Energy Density Research Articles

Self-assembled from monometallic-organic framework to bimetallic-organic framework materials with promoted supercapacitor performance

Designing new metal–organic frameworks (MOFs) materials with definite structure and introducing heterometallic atom is an effective strategy to develop new electrocatalytic and energy storage materials. Herein, one new 3D close-packed type manganese metal–organic frameworks, namely [Mn2(BPTC)(DMSO)2.5] (Mn-MOF) have been constructed from a rigid biphenylic acid with a rigid biphenyl-3,3′,5,5′-tetracarboxylic acid (H4BPTC) ligand under a solvothermal condition. Besides, adopting the metal doping strategy, a series of bimetallic MnM’-MOF (M’=Co, Ni and Cu) crystalline materials has been successfully grown on nickel foam (NF) and were used for supercapacitor electrode material. By contrast, the MnNi-MOF/NF shows a specific capacitance of 3391.7 mF cm−2 at 1 mA‧cm−2 in 1.0 M KOH, which is 1.6 times that of Mn-MOF/NF electrode. It also displays excellent cycle stability to keep 92.6 % of the initial capacity after GCD 20000 cycles. Finally, a hybrid supercapacitor (HSC) made from on the MnNi-MOF electrode and activated carbon (AC) could deliver an energy density of 0.224 mWh cm−2 at a power density of 1.04 mW cm−2, and a high cycle-to-cycle stability with 90.1 % of the primary capacitance over 20,000 cycles. This work not only confirms the potential supercapacitor properties of as-synthesized new Mn-MOF, but also effectively improves the specific capacity and device stability of pure Mn-MOF by introducing different transition metal ions.

Protein Interfacial Gelation toward Shuttle-Free and Dendrite-Free Zn-Iodine Batteries.

Aqueous zinc-iodine (Zn-I2) batteries hold potential for large-scale energy storage but struggle with shuttle effects of I2 cathodes and poor reversibility of Zn anodes. Here, an interfacial gelation strategy is proposed to suppress the shuttle effects and improve the Zn reversibility simultaneously by introducing silk protein (SP) additive. The SP can migrate bidirectionally toward cathode and anode interfaces driven by the periodically switched electric field direction during charging/discharging. For I2 cathodes, the interaction between SP and polyiodides forms gelatinous precipitate to avoid the polyiodide dissolution, evidenced by excellent electrochemical performance, including high specific capacity and Coulombic efficiency (CE) (215 mAh g-1 and 99.5% at 1 C), excellent rate performance (≈170 mAh g-1 at 50 C), and extended durability (6000 cycles at 10 C). For Zn anodes, gelatinous SP serves as protective layer to boost the Zn reversibility (99.7% average CE at 2mA cm-2) and suppress dendrites. Consequently, a 500 mAh Zn-I2 pouch cell with high-loading cathode (37.5 mgiodine cm-2) and high-utilization Zn anode (20%) achieves remarkable energy density (80Wh kg-1) and long-term durability (>1000 cycles). These findings underscore the simultaneous modulation of both cathode and anode and demonstrate the potential for practical applications of Zn-I2 batteries.

Single–crystalline LiNi0.8Co0.1Mn0.1O2 stabilized by F–doping–induced superlattice for 4.8 V lithium–ion batteries

Single–crystalline Ni–rich ternary layered oxides represent the cutting–edge cathode materials for lithium–ion batteries, offering enhanced cycling stability compared to the polycrystalline counterparts by eliminating grain boundaries. However, their structural stability encounters a significant challenge when operated under high voltages (cut–off charging potential ≥ 4.6 V). Excessive extraction of Li+ ions can lead to the localized collapse of transition metal (TM) slabs and accumulation of lattice dislocations, which hinders Li+ diffusion and eventually cause capacity decay. This study demonstrate that the introduction of F dopants triggers an ordered mixing of Li+ and Ni2+ ions to form a superlattice in single–crystalline LiNi0.8Co0.1Mn0.1O2. This unique F–doping–induced superlattice stabilizes the deintercalated structure through Ni2+ (Li layer)–O2––Ni2+ (TM layer) interlayer super–exchange strong interactions, thereby facilitating the reversible H2–H3 phase transformation during cycling. Consequently, when cycled between 2.8–4.8 V at 1C, the F doped single–crystalline LiNi0.8Co0.1Mn0.1O2 exhibits unprecedented cycling stability, retaining 90.3 % of its initial capacity after 200 cycles, while achieving a high discharge capacity of 186.8 mAh/g and an impressive energy density of 706.5 Wh/kg. This work sheds light on the microstructural engineering for Ni–rich layered cathode materials.

Waste PET bottles derived carbon black as electrode material for supercapacitor application

This study explores the conversion of polyethylene terephthalate (PET) waste into carbon black for its use in supercapacitors, offering a sustainable solution to waste management and energy storage needs. PET bottles were pyrolysed in an inert environment to produce carbon black. This plastic waste derived carbon was then characterised and used for electrode fabrication to explore its potential in supercapacitor applications. The supercapacitive properties of these electrodes were evaluated using cyclic voltammetry and charge–discharge techniques in various “Water-in-salt” electrolytes (WIS). WIS are the electrolytes in which the concentration of water is less than the concentration of salts by weight and volume. electrolytes. Sodium acetate (CH3COONa) exhibited the highest potential window and specific capacitance among the tested electrolytes. The derived carbon black demonstrated promising electrochemical performance, with a specific capacitance of 233 F/g and an energy density of 186.6 Wh/kg. These findings underscore the potential of carbon black derived from waste PET bottles as an effective material for supercapacitors, contributing to sustainable energy storage solutions and waste reduction.

Superior energy storage performance achieved in tungsten bronze SBCN-based ceramics through tape-casting

Simultaneously integrating outstanding energy storage density and good energy storage efficiency in advanced ferroelectrics is crucial to implementing the application of dielectrics in high-power pulse devices. In this work, (Sr0.5Ba0.5)2Ca0.5Nb5-xSbxO15 ceramics were designed and prepared by adopting the B sites substitution engineering together with combining strategies of tape-casting method and two-step sintering process. Benefiting from the refined grain size and high density, the breakdown field of (Sr0.5Ba0.5)2Ca0.5Nb4.8Sb0.2O15 (SBCNS0.2) was promoted to 400 kV/cm. By the substitution of Sb5+ in the B sites, the weaker interaction force of Sb-O bond in BO6 octahedral polar unit induced the occurrence of polar nanoregions (PNRs) at room temperature to strengthen the dielectric relaxation behavior. Then it is noteworthy that SBCNS0.2 ceramics simultaneously obtained excellent recoverable energy density (Wrec, 3.9 J/cm3), energy storage efficiency (η, 90.5 %), power density (PD, 156.0 MW/cm3), and current density (CD, 1356.7 A/cm2). In addition, the SBCNS0.2 ceramics exhibited an ultrafast discharge time (t0.9, 67 ns). These results reveal prospective potential of unfilled tungsten bronze SBCNS0.2 ceramics in power capacitor applications and provide an effective strategy for improving excellent energy storage properties from the perspective of preparation methods.

Surface nickel gradient tunes anionic redox activity to stabilize cobalt-free Li-rich cathodes

Constructing a gradient structure of transition metals is promising to improve the electrochemical performance of layered oxide cathodes. However, the nickel gradient spinel layer on the surface of layer Li-rich cathodes is barely successful. Herein, we present a refining strategy of reductive gas to induce a Ni-gradient spinel layer on the surface of Li1.2Mn0.6Ni0.2O2 (LRNMO). The formed gradient spinel layer stabilizes the coordination environment at the interface and reduces oxygen loss. Moreover, the Ni gradient further maintains the reversibility of the Mn3+/Mn4+ redox couple, while the multiple valence states of Mn ions in the gradient layer enhance the electrochemical kinetics. The LRNMO with Ni-gradient spinel layer achieves an initial coulomb efficiency reaching 86.1% and maintaining an energy density of 667.9 Wh kg−1 after 200 cycles at 1 C. The surface gradient strategy is conducive to maintaining structural stability and provides support for the continued development of Li-ion batteries.

Ultralight, dual-conductive, all-fiber based 3D anode current collector for anode-free lithium metal battery

The anode-free Li metal batteries (AFLMBs), by pairing Li-containing cathode with bare anode current collector (CC), have the potential to enable the maximum improvement (>70 %) in energy density of lithium batteries. Here, we report an ultralight, dual-conductive all-fiber based Cu–CNF-CNT as anode CC, which takes advantage of the high electronic conductivity of carbon nanotube (CNT), good ionic conductivity of copper-coordinated cellulose nanofiber (Cu–CNF), and the three-dimensional porous structure by nanofibers. The interactions between CNTs and Cu-CNFs enables good mechanical strength (4.71 MPa), high electrical conductivity (31.7 S/cm), low density (1.1 g/cm3) and good wettability with electrolyte. The 3D microstructure effectively homogenizes the Li+ flux and buffers the volume changes during cycling, leading to stable Li plating/stripping. As a result, AFLMB using Cu–CNF-CNT exhibits improved capacity retention by 33 % compared to that using Cu CC. The significantly elevated energy-density shows great application potential of the Cu–CNF-CNT in AFLMBs.

Functional guanine superstructures derived superior sodiophilic porous carbonaceous metamaterial for anodic-sodium-metal-free sodium metal batteries

Metamaterials, owing to their engineered building blocks, are considered as easily functionalized composites with designed nano-properties, sparking widespread research interest. However, the scalable synthesis and programmatically derived metamaterials into the designed nano-to-macro functionalized structure still pose significant challenges. Here, we report a fast and scalable synthesized Sn-guanine superstructures derived 1D porous carbonaceous metamaterial frameworks (Sn-NCS) that self-assembled by atomic Sn doping high nitrogen content carbon nanosheets. Due to the unique bottom-up designed nano-to-macro functionalized structural characteristics, Sn-NCS exhibited superior sodiophilic property. Using density functional theory (DFT) analysis and in-situ/ex-situ experimental characterization, we reveal that Sn-NCS can not only provide abundant Sn-N4 functional sites to minimize sodium nucleation overpotential and favors a uniform Na nucleation, but also effectively guide sodium deposition within the self-assembled porosity framework of Sn-NCS along the surface of carbon nanosheets to accommodate the volume variation and stress fluctuations within the anode, even under the extremely high current density of 120 mA/cm2 with a deposition/stripping capacity of 20 mAh/cm2. Moreover, the fabricated anode-sodium-metal-free sodium metal batteries (ASM-free SMB), using Cu-Sn-NCS (Sn-NCS coated Cu foil with a mass loading of 0.1 mg/cm2) as anodic current collector, exhibit highlighted energy density and excellent cycling reliability.

Self-Assembled MXene Supported on Carbonization-Free Wood for a Symmetrical All-Wood Eco-Supercapacitor.

As an emerging two-dimensional (2D) material, MXene has garnered significant interest in advanced energy storage systems, yet the stackable structure, poor mechanical stability, and lack of moldability limit its large-scale applications. To address this challenge, herein, the self-assembly of MXene on carbonization-free wood was obtained to serve as high-performance electrodes for symmetrical all-wood eco-supercapacitors by a steam-driven self-assembly method. This method can be implemented in a low-temperature environment, significantly simplifying traditional high-temperature annealing processes and generating minimal impact on the environment, human health, and resource consumption. The environmentally friendly steam-driven self-assembly strategy can be further extended into various wood-based electrodes, regardless of the types and structures of wood. As a typical platform electrode, the optimized MXene@delignified balsa wood (MDBW) achieves high areal capacitance and specific capacitance values of 2.99 F cm-2 and 580.55 F g-1 at an extensive mass loading of 5.16 mg cm-2, respectively, with almost loss-free capacitance after 10,000 cycles at 50 mA cm-2. In addition, an all-solid-state symmetrical all-wood eco-supercapacitor was further assembled based on MDBW-20 as both positive and negative electrodes to achieve a high energy density of 19.22 μWh cm-2 at a power density of 0.58 mW cm-2. This work provides an effective strategy to optimize wood-based electrodes for the practical application of biomass eco-supercapacitors.

High-Voltage Long-Cycling All-Solid-State Lithium Batteries with High-Valent-Element-Doped Halide Electrolytes.

All-solid-state batteries (ASSBs) have garnered considerable attention as promising candidates for next-generation energy storage systems due to their potentially simultaneously enhanced safety capacities and improved energy densities. However, the solid future still calls for materials with high ionic conductivity, electrochemical stability, and favorable interfacial compatibility. In this study, we present a series of halide solid-state electrolytes (SSEs) utilizing a doping strategy with highly valent elements, demonstrating an outstanding combination of enhanced ionic conductivity and oxidation stability. Among these, Li2.6In0.8Ta0.2Cl6 emerges as the standout performer, displaying a superionic conductivity of up to 4.47 mS cm-1 at 30 °C, along with a low activation energy barrier of 0.321 eV for Li+ migration. Additionally, it showcases an extensive oxidation onset of up to 5.13 V (vs Li+/Li), enabling high-voltage ASSBs with promising cycling performance. Particularly noteworthy are the ASSBs employing LiCoO2 cathode materials, which exhibit an extended cyclability of over 1400 cycles, with 70% capacity retention under 4.6 V (vs Li+/Li), and a capacity of up to 135 mA h g-1 at a 4 C rate, with the loading of active materials at 7.52 mg cm-2. This study demonstrates a feasible approach to designing desirable SSEs for energy-dense, highly stable ASSBs.

Sonochemical synthesis and characterization of SnF2 as a potential fluoride-ion conducting solid electrolyte

Fluoride ion batteries (FIBs) are emerging as a promising alternative to conventional lithium-ion batteries, primarily because of their high theoretical energy density and environmentally sustainable characteristics. For the development of a high-performance solid-state fluoride ion battery, an engineered electrolyte is crucial. As the synthesis technique impacts the phase, microstructure, and morphology of the materials, a unique and facile sonochemical route is employed for the first time herein for synthesizing Tin (II) fluoride as a solid electrolyte. The XRD investigations have indicated the formation of the α-SnF2 phase with a monoclinic structure, and space group C2/c. The particle size of SnF2 synthesized using 225 W and 325 W power of probe sonicator is found to be 2 μm and 0.8 μm respectively, as revealed by Scanning Electron Micrographs. SnF2 prepared with 325 W ultrasonic power has exhibited the maximum ionic conductivity of value 3.4 × 10−4 S/cm at room temperature, with a significant enhancement regarding the values reported so far. The anionic transport number of the electrolyte estimated at room temperature using the combined AC-DC technique is found to be 0.96, indicating fluoride ion conduction.

Molecular dynamics simulations on TiO2 quantum dots modified asphalt: Impact of size and concentration of quantum dots

With exceptional solar reflectivity and fluorescent characteristics, TiO2 quantum dots (QDs) modified asphalt has been proposed as an innovative cool pavement technology. However, interaction mechanism and thermodynamic properties of TiO2 QDs modified asphalt at microscale have not been well understood. In this study, electronic and optical properties of TiO2 QDs with varied sizes were investigated based on quantum mechanics (QM) calculations. Moreover, molecular dynamics (MD) simulations were implemented to evaluate mechanical moduli and intermolecular dynamics of TiO2 QDs modified asphalt with different quantum sizes and concentrations. The results from QM calculations unveil that as size of TiO2 QDs rises from 6 Å to 12 Å, energy gap and binding energy of TiO2 QDs decreases by 0.928 eV and 526.38 eV, respectively while density of state (DOS) and absorption coefficient of TiO2 QDs increases. Besides, the results from MD simulations reveal that quantum size imposes significant impact on mechanical moduli of modified asphalt while concentration of TiO2 QDs brings notable influence on interaction between quantum dots and asphalt. Specifically, as concentration of QDs rises from 10 % to 30 %, cohesive energy density (CED) and solubility parameter (SP) of modified asphalt is improved by up to 457 % and 136 %, respectively. With increasing quantum size, bulk modulus, shear modulus, and Young’s modulus of modified asphalt is enhanced by up to 372 %, 206 % and 24 %, respectively. The outcomes of this study provide insights into formula and application of advanced asphalt pavement with TiO2 QDs.

Mitigating chain degradation of lithium-rich manganese-based cathode material by surface engineering

Due to offering joint cationic and anionic redox, lithium-rich manganese-based layered oxides (LMLOs) allow high energy density in lithium-ion batteries. However, the oxygen loss, electrode-electrolyte interface side reactions and the structural degradation have resulted in continuous performance decay, hindering the scale-up application of LMLOs. Here, Li1.3V0.94(BO3)2 (LVB) is uniformly coated on the Li1.2Mn0.54Co0.13Ni0.13O2 (LMNCO) surface by using a sol-gel method combined with a high-temperature calcination. By applying multiple characterizations including in-situ XRD, DEMS, HRTEM, AFM and electrochemical test, we prove that the LVB layer provides a physical barrier, which effectively inhibits the surface reactivity and blocks the chain degradation from the source, improves the reversibility of O2- redox and prevents the phase transition and structural degradation propagating from the surface to the bulk. Moreover, the kinetic investigations and calculations reveal that the LVB modification not only improves the electron conductivity of materials by decreasing the surface work function and increasing the electron density near the Fermi energy level, but also provides expanded pathways with lower impedance to facilitate the Li+ transfer and diffusion. Impressively, the modified cathode exhibits the higher rate performance (151 mAh g-1 at 5C) and improved cycle stability under high cutoff voltage (217.7 mAh g-1 after 200 cycles at 0.2C in 2.0–4.8 V, 92.5 % capacity retention; even in 2.0–5 V, 93.9 % after 100 cycles). This work systematically investigates the inhibiting degradation mechanism and establishes the correlation between the intrinsic structure and surface engineering, and offers valuable insight into the development of high-performance LMLOs.

Effect of Dietary Crude Protein and Apparent Metabolizable Energy Levels on Growth Performance, Nitrogen Utilization, Serum Parameter, Protein Synthesis, and Amino Acid Metabolism of 1- to 10-Day-Old Male Broilers

This research compared how different levels of dietary crude protein (CP) and apparent metabolizable energy (AME) affect the growth performance, nitrogen utilization, serum parameters, protein synthesis, and amino acid (AA) metabolism in broilers aged 1 to 10 days. In a 4 × 3 factorial experimental design, the broilers were fed four levels of dietary CP (20%, 21%, 22%, and 23%) and three levels of dietary AME (2800 Kcal/kg, 2900 Kcal/kg, and 3000 Kcal/kg). A total of 936 one-day-old male Arbor Acres broilers were randomly allocated to 12 treatments with 6 replications each. Growth performance, nitrogen utilization, serum parameter, gene expression of protein synthesis, and AA metabolism were evaluated at 10 d. The results revealed no interaction between dietary CP and AME levels on growth performance (p > 0.05). However, 22% and 23% CP enhanced body weight gain (BWG), the feed conversion ratio (FCR), total CP intake, and body protein deposition but had a detrimental effect on the protein efficiency ratio (PER) compared to 20% or 21% CP (p < 0.05). Broilers fed diets with 2800 Kcal/kg AME showed increased feed intake (FI) and inferior PER (p < 0.05). Broilers fed diets with 3000 Kcal/kg AME showed decreased muscle mRNA expression of mammalian target of the rapamycin (mTOR) and Atrogin-1 compared to those fed diets with 2800 Kcal/kg and 2900 Kcal/kg AME (p < 0.05). Increasing dietary CP level from 20% to 23% decreased muscle mTOR and increased S6K1 mRNA expression, respectively (p < 0.05). The muscle mRNA expression of Atrogin-1 was highest for broilers fed 23% CP diets (p < 0.05). The mRNA expression of betaine homocysteine methyltransferase (BHMT) and Liver alanine aminotransferase of the 22% and 23% CP groups were higher than those of 20% CP (p < 0.05). Significant interactions between dietary CP and AME levels were observed for muscle AMPK and liver lysine-ketoglutarate reductase (LKR) and branched-chain alpha-keto acid dehydrogenase (BCKDH) mRNA expression (p < 0.05). Dietary AME level had no effect on muscle AMPK mRNA expression for broilers fed 21% and 22% CP diets (p > 0.05), whereas increasing dietary AME levels decreased AMPK mRNA expression for broilers fed 23% CP diets (p < 0.05). The mRNA expression of LKR and BCKDH was highest for broilers fed the diet with 2800 Kcal/kg AME and 22% CP, while it was lowest for broilers fed the diet with 3000 Kcal/kg AME and 20% CP. The findings suggest that inadequate energy density hindered AA utilization for protein synthesis, leading to increased AA catabolism for broilers aged 1 to 10 days, and a dietary CP level of 22% and an AME level of 2900 to 3000 kcal/kg may be recommended based on performance and dietary protein utilization.

Powder Bed Fusion-Laser Beam of IN939: The Effect of Process Parameters on the Relative Density, Defect Formation, Surface Roughness and Microstructure.

This study investigates the effects of process parameters in the powder bed fusion-laser beam (PBF-LB) process on IN939 samples. The parameters examined include laser power (160, 180, and 200 W), laser scanning speed (400, 800, and 1200 mm/s), and hatch distance (50, 80, and 110 μm). The study focuses on how these parameters affect surface roughness, relative density, defect formation, and the microstructure of the samples. Surface roughness analysis revealed that the average surface roughness (Sa) values of the sample ranged from 4.6 μm to 9.5 μm, while the average height difference (Sz) varied from 78.7 μm to 176.7 μm. Furthermore, increasing the hatch distance from 50 μm to 110 μm while maintaining constant laser power and scanning speed led to a decrease in surface roughness. Relative density analysis indicated that the highest relative density was 99.35%, and the lowest was 93.56%. Additionally, the average porosity values were calculated, with the lowest being 0.06% and the highest reaching 9.18%. Although some samples had identical average porosity values, they differed in porosity/mm2 and average Feret size. Variations in relative density and average porosity were noted in samples with the same volumetric energy density (VED) due to different process parameters. High VED led to large, irregular pores in several samples. Microcracks, less than 50 μm in length, were present, indicating solidification cracks. The microstructural analysis of the XZ planes revealed arc-shaped melt pools, columnar elongated grains aligned with the build direction, and cellular structures with columnar dendrites. This study provides insights for optimizing PBF-LB process parameters to enhance the quality of IN939 components.

Al-doped Li4SiO4 for cyclic solar energy storage and CO2 capture: An experimental and DFT study

The substantial consumption of fossil fuels gives rise to excessive carbon dioxide emissions, and mitigating them has emerged as a pressing global priority. The use of renewable energy and carbon capture, utilization, and storage are recognized as two major approaches for carbon neutrality. Li4SiO4 materials exhibit promising prospects in both thermochemical heat storage for solar energy power and cyclic high-temperature CO2 capture. The reactivity between Li4SiO4 and CO2 plays the vital role in its energy storage and CO2 capture performance. Herein, we prepare Al-doped Li4SiO4 materials through an impregnated suspension technique, simultaneously achieving high contact areas and lattice defects to enhance both fast chemisorption and ion diffusion processes. The results show that Al-doped Li4SiO4 exhibits high average energy density of 56677.08 kJ/kmol within 30 cycles. Additionally, the granulated Al-doped Li4SiO4-based pellets, produced via the freeze-drying technique, exhibit negligible energy density loss rate of less than 9 % and acceptable mechanical strength. Furthermore, the CO2 sorption performance also reaches a high value of 0.27 g/g. The reaction mechanism between Li4SiO4 and CO2 has been investigated at both macroscopic and microscopic levels through kinetic analysis and DFT calculations. The simulated Al-doped Li4SiO4/CO2 sorption system possesses increased adsorption energy level from −0.81 eV for the undoped one to −0.95 eV, thereby leading to the improved CO2 sorption. In general, Al-doped Li4SiO4 materials demonstrate great potential for applications in thermochemical heat storage and CO2 capture.

First principle investigations of opto-electronic and thermoelectric response of A2TlAsX6 (A = K, Rb; X = Cl, Br) compounds

We have investigated the structural, electronic, optical, and thermoelectric behavior of halide-based double perovskites A2TlAsX6 (A = K, Rb; X = Cl, Br) compounds to reveal their potential in various opto-electronic and thermoelectric applications using first-principle calculations. For the computation of the various properties of A2TlAsX6 (A = K, Rb; X = Cl, Br) compounds, we have used approximations available within density functional theory (DFT). The energy bands and density of states have been used to elucidate the electronic response of the studied compounds, while the interpretation of optical properties is presented in terms of dielectric tensor, absorption coefficient, reflectivity, refraction and energy loss spectra. The investigated compounds exhibit a direct band gap within the energy range of 1.36 to 2.24 eV, indicating the promising nature of these compounds for diverse optoelectronic applications. Moreover, thermoelectric properties such as the figure of merit, power factor, Seebeck coefficient, specific heat, electric and thermal conductivity have also been computed for the studied compounds. Our investigation unveils the remarkable optoelectronic characteristics of the studied perovskites, which can be attributed to their advantageous bandgap and highly effective light absorption capabilities. Furthermore, these perovskites showcase exceptional thermodynamic stability, elevated electrical conductivity, favorable figure of merit (ZT) values, and reduced thermal conductivities. These findings suggest their suitability for applications in optoelectronic devices and thermoelectric applications. In this study, it is found that A2TlAsBr6 compounds exhibit significant absorption in the visible spectrum, rendering them more favorable for optoelectronic applications compared to A2TlAsCl6 compounds. Conversely, for thermoelectric applications, the Cl-based perovskites studied show greater promise than their Br-based counterparts. The modified Becke–Johnson (mBJ) potential emerges as the most precise approach for analyzing the electronic, optical, and thermoelectric characteristics of A2TlAsX6 (where A = K, Rb; X = Cl, Br) perovskites, surpassing other approximations utilized in present study.

Enhancing Volumetric Energy Density of LiFePO4 Battery Using Liquid Metal as Conductive Agent

Enhancing Volumetric Energy Density of LiFePO₄ Battery Using Liquid Metal as Conductive Agent

Perpendicular magnetic anisotropy of Cr/CoFeB/MgO modulated by MgO thickness

The dependence of perpendicular magnetic anisotropy (PMA) on the MgO thickness in Cr/CoFeB/MgO/Ta films has been experimentally investigated. A clear PMA is observed in the as-deposited samples with 1.8 nm MgO while no as-deposited PMA is shown in those with 4.0 nm MgO. This may be attributed to the moderate oxidation degree of CoFeB and larger interfacial anisotropy energy density K i to overcome the volume magnetic anisotropy and demagnetization field. On the contrary, samples with 4.0 nm MgO demonstrate PMA only after annealing, which might be due to the oxygen and boron diffusion during the annealing process. These results would provide a method to optimize the design of CoFeB/MgO structures on 3d metals for future applications in perpendicular magnetic devices.

Basic magnesium carbonate template assisted co-carbonization of potassium citrate toward hierarchical porous carbon for supercapacitors

Hierarchical porous carbon (HPC) as the ideal host material for supercapacitors has received extensive attention. However, traditional methods of fabricating HPC often rely on organic macromolecules and complex procedures. Herein, a simple and straightforward approach is developed for the synthesis of HPC through basic magnesium carbonate template assisted co-carbonization of potassium citrate. Potassium citrate can be effectively embedded and encapsulated with basic magnesium carbonate due to the large bulk density difference between them. In the pyrolysis process, the carbon-containing small molecules produced by the pyrolysis of potassium citrate are deposited on the surface of MgO surface obtained from the decomposition of basic magnesium carbonate, and the etching reaction of potassium salt, CO2 and primary carbon structure occurs. The competitive rate of carbon deposition reaction and etching reaction can be easily controlled by changing the ratio of potassium citrate and basic magnesium carbonate. The obtained carbon materials show the morphology changes of nanoparticle accumulations, discontinuous carbon frames and carbon planar blocks, and the hierarchical porous structure of carbon materials can also be controlled in a wide range. HPC-2 exhibits the morphology of nanoparticle accumulation and generates abundant meso-macropores, which accelerates the rapid transport of electrolytic ions. The micropores inside the nanoparticles provide an accessible room for ionic adsorption. Benefited from this unique microstructural framework, HPC-2 shares a high capacitance of 305.5Fg-1 at 0.5Ag-1 and 173.1Fg-1 at 50Ag-1. Furthermore, the assembled symmetric supercapacitors exhibit a high energy density and power density than YP-50F throughout the test range. The versatility of this synthetic strategy provides an insight into directional tailoring fine pore structure and micro-morphology of carbon materials based on small molecule deposition.