High Energy Storage Efficiency Research Articles

Relaxor ferroelectric ceramics with excellent energy storage density obtained from BT-based ceramics

Lead-free energy storage ceramic capacitors which have high-power density and ultrafast discharge time are widely used in electronic systems. However, lead-free energy storage ceramic materials still suffer from low energy storage density and poor stability. In this study, the synergistic optimization of polarization and electric field breakdown strength (Eb) is realized by doping with highly polarized Bi0.5Na0.5TiO3 (Ps > 42 μC/cm2) in BaTiO3-based ceramics, thereby optimizing the energy storage density. 0.15BNT ceramics have a large ΔP (Pmax-Pr) of 29 μC/cm2 under Eb of 525 kV/cm, resulting in excellent total energy storage density (Wtotal = 5.4 J/cm3), large recoverable energy storage density (Wrec = 4.8 J/cm3) and high energy storage efficiency (η = 89%). In particular, 0.15BNT ceramics also exhibit a high-power density (PD = 80 MW/cm3), a large discharge density (Wdis = 1.9 J/cm3), and an ultrafast discharge time (t0.9 = 37 ns). In addition, 0.15BNT ceramics also show excellent frequency stability (1–120 Hz) and temperature stability (25–200 °C). These excellent properties establish that 0.15BNT ceramics are promising material candidates for applications.

Fast and durable high-capacity Na3V2(PO4)2F2O/rGO by in-situ composite of a small amount of rGO

High-capacity cathode materials with good rate and cycling performances are crucial to the development of advanced sodium batteries for high-efficiency energy storage. As a novel polyanionic cathode, Na3V2(PO4)2F3 shows outstanding structural stability and high theoretical capacity, but the low electric conductivity and sluggish Na+ diffusivity severely hinder its practical performance. In this paper, based on oxygen-tuned Na3V2(PO4)2F2O (NVPFO) and a small amount (0–1 wt%) of reduced Graphene Oxide (rGO), the NVPFO/rGO composite is simply prepared by an in-situ solid-state approach. The usage of rGO is noticeably decreased (so does the cost) due to the synergy effect of NVPFO with rGO as well as the dominated sp3 and amorphous carbon in the composite. As a result, the performance of this class material is significantly improved by rGO with an optimally reduced content. The excellent performance is ascribed to the stable crystallographic structure, high electric conductivity and fast Na+ diffusivity. This work demonstrates facile designing and preparation of graphene-involved energy materials with high-capacity, high-rate, long-durability and low-cost performances using only a small amount of in-situ generated defective rGO.

Heat discharge performance of metal hydride thermal battery under different heat transfer conditions: Experimental findings

Thermal batteries utilizing metal hydride pairs are gaining tremendous research appeal for their applications in thermochemical energy storage. The pair consisting of a high-temperature metal hydride (HTMH: Mg-based hydride) and a low-temperature metal hydride (LTMH: AB2 type hydride) is attractive due to its relatively high energy storage density and medium energy storage efficiency. The energy storage efficiency can be significantly increased by improving the heat discharging performance of the thermal battery. In this study, we experimentally explore the heat releasing performance of an MgH2/(TiZr)(MnFeCr)2-based thermal battery. More specifically, the effects of LTMH bed heat transfer conditions on the heat discharging performance were briefly discussed. These heat transfer conditions include natural convection, forced convection, and resistive heating. The results showed that when operating the LTMH bed under active heat transfer conditions (forced convection or resistive heating), the thermochemical energy storage density varies between 1500 and 1820 kJ/kg-Mg with relatively high-temperature lift (heat upgrade) between 47 and 55 °C. On the other side, the thermal battery discharges heat at a relatively high specific power, ca. 100–225 W/kg-Mg, which can be a benefit for heat-to-work conversion applications using organic or steam Rankine cycles.

Preparation of morph-genetic aluminum-doped calcium oxide templated from cotton and the calcium looping performance for energy storage in the presence of steam

Calcium looping (CaL), which can be combined with concentrated solar power (CSP) plants, is considered a promising technology for energy storage. To overcome the deactivation of calcium based materials with increasing cycles, a novel morph-genetic aluminum doped calcium oxide was prepared by a biomass template method using limestone, aluminum nitrate and cotton as raw materials. The effects of preparation parameters and heat storage conditions (especially in presence of steam) on the energy storage performance were studied. The results showed that the hollow tubular structure of the biomass template was preserved in the synthesized material and stabilized by the support of Ca12Al14O33. The presence of the hollow microtubular structure resulted in an increased pore volume of the synthesized materials and a change of the pore distribution, promoting the diffusion of CO2. This phenomenon also explained the superior performance of the synthesized material in terms of the apparent kinetic properties and resistance to sintering. The optimal synthesized material had a high energy storage density and carbonation fraction, which were more than three times those of limestone. The presence of steam during calcination served to reduce the calcination temperature and mitigate the sintering effect of CaO. An optimization route combining solar steam system and CaL-CSP system was proposed based on the positive effect of steam, which was promising for high-efficiency energy storage.

Exploration of La2O3-CuO nanocomposite as an effective electrode material for asymmetric supercapacitor applications

Supercapacitors (SCs) were recently developed as an inexpensive and high-efficiency energy storage technology. A synergistic effect on binary metal oxide composites has been regarded as the desired strategy for enhancing energy storage. In this research work, a binary metal oxide La2O3-CuO nanocomposite was prepared by an ultrasonic-assisted hydrothermal approach. The electrochemical performance is estimated using techniques such as cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electro-impedance spectroscopy (EIS). The La2O3-CuO nanocomposites attained a maximum specific capacity of 930 mAh g−1 at current density of 0.5 A/g and a better cycling stability of 85.25 % even after 2000 continuous charge-discharge cycle. The electro impedance spectroscopy EIS revealed the La2O3-CuO nanocomposites have lower solution resistance (Rs), charge transfer resistances (Rct) of Rs 0.469 Ω and Rct 0.414 Ω, respectively. Moreover, the synthesised La2O3-CuO electrode material attained energy density 13.02 Wh/kg and excellent power density 1205 W/kg along with significant capacitive retention 88.63 % even after 10,000 cycles.The outstanding electrochemical performance makes the binary nanocomposite La2O3-CuO promising electrode material for electrochemical energy storage supercapacitors.

Realizing ultrahigh energy-storage density in Ca0.5Sr0.5TiO3-based linear ceramics over broad temperature range

In the realm of energy storage, there is an exigent need for dielectric materials that exhibit high energy storage density (Wrec) and efficiency (η) over wide temperature ranges. Linear dielectrics exhibit superior breakdown strength (Eb) compared to ferroelectrics, yet their utility is restricted by low polarization. Here, an ultrahigh Wrec up to 7.92 J/cm3 and η ≈ 94.3% are realized in (Ca0.5Sr0.5)1-1.5xSmxTiO3 ceramic with ultrafast discharge time (t0.9 = 20 ns) which is one of the best energy storage performances recorded linear ceramics. By employing the charge balance method, the production of oxygen vacancies (VO··) can be prevented, leading to improved insulation. The creation of A-site vacancies serves to enhance the breakdown field strength. Furthermore, the incorporation of Sm3+ effectively limits the thermal activation of oxygen vacancies at elevated temperatures, ultimately resulting in an increase in bulk resistivity. The results also unveil the outstanding stability across a wide range of temperatures (20 °C–140 °C) and frequencies (1 Hz–500 Hz). Consequently, this study provides significant insights into enhancing Eb and attaining high-energy storage capacitors.

Structural, optical, microstructure, and giant dielectric behavior of parent, Cu and Sr doped La0.55Li0.35TiO3‐δ

AbstractOptimization of energy storage performance in dielectric ceramics has been a focus in recent decades due to the benefits of high energy storage density, efficiency, and exceptional temperature stability. In this work, we report huge dielectric constant in La0.55Li0.35TiO3‐δ and sharp decrease in its value with the substitution of Sr and Cu at Ti position. These samples La0.55Li0.35TiO3‐δ (LLTO), La0.55Li0.35Ti0.9Cu0.1O3‐δ (LLTCO) and La0.55Li0.35Sr0.1Ti0.9O3‐δ (LLSTO) were prepared by solid state reaction method. The interfacial polarization of lithium ion aggregation close to the grain boundaries and the dipoles of Li ions in the sample are suggested to be the source of the enormous dielectric values. Parent composition (LLTO) shows highest dielectric constant value (6.29 × 105 at frequency 10 Hz, 7.30×104 at 1 kHz) recorded at room temperature while the lowest dielectric loss value (0.124) was observed for LLSTO at frequency 1 kHz. Structural characterization has been done using X‐ray diffraction (XRD) technique to investigate the crystal structure of the prepared compositions. The XRD patterns show the similar crystal structure for all the compositions with the parent composition LLTO. The optical band gap is calculated by Kulbeka Munk function and Tauc plot using UV–visible diffuse reflectance spectroscopy technique. The maximum band gap value (3.32 eV) is obtained for parent composition while doping of Cu and Sr at Ti site in La0.55Li0.35TiO3‐δ decreases the band gap value. Optical microscopy shows the micron size grains in these samples. Doping of Sr and Cu in perovskite structure of LLTO brings tunability in dielectric and optical properties.

Phase-Transition Induced Optimization of Energy Storage and Temperature Stability of NaNbO3 Doped BNBST Ceramics

The 0.5Bi0.5Na0.5TiO3−0.5Ba0.3Sr0.7TiO3 (BNBST) ceramic is a relatively good relaxation component with tripartite phase and tetragonal phase coexisting at room temperature. Tripartite R3c is a polar phase, which can transform to long range ordered ferroelectric structures under the action of an applied electric field, exhibiting large remnant polarization (P r), which limits its application in energy storage. In this work, we designed NaNbO3 (NN) modified Bi0.5Na0.5TiO3-Ba0.3Sr0.7TiO3 ceramics to prepare (1−x) (0.5Bi0.5Na0.5TiO3−0.5Ba0.3Sr0.7TiO3)−xNaNbO3 (abbreviated as (1−x)BNBST-Xnn, x = 0, 0.05, 0.10, 0.15, 0.20, 0.25) relaxor ferroelectrics. By increasing the NN amount, the phase composition is regulated to induce the transformation of the polar phase R3c to the weakly polar phase P4bm, leading to a smaller P r. The ferroelectric test results show that the ceramic sample with x = 0.1 achieves a high effective energy storage density (W rec = 2.58 J cm−3) and energy storage efficiency (ƞ = 91%) at 140 kV cm−1.

Effect of La substitution on energy storage properties of (Bi0.2Na0.2Ca0.2Ba0.2Sr0.2)TiO3 lead‐free high‐entropy ceramics

AbstractIn this study, a novel lead‐free high‐entropy ceramic (HEC) system, (Bi0.2Na0.2Ca0.2Ba0.2Sr0.2)(1–3x/2)LaxTiO3 (0 ≤ x ≤ 0.15) (abbreviated as BNCBST‐xLa), was designed to enhance energy storage performance through La substitution and prepared via a hydrothermal method. Results indicate that La doping at A site in BNCBST induces lattice distortion and further improves dielectric relaxation. Moreover, grain growth is inhibited by the La content, which results in an increase in the insulation resistance and thus significant enhancement in the electric breakdown strength (Eb). Accordingly, the system with x = 0.03 exhibits an excellent recoverable energy density (Wrec) of 2.43 J/cm3 and a high energy storage efficiency (η) of 85.5% under a great Eb of 245 kV/cm, together with wide temperature stability (Wrec and η vary within ± 8.3% and ± 1.1% at 30–150°C). The findings of this study suggest that the obtained La‐modified BNBCST HECs are promising for energy storage applications.

Enhanced energy storage and fast discharge properties of BaTiO3-Bi(Ni0.5Zr0.5)O3 ceramics modified by (Bi0.5Na0.5)0.7Sr0.3TiO3

ABSTRACT Relaxed ferroelectric ceramics with good energy storage stability, high energy storage density and efficiency, and high charge/discharge rates have shown great potential for commercial applications. In this paper, 0.85[0.9BaTiO3 −0.1Bi(Ni0.5Zr0.5)O3]−0.15(Bi0.5Na0.5)0.7Sr0.3TiO3 ceramic was prepared via a solid – phase reaction method by doping (Bi0.5Na0.5)0.7Sr0.3TiO3 into 0.9BaTiO3 > −0.1Bi(Ni0.5Zr0.5)O3; it exhibited excellent energy storage performance values: Wrec = 2.87 J/cm3 and η = 88.10%. Charging and discharging tests were conducted to evaluate the feasibility of the ceramic for practical applications in energy – storage devices; it displayed an ultrafast discharge rate of 1.16 μs. In addition, the developed ceramic has good frequency stability (1–120 Hz) and high temperature stability (40–160°C). This excellent energy storage performance indicates that the ceramic is a suitable candidate for pulse power devices.

Delayed phase switching field and improved capacitive energy storage in Ca2+-modified (Pb,La)(Zr,Sn)O3 antiferroelectric ceramics

Antiferroelectric ceramics have captured great attention on capacitive energy storage because of their giant power density and fast discharge speed, which is highly desirable for high- and pulsed-power devices. Nevertheless, the conflict between breakdown electric field and phase switching field of antiferroelectric ceramics blocks to achieve the optimum energy storage capability. In present letter, Ca2+-modified (Pb0.97La0.02)(Zr0.6Sn0.4)O3 ceramics achieved improved breakdown electric field, delayed phase switching field and multiple phase transition under high electric field simultaneously, giving rise to an ultrahigh recoverable energy density of 10.04 J/cm3 and a high energy storage efficiency of 83.95%. Furthermore, the ceramics also displayed excellent thermal reliability as temperature increased to 150 °C, and superior discharge behavior, characterized by Wdis of 5.17 J/cm3 and t0.9 of 5.18 μs. This work not only demonstrates the promising applications of PbZrO3-based antiferroelectric ceramics in energy storage capacitors, but also supplies an effective route to explore high-performance antiferroelectric materials.

Non-Aqueous Zn-Ion Hybrid Supercapacitors: Acetonitrile vs Propylene Carbonate Based Electrolyte

The development of high efficiency energy storage systems is increasingly important as these systems enable utilize energy from renewable sources and reduce greenhouse gas evolution caused by fuel combustion technologies at the same time. Electrochemical characteristics of Zn-ion hybrid supercapacitor (ZIHS) cells based on 1 M acetonitrile and propylene carbonate electrolytes in zinc tetrafluoroborate (Zn(BF4)2), zinc di[bis(trifluoromethylsulfonyl)imide] (Zn(TFSI)2) and zinc trifluoromethanesulfonate (Zn(OTf)2) have been studied using cyclic voltammetry, constant current charge/discharge and electrochemical impedance methods. The Ragone plots have been calculated from constant power measurement data. Very high energy and power densities (80 Wh kg−1 and 21.2 kW kg−1) have been calculated for 1 M Zn(BF4)2/AN based Zn-ion hybrid supercapacitor. Some assembled ZIHSs had shown excellent cycling and energy stability over 20000 cycles.

High Performance On-Chip Energy Storage Capacitors with Plasma-Enhanced Atomic Layer-Deposited Hf0.5Zr0.5O2/Al-Doped Hf0.25Zr0.75O2 Nanofilms as Dielectrics.

Concurrently achieving high energy storage density (ESD) and efficiency has always been a big challenge for electrostatic energy storage capacitors. In this study, we successfully fabricate high-performance energy storage capacitors by using antiferroelectric (AFE) Al-doped Hf0.25Zr0.75O2 (HfZrO:Al) dielectrics together with an ultrathin (1 nm) Hf0.5Zr0.5O2 underlying layer. By optimizing the Al concentration in the AFE layer with the help of accurate controllability of the atomic layer deposition technique, an ultrahigh ESD of 81.4 J cm-3 and a perfect energy storage efficiency (ESE) of 82.9% are simultaneously achieved for the first time in the case of the Al/(Hf + Zr) ratio of 1/16. Meanwhile, both the ESD and ESE exhibit excellent electric field cycling endurance within 109 cycles under 5~5.5 MV cm-1, and robust thermal stability up to 200 °C. Thus, the fabricated capacitor is very promising for on-chip energy storage applications due to favorable integratability with the standard complementary metal-oxide-semiconductor (CMOS) process.

Role of polarization evolution in the hysteresis effect of Pb-based antiferroelecrtics

The electric field-induced irreversible domain wall motion results in a ferroelectric (FE) hysteresis. In antiferroelectrics (AFEs), the irreversible phase transition is the main reason for the hysteresis effects, which plays an important role in energy storage performance. Compared to the well-demonstrated FE hysteresis, the structural mechanism of the hysteresis in AFE is not well understood. In this work, the underlying correlation between structure and the hysteresis effect is unveiled in Pb(Zr,Sn,Ti)O3 AFE system by using in-situ electrical biasing synchrotron X-ray diffraction. It is found that the AFE with a canting dipole configuration, which shows a continuous polarization rotation under the electric field, tends to have a small hysteresis effect. It presents a negligible phase transition, a small axis ratio, and electric field-induced lattice changing, small domain switching. All these features together lead to a slim hysteresis loop and a high energy storage efficiency. These results offer a deep insight into the structure-hysteresis relationship of AFEs and are helpful for the design of energy storage material.

High-efficiency energy storage in Nd-doped (1-x)BiFeO3–xBaTiO3 relaxor ferroelectric ceramics

Dielectric capacitors as energy storage electronics have drawn much attention due to ultrahigh power densities with quick charging and discharging rates. In this report, A-site Nd-doped (1-x)BiFeO3-xBaTiO3 (x = 0.2–0.45) relaxor ferroelectric ceramics with superior storage efficiencies were prepared with 0.1 wt% MnO2 additive. Energy-storage efficiency (η) increases from 63.7% to 89% at 190 kV/cm as BaTiO3 increases accompanied by recoverable energy densities (Wrec) in the range of 2.5–2.7 J/cm3. The energy-storage performance persists thermally stable up to 125 °C. The superior storage efficiency is associated with growth of the cubic Pm-3m symmetry and the core-shell structure with increasing BaTiO3 content. The formation of nanocluster/nanomosaic structure also plays an essential role as a barrier in suppressing the long-range polarization order. This work provides a design of binary rare-earth doped BiFeO3–BaTiO3 dielectric ceramics for thermally stable and high-efficiency electrical energy storage.

Integrating thermal energy storage and microwave absorption in phase change material-encapsulated core-sheath MoS2@CNTs

Developing advanced nanocomposite integrating solar-driven thermal energy storage and thermal management functional microwave absorption can facilitate the cutting-edge application of phase change materials (PCMs). To conquer this goal, herein, two-dimensional MoS2 nanosheets are grown in situ on the surface of one-dimensional CNTs to prepare core-sheath MoS2@CNTs for the encapsulation of paraffin wax (PW). Benefiting from the synergistic enhancement photothermal effect of MoS2 and CNTs, MoS2@CNTs is capable of efficiently trapping photons and quickly transporting phonons, thus yielding a high solar-thermal energy conversion and storage efficiency of 94.97%. Meanwhile, PW/MoS2@CNTs composite PCMs exhibit a high phase change enthalpy of 101.60 J/g and excellent long-term thermal storage durability after undergoing multiple heating–cooling cycles. More attractively, PW/MoS2@CNTs composite PCMs realize thermal management functional microwave absorption in heat-related electronic application scenarios, which is superior to the single microwave absorption of traditional materials. The minimum reflection loss (RL) for PW/MoS2@CNTs is −28 dB at 12.91 GHz with a 2.0 mm thickness. This functional integration design provides some insightful references on developing advanced microwave absorbing composite PCMs, holding great potential towards high-efficiency solar energy utilization and thermally managed microwave absorption fields.

Enhanced photoelectric properties for BiZn0.5Zr0.5O3 modified KNN-based lead-free ceramics

With the increasing demand for transparent pulse capacitors and elector-optical multifunctional devices, the environmental-friendly K0.5Na0.5NbO3(KNN) based transparent dielectric ceramic has attracted extensive attention, not only for its superior energy storage properties but also for its good optical transparency. However, simultaneously improving the electrical and optical properties of KNN-based ceramics is still challenging. In this study, a new design strategy is proposed to enhance the electrical and optical properties of KNN-based ceramics. The strategy is reducing the grain size, breaking the long-range polar ordering to form disordered polar nanoregions (PNRs), and increasing the bandgap energy. The results showed that high effective storage (Wrec = 2.56 J/cm2) and energy storage efficiency (η = 93 %) are achieved, and the bandgap reaches 3.16 eV and optical transmittance of 73 % at the wavelength of 1200 nm and 67 % at the wavelength of 800 nm simultaneously implemented in the (1-x)K0.5Na0.5NbO3-xBiZn0.5Zr0.5O3((1-x)KNN-xBZZ) ceramics. The design strategy strategies proposed in this study provide a novel way to improve the electrical and optical properties of transparent pulse capacitors.

Research on Magnetic Coupling Flywheel Energy Storage Device for Vehicles

With the increasing pressure on energy and the environment, vehicle brake energy recovery technology is increasingly focused on reducing energy consumption effectively. Based on the magnetization effect of permanent magnets, this paper presents a novel type of magnetic coupling flywheel energy storage device by combining flywheel energy storage with magnetic coupling technology. As a high-efficiency energy storage device, it has the advantages of low energy consumption, low vibration, low noise and easy maintenance. In this paper, firstly, the structural characteristics and working process of vehicle brake energy recovery systems are analyzed, and experiments regarding the transmission and efficiency performance are carried out for key components; then a reasonable control strategy is formulated according to the principle of energy recovery; finally, the speed, acceleration, recovery energy and other parameters are analyzed based on the New European Driving Cycle (NEDC) working conditions. The results show that the energy recovery efficiency reaches 35.59%, which verifies the usability of the device.

High-enthalpy biphasic phase change organogels with shape memory function based on hydrophobic association and H-bonding interaction

Low-temperature solid–liquid organic phase change materials (OPCMs) offer tremendous opportunities in thermal management techniques but suffer from leakage problems above the melting temperature. Here, inspired with the universal hydro/organogels using three-dimensional polymer networks capable of holding large amounts of liquid solvents, a kind of form-stable high-enthalpy biphasic phase change organogels (BPCOGs) were developed by the integration of hydrophobic association for synthesizing intrinsic phase change matrices and H-bonding interaction for binding OPCM liquids. The porous phase separated poly(acrylamide-octadecyl acrylate) (P(AM-co-OA)) matrices with uniformly dispersed thermal conductive carbon nanotubes were fabricated from the hydrophobically associating hydrogels (HAHs), in which POA segments provide the phase change energy storage microdomains and the PAM network is capable of binding a series of melted OPCMs by hydrogen bond engineering. The fabricated BPCOGs possess form-stability, high phase change enthalpy (high up to 215.5 J g−1) and high energy storage efficiency (>90%), and show excellent electrical/optical-thermal energy conversion as well as shape memory performances. This study provides a universal strategy to prepare flexible biphasic OPCMs suitable for a variety of solid–liquid OPCMs including fatty alcohols, fatty acids and polyethylene glycol, and demonstrates the great potentials of these BPCOGs in solar energy utilization and functional flexible devices.

Novel Class of Additive Manufactured NiTi-Based Hierarchically Graded Chiral Structure with Low-force Compressive Actuation for Elastocaloric Heat Pumps

Elastocaloric refrigeration is the most promising green solid-state refrigeration technology to replace conventional vapor compression refrigeration. The development direction of the elastocaloric component that acts as a key part of the elastocaloric refrigeration system contains a large elastocaloric effect, low stress hysteresis, high heat exchange performance, and small driving loads. The first two indices can be realized by material modification; however, the last two are more dependent on a novel porous structure design. However, the conventional porous structure is confronted with some critical challenges, including inhomogeneous stress, a significant hysteresis area, and deformation instability under the alternating cyclic loading. In this study, a NiTi-based elastocaloric structure model with chirality feature and gradient design as innovative elements was presented, bio-inspired by the structure of the plant tendrils. A quantitative optimization for the NiTi-based elastocaloric structure was performed using the finite element analysis (FEA) method. Strain and martensite volume fraction (MVF) fields during the loading and unloading processes were predicted and evaluated. The simulated results indicated that increasing the thickness gradient g1 of the strip or decreasing the diameter gradient g2 of the structure was beneficial to achieving more homogeneous strain and martensite distribution, simultaneously with higher energy storage efficiency and specific surface area. In addition, these NiTi-based chiral structures with different structural parameters were fabricated by laser powder bed fusion (LPBF). At the optimized structure parameters of g1 = 2 and g2 = 1.11, the LPBF-fabricated NiTi-based chiral structure could achieve an adiabatic temperature change ΔTad of 2.3 K, driving force of as low as 149.11 N, and |ΔTad/F| of as high as 15.42 K/kN at a recoverable compressive strain of 10%.