Applications In Energy Storage Devices Research Articles

Cellulose‐based smart materials: Novel synthesis techniques, properties, and applications in energy storage and conversion devices

AbstractThere has been a significant scope toward the cutting‐edge investigations in hierarchical carbon nanostructured electrodes originating from cellulosic materials, such as cellulose nanofibers, available from natural cellulose and bacterial cellulose. Elements of energy storage systems (ESSs) are typically established upon inorganic/metal mixtures, carbonaceous implications, and petroleum‐derived hydrocarbon chemicals. However, these conventional substances may need help fulfilling the ever‐increasing needs of ESSs. Nanocellulose has grown significantly as an impressive 1D element due to its natural availability, eco‐friendliness, recyclability, structural identity, simple transformation, and dimensional durability. Here, in this review article, we have discussed the role and overview of cellulose‐based hydrogels in ESSs. Additionally, the extraction sources and solvents used for dissolution have been discussed in detail. Finally, the properties (such as self‐healing, transparency, strength and swelling behavior), and applications (such as flexible batteries, fuel cells, solar cells, flexible supercapacitors and carbon‐based derived from cellulose) in energy storage devices and conclusion with existing challenges have been updated with recent findings.

Similarities and differences in the ordering at short and long ranges in a NaNbO3 based Pb-free smart system: a key to functional properties

In this study, we have investigated the crystal structure of the solid solution of antiferroelectric NaNbO3(NN) with ferroelectric Ba0.9Ca0.1TiO3(BCT), i.e. (1−x)NN- xBCT for 0⩽x⩽1.0 using High-resolution powder x-ray diffraction (HR-XRD) data, dielectric measurements in conjunction with Raman spectroscopic studies. The investigation of long-range structural phase transitions as a function of composition(x) using x-ray diffraction is complemented by short-range structural insights from Raman spectroscopy. The incorporation of BCT disrupts the delicate antiferroelectric ordering of NN and stabilizes various ferroelectric phases with increasing BCT content(x). At x = 0.10, the simultaneous presence of two ferroelectric phases viz., Pmc21 and Amm2, results in a threefold rise in remanent polarization compared to off-boundary compositions. The composition with higher BCT content (i.e. x⩾0.50 ) has shown the anomalous existence of two long-range cubic structures, both of which are characterized by Pm 3¯ m space group. In spite of having a two-phase long-range centrosymmetric structure, we have observed a slim Polarization vs. Electric field(P-E) hysteresis loop for 0.50⩽x⩽0.80 . This contrapositive behavior (i.e. hysteresis loop in a centrosymmetric structure) has been attributed to the correlations among local static polar distortions of rhombohedral type ascertained using Raman spectroscopy. The coexistence of two ferroelectric phases at room temperature(for x = 0.10) and a slim hysteresis loop (for 0.50⩽x⩽0.80 ) make these compositions potential ingredients for applications in ferroelectric memory and energy storage devices.

Broadband and ascendant nonlinear optical properties of the wide bandgap material GaN nanowires

Gallium nitride (GaN) nanowire, as a type of wide bandgap nanomaterial, has attracted considerable interest because of its outstanding physicochemical properties and applications in energy storage and photoelectric devices. In this study, we prepared GaN nanowires via a facile chemical vapor deposition method and investigated their nonlinear absorption responses ranging from ultraviolet to near-infrared in the z-scan technology under irradiation by picosecond laser pulses. The experiment revealed that GaN nanowires exhibit remarkable nonlinear absorption characteristics attributed to their wide bandgap and nanostructure, including saturable absorption and reverse saturable absorption. When compared to bulk GaN crystals, the nanowires provide a richer and more potent set of nonlinear optical effects. Furthermore, we conducted an analysis of the corresponding electronic transition processes associated with photon absorption. Under high peak power density laser excitation, two-photon absorption or three-photon absorption dominate, with maximum modulation depths of 73.6%, 74.9%, 63.1% and 64.3% at 266 nm, 355 nm, 532 nm, and 1064 nm, respectively, corresponding to absorption coefficients of 0.22 cm/GW, 0.28 cm/GW, 0.08 cm/GW, and 2.82 ×10−4 cm3/GW2. At lower peak energy densities, GaN nanowires demonstrate rare and excellent saturation absorption characteristics at wavelength of 355 nm due to interband transitions, while saturable absorption is also observed at 532 nm and 1064 nm due to band tail absorption. The modulation depths are 85.2%, 41.9%, and 13.7% for 355 nm, 532 nm, and 1064 nm, corresponding to saturation intensities of 3.39 GW/cm2, 5.58 GW/cm2 and 14.13 GW/cm2. This indicates that GaN nanowires can be utilized as broadband optical limiters and high-performance pulse laser modulating devices, particularly for scarce ultraviolet optical limiters, and saturable absorbers for ultraviolet and visible lasers. Furthermore, our study demonstrates the application potential of wide bandgap nanomaterials in nonlinear optical devices.

Morphology-controlled nickel-organic framework nanosheet arrays for efficient urea electrolysis in alkaline media

Urea electrolysis is considered as a promising energy-saving hydrogen production technique to substitute the water electrolysis, but it is restricted by the lack of efficient and cost-effective catalysts. Herein, nickel foam supported three-dimensional (3D) nickel-organic framework nanosheet arrays (Ni-BDC-t/NF, where t is the reaction time) comprising Ni2+ and an organic ligand of 4,4-biphenyl dicarboxylic acid (BDC) are synthesized as catalyst for urea electrolysis in alkaline media. Benefiting from the highly exposed Ni active sites and fast electron transfer rate endowed by 3D nanosheet array architecture, the structurally optimized Ni-BDC-10/NF exhibits preeminent electrocatalytic activity and durability toward urea oxidation reaction (UOR). To deliver a high current density of 100 mA cm−2, the required UOR potential of Ni-BDC-10/NF is only 1.50 V vs. RHE. Significantly, by further coupling with the cathodic hydrogen evolution reaction, the urea electrolysis system based on Ni-BDC-10/NF self-supporting anode exhibits a dramatic voltage decrease by 340 mV at a current density of 50 mA cm−2 as compared with that of water electrolysis under the same conditions. This study provides some new ideas for developing high-efficiency nickel-based organic framework catalysts and their application in urea-related energy storage devices.

Boosting Supercapacitor Efficiency with Amorphous Biomass-Derived C@TiO2 Composites.

Carbon materials are readily available and are essential in energy storage. One of the routes used to enhance their surface area and activity is the decoration of carbons with semiconductors, such as amorphous TiO2, for application in energy storage devices. This work reports the preparation of amorphous TiO2 nanopowders, which were obtained through the anodization of titanium in ethaline media. The obtained amorphous TiO2 was used to obtain TiO2-decorated carbon (obtained through the carbonization of glycogen precursor from mussel cooking wastewater, under N2 atmosphere) composites through three different methods: electrochemical in-situ attachment of TiO2 nanopowders to the carbon matrix using ultrasounds and sonication in ethaline. Commercial TiO2 was used as the comparison material. Morphology, composition, and structure analysis were performed, followed by the electrochemical analysis in ethaline electrolyte. The in-situ attachment of amorphous TiO2 to the carbon matrix shows the most promising electrochemical performance of 956 F g-1 at 1 A g-1 for the three-electrode cell setup, with 100% and 98% capacitance retention after 1000 and 10000 cycles. On a two-electrode symmetric solid-state electrolyte cell, the gravimetric capacitance is 1251 F g-1, at 1 A g-1, with 90% and 78% capacitance retention after 1000 and 10000 cycles, respectively.

Design Strategies for Anti‐Freeze Electrolytes in Aqueous Energy Storage Devices at Low Temperatures

AbstractWith the continuous development of electrochemical energy storage technology, especially in the current pursuit of environmental sustainability and safety, aqueous energy storage devices, due to their high safety, environmental friendliness, and cost‐effectiveness, are becoming an important direction of development in the field of energy storage. Diverse application scenarios require that energy storage systems be capable of continuous power supply under low temperature conditions. However, conventional aqueous electrolytes freeze at extremely low temperatures, causing limited ion transport and slow reaction kinetics, degrading the performance of the energy storage system. The design of low‐temperature anti‐freeze aqueous electrolytes has become an effective way to address this issue. In this review, the deep connection between hydrogen bonds (HBs) interactions in aqueous electrolytes and the liquid‐to‐solid conversion process, and the fundamental principles of the anti‐freeze mechanism is first explored. Subsequently, a systematic categorization and discussion of the design strategies for low‐temperature anti‐freeze aqueous electrolytes are conducted. Finally, potential directions are proposed. This review aims to provide comprehensive scientific guidance and technical reference for the development of anti‐freeze aqueous electrolytes with excellent low‐temperature performance, thereby promoting the application and innovation of aqueous energy storage devices in low‐temperature environments.

Rational design of hierarchical porous reduced graphene oxide/9,10-phenanthraquinone/porous carbon nanocomposites for high-performance supercapacitors

The development of advanced electrode material is crucial for promoting the application of new high-performance green energy storage devices and remains a great challenge. Herein, by introducing porous carbon (PC) or carbon nanotubes (CNTs) to further modify the redox-active 9,10-phenanthrenequinone (PQ) molecule non-covalently functionalized reduced graphene oxide (RGO), we have designed and synthesized RGO/PQ/PCs (RPPs) and RGO/PQ/CNTs-10 (RPC-10) nanocomposites using a simple one-step solvothermal method. Benefiting from the optimization of the hierarchical porous nanostructures and each composition further strengthens their respective advantages in the novel synthesized nanocomposites (RPPs and RPC-10), the RPPs and RPC-10 electrodes demonstrated significantly superior electrochemical energy storage performance over the RGO and RGO/PQ (RP) electrodes, especially for the RPP-10 electrode with a high specific capacitance of 343.5 F g−1 at 0.5 A g−1 and good rate capability (69.23 %, 0.5 − 40 A g−1). Furthermore, both the symmetric supercapacitor assembled with the optimal RPP-10 electrode and the hybrid supercapacitor assembled with the RPP-10 negative electrode and the NCSRC-24 positive electrode previously reported show excellent energy densities and ultra-long cycling stabilities. This result demonstrates that the synthesized novel RPP-10 nanocomposite is a highly promising candidate for new light-weight, sustainable, high-flexible and high-performance energy storage devices.

Balancing Ionic and Electronic Conduction at the LiFePO4 Cathode–Electrolyte Interface and Regulating Solid Electrolyte Interphase in Lithium‐Ion Batteries

AbstractRecently, in electric mobilities and stationary energy storage device applications, the development of long‐lasting, low‐cost, and high‐safety lithium‐ion batteries (LIBs) is widely studied. LiFePO4 (LFP) is a core cathode material for LIBs owing to its cost‐effectiveness and high safety. However, it exhibits low electronic conductivity and sluggish Li+ diffusion, hindering the application of LFP cathodes in high‐power battery industries. Herein, a triazole‐motivated electrolyte additive, 1‐(trimethylsilyl)−1H‐benzotriazole (TMSBTA) is presented, for mitigating iron dissolution via HF scavenging, reinforcing the robustness of the solid electrolyte interphase and constructing a cathode–electrolyte interface (CEI) to balance the ion and electron conduction of the CEI on the LFP cathode. Scanning probe microscopy performed in the conductive atomic force microscopy mode indicates that the electronically conductive CEI created by the oxidative decomposition of TMSBTA enables rapid and homogeneous lithiation and delithiation during cycling without morphological changes in the LFP particles. This study elucidates the design principles of the CEI on the LFP cathode and is expected to guide integrated electrolyte additive engineering for LFP‐containing LIBs.

Proton Self‐Limiting Effect of Solid Acids Boosts Electrochemical Performance of Zinc‐ion Batteries

AbstractAt present, aqueous rechargeable Zn–MnO2 batteries have attracted widespread attention as green potential application for renewable energy storage devices. MnO2 cathode has great potential for application, but its proton reaction results in side reactions of cathode, electrolyte consumption, and dramatic pH value changes, suffering from capacity degradation. To address the issues caused by proton deficit, a proton–limited domain strategy is proposed by integrating solid acids (Sulfonic acid type polystyrene–divinylbenzene, SATP) with proton exchange reactions into MnO2. SATP can act as a new proton source increasing the amount of H+ and reducing the generation of zinc hydroxide sulfate, by–product of proton at the cathode interface, via proton exchange reactions of ‐HSO3– group. As a result, Zn–MnO2/SATP battery delivered with excellent rate performance (218.4 mAh g–1 at 2 A g–1) and high cycling stability (the retained capacity of 115.8 mAh g–1 after 500 cycles at a current density of 1 A g–1. This work provides an innovative strategy for high performance aqueous Zn–MnO2 batteries.

Synthesis and characterization of polyaniline-based composites using cellulose nanocrystals as biological templates

Polyaniline (PANI) is considered as an ideal electrode material due to its remarkable Faradaic activity, exceptional conductivity, and ease of processing. However, the agglomeration and poor cycling stability of PANI largely limit its practical utilization in energy storage devices. To address these challenges, PANI was synthesized via a facile one-pot, two-step process using cellulose nanocrystals (CNCs) as bio-templates in this work. Zeta potential and particle size measurements revealed that the CNC template could impart improved dispersion stability to the synthesized PANI, which exhibited a decrease in average particle size from 1100 nm to 300 nm as a function of 10 % CNCs. Furthermore, the effect of CNC loadings on the performance of PANI was systematically investigated. The results showed that the specific capacitance of PANI/CNC increased from 102.52 F·g−1 to 138.12 F·g−1 with the CNC loading increase from 0 to 10 wt%. Particularly, the PANI/CNC composite film with a 1:9 ratio (C-P-10 %) demonstrated a capacity retention of 84.45 % after 6000 cycles and an outstanding conductivity of 526 S·m−1. This work generally offers an effective solution for the preparation of high-performance PANI-based composites, which might hold great promise in energy storage device applications.

Band gap tunability in DC sputtered Ni-doped ZnO thin films for wide usage in optoelectronic gadgets

ZnO thin films have brought significant applicability in optoelectronic and energy storage devices based on their environmental friendliness. Pristine ZnO, 6.25 % and 12.5 % Ni-doped ZnO thin films were deposited on Si substrate via direct current and radio frequency magnetrons, respectively. The X-ray diffraction patterns exhibited phase purity of synthesized thin films. The micrographs showed reduction in average grain size for pure ZnO, 6.25 % and 12.5 % Ni-doped ZnO as 95 nm, 70 nm and 60 nm, respectively. The elemental purity was confirmed by energy dispersive X-ray. The ellipsometric analysis showed that Ni inclusion brought band gap variation from 3.06 to 3.08 eV for pure ZnO to 12.5 % Ni-doped ZnO thin films. The real part of dielectric constant enhanced from 3.60 to 3.75 for 12.5 % Ni-doped ZnO, simultaneously depicting reduction in dielectric loss from 0.45 to 0.40. Conclusively, proposing Ni-doped ZnO thin films with low dielectric loss as a potential candidate in optoelectronic industry.

Capacitance performance of N/O co-doped hierarchical porous carbon nanosheets synthesized via "one stone for three birds" strategy

The enrichment of heteroatom doping and optimization of pore structure are considered crucial strategies for enhancing the capacitive performance of carbon materials. In this study, utilizing potassium folate as the precursor, we propose a green, simple, and scalable self-activation, self-template, self-doping method to fabricate N/O co-doped porous carbon material. The optimized sample exhibits a specific surface area of 1852 m2 g−1, providing abundant active sites. In a three-electrode system, the specific capacitance of KFA-800 reaches 274.2 F g−1 at 0.2 A g−1 in 6 M KOH electrolyte. Symmetric supercapacitors prepared with KFA-800 as the electrode show a specific capacitance of 129.2 F g−1 at 0.1 A g−1. The maximum energy density of symmetric supercapacitor was 17.9 Wh kg−1 at the power density of 100 W kg−1. After 50,000 cycles at 10 A g−1, it retained 90.91% of the initial capacitance. This work provides a novel approach for the preparation of folate derived porous carbon materials, expanding their applications in energy storage devices.

Studies of optoelectrical properties of Mn-doped ZnO nanostructure for supercapacitor and photodetector applications

The transition metal Manganese (Mn)-doped Zinc Oxide (ZnO) nanoparticles were synthesized using the sol-gel method. The nanomaterials ZnO and Zn1-xMnxO (x=0–0.15) formation, their crystal structure, and morphological properties were confirmed by X-ray Diffraction (XRD) and Scanning Electron Microscope (SEM) analysis of the materials. All the studied materials show hexagonal wurtzite structure with the particle size in nanometres. The optical properties of transition metal Mn-doped ZnO nanomaterials were explored by the absorption and transmission spectra. The band gap of the nanomaterials decreases with the increase of Mn doping concentration from 3.01 to 3.26 eV. The mobility and electrical conductivity of the Mn-doped ZnO thin films show a decreasing trend with the increase of Mn doping concentration in ZnO. The Mn-doped materials were investigated for supercapacitor and photodiode applications. The Zn0.90Mn0.10O nanomaterials show the maximum specific capacitance, power and energy density of ∼ 220 F/g, 2202 W/kg and 1.15 Wh/kg, respectively. The electrochemical properties confirm that the doping of ZnO opens a new window for its application in energy storage devices. The ZnO and Mn-doped ZnO were used as an electron transport layer in perovskite MAPbI3 photodiodes. Under the Illumination of blue (465 nm) light, the highest detectivity of undoped ZnO perovskite photodiode is ∼4.5×1010 Jones and doped ZnO perovskite photodiode is 0.7×1010 Jones, respectively. The low mobility of charges and unfavorable energy level alignment of Mn-doped ZnO with MAPbI3 thin films is the reason for the decrease in photo detectivity. Our studies demonstrate that the Mn-doped ZnO nanomaterials and their thin films have avenues for potential application in energy storage devices and photodiodes of perovskite MAPbI3.

Electrochemistry of 2D-materials for the remediation of environmental pollutants and alternative energy storage/conversion materials and devices, a comprehensive review

This review article explores into the complicated relationship between electrochemistry and 2D materials, exploring their mutual influences and the consequential advancements in energy conversion, storage, and environmental applications. Electrochemical reactions, manifested through oxidations and reductions at submerged electrodes, form the linchpin connecting the electrochemistry of 2D materials with their practical utility. Various electrochemical cell topologies are investigated for their role in enhancing material flexibility, operational states, energy conversion efficiency, and device design adaptability. The comprehensive discussion extends to diverse applications, emphasizing the pivotal roles of 2D materials in environmental remediation, alternate energy storage and conversion, and chemical reactivity. Noteworthy applications include pollutant detection, adsorption and absorption of pollutants, elimination of both organic and inorganic pollutants, and photocatalytic degradation. The review also addresses materials synthesis via electrochemical processes, detailing functionalization, handling, and deposition techniques. Particular focus is directed towards local electrochemical techniques enabling the analysis and local alteration of 2D materials. Moreover, this paper concludes the article published in the recent years with this topic and most significant trends observed in 2022 and 2023 with electrochemistry of materials for the remediation of environmental pollutants. While the trends of article publishing increased from 2020 to 2023 with topic alternative energy storage/conversion materials. Finally, offering a comprehensive overview of the synergistic relationship between electrochemistry and 2D materials and their transformative potential in sustainable technologies. Broader contextThe decreasing availability of energy resources and the contamination of the environment are two significant worldwide concerns that need immediate attention. The focus on 2D materials and associated technologies is important for the efficient conversion of solar energy into chemical energy. These materials have diverse applications in fields such as energy (e.g., water splitting), synthesis (e.g., production of valuable chemicals and N2 reduction), and the environment (e.g., CO2 reduction and environmental remediation). Furthermore, Electrochemical energy storage and conversion (EESC) technologies are widely acknowledged as the most viable solutions to address the escalating energy crisis and environmental degradation because to their exceptional energy efficiency and little environmental footprint. Currently, there have been several reports discussing the use of 2D-materials in energy applications and wastewater treatment. However, there is a lack of comprehensive reviews that summarize the electrochemistry of 2D-materials, their preparation strategies, modification techniques, and related properties. Furthermore, there is a need for detailed analysis of the progress in applying 2D-materials for environmental pollution remediation, electrocatalytic performance, energy storage, and conversion technologies and devices. In this paper, we systematically and comprehensively review the electrochemistry of 2D-materials and innovatively analyze the design principles and difficulties of 2D-materials. We discussed comprehensively the remediation of environmental pollutants through 2D-materials in water treatment fields such as photocatylsts, adsorption/absorption and dyes removal as an entry point and provide an in-depth knowledge and outlook on the current status and development potential of specific applications of energy storage and conversion materials and devices.

Home-made chemical vapor deposition-based synthesis of binder-free nanostructured magnesium-molybdenum-sulfide electrode materials for supercapacitor application

Molybdenum disulfides (MoS2) is considered as promising electrode materials (E-M) for high electrochemical performance (ECP) of lithium-ion batteries and supercapacitors due to their layered nanostructures. Herein, MoS2, MgS and hetrostructure MgS/MoS2 E-Ms comprising of nano-particles/sheets/needles like structures are synthesized on Nickel foam (Ni–F) by a simple home-made chemical vapor deposition (CVD) technique. The XRD analysis confirmed the formation of MoS2, MgS and MgS/MoS2 polycrystalline E-Ms growing along different directions. The FESEM analysis is confirmed that the addition of MgS layer over the surface of MoS2 change the surafce morphology from nano-particles to nano-needles. The change in structural and microstructural features is indicated the appearance of defects, micro-strain and dislocations density which are fruitful for excellent ECP. The cyclic voltammetry analysis is indicated the pseudocapacitive nature of the synthesized E-Ms. The maximum specific capacitance values for MoS2/Ni–F, MgS/Ni–F and MgS/MoS2/Ni–F E-Ms are 1273, 1688 and 3934 F/g at 1 A/g respectively. Moreover, the addition of MgS layer over MoS2/Ni–F is revealed the excellent cyclic stability of 98.76 % at current density of 10 A/g after 4000 cycles, energy density values are ranged from 79 to 136 W h/kg with homologous power density of 250–2500 W/kg and very small charge transfer resistance. The simulations of Power's Law and Dunn's model is confirmed that the excellent ECP is due to both capacitive and diffusive controlled contributions of heterostructured MgS/MoS2/Ni–F E-Ms. Additionally, MgS/MoS2/Ni–F E-Ms have both battery and pseudocapacitive nature due to unique nano-needles like morphology. The excellent electrochemical properties of MgS/MoS2/Ni–F E-Ms substantiate their potential applications in portable energy storage devices.

Polydopamine supporting method fabricating vanadium nitride nanoparticle enclosed into hierarchical hollow carbon nanospheres for supercapacitors

Nanostructure is crucial for achieving electrode materials with high capacity and high-power ascribing to pleasing specific surface area, intrinsic safety, and satisfactory ion transport pathways; nevertheless, the structural collapse that occurs during high-temperature treatment may lead to a decrease in the specific surface area of the electrode material, causing technical obstacles, and hence affecting its practical applicability. Vanadium nitride has become a promising electrode material since its superior conductivity and desirable theoretical capacity; unfortunately, its practical application is hindered by its limited rate capability, cycle stability, and tendency to dissolve in alkaline solutions. In this study, a template-free method is employed to prepare hollow nanosphere structures through the self-supporting effect of dopamine. When subjected to high-temperatures, it can successfully hinder the collapse of the hollow nanostructures. Graded vanadium nitride nanoparticles are generated in this process and encapsulated in hollow nanostructures. The issues of vanadium nitride dissolution and low transport rate in alkaline electrolytes can be efficiently resolved by leveraging the self-supporting action of dopamine and the subsequent formation of hierarchical vanadium nitride nanoparticles. The anode material endows a capacity of 387.14 F g−1 at a current density of 0.5 A g−1, as well as a coulombic efficiency of 98.28 % even after 10, 000 cycles at a current density of 3 A g−1. Additionally，the assembled device can achieve a maximum power density of 4, 000 W kg−1 and an energy density of 22.89 Wh Kg−1. This anode material displays potential applications in energy storage devices and offers a novel approach to material preparation.

Aliovalent Substitution Tunes Physical Properties in a Conductive Bis(dithiolene) Two-Dimensional Metal-Organic Framework.

Two-dimensional conductive metal-organic frameworks have emerged as promising electronic materials for applications in (opto)electronic, thermoelectric, magnetic, electrocatalytic, and energy storage devices. Many bottom-up or postsynthetic protocols have been developed to isolate these materials or further modulate their electronic properties. However, some methodologies commonly used in classic semiconductors, notably, aliovalent substitution, are conspicuously absent. Here, we demonstrate how aliovalent Fe(III) to Ni(II) substitution enables the isolation of a Ni bis(dithiolene) material from a previously reported Fe analogue. Detailed characterization supports the idea that aliovalent substitution of Fe(III) to Ni(II) results in an in situ oxidation of the organic dithiolene linker. This substitution-induced redox tuning modulates the electronic properties in the system, leading to higher electrical conductivity and Hall mobility but slightly lower carrier densities and weaker antiferromagnetic interactions. Moreover, this aliovalent substitution improves the material's electrochemical stability and thus enables pseudocapacitive behavior in the Ni material. These results demonstrate how classic aliovalent substitution strategies in semiconductors can also be leveraged in conductive MOFs and add further support to this class of compounds as emerging electronic materials.

Selective Lattice Doping Enables a Low-Cost, High-Capacity and Long-Lasting Potassium Layered Oxide Cathode for Potassium and Sodium Storage.

Layered transition metal oxides are highly promising host materials for K ions, owing to their high theoretical capacities and appropriate operational potentials. To address the intrinsic issues of KxMnO2 cathodes and optimize their electrochemical properties, a novel P3-type oxide doped with carefully chosen cost-effective, electrochemically active and multi-functional elements is proposed, namely K0.57Cu0.1Fe0.1Mn0.8O2. Compared to the pristine K0.56MnO2, its reversible specific is increased from 104 to 135 mAh g-1. In addition, the Cu and Fe co-doping triples the capacity under high current densities, and contributes to long-term stability over 500 cycles with a capacity retention of 68 %. Such endeavor holds the potential to make potassium-ion batteries particularly competitive for application in sustainable, low-cost, and large-scale energy storage devices. In addition, the cathode is also extended for sodium storage. Facilitated by the interlayer K ions that protect the layered structure from collapsing and expand the diffusion pathway for sodium ions, the cathode shows a high reversible capacity of 144 mAh g-1, fast kinetics and a long lifespan over 1000 cycles. The findings offer a novel pathway for the development of high-performance and cost-effective sodium-ion batteries.

A Comprehensive Study of Cu/W Double Substitution in Strontium Manganate Ceramics for Some Device Applications

AbstractIn this communication, the synthesis and characterizations of modified strontium manganate (SrCu1/3Mn1/3W1/3O3) (SCMWO) by high‐temperature solid‐state method are reported. The structural analysis predicts a monoclinic structure with a crystallite size of 36.8 nm. The analysis of the Raman active modes reveals the presence of all the constituent atomic vibrations. The study of the ultraviolet–visible spectrum provides a bandgap energy of 1.71 eV, which may be suitable for photovoltaic applications. A Maxwell‐Wanger type of polarization effect is observed at low frequency while low dielectric loss makes the material suitable for energy storage devices. The study of the impedance plots reveals the negative temperature coefficient of resistance (NTCR) character. The activation energy increases with both frequency and temperature in the modified perovskite suggesting that conductivity of the sample increases and material characters are changing from dielectric to semiconducting. The symmetrical curves in the electrical modulus plots and shift toward higher frequency region agree with the results of the non‐Debye‐type of relaxation mechanism. The semicircular curves in the Cole–Cole plots confirm the semiconducting nature and are also well supported by the results of Nyquist plots. The studied material exhibits a semiconductor nature, which may be found suitable for energy storage device applications.

Effect of annealing on crystallinity and electrical properties of Bi1.5MgNb1.5O7 thin films

Tunable dielectric materials have extensive applications in various fields; however, existing materials incorporate toxic elements or exhibit poor performance. Bi1.5MgNb1.5O7 (BMN), a Bi-based pyrochlore material, can potentially overcome these obstacles; however, it has not yet been fully characterized. In this study, the influence of annealing temperature on crystallinity and electrical properties of BMN thin films was investigated, and X-ray diffraction (XRD) results indicated that the BMN films exhibited a cubic pyrochlore structure. The surface roughness of the thin films significantly decreased and uniform grain growth was achieved after annealing at 600 °C. Interestingly, energy-level peaks corresponding to metallic Bi were found in the XPS spectra of the as-deposited BMN film. As the annealing temperature was increased to 300 °C, the metallic peak completely disappeared, providing crucial evidence for the improvement of the electrical properties of BMN after annealing. The BMN films prepared in this study exhibited significant dielectric relaxation, which is closely related to the occurrence of displacement disorder. The (442) plane identified via XRD serves as a characteristic feature of displacement disorder. The film annealed at 600 °C exhibited outstanding electrical properties, with an obtained dielectric constant, energy storage density, and tunability of 204, 1.44 J/cm3, 13.1 %, respectively. These results indicate that BMN has a strong potential for application in dielectric and energy storage devices.