Energy Storage Performance Research Articles

Covalent Organic Frameworks Meet Titanium Oxide.

In order to expand the applicability of materials and improve their performance, the combined use of different materials has increasingly been explored. Among these materials, inorganic-organic hybrid materials often exhibit properties superior to those of single materials. Covalent organic frameworks (COFs) are famous crystalline porous materials constructed by organic building blocks linked by covalent bonds. In recent years, the combination of COFs with other materials has shown interesting properties in diverse fields, and the composite materials of COFs and TiO2 have been investigated more and more. These two outstanding materials are combined through covalent bonding, physical mixing, and other methods and exhibit excellent performance in various fields, including photocatalysis, electrocatalysis, sensors, separation, and energy storage and conversion. In this Review, the current preparation methods and applications of COF-TiO2 hybrid materials are introduced in detail, and their future development and possible problems are discussed and prospected, which is of great significance for related research. It is believed that these interesting hybrid materials will show greater application value as research progresses.

Reusable biochars derived from Camellia oleifera shell via K2CO3 activated for phenol-enhanced adsorption

Porous biochar materials (BC) have shown excellent performance in energy storage and water treatment adsorption. Carbonization of agricultural and forestry solid waste and fixation in the form of stable biochar to form biochar materials can achieve green "waste utilization for treatment wastewater". In this study, BC samples were generated by using Camellia oleifera shell (COS) as raw material and K2CO3 as green activator in-situ pyrolysis. The adsorption behavior of COS biochar in aqueous solution was evaluated using phenol as a pollutant probe. The synergistic effect of pyrolysis temperature and K2CO3 activation promoted the development of the pore structure of BC. The X-ray photoelectron spectroscopy results indicated that K2CO3 activation promoted the formation of C-C defects and promoted phenol adsorption. KBC-900 exhibited superior absorption capacity for phenol (300.15 mg/g). The activation of K2CO3 also promoted the adsorption of oxygen. In addition, using H2O2 for regenerating biochar did not show a significant decrease in the adsorption rate after five cycles (decline rate < 5 %). The strong adsorption capacity of KBC-900 for phenol might be due to the presence of π-π interactions, hydrogen bonds, and van der Waals interactions during the adsorption process.

Improving energy storage performance of PbZrO3-Al2O3 composite thin films by regulating distribution of Al2O3 nanoparticles

Improving energy storage performance of PbZrO3-Al2O3 composite thin films by regulating distribution of Al2O3 nanoparticles

Significantly enhancing energy storage performance of biaxially oriented poly(vinylidene fluoride) dielectric film by organic impregnation (surface engineering)

Significantly enhancing energy storage performance of biaxially oriented poly(vinylidene fluoride) dielectric film by organic impregnation (surface engineering)

Thermal energy storage performance of liquid polyethylene glycol in core–shell polycarbonate and reduced graphene oxide fibers

Thermal energy storage is a promising, sustainable solution for challenging energy management issues. We deploy the fabrication of the reduced graphene oxide (rGO)–polycarbonate (PC) as shell and polyethylene glycol (PEG) as core to obtain hydrophobic phase change electrospun core–shell fiber system for low-temperature thermal management application. The encapsulation ratio of PEG is controlled by controlling the core flow rate, and ~ 93% heat energy storage efficacy is apparent for 1.5 mlh−1 of core flow rate. Moreover, the prepared fiber possesses maximum latent melting and freezing enthalpy of 30.1 ± 3.7 and 25.6 ± 4.0 Jg−1, respectively. The transient dynamic temperature vs. time curve of the rGO-loaded phase change fiber demonstrates the delay of fiber surface temperature change compared to pristine fiber. We indeed show that the tunable heat transfer and thermal energy storage efficacy of phase change fiber is achieved via controlled liquid PEG delivery and the addition of rGO in shell architecture. Notably, the effectiveness of unique phase change material (PCM)–based core–shell fibers is concluded from advanced scanning thermal microscopy (SThM) and self-thermoregulation tests.

Optimizing high-temperature energy storage in tungsten bronze-structured ceramics via high-entropy strategy and bandgap engineering

As a vital material utilized in energy storage capacitors, dielectric ceramics have widespread applications in high-power pulse devices. However, the development of dielectric ceramics with both high energy density and efficiency at high temperatures poses a significant challenge. In this study, we employ high-entropy strategy and band gap engineering to enhance the energy storage performance in tetragonal tungsten bronze-structured dielectric ceramics. The high-entropy strategy fosters cation disorder and disrupts long-range ordering, consequently regulating relaxation behavior. Simultaneously, the reduction in grain size, elevation of conductivity activation energy, and increase in band gap collectively bolster the breakdown electric strength. This cascade effect results in outstanding energy storage performance, ultimately achieving a recoverable energy density of 8.9 J cm−3 and an efficiency of 93% in Ba0.4Sr0.3Ca0.3Nb1.7Ta0.3O6 ceramics, which also exhibit superior temperature stability across a broad temperature range up to 180 °C and excellent cycling reliability up to 105. This research presents an effective method for designing tetragonal tungsten bronze dielectric ceramics with ultra-high comprehensive energy storage performance.

Flexible mica films coated by magnetron sputtered insulating layers for high‐temperature capacitive energy storage

AbstractHigh‐temperature energy storage performance of dielectric capacitors is crucial for the next generation of power electronic devices. However, conduction losses rise sharply at elevated temperature, limiting the application of energy storage capacitors. Here, the mica films magnetron sputtered by different insulating layers are specifically investigated, which exhibit the excellent high‐temperature energy storage performance. The experimental results revealed that the PbZrO3/Al2O3/PbZrO3 (PZO/AO/PZO) interface insulating layers can effectively reduce the high‐temperature leakage current and conduction loss of the composite films. Consequently, the ultrahigh energy storage density (Wrec) and charge‒discharge efficiency (η) can be achieved simultaneously in the flexible mica‐based composite films. Especially, PZO/AO/PZO/mica/PZO/AO/PZO (PAPMPAP) films possess excellent Wrec of 27.5 J/cm3 and η of 87.8% at 200°C, which are significantly better than currently reported high‐temperature capacitive energy storage dielectric materials. Together with outstanding power density and electrical cycling stability, the flexible films in this work have great application potential in high‐temperature energy storage capacitors. Moreover, the magnetron sputtering technology can deposit large‐area nanoscale insulating layers on the surface of capacitor films, which can provide technical support for the industrial production of capacitors.

Enhancing the energy storage performance of PVDF films through optimized hot-pressing temperatures

Enhancing the energy storage performance of PVDF films through optimized hot-pressing temperatures

Revealing the Two-Stage Charging Process in Sulfuric Acid Electrolyte by Molecular Dynamics Simulation.

Two-dimensional MXene materials perform excellently in supercapacitor applications, but self-stacking and overlap limit their applications. Constructing a reasonable layered structure by combining MXene and graphene can effectively inhibit the restacking and overlap of MXene and improve the performance of supercapacitors. In this work, we studied the energy storage performance of a conventional MXene electrode and MXene/graphene composite electrode in sulfuric acid aqueous electrolyte by molecular dynamics (MD) simulation and analyzed their energy storage mechanisms. The simulation results reveal that the MXene/graphene composite electrode showed faster charge-discharge speed and larger capacity and had more obvious advantages as a cathode. The charging process of the composite cathode can be divided into two stages. In the first stage, SO42- and H3O+ enter the electrode as a whole in a nearly 1:2 ratio, and a unique three-layer structure is formed in the graphene area, while a large number of HSO4- leaves the electrode. In the second stage, SO42- with a part of H3O+ (ratio of 2:2 to 2:3) leave the electrode, and the three-layer structure is gradually destroyed. The cooperation of these two stages leads to a particular "concave" in the total energy change of the composite cathode. The introduction of graphene has brought about changes in ion distribution, migration mechanism, and energy change, making the MXene/graphene cathode show significant advantages in energy storage. This work is of great significance for understanding the microscopic energy storage mechanism of MXene/graphene-based electrodes.

Highly stable energy-storage performance of donor-acceptor co-doped TiO2 films

Energy-storage films that remain stable at high temperatures and frequencies are crucial for various applications. In this study, we demonstrated that donor-acceptor co-doped simple oxide TiO2 films, viz. V5+-Cr3+ co-doped TiO2 [(V0.5Cr0.5)xTi1-xO2] films, can exhibit highly stable energy-storage performance. The co-doped TiO2 films exhibited high breakdown strength and polarization owing to the local polarization induced by the V5+-Cr3+ ionic pairs. The energy-storage density of the (V0.5Cr0.5)0.02Ti0.98O2 film was approximately 48.93 J/cm3 at room temperature, which is approximately 195 times higher than that of the pure TiO2 film (0.25 J/cm3). In addition, the (V0.5Cr0.5)0.02Ti0.98O2 film exhibited excellent temperature stability from 303 K to 403 K, frequency stability from 0.5 kHz to 7.5 kHz, and fatigue durability over 107 charge-discharge cycles. The proposed strategy can effectively improve the stable energy-storage performance of lead-free donor-acceptor co-doped TiO2 films, which are in high demand in various applications.

Applying Machine Learning to Design Delicate Amorphous Micro-Nano Materials for Rechargeable Batteries

As modern society evolves, the global importance of energy requirements has grown significantly. Thus, exploring new materials for renewable energy storage is urgently needed. Due to its intriguing characteristics, amorphous micro-nanomaterials demonstrate exceptional performance in energy storage. The long experimental periods and high costs associated with traditional methods make it challenging to meet the requirements of materials science. Currently, machine learning (ML) is emerging as a novel research paradigm with the potential to revolutionize the exploration of materials. This review provides an overview of the application of ML in studying amorphous micro-nanomaterials for rechargeable batteries. First, a comprehensive introduction to the fundamentals of amorphous materials and ML is summarized. Then, we highlight a series of representative works to elaborate the relationship between the ML for amorphous nanomaterials. Finally, an insightful perspective on utilization of amorphous materials to establish mature energy storage systems and future directions in ML for amorphous materials are presented. Through this review, we aim to unveil the underlying amorphous structure-function relationship and fuel further research in the design of amorphous materials with outstanding performance across diverse fields.

Superior dielectric energy storage performance of ultrafine-grained BNT-SBT solid-solution ceramics by solution combustion synthesis

The micrometer scale grain size and large remnant polarization of Bi0.5Na0.5TiO3 (BNT) ferroelectric ceramics severely constrain the breakdown strength and energy efficiency, respectively, restricting their energy storage application despite their large polarization. Hereby, superior energy storage performance is reported by a synergistic strategy of introducing Sr0.7Bi0.2TiO3 (SBT) relaxor ferroelectrics and a solution combustion synthesis (SCS) method. The BNT-SBT solid-solution ceramics are comparatively investigated by the two methods, conventional sintering (CS) and SCS. An ultrafine average grain size of ∼0.39 μm was obtained in the SCS-derived ceramic, and thus exhibits an ultra-high critical electric field of 548 kV/cm, and a high recoverable energy density of ∼5.69 J/cm3. Those key energy storage parameters are superior to those of the previous reported samples prepared by the CS method. Meanwhile, a high energy efficiency ∼90 %, a large power density of ∼130.44 MW/cm3 (at 320 kV/cm), and an ultrafast discharge time of ∼61.7 ns are also achieved. This study indicates that grain engineering combing with chemical design is an effective way to enhance the dielectric energy storage performance.

Tailored multilayered films of the PVDF/Ba0.8Sr0.2TiO3 nanocomposites with surface-modified nanoparticles for superior dielectric and energy storage performance

The multilayer thick film (∼40 μm) of polyvinylidene fluoride-Ba0.8Sr0.2TiO3 (PVDF-BST) have been synthesized by a tape-casting technique. The incorporated BST nanoparticles in the PVDF matrix are functionalized by −PO4−3and −OH−group, which are abbreviated as PBST-P and PBST-H multilayer films. The nature of the functional group attached with the BST nanoparticles is found to strongly influence the dielectric properties, breakdown strength and energy storage behavior of the multilayer films. The dielectric constant (at 1 kHz) of PBST-P multilayer film shows a significant increase (∼30) as compared to PBST-H film (∼22), whereas the tangent loss remains the same. The breakdown strength of PBST-P multilayer film is also high (∼381 MV/m) as compared to the PBST-H film (∼318 MV/m). PBST-P film also possesses high discharge energy density (∼7.97 J/cc at 1800 kV) and ultrahigh energy efficiency (∼98 %). Enhanced dielectric and energy storage properties of PBST-P film is attributed to the strong bridging interaction between the PVDF matrix and BST-P nanofiller, which creates additional dipoles and a strong local electric field at the interfaces. The study may lead towards the novel ways of developing polymer-ceramic nanocomposites for high-energy density capacitors, where the incorporation of functionalized nanoparticles in the polymer matrix is accompanied by the architectured structure.

Defect‐Driven Oxidation Enabled V2CTx MXene with Ultralong‐Cycling and High‐Rate Capability in Aqueous K+ Storage

AbstractOwing to the adverse influences of irreversible oxidation, the development of MXene‐based materials, especially those with satisfactory performance and longevity for aqueous energy storage, continues to suffer severe challenges. Herein, the strategy of targeted passivation‐supported defect‐lock‐oxygen is conceived, whereby engineered the V2CTx material for controllable partial oxidation with enhanced regioselectivity. When the material works, inside the intrinsic defects, the outward diffusion of oxidation is confined by the Lewis bases around the defects, which allows for the controllable progress of oxidation. The defect‐locked oxygen oxidizes the exposed carbon, thus forming sufficient amorphous carbons for enhancing the capacitive‐type adsorption of K‐ions. Then the oxidized defects enabled the fast kinetics via the cross‐layer transport of K‐ions. Benefiting from the strategy, the electrode assembly V2CTx‐RTIL (V2CTx equipped with room temperature ionic liquid) exhibits high capacity, good rate capability, and ultra‐longevity compared with those of the MXene materials so far reported. This work presents the first strategy of targeted passivation‐supported defect‐lock‐oxygen for high‐rate capability and super long‐cycling aqueous K+ storage and hopefully would provide the inspiration for the future design of novel electrodes.

Superior energy storage performance achieved in tungsten bronze SBCN-based ceramics through tape-casting

Simultaneously integrating outstanding energy storage density and good energy storage efficiency in advanced ferroelectrics is crucial to implementing the application of dielectrics in high-power pulse devices. In this work, (Sr0.5Ba0.5)2Ca0.5Nb5-xSbxO15 ceramics were designed and prepared by adopting the B sites substitution engineering together with combining strategies of tape-casting method and two-step sintering process. Benefiting from the refined grain size and high density, the breakdown field of (Sr0.5Ba0.5)2Ca0.5Nb4.8Sb0.2O15 (SBCNS0.2) was promoted to 400 kV/cm. By the substitution of Sb5+ in the B sites, the weaker interaction force of Sb-O bond in BO6 octahedral polar unit induced the occurrence of polar nanoregions (PNRs) at room temperature to strengthen the dielectric relaxation behavior. Then it is noteworthy that SBCNS0.2 ceramics simultaneously obtained excellent recoverable energy density (Wrec, 3.9 J/cm3), energy storage efficiency (η, 90.5 %), power density (PD, 156.0 MW/cm3), and current density (CD, 1356.7 A/cm2). In addition, the SBCNS0.2 ceramics exhibited an ultrafast discharge time (t0.9, 67 ns). These results reveal prospective potential of unfilled tungsten bronze SBCNS0.2 ceramics in power capacitor applications and provide an effective strategy for improving excellent energy storage properties from the perspective of preparation methods.

Al-doped Li4SiO4 for cyclic solar energy storage and CO2 capture: An experimental and DFT study

The substantial consumption of fossil fuels gives rise to excessive carbon dioxide emissions, and mitigating them has emerged as a pressing global priority. The use of renewable energy and carbon capture, utilization, and storage are recognized as two major approaches for carbon neutrality. Li4SiO4 materials exhibit promising prospects in both thermochemical heat storage for solar energy power and cyclic high-temperature CO2 capture. The reactivity between Li4SiO4 and CO2 plays the vital role in its energy storage and CO2 capture performance. Herein, we prepare Al-doped Li4SiO4 materials through an impregnated suspension technique, simultaneously achieving high contact areas and lattice defects to enhance both fast chemisorption and ion diffusion processes. The results show that Al-doped Li4SiO4 exhibits high average energy density of 56677.08 kJ/kmol within 30 cycles. Additionally, the granulated Al-doped Li4SiO4-based pellets, produced via the freeze-drying technique, exhibit negligible energy density loss rate of less than 9 % and acceptable mechanical strength. Furthermore, the CO2 sorption performance also reaches a high value of 0.27 g/g. The reaction mechanism between Li4SiO4 and CO2 has been investigated at both macroscopic and microscopic levels through kinetic analysis and DFT calculations. The simulated Al-doped Li4SiO4/CO2 sorption system possesses increased adsorption energy level from −0.81 eV for the undoped one to −0.95 eV, thereby leading to the improved CO2 sorption. In general, Al-doped Li4SiO4 materials demonstrate great potential for applications in thermochemical heat storage and CO2 capture.

Ferroelectric and Relaxor-Ferroelectric Phases Coexisting Boosts Energy Storage Performance in (Bi0.5Na0.5)TiO3-Based Ceramics.

With the intensification of the energy crisis, it is urgent to vigorously develop new environment-friendly energy storage materials. In this work, coexisting ferroelectric and relaxor-ferroelectric phases at a nanoscale were constructed in Sr(Zn1/3Nb2/3)O3 (SZN)-modified (Bi0.5Na0.5)0.94Ba0.06TiO3 (BNBT) ceramics, simultaneously contributing to large polarization and breakdown electric field and giving rise to a superior energy storage performance. Herein, a high recoverable energy density (Wrec) of 5.0 J/cm3 with a conversion efficiency of 82% at 370 kV/cm, a practical discharged energy density (Wd) of 1.74 J/cm3 at 230 kV/cm, a large power density (PD) of 157.84 MW/cm3, and an ultrafast discharge speed (t0.9) of 40 ns were achieved in the 0.85BNBT-0.15SZN ceramics characterized by the coexistence of a rhombohedral-tetragonal phase (ferroelectric state) and a pseudo-cubic phase (relaxor-ferroelectric state). Furthermore, the 0.85BNBT-0.15SZN ceramics also exhibited excellent temperature stability (25-120 °C) and cycling stability (104 cycles) of their energy storage properties. These results demonstrate the great application potential of 0.85BNBT-0.15SZN ceramics in capacitive pulse energy storage devices.

Ultrahigh Energy Storage Performance of BiFeO3-BaTiO3 Flexible Film Capacitor with High-Temperature Stability via Defect Design.

Nanoengineering polar oxide films have attracted great attention in energy storage due to their high energy density. However, most of them are deposited on thick and rigid substrates, which is not conducive to the integration of capacitors and applications in flexible electronics. Here, an alternative strategy using van der Waals epitaxial oxide dielectrics on ultra-thin flexible mica substrates is developed and increased the disorder within the system through high laser flux. The introduction of defects can efficiently weaken or destroy the long-range ferroelectric ordering, ultimately leading to the emergence of a large numbers of weak-coupling regions. Such polarization configuration ensures fast polarization response and significantly improves energy storage characteristics. A flexible BiFeO3-BaTiO3 (BF-BT) capacitor exhibits a total energy density of 43.5 J cm-3 and an efficiency of 66.7% and maintains good energy storage performance over a wide temperature range (20-200 °C) and under large bending deformation (bending radii ≈ 2mm). This study provides a feasible approach to improve the energy storage characteristics of dielectric oxide films and paves the way for their practical application in high-energy density capacitors.

Flexible phase change film based on lignin-derived porous carbon/Eicosane for wearable thermal management and microwave absorption

A flexible phase-change film with thermal management and microwave absorption capabilities was developed for use in wearable devices. The film was created using a solution casting method based on a porous carbon-loaded eicosane (LP33/EI) material. LP33 served as the porous encapsulation medium, while Eicosane (EI) acted as the phase change component. The flexible substrate was a blend of polyvinyl alcohol (PVA) and bacterial cellulose nanocellulose (BC). The ultrathin film had a thickness of 0.262 mm, and LP33/EI-4 exhibited exceptional mechanical strength of 188 MPa. Testing revealed that the phase transition process had melting and crystallization enthalpies of 134.71 J/g and 126.11 J/g, respectively. The encapsulation structure effectively prevented any leakage during the phase transition process. Under simulated solar irradiation of 200 mW/cm2, LP33/EI-4 achieved a photothermal conversion efficiency (η) of 89.46 %. Additionally, the porous LP33 structure and high dielectric loss contributed to remarkable microwave absorption capabilities of −42 dB in the X-band and − 52 dB in the Ku-band. Overall, LP33/EI films demonstrated exceptional performance in thermal management, energy storage, and microwave absorption, making them an ideal choice for a variety of applications in wearable devices.

Stable energy storage performance at high-temperature of PESU-based dielectric composite regulated by SiO2 and BNNSs

Polymer dielectric capacitors are essential components for energy storage in modern electronic devices. They offer several advantages, including excellent voltage resistance, easy processing, and great energy storage density (U). However, with high thermal and electric fields, the more conductivity losses of polymer dielectric materials can be generated and aggregated, and the discharge energy density (Ue) and charging-discharging efficiency (η) of dielectric capacitor are usually significantly lower than that at room temperature. Here, the state-of-the-art composite is proposed, in which the SiO2 filler with excellent insulation strength is introduced into the middle composite layer, and the composite introduced wide band-gap boron nitride nanosheets (BNNSs) is used as the outer composite layer to inhibit carrier migration and reduce leakage current density of composite. The experimental results illustrate that the Ue of 1BP/1SP/1BP dielectric composite reaches about 9.37 J/cm3, and the η is around 82.0 % under the electric field of 540 kV/mm at 80 °C. Significantly, the η of multilayer 1BP/1SP/1BP composite remained >95.0 % after 50,000 cycles, indicating that this multilayer composite has good cycle stability and excellent reliability under a high-temperature. It presents a practical approach to enhance the energy storage performance of dielectric polymer at high-temperature environment.