Energy Storage Applications Research Articles

Nitrogen and oxygen self-doped hierarchical porous carbon nanosheets derived from turmeric leaves for high-performance supercapacitor

It is a formidable challenge to develop efficient and low-cost nanostructured carbonaceous materials for electrochemical energy storage application. Herein, a hierarchical porous carbon nanosheet is successfully synthesized in a facile manner from turmeric leaves by a two-step chemical activation strategy using KOH activator. The biomass-derived interconnected two-dimensional (2D) carbon framework prepared at 900 °C presents high self-doped N (11.42 at%) and O contents (7.77 at%) together with specific surface area and pore volume of 541 m2/g and 0.47 cm3 g−1, respectively. Consequently, the resultant electroactive functional material shows a specific capacitance of 389 and 310 F/g at a current density of 1 A/g in acidic and neutral electrolytes, respectively. Additionally, an assembled symmetric supercapacitor device in Na2SO4 electrolyte delivers good capacitance retention of 90 % after 5000 consecutive charge–discharge cycles along with high specific energy (39.44 Wh kg−1at specific power of 0.49 kW kg−1). This work provides a cost-effective, eco-friendly and sustainable outlook to prepare high-valued porous carbons from reliable biomass sources for high-performance supercapacitor application.

Indium-Mediated Acyloxyallylation-Based Synthesis of Galacto-Configured Higher-Carbon Sugar Alcohols as Potential Phase Change Materials.

Sugar alcohols fulfilling specific structural requirements are a substance class with great potential as organic phase change materials (PCMs). Within this work, we demonstrate the indium-mediated acyloxyallylation (IMA) as a useful strategy for the synthesis of higher-carbon sugar alcohols of the galacto-family featuring all hydroxyl groups in a 1,3-anti-relationship with three major synthetic achievements: first, the dihydroxylation of the IMA-derived allylic sugar derivates was systematically studied in terms of diastereoselectivity, revealing a high degree of substrate control toward anti-addition. Second, we demonstrated the use of a "double Mitsunobu" reaction, inverting the stereochemistry of terminal diols. Third, the IMA toolbox was expanded to accomplish the synthesis of derivatives with up to 10 carbon atoms from particularly unreactive aldoses. Thermal investigations of all synthesized sugar alcohols, including examples with exclusive 1,3-anti- and suboptimal 1,3-syn-relationships as well as even and odd numbers of carbon atoms, were performed. We observed clear trends in melting points and thermal storage densities and discovered limitations of organic substances in this class with melting points above 240 °C as PCMs in terms of thermal stability. With our study, we provide insights into the dependence of thermal properties on structural features, thus contributing to further understanding of organic PCMs for thermal energy storage applications.

One-step Solid-State Synthesis of V1.13Se2/V2O3 Heterostructure as a High Pseudocapacitance Anode for Fast-Charging Sodium-Ion Batteries.

Sodium-ion batteries (SIBs) offer several benefits, including cost-efficiency and fast-charging characteristics, positioning them as attractive substitutes for lithium-ion batteries in energy storage applications. However, the inferior capacity and cycling stability of electrodes in SIBs necessitate further enhancement due to sluggish reaction kinetics. In this respect, the utilization of heterostructures, which can provide an inherent electric field and abundant active sites on the surface, has emerged as a promising strategy for augmenting the cycling stability and rate features of the electrodes. This work delves into the utilization of V1.13Se2/V2O3 heterostructure materials as anodes, initially fabricated via a simplified one-step solid-state sintering technique. The high pseudocapacitance and low characteristic relaxation time constant give the V1.13Se2/V2O3 heterostructure impressive properties, such as a high capacity of 328.5 mAh g-1 even after 1500 cycles at a high current density of 2 A g-1 and rate capability of 278.9 mAh g-1 at 5 A g-1. Moreover, the assembled sodium-ion full battery delivers a capacity of 118.5 mAh g-1 after 1000 cycles at 1 A g-1. These findings provide novel insight and guidance for the rapid synthesis of heterojunction materials and the advancement of SIBs.

Enhancing Energy Storage Capacity of 3D Carbon Electrodes Using Soft Landing of Molecular Redox Mediators.

The incorporation of redox-active species into the electric double layer is a powerful strategy for enhancing the energy density of supercapacitors. Polyoxometalates (POM) are a class of stable, redox-active species with multielectron activity, which is often used to tailor the properties of electrochemical interfaces. Traditional synthetic methods often result in interfaces containing a mixture of POM anions, unreactive counter ions, and neutral species. This leads to degradation in electrochemical performance due to aggregation and increased interfacial resistance. Another significant challenge is achieving the uniform and stable anchoring of POM anions on substrates to ensure the long-term stability of the electrochemical interface. These challenges are addressed by developing a mass spectrometry-based subambient deposition strategy for the selective deposition of POM anions onto engineered 3D porous carbon electrodes. Furthermore, positively charged functional groups are introducedon the electrode surface for efficient trapping of POM anions. This approach enables the deposition of purified POM anions uniformly through the pores of the 3D porous carbon electrode, resulting in unprecedented increase in the energy storage capacity of the electrodes. The study highlights the critical role of well-defined electrochemical interfaces in energy storage applications and offers a powerful method to achieve this through selective ion deposition.

Tailoring the graphene framework by embedding Nb2O5 and silver nanoparticles for electrodes in energy storage applications

In this study, Nb2O5/GNs and Ag/GNs-based nanocomposites were synthesized via a facile single-step hydrothermal approach. Using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Raman spectroscopy, fourier-transform infrared (FTIR) spectroscopy, and UV–vis spectroscopy, the morphology, functional groups, structure, and optical and electrical properties of the as-prepared materials were examined. XPS studies show the predominant signal at 284.8 eV is attributed to the sp2 carbon atoms (C 1) that comprise graphitic areas, indicating that the majority of the C atoms are arranged in a honeycomb lattice. FTIR spectrum confirms bonding, such as CO, CH2, CO, CC, OH, AgO, and NbONb in the nanocomposite. Further, the specific capacitance (Csp) of the Nb2O5/GNs and Ag/GNs was calculated 603 Fg−1 and 810 Fg−1 at different current densities, The Nb2O5/GNs exhibit 109 Wh/kg and 2180 W/kg energy and power density, respectively. However, the Ag/GNs electrode exhibited an energy density of 145.8 Wh/kg and a power density of 3645 W/kg, with cyclic stability retentions of 93.06 % and 97.02 %, respectively. The capacitance retention finished at 1000 cycles. Moreover, the achieved resistance from the I–V characteristics curve shows enhanced electrical conductivity of synthesized nanocomposites. These results suggested that the materials can have bright future in next-generation energy storage devices.

Form-stable Na2CO3-NaCl/mullite phase change composite with SiC enhanced thermal conductivity for high temperature thermal storage

High-temperature energy storage technologies are gaining prominence to meet the needs of concentrating solar power plants and industrial waste heat recovery. In this study a series of form-stable phase change materials are prepared by a simple and efficient cold compression sintering method. In this method, Na2CO3-NaCl will be mixed with mullite ceramic powder; simultaneously, SiC nanoparticles are introduced to improve the thermal conductivity of the material. The leakage, microstructure, chemical compatibility and thermal physical properties of the prepared composites are systematically analyzed using Fourier-transform infrared spectroscopy, X-ray powder diffraction, Scanning electron microscope, Differential Scanning Calorimetry and Thermogravimetric. The results of the study show that good chemical compatibility of the components in the composites, and the latent heat of melting of the encapsulated composites as well as the sample with added SiC are 266.97 J/g and 217.63 J/g, respectively, while the latent heat of crystallization is 197.37 J/g and 151.13 J/g, respectively. Compared to the thermal conductivity of PCMs (0.41 W/(m·K)), the thermal conductivity of the sample with 20 % SiC added is 1.83 W/(m·K), an increase of 8.7 times. Thermal cycling and reliability tests show that even after 300 cycles, good chemical compatibility is maintained between the components in composites, and the phase change properties and quality remain stable. In addition, the thermal storage cost of FSPCM-M40-S20 is 1.90 $/MJ. Therefore, we believe that the prepared Na2CO3-NaCl/mullite/SiC FSPCM has promising applications in high-temperature thermal energy storage, especially in solar power generation and industrial waste heat recovery.

Achieving High Energy Storage Performance under a Low Electric Field in KNbO3-Doped BNT-Based Ceramics.

Ceramic capacitors have great potential for application in power systems due to their fantastic energy storage performance (ESP) and wide operating temperature range. In this study, the (1 - x)Bi0.5Na0.47Li0.03Sn0.01Ti0.99O3-xKNbO3 (BNLST-xKN) energy storage ceramics were synthesized through the solid-phase reaction method. The addition of KN disrupts the long-range ferroelectric order of the BNLST ceramic, inducing the emergence of polar nanoregions (PNRs), which enhances the ESP of the ceramics. The BNLST-0.2KN ceramic demonstrates a high recovered energy density (Wrec ∼ 3.66 J/cm3) and efficiency (η ∼ 85.8%) under a low electric field of 210 kV/cm. Meantime, it exhibits a large current density (CD ∼ 831.74 A/cm2), high power density (PD ∼ 78.86 MW/cm3), and fast discharge rate (t0.9 ∼ 0.1 μs), along with good temperature stability and excellent fatigue stability. These properties make the BNLST-0.2KN ceramic a promising candidate for energy storage applications in low electric fields.

High-Entropy Engineering of Cubic SiP with Metallic Conductivity for Fast and Durable Li-Ion Batteries.

A cost-effective, scalable ball milling process is employed to synthesize the InGeSiP3 compound with a cubic ZnS structure, aiming to address the sluggish reaction kinetics of Si-based anodes for Lithium-ion batteries (LIBs). Experimental measurements and first-principles calculations confirm that the synthesized InGeSiP3 exhibits significantly higher electronic conductivity, larger Li-ion diffusivity, and greater tolerance to volume change than its parent phases InGe (or Si)P2 or In (or Ge, or Si)P. These improvements stem from its elevated configurational entropy. Multiple characterizations validate that InGeSiP3 undergoes a reversible Li-storage mechanism that involves intercalation, followed by conversion and alloy reactions, resulting in a reversible capacity of 1,733 mA h g-1 with an initial Coulombic efficiency of 90%. Moreover, the InGeSiP3-based electrodes exhibit exceptional cycling stability, retaining a 1,121 mA h g-1 capacity with a retention rate of ∼87% after 1,500 cycles at 2,000 mA g-1 and remarkable high-rate capability, achieving 882 mA h g-1 at 10,000 mA g-1. Inspired by the distinctive characteristic of high entropy, we extend our synthesis to high entropy GaCu (or Zn)InGeSiP5, CuZnInGeSiP5, GaCuZnInGeSiP6, InGeSiP2S (or Se), and InGeSiPSSe. This endeavor overcomes the immiscibility of different metals and non-metals, paving the way for electrochemical energy storage application of high-entropy silicon-phosphides. This article is protected by copyright. All rights reserved.

Exfoliation of Ca3Co4O9 to Two-Dimensional Single-Crystalline Misfit Calcium Cobaltates for Energy Storage Applications.

Layered materials have become indispensable in the development of two-dimensional (2D) systems, offering extensive specific surface area and exceptional electrical, electrochemical, and optical properties critical for diverse applications in energy storage, catalysis, sensing, and optoelectronics. While mono- and biatomic layered materials have demonstrated remarkable characteristics in lower dimensions, the quest for complexity in materials has opened new avenues for tailoring properties to specific requirements. Within this context, misfit-layered compounds (MLCs) stand out as promising candidates. In this study, we present a successful synthesis of few-layered misfit CaCoO2-CoO2 2D nanosheets in bulk quantities from bulk calcium cobalt oxide (CCO-B or CCO). These newly synthesized 2D exfoliated misfit nanosheets demonstrate remarkable 7-fold electrochemical energy storage properties, surpassing their parent bulk CCO, as cathode materials in aqueous Zn-ion batteries. This work addresses the longstanding challenge of exfoliating bulk MLCs to nanostructured, lower dimensional MLCs, opening doors for utilization in advanced energy storage systems and beyond.

Fabrication of nickel foam/MXene/CoAl-layered double hydroxide by electrodeposition as electrode material for high-performance asymmetric supercapacitor

Layered double hydroxides (LDH) have become one of the highly promising electrode materials due to large specific area, excellent cycling stability and high energy density. However, the large internal resistance limits their applications in energy storage. The introduction of highly conductive materials is expected to solve this problem. In here, nickel foam (NF)/MXene/CoAl-LDH is prepared by electrodepositing CoAl-LDH on the surface of MXene-coated NF, and the effects of Co:Al ratio on the electrochemical properties are investigated in detail. The best electrochemical performance of the composite is obtained when Co:Al=2:1, with a specific capacitance of 646.7 F g−1 at 0.5 A g−1 and 450.8 F g−1 at 5 A g−1. Furthermore, the asymmetric supercapacitor is assembled with NF/MXene/CoAl-LDH as the positive electrode and activated carbon (AC) as the negative electrode. The voltage window of the device can reach 1.6 V. The specific capacitance of the device is 126.87 F g−1 at a current density of 0.5 A g−1. At the power density of 400 W kg−1, the energy density of 45.11 Wh kg−1 is provided. Even at the high power density of 4000 W kg−1, the energy density can still reach 17.88 Wh kg−1. After 5000 cycles at a current density of 5 A g−1, it still maintains a capacity retention rate of 92.9%. The asymmetric device with its high specific capacitance, long term stability and good power density and energy density has a great potential in energy storage applications.

Box-Behnken design for the synthesis optimization of mesoporous sulfur-doped carbon-based materials from birch waste: Promising candidates for environmental and energy storage application

The development of biomass-based carbon materials has accelerated the research interest in environmental (e.g., adsorbents for wastewater decontamination) and energy applications (e.g., batteries). In this paper, we developed a series of carbon materials (CMs) using a sulfur doping strategy to improve the physicochemical, adsorptive and energy storage properties of the aforementioned CMs. CMs were prepared and optimized using an experimental design denoted as the Box-Behnken design approach with three independent factors (i.e., the temperature of pyrolysis, zinc chloride: biomass ratio and sulfur: biomass ratio), and the responses were evaluated, namely the Specific Surface Area (SBET), mesopore area (AMeso) and micropore area (AMicro) with the help of Nitrogen Physisorption. According to the statistical analysis, under the studied conditions, the responses were mainly influenced by the pyrolysis temperature and ZnCl2 ratio, while the sulfur content did not give rise to any remarkable differences in the selected responses. The physicochemical characterization of the CMs suggested that very high Specific Surface Areas ranging from 1069 to 1925 m2 g−1 were obtained. The sulfur doping resulted in up to 7.33 wt% of sulfur in the CM structure, which yielded CMs with more defects and hydrophilic surfaces. When tested as adsorbents, CMs exhibited a very high adsorption capacity (190 – 356 mg g−1), and as anodes, they demonstrated a competitive Lithium Ion Battery (LIB) storage capacity, at least during the first five cycles (306 mAhg−1 at 1 C for CM9). However, further studies on long-term cyclability are required to prove the CM materials suitability in LIBs. This work extends our understanding of how pyrolysis and sulfur doping of biomass feedstock affects carbon materials' usability, final characteristics and potential to use in wastewater decontamination by adsorption and as anodes in LIBs.

Biomass valorization of Mangifera Indica into hierarchical carbon materials with self-doping oxygen assisted carbonization for supercapacitor applications

ABSTRACT The exploration of biocompatible energy storage media for future generations has been continuously carried out. This includes the investigations of electrode materials that are renewable, environmentally friendly, cost-effective, and rich in heteroatoms. The electrode materials undergo carbonization as a promising thermochemical process to create an active material with a porous structure of well-defined and controlled geometry. The main objective of this study is to thoroughly examine the conversion process of electrode materials derived from Mangifera Indica Seed Shells (MIS) using carbonization and activation methods for supercapacitor applications. Pyrolysis at various temperatures was carried out to determine the definitive influence of carbonization temperature on the capacitive performance of MIS active materials. The optimum carbonization temperature of 600°C significantly enhances mesoporosity, which is positively correlated to the specific surface area, hierarchical structure, and the presence of self-doping oxygen, leading to a substantial increase in capacitive behavior. In the experiment, the MIS samples were used as electrodes for supercapacitor cells, and they were found to exhibit a specific capacitance of 255 Fg−1. The goal of this study is to offer a sustainable solution by using biomass as an active material for high-performance supercapacitor cells that can be utilized in energy storage applications.

Laser-Induced Crafting of Modulated Structural Defects in MOF-Based Supercapacitor for Energy Storage Application

Laser-Induced Crafting of Modulated Structural Defects in MOF-Based Supercapacitor for Energy Storage Application

Techno-economic assessment of isolated micro-grids with second-life batteries: A reliability-oriented iterative design framework

Reusing lithium-ion batteries retired from electric vehicles (EVs) has received great attention as the performance of these batteries is still adequate for many stationary energy storage applications, such as micro-grids (MGs). To date, the economic and technical performance of second-life batteries (SLBs) in isolated MG systems remains obscure. Hence, this study focuses on the economic assessment of SLBs in an isolated 100% renewable MG, in order to identify a profitable application that promotes SLBs. The MG capacity design parameters are obtained by a two-stage chance-constrained stochastic optimization framework. To enhance the robustness of the MG design, a reliability-oriented iterative design process is proposed. This process involves continuous updates to the MG design, guided by validation results, until all specified requirements are satisfied. The lifetime of SLBs is determined using a semi-empirical degradation model seamlessly integrated into the validation process. Economic comparisons between SLBs and first-life batteries (FLBs) are conducted under identical design requirements, with consideration given to estimating the “price ceiling” and the impact of market factors. The results show that SLBs prove to be a more cost-effective option, especially when there is a demand for high reliability standards and the local electricity prices are comparatively lower.

CuCo2S4@MnO2 hollow porous heterostructure for high-performance supercapacitors

The design and synthesis of hollow porous heterostructures from multiple components is expected to impart excellent properties to the electrochemically active materials owing to their high internal voids, high surface area, and high pore volume, which are beneficial for electrolyte infiltration. However, the development of optimized electrode materials for hollow porous heterostructure storage fell behind expectations. To address these challenges, we prepared a CuCo2S4@MnO2 composite on a foam nickel substrate to create a hollow porous heterostructure. The optimized composite possesses high areal capacitance of 14.9 F cm−2 (or a specific capacitance of 1643 F g−1) at 3 mA cm−2, and 83.4% capacitance retention after 30,000 cycles in a three-electrode configuration. The NF@CuCo2S4@MnO2//AC asymmetric supercapacitor can achieve high energy density (1.2 mWh cm−2) and power density (2.4 mW cm−2) due to the wide cell voltage in aqueous electrolyte and high particular capacitances from both CuCo2S4 and MnO2 improved by the hollow porous heterostructure. Furthermore, the NF@CuCo2S4@MnO2//AC ASC can light up an LED display screen. Overall, this work demonstrates the great potential and broad prospects for application in energy storage of hollow porous heterostructures.

Thermodynamic phase equilibria study of Hythane (methane + hydrogen) gas hydrates for enhanced energy storage applications

Hydrogen blending with natural gas has become an effective technique for incorporating the characteristics of natural gas and facilitating the storage and transportation of hydrogen gas. The transportation of hydrogen and natural gas (methane) blend, also referred to as Hythane, presents numerous challenges, advantages, and disadvantages that differ based on the technology employed. The current research showcased a thorough examination of the thermodynamics involved in studying the three phase equilibrium analysis of gas hydrate technology for storing Hythane gas mixtures. Three different Hythane compositions varying in hydrogen percentage were selected, and the isochoric gas hydrate phase equilibria study was performed. The experimental results of phase equilibria and thermodynamic modelling using CPA EOS in software were compared. A similar study was also conducted in the presence of a 5.56 mol % THF solution to understand the reduction in the pressure requirement for the phase equilibria. Results from the mixed Hythane+THF gas hydrate findings suggested stable gas hydrate formation at much lower pressure requirements, increasing the credibility of storing Hythane mixtures in gas hydrates at moderate conditions. The gas compositions for each experiment were analyzed using gas chromatography to evaluate the presence of the desired gas in the hydrate phase. Heat exchange during the gas hydrate dissociation was analyzed using a high pressure differential scanning calorimeter (DSC). The change in the heat release temperature also indicates the stability of the gas hydrate, and with increasing hydrogen gas in the blend, the gas hydrate stability decreased. The Clausius-Clapeyron equation was employed to compute the heat of gas hydrate dissociation, and a comparison was made with the heat of dissociation obtained from the DSC study. The experimental investigations on Hythane gas hydrates were performed to find the hydrogen storage inside the gas hydrate phase and compare it with the previous studies of pure hydrogen hydrates. To demonstrate the Hythane gas transportation, Hythane gas hydrate pellets were formed, followed by their storage in a controlled environment to observeany changes in pressure and temperature. The Hythane gas hydrate pellets demonstrated exceptional stability of Hythane gas presenting an intriguing prospect for utilizing gas hydrate technology in Hythane gas transportation.

Boosted electrochemical performance of flower-like carbon microspheres derived from polyimides containing hydroxyl groups for supercapacitor electrodes

Herein, the flower-like microspheres derived from polyimides containing hydroxyl groups are firstly synthesized through a solvothermal technique. Then, the corresponding flower-like carbon microspheres are obtained after high-temperature carbonization. The influences of the poly(amic acid) concentration, solvothermal temperature, and treatment time on the electrochemical behaviors of carbon microspheres are investigated. The optimized carbon sample PC-2-180-10 demonstrates a distinct micro/mesopore characteristic, leading to a specific capacitance of 254.4 F g−1 at 0.5 A g−1. Subsequently, the sample is chemically activated with HNO3 for improving its electrochemical performance. When the HNO3 concentration is optimized as 6 M, the treatment temperature and time are 75 °C and 30 h respectively, the activated carbon microspheres APC-6-75-30 exhibit a maximum specific capacitance of 387.6 F g−1. Moreover, the APC-6-75-30 is symmetrically fabricated into a button-type supercapacitor (SC) device, and the SC shows a specific capacitance of 88.5 F g−1, with an energy density of 11.81 Wh kg−1 at a power density of 240.1 W kg−1. Six months later, the SC still demonstrates a better capacitive performance. Optimizing the solvothermal parameters and HNO3 treatment conditions, this work presents an effective strategy for boosting the electrochemical performance of flower-like carbon microspheres as a promising electrode for energy storage applications.

Synthesis and Characterization of the Electrical and Energy Storage Properties of New Barium Titanate - Europium Titanate Solid Solution

In the present work, the investigation of the structural, dielectric, ferroelectric and energy storage properties of polycrystalline samples of (1-x)BaTiO3 – xEuTiO3 (BT-ET) solid solution materials prepared by conventional solid-state reaction method has been carried out. X-ray diffraction analyses have revealed the formation of a single-phase tetragonal structure with the P4mm space group. Furthermore, the temperature dependence of the dielectric constants marked the presence of the following sequence of structural phase transitions, namely from rhombohedral to orthorhombic, from orthorhombic to tetragonal and from tetragonal to cubic phase transitions with the increase of temperature. A diffuse phase transition has been observed from the dielectric permittivity peak and has been analyzed using the modified Curie-Weiss law and the degree of diffuseness is found to be in the range of 1.16 - 1.76 due to the existence of different states of polarization. A phase diagram has been established based on the temperature-dependent dielectric permittivity studies. The room temperature ferroelectric properties point to a coercive field larger than that of BaTiO3 ceramics. Broad dielectric peaks associated with diffuse phase transition appear in a wide temperature range (40 - 100 °C) with the highest dielectric permittivity ε’ = 6498 found in the x = 0.05 ceramics. Moreover, an improved energy storage performance is obtained in the 0.95BaTiO3-0.05EuTiO3 ceramic with a recoverable energy density of Wrec = 0.797 J/cm3, coupled with an efficiency η = 73% at 170 kV/cm and the highest storage energy density of Wst = 1.571 J/cm3 is obtained for 0.90BaTiO3-0.10EuTiO3, which is superior to other lead-free BT-based ceramics. All these features demonstrate that the BT-ET ceramics can be widely used in energy storage applications and also in high-temperature multilayer capacitors for automotive, aerospace and related industries.

Co-assisted strategy of sacrificial salt-template and nitrogen-doping to promote lithium storage performance of NiO-Ni/N-C frameworks

Tailoring the omnidirectional conductivity networks in nickel oxide-based electrodes is important for ensuring their long lifespan, stability, high capacity, and high-rate capability. In this study, nickel metal nanoparticles and a three-dimensional nitrogen-doped carbon matrix were used to embellish the nickel oxide composite NiO–Ni/N–C via simplified hard templating. When a porous nitrogen-doped carbon matrix is present, a rapid pathway would be established for charging and discharging the electrons and lithium ions in a lithium-ion battery, thereby alleviating the volumetric expansion of the NiO nanoparticles during the operation of the battery. Moreover, the Ni0 ions added to serve as active sites to improve the capacity of the NiO-based electrodes and strengthen their conductivities. The multielement-effects of the optimal NiO–Ni/N–C electrode leads it to exhibit a capacity of 1310.8 mAh/g at 0.1 A/g for 120 loops and a rate capability of 441.5 mAh/g at 20.0 A/g. Kinetic analysis of the prepared electrodes proved their ultrafast ionic and electronic conductivities. This strategy of hard templating reduces the number of routes required for preparing different types of electrodes, including NiO-based electrodes, and improves their electrochemical performance to enable their use in energy storage applications.

Dielectric relaxation studies in Sm2O3 doped boro-zinc-vanadate glasses

In this work, the conventional melting procedure was adopted to synthesize glasses with a composition of (ZnO)0.3 – (V2O5)0.3 – (B2O3)0.4-x – (Sm2O3)x, x = 0.002, 0.005, 0.007, 0.01 and 0.02 mol%. The dielectric properties of these glasses were measured. The dielectric constant (εʹ) and dielectric loss (εʹʹ) of glasses are found to vary in the range from 1.9177x102 to 3.9456x103 and from 1.5751 to 6.9095x105 respectively for the temperature range 343 K – 573 K and frequency range 50 Hz to 10 MHz. With increase of frequency, both dielectric constant and loss decreased and increased with increase of temperature. The analysis of dielectric constant and dielectric loss confirmed that the phenomenon of dielectric relaxation is mainly due to the frequency-dependent polarization mechanism. Electric modulus and impedence spectroscopy revealed non-Debye type and a single phase relaxation process. Activation energy for dc conductivity and dielectric relaxation are found to be of same size indicating that the potential barrier encountered by the charge carriers is same in both the processes. The master curves suggested that temperature-independent relaxation is occurring in the present glasses. The high values of measured dielectric parameters suggest that the present glasses are suitable in semiconducting and energy storage applications.