolytes (2.5 + x)GeS₂-27.5Sb₂S₃-(70 − x)AgI, x = 0, 5, 10, 15 were synthesized using the melt-quenching technique in evacuated quartz ampoules. The temperature dependence of conductivity and glass stability parameters (Hruby’s, Weinberg’s and Lu–Liu’s) were determined for them, and the mechanism for increasing glass-forming ability was clarified. It was shown that the presence of iodine in a germanium structural unit is more preferable than in an antimony structural unit; germanium structural units compete for iodine, reducing the number of SbI₃ crystallization centers and chain terminations, resulting in additional structural connectivity and stability. It was shown that when silver iodide was replaced by germanium sulfide, the decrease in conductivity due to the reduction in charge carriers was less than expected due to the expansion of the conduction channels. Full article

The hydrogen ions in superionic ice can move freely, playing the role of electrons in metals. Its electromagnetic behavior is the key to explaining the anomalous magnetic fields of Uranus and Neptune. Based on an ab initio evolutionary algorithm, we searched for the stable H₄O crystal structure under pressures of 500–5000 GPa and discovered a new layered-chain Pmn2₁-H₄O structure with H₃ ion clusters. Interestingly, H₃ ion clusters rotate above 900 K (with an instantaneous speed of 3000 m/s at 900 K), generating an instantaneous magnetic moment (~10⁻²⁶ A·m² ≈ 0.001 ${\mu }_{\mathrm{B}}$). Moreover, H ions diffuse in a direction perpendicular to the H-O atomic layer at 960–1000 K. This is because the hydrogen–oxygen covalent bonds within the hydrogen–oxygen plane hinder the diffusion behavior of H₃ ion clusters within the plane, resulting in the diffusion of H₃ ion clusters between the hydrogen–oxygen planes and the formation of a one-dimensional conductive superionic state. One-dimensional diffusion of ions may generate magnetic fields. We refer to these two types of magnetic moments as “thermally induced ion magnetic moments”. When the temperature exceeds 1000 K, H ions diffuse in three directions. When the temperature exceeds 6900 K, oxygen atoms diffuse and the system becomes fluid. These findings provide important references for people to re-recognize the physical and chemical properties of hydrogen and oxygen under high pressure, as well as the sources of abnormal magnetic fields in Uranus and Neptune. Full article

The need to reduce greenhouse gas emissions and guarantee a stable and reliable energy supply has resulted in an increase in the demand for sustainable energy storage solutions over the last decade. Rechargeable batteries with solid-state electrolytes (SSE) have become a focus area due to their potential for increased energy density, longer cycle life, and safety over conventional liquid electrolytic batteries. The superionic sodium conductor (NASICON) Na₃Zr₂Si2PO₁₂ has gained a lot of attention among ESS because of its exceptional electrochemical properties, which make it a promising candidate for solid-state sodium-ion batteries. NASICON’s open frame structure makes it possible to transport sodium ions efficiently even at room temperature, while its wide electrochemical window enables high-voltage operation and reduces side reactions, resulting in safer battery performance. Furthermore, NASICON is more compatible with sodium ion systems, can help with electrode interface issues, and is simple to process. The characteristics of NASICON make it a highly desirable and vital material for solid-state sodium-ion batteries. The aim of this study is to prepare and characterize ceramic membranes that contain Na_3.06Zr₂Si₂PO₁₂ and Na_3.18Zr₂Si₂PO₁₂, and measure their stability in seawater batteries that serve as solid electrolytes. The surface analysis revealed that the Na_3.06Zr₂Si₂PO₁₂ powder has a specific surface area of 7.17 m² g⁻¹, which is more than the Na_3.18Zr₂Si₂PO₁₂ powder’s 6.61 m² g⁻¹. During measurement, the NASICON samples showed ionic conductivities of 8.5 × 10⁻⁵ and 6.19 × 10⁻⁴ S cm⁻¹. Using platinum/carbon (Pt/C) as a catalyst and seawater as a source of cathodes with sodium ions (Na⁺), batteries were charged and discharged using different current values (50 and 100 µA) for testing. In an electrochemical cell, a battery with a NASICON membrane and Pt/C catalysts with 0.00033 g platinum content was used to assess reproducibility at a constant current of 2 h. After 100 h of operation, charging and discharging voltage efficiency was 71% (50/100 µA) and 83.5% (100 µA). The electric power level is observed to increase with the number of operating cycles. Full article

Solid-state lithium batteries are considered ideal due to the safety of solid-state electrolytes. The Na superionic conductor-type Li_1.3Al_0.3Ti_1.7(PO₄)₃ (LATP) is a solid electrolyte with high ionic conductivity, low cost, and stability. However, LATP is reduced upon contact with metallic lithium, leading to lithium dendrite growth on the anode during charging. In this study, LATP was synthesized, and the relationship between crystallinity and ionic conductivity was investigated at different heat treatment temperatures. Optimal sintering conditions and ionic conductivity were analyzed for sintering temperatures from 800 to 1000 °C. To suppress reactions with Li metal, 50 nm thick Ag and 10 nm thick Al₂O₃ layers were deposited on LATP via DC sputtering and plasma-enhanced atomic layer deposition. The electrochemical stability was tested under three conditions: uncoated LATP, Al₂O₃-coated LATP, and Ag+Al₂O₃-coated LATP. The stability improved in the following order: uncoated < Al₂O₃-coated < Ag+Al₂O₃-coated. The Al₂O₃ coating suppressed secondary phase formation by preventing direct contact between LATP and Li, while Ag coating mitigated charge concentration, inhibiting dendrite growth. These findings demonstrate that Ag and Al₂O₃ nano-layers enhance electrolyte stability, advancing solid-state battery reliability and commercialization. Full article

Sodium-ion batteries offer an attractive alternative to lithium-based chemistries due to the lower cost and abundance of sodium compared to lithium. Using solid electrolytes instead of liquid ones in such batteries may help improve safety and energy density, but they need to combine easy processing with high stability toward the electrodes. Herein, we describe a new class of solid electrolytes that are accessible by room-temperature, aqueous synthesis. The materials exhibit a garnet-type zinc hexacyanoferrate framework with large diffusion channels for alkaline ions. Specifically, they show superionic behavior and allow for facile processing into pellets. We compare the structure, stability, and transport properties of lithium-, sodium-, and potassium-containing zinc hexacyanoferrates and find that Na₂Zn₃[Fe(CN)₆]₂ achieves the highest ionic conductivity of up to 0.21 mS/cm at room temperature. In addition, the electrochemical performance and stability of the latter solid electrolyte are examined in solid-state sodium-ion batteries. Full article

Using first-principles density functional theory (DFT) calculations and ab initio molecular dynamics (AIMD) simulations, we performed this study on the phase stability, the intrinsic redox stability, and the Li⁺ conductivity of Li₁₀Ge_xMo_1−xP₂S₁₂ (x = 0~1) superionic conductors. Molybdenum (Mo) is expected to replace expensive germanium (Ge) to lower tmaterial costs, reduce sensitivity to ambient water and oxygen, and achieve acceptable Li⁺ conductivity. The ab initio first principle molecular dynamics simulations show that room-temperature Li⁺ conductivity is 1.12 mS·cm⁻¹ for the Li₁₀Ge_0.75Mo_0.25P₂S₁₂ compound, which is comparable to the theoretical value of 6.81 mS·cm⁻¹ and the experimental measured one of 12 mS·cm⁻¹ of the Li₁₀GeP₂S₁₂ (LGPS) structure. For Li₁₀Ge_xMo_1−xP₂S₁₂ (x = 0, 0.25, 0.5 and 1) compounds, the density of states and the projection fractional wave state density were calculated. It was found that when Ge atoms were partially replaced by Mo atoms, the band gap remained unchanged at 2.5 eV, but deep level defects appeared in Mo-substituted compounds. Fortunately, this deep level defect is difficult to ionize at room temperature, so it has no effect on the electronic conductivity of Mo substitute compounds, making Mo substitution a suitable solution for electrolyte materials. The projection fractional wave state density calculation shows that the covalent bond between Mo and S is stronger than that between Ge and S, which reduces the sensitivity of Mo-substituted compounds to water and oxygen contents in the air. In addition, the partial state density coincidence curve between Li and S elements disappears in the 25% Mo-substituted compound with energies of 4–5 eV, indicating that the Li₂S by-product is decreased. Full article

Although in general ions are not able to migrate in the solid-state position due to rigid skeletal structure, in some solid electrolytes with a low energy barrier and high ionic conductivities, these ion transition can occur. In this work, we considered several solid electrolytes including lithium phosphorus oxy-nitride (LIPON), a lithium super-ionic conductor (SILICON), and thio-LISICON. For the fabrication and characterization of the solid electrolyte’s fabrication, we used a single-step ball milling (SSBM) procedure. Through this research on all-solid-state rechargeable lithium-ion batteries, our target is to discuss solving several problems in solid LIBs that have recently escalated due to raised concerns relating to safety hazards such as solvent leakage and the flammability of the liquid electrolytes used for commercial LIBs. Through this research, we tested the conductivity amounts of various substrates containing amorphous glass, SSBM, and glass-ceramic samples. Obviously, the SSBM glass-ceramics increased the conductivity, and we also found that the values for conductivity attained by SSBM were higher than those values for glass-ceramics. Using an SSBM technique, silicon nanoparticles were used as an anode material and it was found that the charge and discharge curves in the battery cell cycled between 0.009 and 1.45 V versus Li⁺/Li at a current density of 210 mA g⁻¹ at room temperature. Since high resistance causes degradation between the cathode material (LiCoO₂) and the solid electrolyte, we added GeS2 and SiS₂ to the Li₂S-P₂S₅ system to obtain higher conductivities and better stability of the electrode–electrolyte interface. Full article

Materials with high ion mobility are widely used in many fields of modern science and technology. Over the last 40 years, they have thoroughly changed our world. The paper characterizes the structural features of minerals and their synthetic analogs possessing this property. Special attention is paid to the ionic conductors with tetrahedral (zincite- and wurtzite-like), octahedral (ilmenite-like), and mixed (NASICON-like) frameworks. It is emphasized that the main conditions for fast ionic transport are related to the size and positions occupied by a mobile ion, their activation energy, the presence and diameter of conduction channels running inside the structure, isomorphic impurities, and other structural peculiarities. The results of the studies of solid electrolytes are dispersed in different editions, and the overview of new ideas related to their crystal structures was the focus of this paper. Full article

Nonaqueous flow batteries hold promise given their high cell voltage and energy density, but their performance is often plagued by the crossover of redox compounds. In this study, we used permselective lithium superionic conducting (LiSICON) ceramic membranes to enable reliable long-term use of organic redox molecules in nonaqueous flow cells. With different solvents on each side, enhanced cell voltages were obtained for a flow battery using viologen-based negolyte and TEMPO-based posolyte molecules. The thermoplastic assembly of the LiSICON membrane realized leakless cell sealing, thus overcoming the mechanical brittleness challenge. As a result, stable cycling was achieved in the flow cells, which showed good capacity retention over an extended test time. Full article

Silver iodide is a prototype compound of superionic conductors that allows ions to flow through its structure. It exhibits a first-order phase transition at 420 K, characterized by an abrupt change in its ionic conductivity behavior, and above this temperature, its ionic conductivity increases by more than three orders of magnitude. Introducing small concentrations of carbon into the silver iodide structure produces a new material with a mixed conductivity (ionic and electronic) that increases with increasing temperature. In this work, we report the experimental results of the ionic conductivity as a function of the reciprocal temperature for the (AgI)_x − C_(1−x) mixture at low carbon concentrations (x = 0.99, 0.98, and 0.97). The ionic conductivity behavior as a function of reciprocal temperature was well fitted using a phenomenological model based on a random variable theory with a probability distribution function for the carriers. The experimental data show a proximity effect between the C and AgI phases. As a consequence of this proximity behavior, carbon concentration or temperature can control the conductivity of the (AgI)_x − C_(1−x) mixture. Full article

The quantum statistical properties of the proton subsystem in hydrogen-bonded crystals (HBC) are investigated. Based on the non-stationary Liouville operator equation (taking into account a number of assumptions established in the experiment), a quantum kinetic equation is constructed for the ensemble of non-interacting protons (an ideal proton gas) moving in the crystal potential image perturbed by the external electric field. The balanced density matrix for the unperturbed proton subsystem is constructed using the quantum canonical Gibbs distribution, and the non-balanced density matrix is calculated from the solutions of the nonlinear quantum kinetic equation by methods in linear approximation of perturbation theory for the blocking electrode model. Full quantum mechanical averaging of the polarization operator makes it possible to study the theoretical frequency-temperature spectra of the complex dielectric permittivity (CDP) calculated using quantum relaxation parameters that differ significantly from their semiclassical counterparts. A scheme is presented for an analytical study of the dielectric loss tangent in the region of quantum nonlinear relaxation in HBC. The results obtained in the given paper are of scientific interest in developing the theoretical foundations of proton conduction processes in energy-independent memory elements (with anomalously high residual polarization) based on thin films of ferroelectric materials in the ultralow temperature range (1–10 K). The theoretical results obtained have a direct application to the study of the tunneling mechanisms of spontaneous polarization in ferroelectric HBC with a rectangular hysteresis loop, in particular in crystals of potassium dideutrophosphate (KDP), widely used in nonlinear optics and laser technology. The quantum properties of proton relaxation in HBC can be applied in the future to the study of solid-state electrolytes with high proton conductivity for hydrogen energy, capacitor technology (superionics, varicodes), and elements of MIS and MSM structures in the development of resonant tunnel diodes for microelectronics and computer technology. Full article

Thermal polymorphism in the alkali-metal salts incorporating the icosohedral monocarba-hydridoborate anion, CB₁₁H₁₂⁻, results in intriguing dynamical properties leading to superionic conductivity for the lightest alkali-metal analogues, LiCB₁₁H₁₂ and NaCB₁₁H₁₂. As such, these two have been the focus of most recent CB₁₁H₁₂⁻ related studies, with less attention paid to the heavier alkali-metal salts, such as CsCB₁₁H₁₂. Nonetheless, it is of fundamental importance to compare the nature of the structural arrangements and interactions across the entire alkali-metal series. Thermal polymorphism in CsCB₁₁H₁₂ was investigated using a combination of techniques: X-ray powder diffraction; differential scanning calorimetry; Raman, infrared, and neutron spectroscopies; and ab initio calculations. The unexpected temperature-dependent structural behavior of anhydrous CsCB₁₁H₁₂ can be potentially justified assuming the existence of two polymorphs with similar free energies at room temperature: (i) a previously reported, ordered R3 polymorph stabilized upon drying and transforming first to R3c symmetry near 313 K and then to a similarly packed but disordered I43d polymorph near 353 K and (ii) a disordered Fm3 polymorph that initially appears from the disordered I43d polymorph near 513 K along with another disordered high-temperature P6₃mc polymorph. Quasielastic neutron scattering results indicate that the CB₁₁H₁₂⁻ anions in the disordered phase at 560 K are undergoing isotropic rotational diffusion, with a jump correlation frequency [1.19(9) × 10¹¹ s⁻¹] in line with those for the lighter-metal analogues. Full article

Composite solid electrolytes (CSEs), composed of sodium superionic conductor (NASICON)-type Li_1+xAl_xTi_2-x(PO₄)₃ (LATP), poly (vinylidene fluoride-hexafluoro propylene) (PVDF-HFP), and lithium bis (trifluoromethanesulfonyl)imide (LiTFSI) salt, are designed and fabricated for lithium-metal batteries. The effects of the key design parameters (i.e., LiTFSI/LATP ratio, CSE thickness, and carbon content) on the specific capacity, coulombic efficiency, and cyclic stability were systematically investigated. The optimal CSE configuration, superior specific capacity (~160 mAh g⁻¹), low electrode polarization (~0.12 V), and remarkable cyclic stability (a capacity retention of 86.8%) were achieved during extended cycling (>200 cycles). In addition, with the optimal CSE structure, a high ionic conductivity (~2.83 × 10⁻⁴ S cm⁻¹) was demonstrated at an ambient temperature. The CSE configuration demonstrated in this work can be employed for designing highly durable CSEs with enhanced ionic conductivity and significantly reduced interfacial electrolyte/electrode resistance. Full article