Excellent Energy Storage Performance Research Articles

Synthesis of Binder-Free, Low-Resistant Randomly Orientated Nanorod/Sheet ZnS-MoS2 as Electrode Materials for Portable Energy Storage Applications.

The scientific community needs to conduct research on novel electrodes for portable energy storage (PES) devices like supercapacitors (S-Cs) and lithium-ion batteries (Li-ion-Bs) to overcome energy crises, especially in rural areas where no electrical poles are available. Herein, the nanostructured MoS2 and ZnS-MoS2 E-Ms consisting of nanoparticles/rods/sheets (N-Ps-Rs-Ss) are deposited on hierarchical nickel foam by a homemade chemical vapor deposition (H-M CVD) route. The X-ray diffraction patterns confirm the formation of polycrystalline films growing along various orientations, whereas the field-emission scanning electron microscope analysis confirms the formation of N-Ps-Rs-Ss. The change in structural and microstructural parameters indicates the existence of defects improving the energy storage ability of the deposited ZnS-MoS2@Ni-F electrodes. The specific capacitances of MoS2@Ni-F and ZnS-MoS2@Ni-F electrodes are found to be 1763 and 3565 F/g at 0.5 mV/s and 1451 and 3032 F/g at 1 A/g, respectively. The growing behavior of impedance graphs indicates their capacitive nature; however, the shifting of impedance curves toward y-axis indicates that the increasing diffusion rates due to the formation of nanostructures of ZnS-MoS2 results in low impedance. An excellent energy storage performance, minimum capacity fading, and improved electrical conductivity of the deposited E-Ms are due to the combined contributions of the electrical double layer and pseudocapacitor nature, which is again confirmed by theoretical Dunn's model. The absence of charge transfer resistance and good capacitance retention (95%) even after 10,000 cycles indicates that the deposited E-Ms are better for PES devices like S-Cs and Li-ion-Bs than MoS2 E-Ms. The assembled asymmetric supercapacitor device exhibited the maximum specific capacitance = 996 F/g, energy density = 354-285 W h/kg, power density = 2400-24,000 W/kg, capacitance retention = 95% and Coulombic efficiency = 100% even after a long charging-discharging of 10,000 cycles.

High-entropy relaxor ferroelectric ceramics for ultrahigh energy storage

Dielectric ceramic capacitors with ultrahigh power densities are fundamental to modern electrical devices. Nonetheless, the poor energy density confined to the low breakdown strength is a long-standing bottleneck in developing desirable dielectric materials for practical applications. In this instance, we present a high-entropy tungsten bronze-type relaxor ferroelectric achieved through an equimolar-ratio element design, which realizes a giant recoverable energy density of 11.0 J·cm−3 and a high efficiency of 81.9%. Moreover, the atomic-scale microstructural study confirms that the excellent comprehensive energy storage performance is attributed to the increased atomic-scale compositional heterogeneity from high configuration entropy, which modulates the relaxor features as well as induces lattice distortion, resulting in reduced polarization hysteresis and enhanced breakdown endurance. This study provides evidence that developing high-entropy relaxor ferroelectric material via equimolar-ratio element design is an effective strategy for achieving ultrahigh energy storage characteristics. Our results also uncover the immense potential of tetragonal tungsten bronze-type materials for advanced energy storage applications.

Construction of core-shell heterostructures Co3S4@NiCo2S4 as cathode and covalent organic framework derived carbon as anode for hybrid supercapacitors

Structured design helps to play out the coordination advantage and optimize the performance of electrochemical reactions. In this work, hierarchical hollow microspheres (Co3S4@NiCo2S4) with unique core-shell heterostructure were successfully prepared through simple template and solvothermal methods. Thanks to the hollow structure, cross-linked nanowire arrays, and in-situ coating of zeolite imidazole framework (ZIF), Co3S4@NiCo2S4 demonstrated excellent electrochemical performance with a specific capacitance of up to 2697.7 F g−1 at 1 A g−1 and cycling stability of 80.5% after 5000 cycles. The covalent organic framework (COF) derived nano carbon, which had undergone secondary calcination and ZnCl2 activation, also exhibited excellent double-layer energy storage performance. Compared to a single calcination, the incredible increase in capacitance was up to 208.5 times greater, reaching 291.9 F g−1 at 1 A g−1 while maintaining ultra-high rate performance (81.0% at 20 A g−1). The hybrid supercapacitor, assembled with Co3S4@NiCo2S4 as the cathode and COF-derived carbon as the anode, exhibited an extremely high energy density (79.7 Wh kg−1 at 693.5 W kg−1) and excellent cyclic stability (maintained 79.3% after 10,000 cycles of 20 A g−1), further explaining the reliable and practical characteristics. This work provided reference for the structural optimization of transition metal sulfides and the high-temperature activation of COF-derived carbon.

Antiferroelectric domain modulation enhancing energy storage performance by phase-field simulations

Antiferroelectric materials represented by PbZrO3(PZO) have excellent energy storage performance and are expected to be candidates for dielectric capacitors. It remains a challenge to further enhance the effective energy storage density and efficiency of PZO-based antiferroelectric films through domain engineering. In this work, the effects of three variables, misfit strain between the thin film and substrate, defect dipoles doping, and film thickness, on the domain structure and energy storage performance of PZO-based antiferroelectric materials are comprehensively investigated via phase-field simulations. The results show that applying tensile strain to the films can effectively increase the transition electric field from antiferroelectric to ferroelectric. In addition, the introduction of defect dipoles while applying tensile strain can significantly reduce the hysteresis and improve energy storage efficiency. Ultimately, a recoverable energy density of 38.3 J/cm3 and an energy storage efficiency of about 89.4% can be realized at 1.5% tensile strain and 2% defect dipole concentration. Our work provides a new idea for the preparation of antiferroelectric thin films with high energy storage density and efficiency by domain engineering modulation.

Equimolar high-entropy for excellent energy storage performance in Bi0.5Na0.5TiO3-based ceramics

High-entropy ceramics hold tremendous promise for energy-storage applications. However, it is still a great challenge to achieve an ultrahigh recoverable energy density (Wrec > 10 J/cm3) with high efficiency (η > 80 %) in equimolar high-entropy materials. Herein, the Bi1/5Na1/5Ba1/5Nd1/5K1/5TiO3, Bi1/6Na1/6Ba1/6Nd1/6K1/6Sr1/6TiO3, and Bi1/7Na1/7Ba1/7Nd1/7K1/7Sr1/7Ca1/7TiO3 high-entropy ceramics were designed based on the Bi0.5Na0.5TiO3 matrix by compositing highly insulative equimolar components at A-site in order to reduce mismatch of the resistance between grain and grain boundary. Our results reveal that the high-entropy design significantly suppresses the interfacial polarization, leading to a remarkable increase in breakdown strength, relaxor diffuse factor, band gap, and decreases in grain size. As a result, an unprecedented Wrec of 11.8 J/cm3 with a large η 86.4 % was achieved in BNBNKSCT. The energy-storage performance of the sample also exhibits excellent discharge performance and good thermal/frequency stability. This work indicates that the Bi1/7Na1/7Ba1/7Nd1/7K1/7Sr1/7Ca1/7TiO3 high-entropy ceramic is a promising material with great potential for energy-storage capacitors, confirming that suppressing interfacial polarization via high-entropy design is an efficient strategy for exploring high energy-storage performance dielectric materials.

Successful In Situ Growth of Conductive MOFs on 2D Cobalt-Based Compounds and Their Electrochemical Performance.

Conductive metal-organic frameworks (cMOFs), as a kind of porous material, are considered to be highly promising materials in the field of electrochemistry due to their excellent conductivity. However, due to the low specific capacitance of pure cMOFs, their application in supercapacitors is limited. By virtue of the high theoretical capacity and excellent chemical stability of Co-based compounds, in this work, cMOFs' M-HHTP (M = Ni, Co, NiCo, HHTP = 2,3,6,7,10,11-hexahydroxytriphenylene) are grown in situ on Co(OH)2, CoP, and Co3O4 nanosheets, resulting in a series of electroactive compounds as electrode materials used in supercapacitors. Among all of the compounds, Ni-HHTP@Co(OH)2 shows the most excellent energy storage performance and outstanding cyclic stability in the application of aqueous asymmetric supercapacitors.

High-temperature dielectric nanocomposite film of 2D Bi4Ti3O12/ABS with excellent energy storage performance

The utilization of high-temperature dielectrics in capacitive energy storage is of great significance in contemporary electronic systems. Nevertheless, the thermal stability of most emerging polymers exhibits a significant decline in their energy storage capacity as temperatures rise. In this study, a unique type of 2D Bi4Ti3O12 nanofillers was synthesized in order to improve the breakdown strength. A nanocomposite consisting of Bi4Ti3O12/poly(acrylonitrile-butadiene-styrene) (ABS) was synthesized with the aim of attaining enhanced dielectric characteristics and energy storage density under elevated temperatures. The Bi4Ti3O12/ABS nanocomposites exhibited notable temperature stability in relation to their dielectric and energy storage capabilities across a temperature range spanning from room temperature to 120 °C. Ultrahigh discharged energy density (Ue) of 12.44 J/cm3 for 3 wt%- Bi4Ti3O12/ABS nanocomposites and high efficiency of 87 % under 550 MV/m were achieved at room temperature. An excellent Ue of 9.12 J/cm3 and high efficiency of 86.2 % for 3 wt%- Bi4Ti3O12/ABS nanocomposites were also observed in 3 wt%- Bi4Ti3O12/ABS nanocomposites under 450 MV/m at 120 °C, which was 117 % and 114 % of ABS films. These capacitive performances could match or be higher than previously reported values for high-temperature capacitor applications.

Enhanced Energy Storage in PVDF-Based Nanocomposite Capacitors through (00l)-Oriented BaTiO3 Single-Crystal Platelets.

Flexible nanocomposite dielectrics with inorganic nanofillers exhibit great potential for energy storage devices in advanced microelectronics applications. However, high loading of inorganic nanofillers in the matrix results in an inhomogeneous electric field distribution, thereby hindering the improvement of the energy storage density (Ue) of the dielectrics. Herein, we proposed a strategy that utilized (00l)-oriented barium titanate (BT) single-crystal platelets to fabricate trilayered nanocomposite dielectrics for energy storage applications. The trilayered nanocomposites consisted of two high-permittivity layers of (Ta2O5, Al2O3) codoped TiO2 nanoparticles (Ta-Al@TiO2 nps) dispersed in a poly(vinylidene fluoride) (PVDF) matrix to facilitate large electric displacement and a middle layer of (00l)-oriented BT single-crystal platelets to provide high breakdown strength. Hence, the trilayered PVDF/Ta-Al@TiO2 nps/BT single-crystal platelet nanocomposite film attains an outstanding Ue of 16.9 J cm-3 at 370 kV mm-1, which is ∼625% higher than that of the single-layer PVDF/Ta-Al@TiO2 nps film. Finite element simulation further clarified that the successive inner layer of highly (00l)-oriented BT single-crystal platelets could effectively restrain the propagation of electrical treeing in trilayered nanocomposites. This research offers an effective approach for developing flexible dielectric capacitors with an excellent energy storage performance.

Bi-Interlayer Strategy for Modulating NiCoP-Based Heterostructure toward High-Performance Aqueous Energy Storage Devices.

Nickel-cobalt (NiCo) phosphides (NCPs) possess high electrochemical activity, which makes them promising candidates for electrode materials in aqueous energy storage devices, such as supercapacitors and zinc (Zn) batteries. However, the actual specific capacitance and rate capability of NCPs require further improvement, which can be achieved through reasonable heterostructural design and loading conditions of active materials on substrates. Herein, novel hierarchical Bi-NCP heterogeneous structures with built-in electric fields consisting of bismuth (Bi) interlayers (electrodeposited on carbon cloth (CC)) are designed and fabricated to ensure the formation of uniform high-load layered active materials for efficient charge and ion transport. The resulting CC/Bi-NCP electrodes show a uniform, continuous, and high mass loading (>3.5mg) with a superior capacitance reaching 1200 Fg-1 at 1 Ag-1 and 4129 mFcm-2 at 1 mAcm-2 combined with high-rate capability and durable cyclic stability. Moreover, assembled hybrid supercapacitors (HSCs), supercapatteries, and alkaline Zn-ion (AZBs) batteries constructed using these electrodes deliver high energy densities of 64.4, 81.8, and 319.1 Whkg-1, respectively. Overall, the constructed NCPs with excellent aqueous energy storage performance have the potential for the development of novel transition metal-based heterostructure electrodes for advanced energy devices.

High energy storage properties of (Nb0.5La0.5)4+ complex-ion modified (Ba0.85Ca0.15)(Zr0.10Ti0.90)O3 ceramics

In this work, a traditional solid-state method was adopted to prepare dense Ba[Formula: see text]Ca[Formula: see text][(Zr[Formula: see text]Ti[Formula: see text])[Formula: see text]–(Nb[Formula: see text]La[Formula: see text])x]O3(BCZT–xNL) lead-free relaxation ferroelectrics with excellent energy storage performance (ESP). Remarkably, a large breakdown field strength of BDS ([Formula: see text][Formula: see text]kV/cm) resulting from decreased grain size by double ions doping at the B-site was achieved in BCZT–xNL ceramics. Especially, the BCZT–0.12NL ceramic displays a good recoverable energy density ([Formula: see text]) of 3.1[Formula: see text]J/cm3, a high efficiency of 86.7% ([Formula: see text]) and a superior fatigue resistance, as well as a superior charge–discharge performance ([Formula: see text][Formula: see text]A/cm2, [Formula: see text][Formula: see text]MW/cm3, [Formula: see text][Formula: see text]J/cm3, [Formula: see text][Formula: see text]ns) and good thermal stability. Besides, upon NL doping, the FE to RFE phase transition results in a dielectric behavior traversing the relaxation phase ([Formula: see text]) accompanied by frequency dispersion, which is beneficial to improve ESP. The superior ESP in this work indicates that BCZT–0.12[Formula: see text]NL ceramics are a promising candidate used in energy storage capacitors.

Electrochemical and dielectric analysis of multifunctional GQDs@PEG@Mg-ZnFe2O4 ternary nanohybrid for low-frequency electronics, water splitting, and sustainable energy storage applications

This work explores the potential of GQDs@PEG@Mg-ZnFe2O4 nanocomposite in water splitting and energy storage applications. The synthesized hybrid showed remarkable dielectric properties indicating its potential for low-frequency telecommunications and electronics applications. The impedance spectroscopy disclosed the contribution of grains and grain boundaries in the realization of colossal permittivity (104) in GQDs@PEG@Mg-ZnFe2O4. Moreover, GQDs@PEG@Mg-ZnFe2O4 showed excellent energy storage performance, indicated by its specific capacitance of 100 Fg−1 and a retention ratio of 99 % over 1000 cycles at a 1 Ag−1 current density. GQDs@PEG@Mg-ZnFe2O4 nanohybrid also showed remarkable electrocatalytic activity, both for hydrogen evolution reaction and oxygen evolution reaction. The determined Tafel slope value was found to be 90 mVdec−1 and 110 mVdec−1 at a 10 mA/cm2 current density, respectively. These results highlight the multifunctional nature of the GQDs@PEG@Mg-ZnFe2O4 nanocomposite and its potential as a versatile material to address challenges in both energy storage and conversion technologies.

Atomic-Level Matching Metal-Ion Organic Hybrid Interface to Enhance Energy Storage of Polymer-Based Composite Dielectrics.

In this work, a distinctive "metal-ion organic hybrid interface" (MOHI) between polyimide (PI) and calcium niobate (CNO) nanosheets is designed. The metal ions in the MOHI can achieve atomic-level matching not only with the inorganic CNO, but also with the PI chains, forming uniform and strong chemical bonds. These results are demonstrated by experiment and theory calculations. Significantly, the MOHI reduces the free volume and introduces deep traps across the filler-matrix interfacial area, thus suppressing the electric field distortion in PI-based composite dielectrics. Consequently, PI-based dielectric containing the MOHI exhibits excellent energy storage performance. The energy storage densities (Ue) of the composite dielectric reach 9.42 J cm-3 and 4.75 J cm-3 with energy storage efficiency (η) of 90% at 25°C and 150°C respectively, which are 2.6 and 11.6 times higher than those of pure PI. This study provides new ideas for polymer-based composite dielectrics in high energy storage.

Excellent energy storage performance with high breakdown strength in Nb2O5-modified (Bi0.5Na0.5)TiO3-based ceramics

The development of lead-free dielectric capacitors with good energy storage performance and high reliability is of great practical significance for pulsed power systems. In this study, Nb2O5-modified 0.6(Bi0.5Na0.5)TiO3-0.4(Sr0.7Bi0.2)TiO3 (BNT-SBT-xNb, 0 ≤ x ≤ 0.07) ceramics were designed to enhance their energy storage performance and prepared using a hydrothermal method. The results show that Nb doping into the B site of BNT-SBT can induce lattice expansion and promote polar nanoregions, resulting in improved dielectric relaxation behavior. Moreover, the introduction of Nb can lead to the refinement of grain size, the increase in resistivity, the reduction of oxygen vacancies, and the broadening of band gap, thereby significantly enhancing the electrical breakdown strength (Eb). Accordingly, the BNT-SBT-0.05Nb system presents excellent energy storage performance with high Wrec ∼6.26 J/cm3 and η ∼87.9 % under an large Eb of 518 kV/cm in accompany with the wide temperature stability (Wrec and η vary within ±6.8 % and ±3.2 % at 40–100 °C). The significant improvement of Eb and energy storage performance demonstrates that the BNT-SBT-0.05Nb system is a potential candidate for applications in high-energy storage capacitors.

Barium Strontium Titanate-based multilayer ceramic capacitors with excellent energy storage and charge-discharge performance

Energy storage capacitors for advanced pulse power systems and high-power electric devices is a kind of important electronic components, the demand continues to grow, specifications are constantly being upgraded, and performance boundaries are continuously being pushed. Multilayer ceramic capacitors (MLCCs) for energy storage applications have received increasing attention due to the advantages of ultralow equivalent series inductance, equivalent series resistance, good frequency characteristics, strong voltage overload ability, and stable operability at high temperatures. However, the relatively low energy storage density significantly limits its broader applications. Here, 0.4Ba0.55Sr0.45TiO3-0.4Bi0.5Na0.5TiO3-0.2SrZrO3 (0.4BST-0.4BNT-0.2SZ) relaxor ferroelectric MLCCs are prepared at different heating rates. Excellent recoverable energy storage density of 10.3 J cm−3 and high energy efficiency of 93 % are achieved in fast-fired MLCCs under the electric field of 106.3 V μm−1. The impedance spectroscopy and thermally stimulated depolarization current technologies are employed to investigate the conductance mechanism of MLCCs, and the results can explain the effect of heating rate on the performance of MLCCs. In addition, the charge-discharge performances of fast-fired MLCCs are also thoroughly investigated, exhibiting great thermal and fatigue stability.

A Mini Review on Sewage Sludge and Red Mud Recycling for Thermal Energy Storage

Sewage sludge and red mud, as common industrial waste, have become a research hotspot in the field of achieving carbon peaking and carbon neutrality, reducing carbon emissions, and solving environmental problems. However, their treatment and disposal have always been a difficult problem in the environmental field. Utilizing these two materials for thermal energy storage can not only improve energy utilization efficiency but also further reduce carbon emissions during their treatment process, providing a new approach for sustainable development in the industrial sector. This article summarizes the research progress for the resource recovery of sewage sludge and red mud for direct thermal energy recovery and composite phase change energy storage. After proper treatment, sludge and red mud can be directly used as energy storage materials. In addition, sludge and red mud can be combined with phase change materials to prepare composite materials with an excellent energy storage performance. This composite has broad application prospects in fields such as solar energy utilization and building energy efficiency. However, there are still some challenges and issues in this resource recovery and utilization, such as potential environmental pollution during the treatment process, the long-term stability of energy storage materials, and cost-effectiveness, which require further research and resolution. The purpose of this paper is to evaluate the potential of sewage sludge and red mud as energy storage materials, to explore their feasibility and advantages in practical applications, and to reveal the research progress, technical challenges, and future development directions of these two materials in the field of thermal energy storage.

Optimize energy storage performance of NaNbO3 ceramics by multivariable control strategy

NaNbO3 ceramics have broad application prospects in ultra-high power electronic systems, electromagnetic pulses, and other applications. In this study, (1-y)[(1-x)NaNbO3-xSmMg0.5Zr0.5O3]-y(Bi0.5Na0.5)0.7Sr0.3TiO3 (x = 0.06, 0.08 and 0.10)(y = 0.30, 0.35, 0.40 and 0.45) ceramics were fabricated. The effects of the incorporation of SmMg0.5Zr0.5O3 (SMZ) and (Bi0.5Na0.5)0.7Sr0.3TiO3 (BNST) on the energy storage performance, impedance, actual charge and discharge capacity, phase structure and microstructure of the ceramic samples were analyzed. Finally, when x = 0.08, and y = 0.35, the recoverable energy storage density of the sample was 5.8 J/cm3 and a high energy storage efficiency of 88 % was obtained at 545 kV/cm. In addition, the ceramic maintains a stable actual charge and discharge capacity and an extremely fast discharge time (16.1 ns) in a wide temperature range (20–160 °C). These excellent energy-storage performances may be due to the fine grain size and large relaxation and activation energies.

Rational Design of Nanosheet Array-Like Layered-Double-Hydroxide-Derived NiCo2O4 In Situ Grown on Reduced-Graphene-Oxide-Coated Nickel Foam for High-Performance Solid-State Supercapacitors.

The investigation of high-performance supercapacitors is essential for accelerating the development of energy storage devices. In this work, a 3D hierarchical nanosheet array-like nickel cobaltite/reduced graphene oxide/nickel foam composite (NiCo2O4/rGO/NF) was assembled via an aqueous coprecipitation-hydrothermal strategy assisted by citric acid. Benefiting from a NiCo layered-double-hydroxide precursor with an atomic-level lattice confinement effect of metal ions and effective hybridization with rGO, the NiCo2O4/rGO/NF composite is featured as thin NiCo2O4 nanosheets (∼113.6 nm × 11.2 nm) composed of NiCo2O4 nanoparticles (∼10.9 nm) vertically staggered on the surface of a rGO-modified NF skeleton, leading to high surface area, abundant mesoporous structure, and active site exposure. The as-obtained NiCo2O4/rGO/NF was directly used as a binder-free integrated electrode for supercapacitors, achieving an excellent specific capacitance of 2863.4 F g-1 (1503.3 C g-1) at 1 A g-1, a superior rate performance of 2335.2 F g-1 at 20 A g-1, and a stability retention of 91.7% after 5000 cycles. More impressively, a solid-state asymmetric supercapacitor assembled by the present NiCo2O4/rGO/NF integrated electrode as the positive electrode and commercial activated carbon as the negative electrode achieved a high energy density of 69.2 Wh kg-1 at a power density of 800 W kg-1, and the energy density at a peak power density of 20004 W kg-1 still remained at 48.9 Wh kg-1, also showing a good cycling stability of 87.2% retention over 10000 cycles. The present facile synthesis strategy of the as-obtained NiCo2O4/rGO/NF nanosheet array composite can be used for the design and construction of many other transition-metal oxide/graphene/NF composite materials with excellent structural stability and performance in energy storage and other related areas.

A graded structure of silicon/carbon composite powder for highly stable lithium ion battery anode

Silicon has much higher theoretical specific capacity than traditional graphite materials (3579 mAh g−1vs. Graphite: 372mAh g−1). However huge volumetric expansion (∼300%) of silicon seriously reduces its cyclic stability as anode in lithium-ion batteries. Though reduce the size of silicon based composites to nanoscale and tuning their porosity have been extensively studied, above strategies reduce the vibration density of the anode material unsurprisingly, which is not conducive to the advantage of high volumetric capacity anode. In this work, we design a unique graded silicon/carbon powder to maintain excellent energy storage performance at high vibration density. The composite of graded structure is constructed by first particles and second particles. The construction strategy is proved to be adoptable to achieve cost effective production of high performance silicon/carbon composite anode for development of advanced lithium-ion battery. Under the premise of industrial powder materials’ production technologies, a graded structure silicon/carbon composite with optimized synthetic condition shows high-reversible capacity of 827.4 mAh g−1 at 200 mAh g−1 (equal to 1464.5 Ah L−1) and it capacity remains at 715.0 mAh g−1 after 800 cycles, with a capacity retention rate of 86.37%, which shows high cycle life.

Enhanced energy storage performance of Na0.5Bi0.5TiO3-based relaxor ferroelectric ceramics by synergistic optimization strategies

Despite the fact that Na0.5Bi0.5TiO3 (NBT) based lead-free ceramics have attracted widespread interest due to their various advantages, their lower recoverable energy storage density (Wrec) and energy storage efficiency (η) limit their development in pulsed power capacitors. In this work, we propose a synergistic optimization strategy to enhance the energy storage performance of 0.65Na0.5Bi0.5TiO3-0.35SrTiO3(NBST) based lead-free ceramics by introducing Bi0.8La0.2(Ni0.5Zr0.5)O3 (BLNZ) and employing viscous polymer process (VPP). The former converts the macroscopic domains into microscopic domains, limiting the polarization response hysteresis to give a large Pm–Pr. The latter reduces the thickness and porosity of the samples, resulting in a substantial increase in breakdown strength. Ultimately, by stepwise optimization of this strategy, the x = 0.15 ceramic by VPP (0.15VPP) achieves excellent energy storage performance (Wrec = 7.6 J/cm3, η = 92%) under 620 kV/cm and reliable temperature stability from 20-140 °C. The combined excellent results of this study show that our synergistic optimization strategy can effectively enhance the energy storage performance of NBT-based dielectric ceramics and could be further extended to other ceramic materials for pulsed power capacitors.

Synthesis and Electrochemical Properties of One‐Dimensional γ‐MnOOH Nanorods

AbstractMnOOH has received much attention from researchers as a supercapacitor electrode material. In this article, one‐dimensional γ‐MnOOH nanorods were prepared by the hydrothermal method using the redox reaction between MnO4− and Mn2+, and the effects of temperatures on the crystalline phases and electrochemical properties of the samples were investigated. The materials were characterized using XRD, FT‐IR, SEM, TEM, Raman and XPS; electrochemical properties were tested using CV, GCD and EIS. The results show that the reaction temperature plays an important role in the generation of γ‐MnOOH. The samples were pure phases of γ‐MnOOH (M‐140) at the reaction temperature of 140 °C, showing interlaced nanorod morphology, and when the reaction temperature was increased to 180 °C, a mixed phase of MnOOH and Mn3O4 appeared. In contrast, the electrochemical performance of γ‐MnOOH nanorods (M‐140) was superior to the other samples, reaching a specific capacitance of 221 F/g at a current density of 0.2 A/g. The capacitance retention was 93.8 % after charging and discharging the M‐140 2000 times at a current density of 6 A/g. Supercapacitors assembled with γ‐MnOOHand activated carbon (AC) have excellent energy storage performance, and a high energy density of 40.6 Wh/kg is obtained at a power density of 196.7 W/kg.