Charge-discharge Rate Research Articles

Ultra-low loadings of gold nanoparticles significantly boost capacitive energy storage of multilayer polymer composites

Polymer dielectrics have been extensively studied for their high power density and fast charge-discharge rate. It is crucial to balance dielectric constant and breakdown strength to achieve high energy storage...

Enhanced energy-storage density in (Pb0.98La0.02)(Zr0.45-xSn0.55Hfx)0.995O3 antiferroelectric ceramics

Antiferroelectric ceramics with unique characteristics of electric-field-induced antiferroelectric to ferroelectric phase transitions and ultra-fast charging-discharging rate, which are demanded in high pulse power devices. In this work, (Pb0.98La0.02)(Zr0.45-xSn0.55Hfx)0.995O3 (PLZSH) antiferroelectric ceramics with x = 0∼0.20 were prepared via a conventional solid-state reaction approach. Incommensurate modulation structure with a 1/n<110> superlattice was observed in AFE at room temperature, which was associated with the unique domain boundaries, contributing the obvious declined AFE-FE phase transition electric field as well as the enhanced energy storage density. It was also observed that the maximum recoverable energy storage density (Wrec) increases from 2.93 J/cm3 (x = 0) to 5.72 J/cm3 (x = 0.15), and the corresponding energy-storage efficiency uprises from 82.4 % to 87.8 % with the increasing x at 280 kV/cm. The superior energy density and efficiency indicate that the obtained PLZSH antiferroelectric ceramics are promising for practical applications in pulse power devices.

Comprehensive Analysis of Performance Evolution and Failure Mechanisms for Commercial Large-Format NMC-Gr Lithium-Ion Pouch Cells

With the accelerating adoption of lithium-ion battery systems, careful analysis of the performance evolution and failure mechanisms of commercially produced batteries is crucial for predicting the lifetime of battery systems, estimating operating and maintenance costs, and ensuring safe operation. Here, we present the results of a 2-year aging study conducted on large-format NMC-Gr pouch cells from a large battery manufacturer. Calendar and cycle aging tests were conducted on 23 cells, with calendar aging conducted at varying temperature and state-of-charge, and cycle aging conducted at varying temperatures, average voltage, voltage window, charge-discharge rates, using both constant-current cycling and drive cycles.The evolution of cell performance throughout aging was observed using electrochemical characterization tests. DC pulses show a general trend of decreasing then increasing resistance, while EIS measurements are used to deconvolute resistance evolution modes. Capacity checks show decreasing capacity throughout life for all cells. Fitting of C/20 charge and discharge curves using half-cell voltage data is used to quantify loss of lithium inventory and loss of active material degradation modes, as well as reveal the de/lithiation window experienced by electrodes throughout aging.While cell performance evolution is often neatly explained by a few key degradation modes, cell failures observed during testing were often the result of several interacting degradation mechanisms. Degradation mechanisms were identified by a variety of physical, electrochemical, and microstructural characterizations. Key degradation mechanisms observed were SEI growth at graphite/electrolyte interfaces, electrolyte decomposition and gassing leading, NMC particle cracking, Li plating, and electrode dry-out. Degradation mechanisms observable in early life often initiate new failure mechanism that lead to cell failure or safety concerns through physical or electrochemical interactions. The findings demonstrate the multi-faceted challenge of cell lifetime and failure prediction in real-world systems.

(Invited) Engineering Local Chemical Environments in Electrolytes and at Electrode-Electrolyte Interface for Efficient Aqueous Batteries

Electrolytes are an essential component of energy storage devices. Electrolyte composition has a significant impact on the environmental footprint, safety, price and performance of a battery. Aqueous electrolytes are non-flammable and can offer safer battery operation and lower toxicity. However, they suffer from a smaller electrochemical stability window compared to traditional organic electrolytes, which leads to lower energy density. To circumvent the small electrochemical stability window, highly concentrated “water-in-salt” (WIS) electrolytes, which demonstrate significantly wider stability window, were proposed and successfully applied to various aqueous energy storage systems including Li-ion and Zn metal batteries that are highly attractive for grid energy storage. However, since WIS electrolytes require large amounts of salt (often toxic) and have dramatically increased viscosity, it in turn limits their transport properties, charge-discharge rates, and usability in batteries.In this talk, the use of highly concentrated "water-in-salt" (WIS) electrolytes as a means of achieving increased charging efficiency and a wider stability window will be discussed in the context of aqueous Li-ion and Zn metal batteries. Further, we elaborate the role of cation solvation environment, electrolyte structure and hydrogen bonding on the physicochemical properties and electrochemical response of the system. We show that electrolyte composition affects the interfacial kinetics of Zn plating/stripping as well as the kinetics of the parasitic processes of electrolyte decomposition. Finally, we discuss how relatively dilute electrolytes can be engineered for efficient aqueous batteries. References Suo, O. Borodin, T. Gao, M. Olguin, J. Ho, X. Fan, C. Luo, C. Wang and K. Xu, Science, 2015, 350, 938Yamada, K. Usui, K. Sodeyama, S. Ko, Y. Tateyama and A. Yamada, Nat. Energy, 2016, 1, 16129R. Lukatskaya, J.I. Feldblyum, D.G. Mackanic, F. Lissel, D.L. Michels, Y. Cui, Z. Bao, Energy Environ. Sci., 2018, 11, 2876-2883 D.G. Vazquez, T. P. Pollard, J. Mars, J.M. Yoo, H.G. Steinrück, S. E. Bone, O. V. Safonova, M. F. Toney, O. Borodin, M.R. Lukatskaya, Energy Environ. Sci., 2023, DOI: 10.1039/D3EE00205E

Preparation and Electrochemical Performance of Na2-xLixFePO4F/C Composite Cathode Materials with Different Lithium/Sodium Ratios.

With their advantages of abundant raw material reserves, safety, and low toxicity and cost, sodium-ion batteries (SIBs) have gained increasing attention in recent years. Thanks to a high theoretical specific capacity (124 mAh g-1), a high operating voltage (about 3.2 V), and a very stable three-dimensional layered structure, sodium ferric fluorophosphate (Na2FePO4F, NFPF) has emerged as a strong candidate to be used as a cathode material for SIBs. However, applications are currently limited due to the low electronic conductivity and slow ion diffusion rate of NFPF, which result in a low actual specific capacity and a high rate performance. In this study, the authors used a high-temperature solid-phase technique to produce Na2-xLixFePO4F/C (0 ≤ x ≤ 2) and evaluated the impact on electrode performance of materials with different Na+ and Li+ contents (values of x). Transmission electron microscopy (TEM) and X-ray diffraction (XRD) were also used to analyze the material's crystal structure and nanostructure. The results show that the material had the best room-temperature performance when x = 0.5. At a charge-discharge rate of 0.1 C, the first discharge-specific capacity of the resulting Na1.5Li0.5FePO4F/C cathode material was 122.9 mAh g-1 (the theoretical capacity was 124 mAh g-1), and after 100 cycles, it remained at 118 mAh g-1, representing a capacity retention rate of 96.2% and a Coulomb efficiency of 98%. The findings of this study demonstrate that combining lithium and sodium ions improves the electrochemical performance of electrode materials.

Flexible micro-supercapacitors with organic gel electrolytes based on screen-printable CuO-ink

In recent years, due to the increase in the demand for miniaturized devices, there has been a massive increase in research to develop flexible, thin and scalable rechargeable energy storage micro-devices. Micro-supercapacitors (MSCs) with high charge-discharge rates and power density are excellent options for small, lightweight, easy-to-incorporate, flexible energy storage devices. However, the main problem with modern MSCs is their low energy density and money-intensive, time taking, sophisticated construction methods. Screen-printing is a simple, cost-effective and scalable method for fabricating MSCs. Using silver as the current collector, copper oxide as the active material, and gel electrolyte, we present a screen-printable method for constructing flexible MSCs on a PET substrate. The printed MSC was found to give 10.13 mA h cm−3 of volumetric specific capacity and energy density of 10.1 mW h cm−3 with an excellent stability of 99.5% over 3000 cycles and very small capacity degradation even with 120° bending deformation, suggesting outstanding mechanical flexibility and operation stability. Additionally, by connecting numerous MSC devices in series and parallel, the output voltage and current are intelligently adjusted to meet the requirements of varied applications. This study offers an efficient and economical approach to generate MSCs characterized by a substantial energy density. This breakthrough opens avenues for incorporating these MSCs into upcoming wearable technologies.

Sustainable recovery of LiCoO2 from spent lithium-ion batteries: Simplicity, scalability, and superior electrochemical performance

In light of the ecological ramifications and material consumption stemming from exhausted lithium-ion batteries, an exigent requirement persists for efficient and expansible recycling techniques. Herein, we investigate an innovative expedited method to directly regenerate and enhance spent LiCoO2 (SLCO). The profoundly discharged SLCO powders, featuring an unimpaired crystal lattice, are isolated. These powders are then amalgamated with Li, Ni, and Mn precursors. Subsequent heating at elevated temperatures yields LNMO-SLCO, effecting the direct regeneration of LCO, accompanied by a synergistic re-lithiation process and the application of a LiNi0.5Mn1.5O4 (LNMO) coating, all achieved in a single step. The homogeneously thin spinel LNMO coating layer (10–15 nm) bestows upon LNMO-SLCO an enhanced cycling performance and charge–discharge rate capacity when benchmarked against SLCO and commercial LiCoO2 (CLCO). Evidently, at 0.1C, 0.5C, and 2C rates, LNMO-SLCO delivers discharge capacities of 214.4 mAh g−1, 187.4 mAh g−1, and 144.1 mAh g−1, respectively. Notably, it sustains 77.68 % of its original capacity following 100 cycles at 0.5 C. The merits of LNMO-SLCO are corroborated through cyclic voltammetry and electrochemical impedance spectroscopy, affirming its reduced charge transfer resistance and augmented lithium-ion solid phase diffusion coefficient. This endeavor stands as the foremost documented instance of a direct approach to SLCO reconstruction involving LNMO coating, culminating in the formation of LNMO-SLCO, characterized by sustained high-voltage cycling performance. The outlined re-lithiation and LNMO coating stratagem proffer valuable insights for the scalable, high-value recycling of SLCO, while remaining transposable to other spent cathode materials.

Synthesis of heterostructured ZnO-CeO2 nanocomposite for supercapacitor applications

Supercapacitors (SCs) are receiving increasing attention owing to their unique characteristics, including moderate energy density, long service life, rapid discharge–charge rates, and exceptional safety. In this study, a ZnO-CeO2 nanocomposite was synthesized via a facile hydrothermal method. The hexagonal nanorods of ZnO and the particle morphology of CeO2 with high purity and crystallinity were confirmed using morphological and phase analyses. The cyclic voltammetry (CV) voltammogram from prolonged scan rates and the maximum response current in the three-electrode cell demonstrates the ZnO-CeO2 nanocomposite ideal capacitive behavior. The ZnO-CeO2 nanocomposite exhibited excellent electrochemical properties owing to the typical pseudocapacitive nature of fast redox reactions from Ce3+/Ce4+ and Zn2+ ions, with an initial capacitive contribution of 80 % at 10 mV s−1, calculated using the Dunn’s method. It exhibited a high capacitance of 1040.9 F/g at a current density of 1 A/g and excellent long-term cycling stability (97.0 %) and rate capability (68.1 %) over 8000 charge–discharge cycles. Density functional theory (DFT) calculations indicated that the ZnO-CeO2 composites show superior transport properties owing to the heterointerfaces of the formed heterostructure. The promising results of this study indicate that the ZnO-CeO2 nanocomposite could be used as an electrode material for supercapacitors.

High-pressure and high-temperature synthesis of black phosphorus-graphite anode material for lithium-ion batteries

Phosphorus-based materials with a high theoretical specific capacity and a fast charge-discharge rate are considered as promising anode materials for high energy density lithium-ion batteries (LIBs). Red phosphorus (RP) and black phosphorus (BP) are two main allotropes to be used as anode materials. However, huge volume expansion during charge-discharge processes hinders the application of RP and BP in LIBs. Composites of phosphorus and carbon-based materials have been extensively fabricated to withstand volume expansion of phosphorus and improve cycle performance. Here, composites of BP and graphite (BP-G) with three P-G mass ratios (8 : 2, 7 : 3, and 6 : 4) have been synthesized by a facile and scalable high-pressure and high-temperature (HPHT) method using RP and graphite composites (RP-G) prepared by ball milling as precursors. Their microstructure and bonding configurations have been analyzed by various characterization techniques. Among three RP-G composites, 7RP-3G exhibits the most excellent cycling stability, a high reversible capacity of 1331 mAh/g after 200 cycles at a current density of 0.78 A/g. However, RP-G composites show poor stability at high current densities. Among three BP-G composites, 6BP-4G shows the best cycle stability at high current densities, a reversible capacity of 634.6 mAh/g after 500 cycles at a current density of 2.6 A/g. Although, the reversible specific capacities of BP-G composites after long cycles are lower than those of RP-G, BP-G composites show more stable cycle performance than RP-G, especially at high current densities. The present work illustrates a direct and facile method to synthesize BP-G composites, and sheds light to explore new synthetic route of BP-based composites.

Interfacial Synergy in Mo2C/MoC Heterostructure Promoting Sequential Polysulfide Conversion in High-Performance Lithium-Sulfur Battery.

A rational design of sulfur host is the key to conquering the"polysulfide shuttle effects" by accelerating the polysulfide conversion. Since the process involves solid-liquid-solid multistep phase transitions, purposely-engineered heterostructure catalysts with various active regions for catalyzing conversion steps correspondingly are beneficial to promote the overall conversion process. However, the functionalities of the materials surface and interface in heterostructure catalysts remain unclear. In this work, an Mo2C/MoC catalyst with abundant Mo2C surface-interface-MoC surface tri-active-region is developed by in situ converting the MoZn-metal organic framework. The experimental and simulation studies demonstrate the interface can catch long-chain polysulfides and promote their conversion. Instead, the Mo2C and MoC tend to accommodate the short-chain polysulfide and accelerate their conversion and the Li2S dissociation. Benefitting from the high catalytic ability, the Li-S battery assembled with the Mo2C/MoC-S cathode shows more discrete redox reactions and delivers a high initial capacity of 1603.6 mAh g-1 at 1 C charging-discharging rate, which is over twofolds of the one assembled using individual hosts, and 80.4% capacity can be maintained after 1000 cycles at 3 C rate. This work has demonstrated a novel synergy between the interface and material surface, which will help the future design of high-performance Li-S batteries.

Tetragonal BN monolayer: A high-performance anode material for lithium-ion batteries

Searching for high-performance anode materials with fast charge-discharge rates, high specific capacity, low open circuit voltages, and good reversibility has attracted much attention over the past few decades. Herein, based on first-principles calculations, the performance of t-BN monolayer as an anode material for Li-ion batteries is investigated. The excellent stretchability of t-BN monolayer makes it good reversibility in the case of volume expansion caused by full adsorption. Additionally, t-BN monolayer with Li-adsorbed possesses metallic behavior, indicating excellent electrical conductivity. Furthermore, t-BN monolayer exhibits well-balanced performances with a low diffusion energy barrier (0.35 eV), a high specific capacity (1620 mA h g−1), an appropriate average open-circuit voltage (0.49 V), and small lattice constants change (2.5%). Finally, solvent effects are considered. The adsorption of Li-ions becomes more stable as dielectric constant of the solvent increases. Based on the above excellent properties, we speculate that t-BN monolayer can act as a promising anode material for LIBs.

A multi-time-scale framework for state of energy and maximum available energy of lithium-ion battery under a wide operating temperature range

Lithium-ion batteries are one of the best choices as energy storage devices for self-powered nodes in wireless sensor networks (WSN) due to their advantages of no memory effect, high energy density, long cycle life, and being pollution-free after being discarded, ensuring that the sensor nodes maintain high power operation for a long time. An improved co-estimation framework for SOE and maximum available energy has been established, considering the problem of maximum available energy decay caused by temperature and battery charge-discharge rate, which can update the maximum available energy in real-time and reduce SOE errors caused by fixed energy values. A multi-timescale SOE and maximum available energy co-estimation framework is proposed to address the asynchronous and coupled characteristics of maximum available energy and SOE estimation, effectively reducing the algorithm's computational complexity. The proposed algorithm is experimentally verified according to the designed dynamic stress test conditions of lithium-ion batteries in WSN nodes. The experimental results show that smaller time scales can provide more accurate and reliable maximum available energy correction and higher SOE estimation accuracy, but the computational time cost is higher than that of larger time scales. To balance SOE estimation accuracy and algorithm computational complexity, the appropriate time scale should be selected based on the SOE estimation accuracy and time cost in practical battery management system working conditions.

Comparative study of commercialized sodium-ion batteries and lithium-ion batteries

Developing new energy storage technologies is the foundation for advancing renewable energy. Among them, the development of electrochemical energy storage technology has received widespread attention. Due to its high energy density, lengthy cycle life, and environmental friendliness, lithium-ion batteries (LIBs) are being utilized extensively in everyday life. With a similar structure to LIBs, sodium-ion batteries (SIBs) are also promising for broad use in the new energy sector due to their abundant Na supplies and considerable cost benefits. In addition to introducing typical battery types and their benefits and drawbacks, this paper investigates the structures and operational concepts of LIBs and SIBs. SIBs have the advantages of low cost, abundant resources, and faster charge-discharge rates. However, they have lower energy density and require larger volume and weight. On the other hand, LIBs have a higher energy density, and more stable cycle life, but also have disadvantages such as poor safety, high cost, significant environmental impact, and destructive mining processes. The paper also focuses on the industrialization progress of SIBs by internationally renowned new energy companies such as Contemporary Amperex Technology Ltd. (CATL) and Natron Energy, highlighting the advantages of SIBs in the field of energy storage.

Development of ultrathin nanoflakes of Ni–Co LDH films by hydrothermal route for energy storage application

For energy storage systems, high capacitance, long cycling life, superior energy density, and ultrafast charge-discharge rates are important characteristics to meet the energy demands of various modern areas. Recently, the combination of Nickel (Ni) and Cobalt (Co) binary hydroxides has been recognized as a class of new materials due to their excellent electrochemical activity, high capacitance, excellent redox reversibility, spatial structure, and good electrical conductivity. Herein, Ni–Co layered double hydroxides (LDH) nanocomposites were prepared from different Ni–Co precursors under optimized preparation conditions by hydrothermal technique for supercapacitor application. As-obtained Ni–Co LDH exhibits an exceptionally high specific capacitance of 700.42 F/g was achieved at a current density of 1 A/g. Moreover, the Ni–Co LDH electrode showed a superior specific energy density of 19.69 Wh/kg and a specific power density of 2.8 Wh/kg. These excellent electrochemical results illustrate the potential of utilizing Ni–Co LDH materials for supercapacitor application and provide innovative direction for the development of future high-performance energy storage systems.

In situ doping of lithium iron phosphate with excellent water-soluble zinc salt was used to improve its magnification performance

It has always been an important research direction for improving the intrinsic conductivity of Lithium iron phosphate materials. Doping can not only improve the intrinsic conductivity but also induce lattice distortion to increase the diffusion rate of lithium ions to improve the electrochemical performance. Zn-doped LiFe1-xZnxPO4 (x = 0, 0.025, 0.05, 0.075) is prepared from LiOH·H2O, FeSO4·7H2O, H3PO4, ZnSO4·7H2O. The composition, structure, morphology and electrochemical performance of the material are characterized in detail by XRD, SEM, EDS, cyclic voltammetry test, AC impedance test and other methods. The results show that the nano-spherical LiFe0.075Zn0.025PO4 exhibits excellent capacity performance and rate performance without intentionally coating C. The initial discharge specific capacity of the positive electrode material is 153.6 mAh·g−1 at 0.2C. The material also exhibits excellent cycle performance, with a discharge-specific capacity of 148.6mAh g−1 and a capacity retention rate of 96.7% after 100 cycles at a current density of 0.2C. Compared with the undoped samples, the doped ZnSO4 improves the actual capacitance of the samples. The high specific capacity retention rate at large rate charge-discharge indicates that zinc doping improves the structural stability of the samples. The crystal structure is not significantly damaged during the large current charge discharge process, and the magnification performance is improved.

N-doped ZnCo-LDH ultrathin nanosheet array on nickel foam for high performance supercapacitors

Layered double hydroxides (LDH) are regarded as promising electrode materials for supercapacitors due to their abundance, multiple oxidation states, and high theoretical capacitance. However, the limited active sites and dull reaction kinetics restrict their commercialization. In this work, the 3D hierarchical N-doping ZnCo-LDH array on nickel foam (NF) as an electrode material (N-ZnCo-LDH) was designed and directly fabricated via a hydrothermal method using 2-Methylimidazole as a nitrogen source. Consequently, the N-doping confined the growth of the N-ZnCo-LDH to form ultrathin nanosheets, which exposed more redox reaction active sites and facilitated the charge transfer, resulting in the enhancement in charge storage capacity. As a result, the optimal N(0.5)-ZnCo-LDH achieved a high specific charge of 942.6 C g−1 at 1.0 A g−1, excellent charge-discharge rate property (68.9% retention) and long durability (84.1% after 5 000 cycles). Also, the hybrid supercapacitor (N-ZnCo-LDH//AC) was fabricated employing N(0.5)-ZnCo-LDH as anode and activated carbon (AC) as cathode, which achieved an energy density of 29.2 Wh kg−1 at a power density of 750.0 W kg−1, and excellent cycling stability (84.0% retention after 10,000 cycles), which highlighted the potential of the N(0.5)-ZnCo-LDH electrode material towards practical application of supercapacitors.

Fabrication of Ni-Cr-FeOx ceramic supercapacitor electrodes and devices by one-step electric discharge ablation

This investigation addresses the need in the development of a facile, low-cost and computer-aided design method to fabricate ceramic supercapacitors, based on patterned metal oxide films. It is motivated by the promising advantages of planar electrode arrangement for the fabrication of ceramic supercapacitors operating at extremely high charge-discharge rates. Herein, one-step electric discharge ablation (EDA) technique is developed for fabricating Ni-Cr-FeOx electrodes using commercial 304 stainless steel current collectors for the first time. The binder-free, noble materials-free, toxic chemical-free and conductive additives-free Ni-Cr-FeOx based in-plane microsupercapacitors (IMSC) are fabricated by the EDA technique. The obtained IMSC delivers a high areal capacitance of 38.3 mF cm−2 at 1 mV s−1 and shows superior capacitive behavior at an ultrahigh scan rate of 152,000 mV s−1, which is >760 times higher than the reported values for ceramic metal oxide based electrodes in the literature. This one-step, low-cost, environmental friendly, and automatic fabrication method is promising for the scale-up synthesis of various ceramic metal oxides and fabrication of supercapacitor devices.

Designing a new KBT-based binary solid solution as a candidate for dielectric energy storage materials

Dielectric energy storage capacitors offer great potential in pulsed power devices due to the high power density and fast charging-discharging rate. Designing a host material with high field-induced polarization is of importance for developing dielectric energy storage materials via further composition modulation. In this paper, we compare the microstructure, dielectric, and ferroelectric properties as well as the energy storage performance of samples K1/2Bi1/2TiO3(KBT), 75KBT-25BiFeO3 (KBTF25), and 88KBT-12Bi0.85Nd0.15FeO3 (KBNTF12) in detail. It is found that, among three samples, sample KBNTF12 possesses the most complex local structure coexisting of a four-distortions with different polarities; meanwhile, sample KBNTF12 behaves as a strong relaxor, thus giving a high field-induced polarization. Besides, sample KBNTF12 realizes the highest electric breakdown strength Eb among three samples, which is resorted to the highest resistivity of grain boundary. Highest ΔP and Eb of sample KBNTF12 among three samples render it achieve ultrahigh stored energy density Ws of 6.94 J/cm3, high recoverable energy density Wr of 5.23 J/cm3, and high efficiency η of 75.4%. Our work suggests that 88KBT-12BNF binary composition be an optimal candidate for dielectric energy storage ceramics.

Ultrahigh Capacitive Energy Density in Stratified 2D Nanofiller-Based Polymer Dielectric Films.

Dielectric capacitors are critical components in electronics and energy storage devices. The polymer-based dielectric capacitors have the advantages of device flexibility, fast charge-discharge rates, low loss, and graceful failure. Elevating the use of polymeric dielectric capacitors for advanced energy applications such as electric vehicles (EVs), however, requires significant enhancement of their energy densities. Here, we report a polymer thin film heterostructure-based capacitor of poly(vinylidene fluoride)/poly(methyl methacrylate) with stratified 2D nanofillers (Mica or h-BN nanosheets) (PVDF/PMMA-2D fillers/PVDF), that shows enhanced permittivity, high dielectric strength, and an ultrahigh energy density of ≈75 J/cm3 with efficiency over 79%. Density functional theory calculations verify the observed permittivity enhancement. This approach of using oriented 2D nanofillers-based polymer heterostructure composites is expected to be versatile for designing high energy density thin film polymeric dielectric capacitors for myriads of applications.

Enhanced energy storage properties and good stability of novel (1–x)Na0.5Bi0.5TiO3–xCa(Mg1/3Nb2/3)O3 relaxor ferroelectric ceramics prepared by chemical modification

The increase in energy consumption and its collateral damage on the environment has encouraged the development of environment-friendly ceramic materials with good energy storage properties. In this work, (1–x)Na0.5Bi0.5TiO3-xCa(Mg1/3Nb2/3)O3 ceramics were synthesized by the solid-state reaction method. The 0.88Na0.5Bi0.5TiO3-0.12Ca(Mg1/3Nb2/3)O3 ceramic exhibited a high recoverable energy storage density of 8.1 J/cm3 and energy storage efficiency of 82.4% at 550 kV/cm. The introduction of Ca(Mg1/3Nb2/3)O3 reduced the grain size and increased the band gap, thereby enhancing the breakdown field strength of the ceramic materials. The method also resulted in good temperature stability (20–140 °C), frequency stability (1–200 Hz), and fatigue stability over 106 cycles. In addition, an ultrahigh power density of 187 MW/cm3 and a fast charge-discharge rate (t0.9 = 57.2 ns) can be obtained simultaneously. Finite element method analysis revealed that the decrease of grain size was beneficial to the increase of breakdown field strength. Therefore, the 0.88Na0.5Bi0.5TiO3-0.12Ca(Mg1/3Nb2/3)O3 ceramics resulted in high energy storage properties with good stability and were promising environment-friendly materials for advanced pulsed power systems applications.