Solution‐processable ferroelectric polymer nanocomposites are developed as a new form of electrocaloric materials that can be effectively operated under both modest and high electric fields at ...ambient temperature. By integrating the complementary properties of the constituents, the nanocomposites exhibit state‐of‐the‐art cooling energy densities. Greatly improved thermal conductivity also yields superior cooling power densities validated by finite volume simulations.
Lead-free pyroelectric materials with high room-temperature pyroelectric coefficient (p) and depolarization temperature (Td) are in great demand for uncool infrared detectors. However, the ...state-of-the-art unleaded pyroelectric ceramics are confronted with challenge of increasing room-temperature pyroelectric coefficient at cost of declining depolarization temperature. Herein, we report that high room-temperature p of 5.28 × 10−4C m − 2K−1 with Td of 175 °C can be simultaneously achieved by introducing Na0.5Bi4.5Ti4O15 into Na0.5Bi0.5TiO3 solid solution system. Structure resolution revealed that the diffusing of Na0.5Bi4.5Ti4O15 not only modifies the structures of TiO6 octahedra and wipes the P4bm nanodomains from the long-range ordered R3c phase, resulting in high remnant polarizations and enhanced room-temperature p, but also facilitates the electron transfer in the formation of Ti-O covalent bond and enhances the strength of Ti-O covalent bonds to improve the stability of crystal structure, leading to the enhancement of Td. Combined with enhanced room-temperature pyroelectric coefficient and high depolarization temperature, the Na0.5Bi0.5TiO3-xNa0.5Bi4.5Ti4O15 systems could be a promising lead-free pyroelectrics for uncool infrared detection.
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Currently, various electronic devices make our life more and more safe, healthy, and comfortable, but at the same time, they produce a large amount of nondegradable and nonrecyclable electronic waste ...that threatens our environment. In this work, we explore an environmentally friendly and flexible mechanical sensor that is biodegradable and recyclable. The sensor consists of a bacterial cellulose (BC) hydrogel as the matrix and imidazolium perchlorate (ImClO
) molecular ferroelectric as the functional element, the hybrid of which possesses a high sensitivity of 4 mV kPa
and a wide operational range from 0.2 to 31.25 kPa, outperforming those of most devices based on conventional functional biomaterials. Moreover, the BC hydrogel can be fully degraded into glucose and oligosaccharides, while ImClO
can be recyclable and reused for the same devices, leaving no environmentally hazardous electronic waste.
The applications of antiferroelectric (AFE) materials in miniaturized and integrated electronic devices are limited by their low energy density. To address the above issue, the antiferroelectricity ...of the reinforced material was designed to improve its AFE-ferroelectric (FE) phase transition under electric fields. In this present study, the composition of Zr4+ (0.72 Å) and Ti4+ (0.605 Å) at B-site of Pb0.97La0.02(ZrxSn0.05Ti0.95-x)O3 ceramics with orthogonal reflections are synthesized via the tape-casting method. These ceramics are modified to enhance their antiferroelectricity by reducing their tolerance factor. A recoverable energy storage density Wrec 12.1 J/cm3 was obtained for x = 0.93 under 376 kV/cm, which is superior value than reported until now in lead-based energy storage systems. Moreover, the discharge energy density can reach 10.23 J/cm3, and 90 % of which can be released within 5.66 μs. This work provides a new window and potential materials for further industrialization of pulse power capacitors.
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•Si-based anode (NSi@C/CNTs@GS) with hierarchical protective function and hollow ring-like carbon matrix has been prepared.•The NSi@C/CNTs@GS exhibits excellent electrochemical ...performance.•The NSi@C/CNTs@GS exhibits a favorable structural stability from the SEM and TEM images after operating cycles.
Si-based anode with hierarchical protective function and hollow ring-like carbon matrix has been successfully designed and prepared by a simple one-step spray drying method. Nano-Si particles are coated by carbon layer and then encapsulated in a strong carbon matrix with hollow ring-like structure composed of carbon nanotubes and wrinkled graphene sheets. The Si-based anode, nano-Si@carbon/carbon nanotubes@graphene sheets, exhibits excellent electrochemical performance including high initial coloumbic efficiency, favorable cyclic stability and outstanding rate capability. The composite delivers an initial discharge/charge capacity of 2891.7/2533.3 mAh g−1 with a high initial coloumbic efficiency of 87.6%, high capacity of 1524.3 mAh g−1 after 130 cycles with high capacity retention of 92.4% (vs. 1618.4 mAh g−1 for the 100 cycles), and high capacity maintaining at 1073.2/1016.2 mAh g−1 at a large current density of 1.6 A g−1. Furthermore, the scanning electron microscopy and transmission electron microscopy images of the composite electrode after several operating cycles also indicate that composite electrode exhibits structural stability and nano-Si particles are still wrapped by the carbon matrix material. Therefore, the composite is very promising anode for lithium ion batteries.
Flexible piezoelectric materials have attracted rapidly growing attention because they offer an efficient route to scavenge energies from the living environment to power personal electronics and ...nanosystems. Current polymer composites with low-dimensional piezoceramic fillers suffer from poor stress transfer from the polymer matrix to the active ceramic fillers, thus significantly limiting the energy harvesting performance. Herein, an interconnected 3D piezoceramic skeleton has been developed by a biofibril template method using the newly developed rare-earth Samarium-doped Pb(Mg1/3Nb2/3)O3-PbTiO3 (Sm-PMN–PT) for flexible piezoelectric polymer composites. When subjected to external mechanical stimulation, the 3D interconnected structure results in effective stress transfer, and consequently, greatly enhanced energy harvesting output. The 3D piezocomposite shows the open-circuit output voltage and short-circuit current density up to ~ 60 V and ~ 850 nA cm−2, respectively, with the maximum instantaneous power density of ~ 11.5 µW cm−2 which is ~ 16 times higher than that of the conventional nanoparticle-based composite. The remarkable enhancement in the tress transfer ability and piezoelectric response of the biofibril-templated 3D structure have also been verified by phase-field simulations. This work provides a promising paradigm for the development of high-performance flexible energy harvesting materials.
An interconnected 3D piezoceramic structure has been prepared using the biofibril-templated approach and the state-of-the-art piezoelectric ceramic of rare-earth-doped Pb(Mg1/3Nb2/3)O3–PbTiO3. Both phase-field computations and experimental mechanics confirm the great improvement in the electromechanical properties of the polymer composites based on the biofibril-templated 3D piezoceramic fillers. The flexible 3D piezocomposite display a power density that is 16 times higher than that of the corresponding nanoparticle-based polymer piezocomposite. Display omitted
•Three-dimensional piezoelectric ceramic foam is designed for the flexible piezocomposite.•3-D morphology of the piezoceramic skeleton is controlled by using biological template.•This approach overcomes the major limitation of the current piezoelectric polymer composites.•3-D composite yields ~ 16 times higher power density than the nanoparticle-containing composite.•Phase-field simulations have been performed to analyze the 3D interconnected piezoceramics.
The low breakdown strength of BNT-based dielectric ceramics limits the increase in energy-storage density. In this study, we successfully reduced the sintering temperature of BNT-ST-5AN relaxor ...ferroelectric ceramics from 1150 to 980 °C by two-phase compounding with nano-SiO2. Meanwhile, the average grain size of the composite ceramics is also greatly reduced from 4.45 μm to 0.37 μm. Thus, a large recoverable energy-storage density (3.22 J/cm3) is achieved under the ultrahigh breakdown strength (316 kV/cm). Moreover, good temperature (25–150 °C) and frequency (10–200 Hz) stabilities are simultaneously achieved. The excellent energy-storage properties suggest that BNT-ST-based ceramics composited with SiO2 form a promising low-temperature sintered dielectric material for pulsed power multilayer ceramic capacitors.
Dielectric energy storage capacitors have been explored to obtain excellent energy storage density along with high energy storage efficiency with the development of electronic devices. In this work, ...linear dielectric CaTi0.5Zr0.5O3 is introduced into Bi0.5Na0.5TiO3-NaNbO3 matrix to form 0–3 type composites to vary the size and conductivity of the composite grain, which lead to ultra-high breakdown electric field of 410 kV/cm and the quasi-linear hysteresis loops. Meanwhile, linear dielectric does not change the characteristic of ferroelectric, and thus composites maintain high maximum polarization of 26.4 μC/cm2. Integrating the advantages of linear dielectric and ferroelectric, an excellent recoverable energy density of 4.93 J/cm3 with an efficiency of 93.3% have been achieved in BNT-NN/7 wt%CZT ceramics. This work contributes to the development of dielectric energy storage capacitors for practical applications in pulsed power devices.
•A design was proposed to achieve both high polarization and breakdown strength.•The interfacial blocking effect has been introduced for high P and Eb.•Both high energy density and efficiency are ...obtained in the multilayer ceramics.
Dielectric ceramics are desired for pulse power electronic systems owing to their high power density. However, there are obstacles in the simultaneous enhancement of energy density (Wrec) and energy efficiency (ƞ). The two crucial parameters affecting the energy storage performance are polarization (P) and electric breakdown strength (Eb). Although considerable efforts have been made, the contradiction between high P and high Eb is still a challenging problem. In this work, the macroscopic properties and microstructure of (Pb0.9Ba0.04La0.04)(Zr0.65Sn0.3Ti0.05)O3 (PBLZST) / (Pb0.95Ca0.02La0.02)(Zr0.93Sn0.05Ti0.02)O3 (PCLZST) antiferroelectric multilayer ceramics prepared by a tape-casting method are combined to realize the synergic optimization of P and Eb. The huge difference in dielectric constants (εr) of these two materials leads to the interfacial polarization effect and interfacial blocking effect. Despite their different electric characteristics, they have similar elemental compositions, matching lattice structures and compatible sintering processability, forming dense interface bonding. Ultimately, the structured ceramics achieve a high Wrec of 9.4 J cm−3 and a high ƞ of 86.5 % at 278 kV cm−1, as well as favorable temperature stability, frequency stability and anti-fatigue property. The structure design combined with interfacial effects in this study provides a new strategy for the preparation of multilayer ceramics with superior energy storage performance.
Phonon engineering focuses on heat transport modulation in atomic-scale. Different from reported methods, it is shown that electric field can also modulate heat transport in ferroelectric polymers, ...poly(vinylidene fluoride), by both simulation and measurement. Interestingly, the thermal conductivities of poly(vinylidene fluoride) array can be enhanced by a factor of 3.25 along the polarization direction by simulation. The thermal conductivities of semi-crystalline poly(vinylidene fluoride) film can be also enhanced by a factor of 1.5 which is shown by both simulation and measurement. The mechanism is analyzed by morphology and phonon properties. It is found that the enhancement arises from the higher inter-chain lattice order, stronger inter-chain interaction, higher phonon group velocity and suppressed phonon scattering. This study offers a new modulation strategy with quick response and without fillers.
Poled by electric field, thermal conductivity of poly(vinylidene fluoride) (PVDF) can be increased, which is proved by both simulations and experiments. The study offers a brand new strategy to modulate thermal conductivity. Display omitted
•A new strategy to modulate thermal conductivity of polymer with electric field is proposed and proved.•Thermal conductivities in poly(vinylidene fluoride) can be modulated without sacrificing other mechanical properties.•Modulation with electric field is in situ, flexible control, quick response and low energy consumption.•A detailed analysis on the mechanism of thermal conductivity enhancement is presented.
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