Synthesis of Sb2S3 NRs@rGO Composite as High-Performance Anode Material for Sodium-Ion Batteries

Sodium ion batteries (SIBs) have drawn interest as a lithium ion battery (LIB) alternative owing to their low price and low deposits. To commercialize SIBs similar to how LIBs already have been, it is necessary to develop improved anode materials that have high stability and capacity to operate over many and long cycles. This paper reports the development of homogeneous Sb₂S₃ nanorods (Sb₂S₃ NRs) on reduced graphene oxide (Sb₂S₃ NRs @rGO) as anode materials for SIBs. Based on this work, Sb₂S₃ NRs show a discharge capacity of 564.42 mAh/g at 100 mA/g current density after 100 cycles. In developing a composite with reduced graphene oxide, Sb₂S₃ NRs@rGO present better cycling performance with a discharge capacity of 769.05 mAh/g at the same condition. This achievement justifies the importance of developing Sb₂S₃ NRs and Sb₂S₃ NRs@rGO for SIBs.     

Flake (NH4)6Mo7O24/Polydopamine as a High Performance Anode for Lithium Ion Batteries

Ammonium molybdate tetrahydrate ((NH₄)₆Mo₇O₂₄) (AMT) is commonly used as the precursor to synthesize Mo-based oxides or sulfides for lithium ion batteries (LIBs). However, the electrochemical lithium storage ability of AMT itself is unclear so far. In the present work, AMT is directly examined as a promising anode material for Li-ion batteries with good capacity and cycling stability. To further improve the electrochemical performance of AMT, AMT/polydopamine (PDA) composite was simply synthesized via recrystallization and freeze drying methods. Unlike with block shape for AMT, the as-prepared AMT/PDA composite shows flake morphology. The initial discharge capacity of AMT/PDA is reached up to 1471 mAh g⁻¹. It delivers a reversible discharge capacity of 702 mAh g⁻¹ at a current density of 300 mA g⁻¹, and a stable reversible capacity of 383.6 mA h g⁻¹ is retained at a current density of 0.5 A g⁻¹ after 400 cycles. Moreover, the lithium storage mechanism is fully investigated. The results of this work could potentially expand the application of AMT and Mo-based anode for LIBs.     

Effect of Residual Trace Amounts of Fe and Al in Li[Ni1/3Mn1/3Co1/3]O2 Cathode Active Material for the Sustainable Recycling of Lithium-Ion Batteries

As the explosive growth of the electric vehicle market leads to an increase in spent lithium-ion batteries (LIBs), the disposal of LIBs has also made headlines. In this study, we synthesized the cathode active materials Li[Ni_1/3Mn_1/3Co_1/3]O₂ (NMC) and Li[Ni_1/3Mn_1/3Co_1/3Fe_0.0005Al_0.0005]O₂ (NMCFA) via hydroxide co-precipitation and calcination processes, which simulate the resynthesis of NMC in leachate containing trace amounts of iron and aluminum from spent LIBs. The effects of iron and aluminum on the physicochemical and electrochemical properties were investigated and compared with NMC. Trace amounts of iron and aluminum do not affect the morphology, the formation of O3-type layered structures, or the redox peak. On the other hand, the rate capability of NMCFA shows high discharge capacities at 7 C (110 mAh g⁻¹) and 10 C (74 mAh g⁻¹), comparable to the values for NMC at 5 C (111 mAh g⁻¹) and 7 C (79 mAh g⁻¹), respectively, due to the widened interslab thickness of NMCFA which facilitates the movement of lithium ions in a 2D channel. Therefore, iron and aluminum, which are usually considered as impurities in the recycling of LIBs, could be used as doping elements for enhancing the electrochemical performance of resynthesized cathode active materials.     

Photo-Charging of Li(Ni0.65Co0.15Mn0.20)O2 Lithium-Ion Battery Using Silicon Solar Cells

This study reports an integrated device in which a lithium-ion battery (LIB) and Si solar cells are interconnected. The LIB is fabricated using the Li(Ni_0.65Co_0.15Mn_0.20)O₂ (NCM622) cathode and the Li₄Ti₅O₁₂ (LTO) anode. The surface and shape morphologies of the NCM and LTO powders were investigated by field emission scanning electron microscopy (FE-SEM). In addition, the structural properties were thoroughly examined by X-ray diffraction (XRD). Further, their electrochemical characterization was carried out on a potentiostat. The specific discharge capacity of the NCM cathode (half-cell) was 188.09 mAh/g at 0.1 C current density. In further experiments, the NCM-LTO full-cell has also shown an excellent specific capacity of 160 mAh/g at a high current density of 1 C. Additionally, the capacity retention was outstanding, with 99.63% at 1 C after 50 cycles. Moreover, to meet the charging voltage requirements of the NCM-LTO full-cell, six Si solar cells were connected in series. The open-circuit voltage (V_OC) and the short-circuit photocurrent density (J_SC) for the Si solar cells were 3.37 V and 5.42 mA/cm². The calculated fill factor (FF) and efficiency for the Si solar cells were 0.796 and 14.54%, respectively. Lastly, the integrated device has delivered a very high-power conversion-storage efficiency of 7.95%.     

Designing Spinel Li4Ti5O12 Electrode as Anode Material for Poly(ethylene)oxide-Based Solid-State Batteries

The development of a promising Li metal solid-state battery (SSB) is currently hindered by the instability of Li metal during electrodeposition; which is the main cause of dendrite growth and cell failure at elevated currents. The replacement of Li metal anode by spinel Li₄Ti₅O₁₂ (LTO) in SSBs would avoid such problems, endowing the battery with its excellent features such as long cycling performance, high safety and easy fabrication. In the present work, we provide an evaluation of the electrochemical properties of poly(ethylene)oxide (PEO)-based solid-state batteries using LTO as the active material. Electrode laminates have been developed and optimized using electronic conductive additives with different morphologies such as carbon black and multiwalled carbon nanotubes. The electrochemical performance of the electrodes was assessed on half-cells using a PEO-based solid electrolyte and a lithium metal anode. The optimized electrodes displayed an enhanced capability rate, delivering 150 mAh g⁻¹ at C/2, and a stable lifespan over 140 cycles at C/20 with a capacity retention of 83%. Moreover, postmortem characterization did not evidence any morphological degradation of the components after ageing, highlighting the long-cycling feature of the LTO electrodes. The present results bring out the opportunity to build high-performance solid-state batteries using LTO as anode material.     

Boron Oxide Enhancing Stability of MoS2 Anode Materials for Lithium-Ion Batteries

Molybdenum disulfide (MoS₂) is the most well-known transition metal chalcogenide for lithium storage applications because of its simple preparation process, superior optical, physical, and electrical properties, and high stability. However, recent research has shown that bare MoS₂ nanosheet (NS) can be reformed to the bulk structure, and sulfur atoms can be dissolved in electrolytes or form polymeric structures, thereby preventing lithium insertion/desertion and reducing cycling performance. To enhance the electrochemical performance of the MoS₂ NSs, B₂O₃ nanoparticles were decorated on the surface of MoS₂ NSs via a sintering technique. The structure of B₂O₃ decorated MoS₂ changed slightly with the formation of a lattice spacing of ~7.37 Å. The characterization of materials confirmed the formation of B₂O₃ crystals at 30% weight percentage of H₃BO₃ starting materials. In particular, the MoS₂_B3 sample showed a stable capacity of ~500 mAh·g⁻¹ after the first cycle. The cycling test delivered a high reversible specific capacity of ~82% of the second cycle after 100 cycles. Furthermore, the rate performance also showed a remarkable recovery capacity of ~98%. These results suggest that the use of B₂O₃ decorations could be a viable method for improving the stability of anode materials in lithium storage applications.     

Impact of Li3BO3 Addition on Solid Electrode-Solid Electrolyte Interface in All-Solid-State Batteries

All-solid-state lithium-ion batteries raise the issue of high resistance at the interface between solid electrolyte and electrode materials that needs to be addressed. The article investigates the effect of a low-melting Li₃BO₃ additive introduced into LiCoO₂- and Li₄Ti₅O₁₂-based composite electrodes on the interface resistance with a Li₇La₃Zr₂O₁₂ solid electrolyte. According to DSC analysis, interaction in the studied mixtures with Li₃BO₃ begins at 768 and 725 °C for LiCoO₂ and Li₄Ti₅O₁₂, respectively. The resistance of half-cells with different contents of Li₃BO₃ additive after heating at 700 and 720 °C was studied by impedance spectroscopy in the temperature range of 25–340 °C. It was established that the introduction of 5 wt% Li₃BO₃ into LiCoO₂ and heat treatment at 720 °C led to the greatest decrease in the interface resistance from 260 to 40 Ω cm² at 300 °C in comparison with pure LiCoO₂. An SEM study demonstrated that the addition of the low-melting component to electrode mass gave better contact with ceramics. It was shown that an increase in the annealing temperature of unmodified cells with Li₄Ti₅O₁₂ led to a decrease in the interface resistance. It was found that the interface resistance between composite anodes and solid electrolyte had lower values compared to Li₄Ti₅O₁₂|Li₇La₃Zr₂O₁₂ half-cells. It was established that the resistance of cells with the Li₄Ti₅O₁₂/Li₃BO₃ composite anode annealed at 720 °C decreased from 97.2 (x = 0) to 7.0 kΩ cm² (x = 5 wt% Li₃BO₃) at 150 °C.     

Phase Formation,Mechanical Strength,and Bioactive Properties of Lithium Disilicate Glass–Ceramics with Different Al2O3 Contents

Owing to its excellent mechanical properties and aesthetic tooth-like appearance, lithium disilicate glass–ceramic is more attractive as a crown for dental restorations. In this study, lithium disilicate glass–ceramics were prepared from SiO₂–Li₂O–K₂O–P₂O₅–CeO₂ glass systems with various Al₂O₃ contents. The mixed glass was then heat-treated at 600 °C and 800 °C for 2 h to form glass–ceramic samples. Phase formation, microstructure, mechanical properties and bioactivity were investigated. The phase formation analysis confirmed the presence of Li₂Si₂O₅ in all the samples. The glass–ceramic sample with an Al₂O₃ content of 1 wt% showed rod-like Li₂Si₂O₅ crystals that could contribute to the delay in crack propagation and demonstrated the highest mechanical properties. Surface treatment with hydrofluoric acid followed by a silane-coupling agent provided the highest micro-shear bond strength for all ceramic conditions, with no significant difference between ceramic samples. The biocompatibility tests of the material showed that Al₂O₃-added lithium disilicate glass–ceramic sample was bioactive, thus activating protein production and stimulating the alkaline phosphatase (ALP) activity of osteoblast-like cells.     

Synthesis and Electrochemical Performance of V6O13 Nanosheets Film Cathodes for LIBs

V₆O₁₃ thin films were deposited on indium-doped tin oxide (ITO) conductive glass by a concise low-temperature liquid-phase deposition method and through heat treatment. The obtained films were directly used as electrodes without adding any other media. The results indicate that the film annealed at 400 °C exhibited an excellent cycling performance, which remained at 82.7% of capacity after 100 cycles. The film annealed at 400 °C with diffusion coefficients of 6.08 × 10⁻¹² cm²·s⁻¹ (Li⁺ insertion) and 5.46 × 10⁻¹² cm²·s⁻¹ (Li⁺ extraction) in the V₆O₁₃ film electrode. The high diffusion coefficients could be ascribed to the porous morphology composed of ultrathin nanosheets. Moreover, the film endured phase transitions during electrochemical cycling, the V₆O₁₃ partially transformed to Li_0.6V_1.67O_3.67, Li₃VO₄, and VO₂ with the insertion of Li⁺ into the lattice, and Li_0.6V_1.67O_3.67, Li₃VO₄, and VO₂ partially reversibly transformed backwards to V₆O₁₃ with the extraction of Li⁺ from the lattice. The phase transition can be attributed to the unique structure and morphology with enough active sites and ions diffusion channels during cycles. Such findings reveal a bright idea to prepare high-performance cathode materials for LIBs.     

High-capacity electrode materials for rechargeable lithium batteries: Li3NbO4-based system with cation-disordered rocksalt structure

Rechargeable lithium batteries have rapidly risen to prominence as fundamental devices for green and sustainable energy development. Lithium batteries are now used as power sources for electric vehicles. However, materials innovations are still needed to satisfy the growing demand for increasing energy density of lithium batteries. In the past decade, lithium-excess compounds, Li₂MeO₃ (Me = Mn⁴⁺, Ru⁴⁺, etc.), have been extensively studied as high-capacity positive electrode materials. Although the origin as the high reversible capacity has been a debatable subject for a long time, recently it has been confirmed that charge compensation is partly achieved by solid-state redox of nonmetal anions (i.e., oxide ions), coupled with solid-state redox of transition metals, which is the basic theory used for classic lithium insertion materials, such as LiMeO₂ (Me = Co³⁺, Ni³⁺, etc.). Herein, as a compound with further excess lithium contents, a cation-ordered rocksalt phase with lithium and pentavalent niobium ions, Li₃NbO₄, is first examined as the host structure of a new series of high-capacity positive electrode materials for rechargeable lithium batteries. Approximately 300 mAh⋅g⁻¹ of high-reversible capacity at 50 °C is experimentally observed, which partly originates from charge compensation by solid-state redox of oxide ions. It is proposed that such a charge compensation process by oxide ions is effectively stabilized by the presence of electrochemically inactive niobium ions. These results will contribute to the development of a new class of high-capacity electrode materials, potentially with further lithium enrichment (and fewer transition metals) in the close-packed framework structure with oxide ions.To realize sustainable energy development in the future, it is widely admitted that the substitution of energy sources for fossil fuels must be considered. An efficient energy storage system using an electrochemical method, such as rechargeable lithium batteries (Li-ion batteries, LIBs), potentially provides the solution to meet these tough challenges. Now, electric vehicles equipped with an electric motor and LIB have been launched in the market, and LIBs are starting to substitute for fossil fuels as power sources in the transportation system using the technology of internal combustion engines. Since their first appearance as power sources for portable electronic devices in 1991, the technology of LIBs has now become sufficiently sophisticated. Nevertheless, the demands for a further increase in energy density are still growing to extend the driving distance for electric vehicles.In 1980, LiCoO₂ with a cation-ordered rocksalt structure (layered type) was first proposed as a positive electrode material for LIBs (1) and is still widely used for high-energy mobile applications. After this finding, lithium insertion materials with cation-ordered rocksalt-type structures, LiMeO₂ (Me = Co³⁺, Ni³⁺, etc.) have been extensively studied as electrode materials. In the past decade, Li-enriched materials, Li₂MeO₃-type layered materials (Me = Mn⁴⁺, Ru⁴⁺, etc.), which are also classified as having cation-ordered rocksalt-type structures (2), have been extensively studied as potential high-capacity electrode materials, especially for the Mn⁴⁺ system (Li₂MnO₃) (3–7). Li₂MnO₃ had been originally thought to be electrochemically inactive because oxidation of Mn ions beyond the tetravalent state is difficult. However, the fact is that Li₂MnO₃ is electrochemically active, presumably because of the contribution of oxide ions for redox reaction. Although the oxidation of oxide ions in Li₂MnO₃ results in partial oxygen loss with irreversible structural changes (5, 6), solid-state redox reaction of oxide ions is effectively stabilized in the Li₂Ru_1-xSn_xO₃ system (8). Nearly 1.6 mol of Li⁺ are reversibly extracted from Li₂Ru_0.75Sn_0.25O₃ with excellent capacity retention, indicating that unfavorable phase transition is effectively suppressed in this system.Historically, such charge compensation by nonmetal anions has already been evidenced in sulfides before 1990 (9). Because sulfide ions are relatively soft and polarizable anion compared with oxide ions, oxidation of sulfide ions to persulfide ions is easier than that of oxide ions. The voltage as positive electrode materials is also much more attractive for the oxide ions [∼2 V vs. Li for S²⁻/S₂²⁻ (9) and more than 3 V vs. Li for O²⁻/O₂²⁻ (8)]. The possibility of charge compensation by oxide ions on lithium extraction was also discussed for late-transition metal oxides before 2000 (10, 11). Similarly, such rearrangement of charge was known when metal 3d orbital was heavily hybridized with oxygen 2p orbital, for instance Fe⁴⁺ in SrFeO₃ (12). Nevertheless, a clear and unambiguous contribution of the oxide ions for charge compensation on “electrochemical lithium extraction” was first evidenced in 2013 on the basis of an arsenal of characterization techniques with a concept of a reductive coupling mechanism (8).The use of oxide ion redox is an important strategy to further increase the reversible capacity of positive electrode materials for LIBs because the lithium content is potentially further enriched with a lower amount of transition metals in the framework structure. Reversible capacity as electrode materials is not limited by the absence of oxidizable transition metals as a redox center. Negatively charged oxide ions can potentially donate electrons instead of transition metals. However, oxidation without transition metals inevitably results in the release of oxygen molecules (e.g., electrochemical decomposition of Li₂O₂) (13).Based on these considerations, we have decided to investigate the rocksalt phase with pentavalent niobium ions (i.e., Li₃NbO₄). Approximately 300 mAh⋅g⁻¹ of reversible capacity at 50 °C is experimentally observed for a manganese-substituted Li₃NbO₄-based sample. Large reversible capacity is seen to partly originate from charge compensation by reversible solid-state redox of oxide ions, coupled with conventional redox reactions of transition metals. From these results, we will discuss the possibility of a new class of high-capacity electrode materials, potentially with further lithium enrichment in the close-packed framework structure with oxide ions.     

Spray Flame Synthesis (SFS) of Lithium Lanthanum Zirconate (LLZO) Solid Electrolyte

A spray-flame reaction step followed by a short 1-h sintering step under O₂ atmosphere was used to synthesize nanocrystalline cubic Al-doped Li₇La₃Zr₂O₁₂ (LLZO). The as-synthesized nanoparticles from spray-flame synthesis consisted of the crystalline La₂Zr₂O₇ (LZO) pyrochlore phase while Li was present on the nanoparticles’ surface as amorphous carbonate. However, a short annealing step was sufficient to obtain phase pure cubic LLZO. To investigate whether the initial mixing of all cations is mandatory for synthesizing nanoparticulate cubic LLZO, we also synthesized Li free LZO and subsequently added different solid Li precursors before the annealing step. The resulting materials were all tetragonal LLZO (I4₁/acd) instead of the intended cubic phase, suggesting that an intimate intermixing of the Li precursor during the spray-flame synthesis is mandatory to form a nanoscale product. Based on these results, we propose a model to describe the spray-flame based synthesis process, considering the precipitation of LZO and the subsequent condensation of lithium carbonate on the particles’ surface.     

Establish TiNb2O7@C as Fast-Charging Anode for Lithium-Ion Batteries

Intercalation-type metal oxides are promising active anode materials for the fabrication of safer rechargeable lithium-ion batteries, as they are capable of minimizing or even eliminating Li plating at low voltages. Due to the excellent cycle performance, high specific capacity and appropriate working potential, TiNb₂O₇ (TNO) is considered to be the candidate of anode materials. Despite a lot of beneficial characteristics, the slow electrochemical kinetics of the TNO-based anodes limits their wide use. In this paper, TiNb₂O₇@C was prepared by using the self-polymerization coating characteristics of dopamine to enhance the rate-performance and cycling stability. The TNO@C-2 particles present ideal rate performance with the discharge capacity of 295.6 mA h g⁻¹ at 0.1 C. Moreover, the TNO@C-2 anode materials exhibit initial discharge capacity of 177.4 mA h g⁻¹, providing 91% of capacity retention after 400 cycles at 10 C. The outstanding electrochemical performance can be contributed to the carbon layer, which builds fast lithium ion paths, enhancing the electrical conductivity of TNO. All these results confirm that TNO@C is a valid methodology to enhance rate-performance and cycling stability and is a new way to provide reliable and quickly rechargeable energy storage resources.     

Phonon Structure,Infra-Red and Raman Spectra of Li2MnO3 by First-Principles Calculations

The layer-structured monoclinic Li₂MnO₃ is a key material, mainly due to its role in Li-ion batteries and as a precursor for adsorbent used in lithium recovery from aqueous solutions. In the present work, we used first-principles calculations based on density functional theory (DFT) to study the crystal structure, optical phonon frequencies, infra-red (IR), and Raman active modes and compared the results with experimental data. First, Li₂MnO₃ powder was synthesized by the hydrothermal method and successively characterized by XRD, TEM, FTIR, and Raman spectroscopy. Secondly, by using Local Density Approximation (LDA), we carried out a DFT study of the crystal structure and electronic properties of Li₂MnO₃. Finally, we calculated the vibrational properties using Density Functional Perturbation Theory (DFPT). Our results show that simulated IR and Raman spectra agree well with the observed phonon structure. Additionally, the IR and Raman theoretical spectra show similar features compared to the experimental ones. This research is useful in investigations involving the physicochemical characterization of Li₂MnO₃ material.     

Counter-Intuitive Magneto-Water-Wetting Effect to CO2 Adsorption at Room Temperature Using MgO/Mg(OH)2 Nanocomposites

MgO/Mg(OH)₂-based materials have been intensively explored for CO₂ adsorption due to their high theoretical but low practical CO₂ capture efficiency. Our previous study on the effect of H₂O wetting on CO₂ adsorption in MgO/Mg(OH)₂ nanostructures found that the presence of H₂O molecules significantly increases (decreases) CO₂ adsorption on the MgO (Mg(OH)₂) surface. Furthermore, the magneto-water-wetting technique is used to improve the CO₂ capture efficiency of various nanofluids by increasing the mass transfer efficiency of nanobeads. However, the influence of magneto-wetting to the CO₂ adsorption at nanobead surfaces remains unknown. The effect of magneto-water-wetting on CO₂ adsorption on MgO/Mg(OH)₂ nanocomposites was investigated experimentally in this study. Contrary to popular belief, magneto-water-wetting does not always increase CO₂ adsorption; in fact, if Mg(OH)₂ dominates in the nanocomposite, it can actually decrease CO₂ adsorption. As a result of our structural research, we hypothesized that the creation of a thin H₂O layer between nanograins prevents CO₂ from flowing through, hence slowing down CO₂ adsorption during the carbon-hydration aging process. Finally, the magneto-water-wetting technique can be used to control the carbon-hydration process and uncover both novel insights and discoveries of CO₂ capture from air at room temperature to guide the design and development of ferrofluid devices for biomedical and energy applications.     

Study on Crystallization Process of Li2O–Al2O3–SiO2 Glass-Ceramics Based on In Situ Analysis

In this paper, we used differential scanning calorimetry (DSC), high-temperature X-ray diffraction (HT-XRD), and confocal scanning laser microscopy (CSLM) to investigate the Li₂O–Al₂O_3–SiO₂ glass crystallization process. At 943 K, lithium disilicate (Li₂Si₂O₅) phase crystals began to precipitate in the Li₂O–Al₂O₃–SiO₂ glass with a crystal size of 50–70 nm. At the temperature of 1009 K, petalite (LiAlSi₄O₁₀) crystals began to precipitate in the vitreous phase, forming composite spherical crystals of LiAlSi₄O₁₀ and Li₂Si₂O₅ with size in the range of 90–130 nm. Furthermore, the Kissinger method and KAS method of the JMAK model were used to calculate the crystallization activation energy and the Avrami index “n”. It was found that the precipitation mechanism of the two kinds of crystals is whole crystallization; accordingly, the selection of crystallization heat treatment system was guided to determine the nucleation and crystallization temperature.     

Scalable Synthesis and Electrochemical Properties of Porous Si-CoSi2-C Composites as an Anode for Li-ion Batteries

Si-based anodes for Li-ion batteries (LIBs) are considered to be an attractive alternative to graphite due to their higher capacity, but they have low electrical conductivity and degrade mechanically during cycling. In the current study, we report on a mass-producible porous Si-CoSi₂-C composite as a high-capacity anode material for LIBs. The composite was synthesized with two-step milling followed by a simple chemical etching process. The material conversion and porous structure were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and electron microscopy. The electrochemical test results demonstrated that the Si-CoSi₂-C composite electrode exhibits greatly improved cycle and rate performance compared with conventional Si-C composite electrodes. These results can be ascribed to the role of CoSi₂ and inside pores. The CoSi₂ synthesized in situ during high-energy mechanical milling can be well attached to the Si; its conductive phase can increase electrical connection with the carbon matrix and the Cu current collectors; and it can accommodate Si volume changes during cycling. The proposed synthesis strategy can provide a facile and cost-effective method to produce Si-based materials for commercial LIB anodes.     

Fabrication of Si3N4@Si@Cu Thin Films by RF Sputtering as High Energy Anode Material for Li-Ion Batteries

Silicon and silicon nitride (Si₃N₄) are some of the most appealing candidates as anode materials for LIBs (Li-ion battery) due to their favorable characteristics: low cost, abundance of Si, and high theoretical capacity. However, these materials have their own set of challenges that need to be addressed for practical applications. A thin film consisting of silicon nitride-coated silicon on a copper current collector (Si₃N₄@Si@Cu) has been prepared in this work via RF magnetron sputtering (Radio Frequency magnetron sputtering). The anode material was characterized before and after cycling to assess the difference in appearance and composition using XRD (X-ray Powder Diffraction), XPS (X-ray Photoelectron Spectroscopy), SEM/EDX (Scanning Electron Microscopy/ Energy Dispersive X-Ray Analysis), and TEM (Transmission Electron Microscopy). The effect of the silicon nitride coating on the electrochemical performance of the anode material for LIBs was evaluated against Si@Cu film. It has been found that the Si₃N₄@Si@Cu anode achieved a higher capacity retention (90%) compared to Si@Cu (20%) after 50 cycles in a half-cell versus Li⁺/Li, indicating a significant improvement in electrochemical performance. In a full cell, the Si₃N₄@Si@Cu anode achieved excellent efficiency and acceptable specific capacities, which can be enhanced with further research.     

Transport and Electrochemical Properties of Li4Ti5O12-Li2TiO3 and Li4Ti5O12-TiO2 Composites

The study demonstrates that the introduction of the electrochemically inactive dielectric additive Li₂TiO₃ to LTO results in a strong decrease in the grain boundary resistance of LTO-Li₂TiO₃ (LTC) composites at a low concentration of Li₂TiO₃. With the increase in the concentration of Li₂TiO₃ in LTC composites, the grain boundary resistance goes through a minimum and increases again due to the growth of the insulation layer of small Li₂TiO₃ particles around LTO grains. For LTO-TiO₂ (LTT) composites, a similar effect was observed, albeit not as strong. It was found that LTC composites at low concentration of Li₂TiO₃ have unusually high charge–discharge capacity exceeding the theoretical value for pure LTO. This effect is likely to be caused by the occurrence of the electrochemical activity of Li₂TiO₃ in the vicinity of the interfaces between LTO and Li₂TiO₃. The increase in the capacity may be qualitatively described in terms of the model of two-phase composite in which there is the interface layer with a high capacity. Contrasting with LTC composites, in LTT composites, no capacity enhancement was observed, which was likely due to a noticeable difference in crystal structures of LTO and TiO₂ preventing the formation of coherent interfaces.     

Effects of Na2CO3/Na2SiO3 Ratio and Curing Temperature on the Structure Formation of Alkali-Activated High-Carbon Biomass Fly Ash Pastes

This study explored unprocessed high-carbon biomass fly ash (BFA) in alkali-activated materials (AAM) with less alkaline Na₂CO₃ as the activator. In this paper, the effects of the Na₂CO₃/Na₂SiO₃ (C/S) ratio and curing temperature (40 °C and 20 °C) on the setting time, structure formation, product synthesis, and physical-mechanical properties of alkali-activated BFA pastes were systematically investigated. Regardless of curing temperature, increasing the C/S ratio increased the density and compressive strength of the sample while a decrease in water absorption. The higher the curing temperature, the faster the structure evolution during the BFA-based alkaline activation synthesis process and the higher the sample’s compressive strength. According to XRD and TG/DTA analyses, the synthesis of gaylussite and C-S-H were observed in the sample with an increasing C/S ratio. The formation of the mentioned minerals contributes to the compressive strength growth of alkali-activated BFA pastes with higher C/S ratios. The findings of this study contribute to the applicability of difficult-to-recycle waste materials such as BFA and the development of sustainable BFA-based AAM.     

The Gd2−xMgxZr2O7−x/2 Solid Solution: Ionic Conductivity and Chemical Stability in the Melt of LiCl-Li2O

Materials with pyrochlore structure A₂B₂O₇ have attracted considerable attention owing to their various applications as catalysts, sensors, electrolytes, electrodes, and magnets due to the unique crystal structure and thermal stability. At the same time, the possibility of using such materials for electrochemical applications in salt melts has not been studied. This paper presents the new results of obtaining high-density Mg²⁺-doped ceramics based on Gd₂Zr₂O₇ with pyrochlore structure and comprehensive investigation of the electrical properties and chemical stability in a lithium chloride melt with additives of various concentrations of lithium oxide, performed for the first time. The solid solution of Gd_2−xMg_xZr₂O_7−x/2 (0 ≤ x ≤ 0.10) with the pyrochlore structure was obtained by mechanically milling stoichiometric mixtures of the corresponding oxides, followed by annealing at 1500 °C. The lattice parameter changed non-linearly as a result of different mechanisms of Mg²⁺ incorporation into the Gd₂Zr₂O₇ structure. At low dopant concentrations (x ≤ 0.03) some interstitial positions can be substituted by Mg²⁺, with further increasing Mg²⁺-content, the decrease in the lattice parameter occurred due to the substitution of host-ion sites with smaller dopant-ion. High-density ceramics 99% was prepared at T = 1500 °C. According to the results of the measurements of electrical conductivity as a function of oxygen partial pressure, all investigated samples were characterized by the dominant ionic type of conductivity over a wide range of pO₂ (1 × 10^–18 ≤ pO₂ ≤ 0.21 atm) and T < 800 °C. The sample with the composition of x = 0.03 had the highest oxygen-ion conductivity (10⁻³ S·cm⁻¹ at 600 °C). The investigation of chemical stability of ceramics in the melt of LiCl with 2.5 mas.% Li₂O showed that the sample did not react with the melt during the exposed time of one week at the temperature of 650 °C. This result makes it possible to use these materials as oxygen activity sensors in halide melts.