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1.
    
Nanoengineered polar oxide films have attracted much attention for electric energy storage thanks to their high energy density, though they are all deposited on thick and rigid substrates, resulting in inferior overall energy density and poor manufacturability. Herein, an alternative strategy is developed for oxide dielectrics utilizing van der Waals epitaxy on ultrathin and flexible mica substrate, with a dielectric superlattice of Pb0.92La0.08(Zr0.95Ti0.05)O3-SrTiO3 carefully engineered to break its long-range antiferroelectric polar order. An ultrathin flexible capacitor is obtained as a result, with a record high overall energy density of 12.19 J cm−3 and an efficiency of 90.98%, and there is much room for further improvement since mica substrate can approach 2D limit. The superlattice can be easily rolled for large-scale manufacturing, and the energy storage performances are well maintained under large bending deformation as well as extended bending cycling. The study thus establishes a viable route for dielectric oxide films, paving way for their practical applications in high-energy density capacitors.  相似文献   

2.
    
Tunable dynamic networks of cellulose nanofibrils (CNFs) are utilized to prepare high-performance polymer gel electrolytes. By swelling an anisotropically dewatered, but never dried, CNF gel in acidic salt solutions, a highly sparse network is constructed with a fraction of CNFs as low as 0.9%, taking advantage of the very high aspect ratio and the ultra-thin thickness of the CNFs (micrometers long and 2–4 nm thick). These CNF networks expose high interfacial areas and can accommodate massive amounts of the ionic conductive liquid polyethylene glycol-based electrolyte into strong homogeneous gel electrolytes. In addition to the reinforced mechanical properties, the presence of the CNFs simultaneously enhances the ionic conductivity due to their excellent strong water-binding capacity according to computational simulations. This strategy renders the electrolyte a room-temperature ionic conductivity of 0.61 ± 0.12 mS cm−1 which is one of the highest among polymer gel electrolytes. The electrolyte shows superior performances as a separator for lithium iron phosphate half-cells in high specific capacity (161 mAh g−1 at 0.1C), excellent rate capability (5C), and cycling stability (94% capacity retention after 300 cycles at 1C) at 60 °C, as well as stable room temperature cycling performance and considerably improved safety compared with commercial liquid electrolyte systems.  相似文献   

3.
通过分析极化微区形成过程中自由能的变化，确定极化微区的尺寸。以相变过程中的潜热做为均匀铁电体顺电态转变为铁电态自由能变化的近似值。随着温度降低，某些区域铁电态自由能密度降低；当铁电态自由能密度低于顺电态自由能密度时导致该区域出现极化，而晶格畸变在微区表面产生的弹性势能随着极化微区长大而逐渐增大，成为阻碍微区长大的主要原因。通过自由能极值分析，所得Pb（Mg1/3 Nb2/3）O3-PbTiO3微区尺寸与实验结果相近。  相似文献   

4.
    
The existence of polar nanoregions is the most important characteristic of relaxor‐based ferroelectric materials. Recently, the contributions of polar nanoregions to the shear piezoelectric property of relaxor‐PbTiO3 (PT) crystals are confirmed in a single domain state, accounting for 50%–80% of room temperature values. For electromechanical applications, however, the outstanding longitudinal piezoelectricity in domain‐engineered relaxor‐PT crystals is of the most significance. In this paper, the contributions of polar nanoregions to the longitudinal properties in [001]‐poled Pb(Mg1/3Nb2/3)O3‐0.30PbTiO3 and [110]‐poled Pb(Zn1/3Nb2/3)O3‐0.15PbTiO3 (PZN‐0.15PT) domain‐engineered crystals are studied. Taking the [110]‐poled tetragonal PZN‐0.15PT crystal as an example, phase‐field simulations of the domain structures and the longitudinal dielectric/piezoelectric responses are performed. According to the experimental results and phase‐field simulations, the contributions of polar nanoregions (PNRs) to the longitudinal properties of relaxor‐PT crystals are successfully explained on the mesoscale, where the PNRs behave as “seeds” to facilitate macroscopic polarization rotation and enhance electric‐field‐induced strain. The results reveal the importance of local structures to the macroscopic properties, where a modest structural variation on the nanoscale greatly impacts the macroscopic properties.  相似文献   

5.
    
Relaxor ferroelectrics are a prototypical example of ferroic systems in which interplay between atomic disorder and order parameters gives rise to emergence of unusual properties, including non‐exponential relaxations, memory effects, polarization rotations, and broad spectrum of bias‐ and temperature‐induced phase transitions. Despite more than 40 years of extensive research following the original discovery of ferroelectric relaxors by the Smolensky group, the most basic aspect of these materials – the existence and nature of order parameter – has not been understood thoroughly. Using extensive imaging and spectroscopic studies by variable‐temperature and time resolved piezoresponse force microscopy, we find that the observed mesoscopic behavior is consistent with the presence of two effective order parameters describing dynamic and static parts of polarization, respectively. The static component gives rise to rich spatially ordered systems on the ～100 nm length scales, and are only weakly responsive to electric field. The surface of relaxors undergoes a mesoscopic symmetry breaking leading to the freezing of polarization fluctuations and shift of corresponding transition temperature.  相似文献   

6.
    
Electric‐field‐induced phase transitions in Bi0.5Na0.5TiO3‐based relaxor ferroelectrics are essential to the control of their electrical properties and consequently in revolutionizing their dielectric and piezoelectric applications. However, fundamental understanding of these transitions is a long‐standing challenge due to their complex crystal structures. Given the structural inhomogeneity at the nanoscale or sub‐nanoscale in these materials, dielectric response characterization based on terahertz (THz) electromagnetic‐probe beam fields is intrinsically coordinated to lattice dynamics during DC‐biased poling cycles. The complex permittivity reveals the field‐induced phase transitions to be irreversible. This profoundly counters the claim of reversibility, the conventional support for which is based upon the peak that is manifest in each of four quadrants of the current–field curves. The mechanism of this irreversibility is solely attributed to polar clusters in the transformed lattices. These represent an extrinsic factor, which is quiescent in the THz spectral domain.  相似文献   

7.
    
As the demand for power systems, including portable ones, is growing at an ever-faster pace, many studies are approaching to discover innovative materials for current battery technology or replace the existing ones with new systems through mimicking living things or nature. Here, a soft, solid-state power storage system featuring electric eel-inspired artificial electric organs capable of converting the chemical potential of an ionic gradient into electricity is introduced. These organs are constructed through the assembly of low and high ion-concentrated zwitterionic gel films with cation- and anion-selective intermembranes, which generate a rechargeable open-circuit voltage of ≈135 mV. Combined use of a chemically synthesized room-temperature ionic liquid and a high-boiling point organic solvent as ion-conducting electrolyte allows electric organs to withstand extreme temperatures ranging from −20 and 100 °C, while the thin and stretchable constituent layers facilitate mechanical flexibility without compromising electrical performance. Scalable integration of electric organs in series and parallel configurations achieves high levels of voltage and current outputs, and employment of origami folding geometry enables on-demand discharge upon self-registered folding, paving the way for portable, high-voltage energy sources in the fields of wearable electronics and soft robotics.  相似文献   

8.
    
The optoelectronic response of a material governs its suitability for a wide range of applications, from photon detection to photovoltaic conversion. To conquer the material limitations and achieve improved optoelectronic responses, nanotechnology has been employed to arrange subunits with specific size‐dependent quantum mechanical properties in a hierarchically organized structure. However, building a functional optoelectronic system from nano‐objects remains a formidable challenge. In this paper, the fabrication of a new artificially engineered optoelectronic material by the preferential growth of silicon nanocrystals on the bottom of the pore‐channels of mesoporous silica is reported. The nanocrystals form highly stable interface structures bonded on one side; these structure show strong electron–phonon coupling and a ferroelectric‐like hysteretic switching property. A new class of multifunctional materials is realized by invoking a concept that employs semiconductor nanocrystals for optical sensing and utilizes interfacial polar layers to facilitate carrier transport and emulate ferroelectric‐like switching.  相似文献   

9.
    
Long‐range ordering of dipoles is a key microscopic signature of ferroelectrics. These ordered dipoles form ferroelectric domains, which can be reoriented by electric fields. Relaxor ferroelectrics are a type of ferroelectric where the long‐range ordering of dipoles is disrupted by cation disorder, exhibiting complex polar states with a significant amount of local structural heterogeneity at the nanoscale. They are the materials of choice for numerous devices such as capacitors, nonlinear optical devices, and piezoelectric transducers, owing to their extraordinary dielectric, electro‐optic, and electromechanical properties. However, despite their extensive applications in these devices, the origins of their unique properties are yet to be fully understood, hindering the design and exploration of new relaxor ferroelectric‐based materials. Herein, the complex polar states and applications of relaxor ferroelectrics are first introduced. Attention is then focused on their electromechanical properties, where the relationship between local structural heterogeneity and the extraordinary electromechanical properties is discussed. Based on the understanding of relaxor ferroelectrics, potential strategies to exploit the local structural heterogeneity to design ferroelectrics for drastically enhancing their electromechanical performances are also discussed. It is expected that this article will stimulate future studies on the important roles of local structural heterogeneity in improving the properties of various functional materials.  相似文献   

10.
    
All‐solid‐state batteries are promising energy storage devices in which high‐energy‐density and superior safety can be obtained by efficient cell design and the use of nonflammable solid electrolytes, respectively. This paper presents a systematic study of experimental factors that affect the electrochemical performance of all‐solid‐state batteries. The morphological changes in composite electrodes fabricated using different mixing speeds are carefully observed, and the corresponding electrochemical performances are evaluated in symmetric cell and half‐cell configurations. We also investigate the effect of the composite electrode thickness at different charge/discharge rates for the realization of all‐solid‐state batteries with high‐energy‐density. The results of this investigation confirm a consistent relationship between the cell capacity and the ionic resistance within the composite electrodes. Finally, a concentration‐gradient composite electrode design is presented for enhanced power density in thick composite electrodes; it provides a promising route to improving the cell performance simply by composite electrode design.  相似文献   

11.
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12.
    
Rechargeable Li-metal batteries (RLBs) can boost energy yet possess poor cycle stability and safety concerns when utilizing carbonate electrolytes. Countless effort has been invested in researching and developing electrolytes for RLBs to obtain stable and safe batteries. However, only few existing electrolytes meet the requirements for practical RLBs. In this perspective, the challenges of organic liquid electrolytes in the application in RLBs are summarized, and requirements for electrolytes for practical RLBs are proposed. This perspective briefly reviews the recent achievements of electrolytes (liquid- and solid-state) for RLBs and analyzes the corresponding drawbacks of each electrolyte. Further, possible solutions to the existing shortcomings of various electrolytes are proposed. In particular, this perspective outlines the development strategy of in situ gelation electrolytes, accompanied by a call for people using pouch cells to evaluate performance and paying more attention to battery safety research. This perspective aims to expound on the challenges and the possible research directions of RLBs electrolytes to promote practical RLBs better.  相似文献   

13.
    
Polymer-based solid electrolytes (PSEs) have attracted tremendous interests for the next-generation lithium batteries in terms of high safety and energy density along with good flexibility. Remarkable performances have been demonstrated in PSEs, which endowed PSEs with the potential to replace liquid electrolytes to meet the market demands. In this review, polymer matrices, different polymer architectures, and functional filler materials used in PSEs are discussed to explore the design concepts, methodologies, working mechanisms, and pros and cons of various PSEs. In addition, their recent notable applications in all-solid-state lithium ion batteries, lithium–sulfur batteries, suppression of lithium dendrites, and flexible lithium batteries are also introduced. Finally, the challenges and future prospects are sketched to provide strategies to explore novel PSEs for high-performance all-solid-state lithium batteries.  相似文献   

14.
    
Mo‐based binary oxides (MBOs) and Mo‐based ternary oxides (MTOs) are a research focus because of their widespread applications. The traditional synthesis routes for MBOs and MTOs require high temperature and are time intense. Here, a rapid, facile, and scalable strategy to efficiently fabricate MBOs and MTOs with various morphologies and crystal structures is reported. Only 1 min is required for the whole process and the yield is above 90%. This strategy is the simplest and the fastest method reported and exhibits large potential for application. Furthermore, the as‐synthesized Hx MoO3 nanobelts and NiMoO4·x H2O nanowires display a specific capacitance of 660.3 F g?1 at 2 mV s?1 and a specific capacity of 549 C g?1 at 1 A g?1. In addition, to assemble the Hx MoO3 and NiMoO4·x H2O electrodes together, the solid state hybrid electrolyte is employed to take advantage of MBOs and MTOs. The obtained NiMoO4·x H2O//Hx MoO3 device delivers a specific capacitance of 156 F g?1 at 0.8 A g?1 and an energy density of 55.6 Wh kg?1 at a power density of 640 W kg?1, making it attractive for application as an energy storage material.  相似文献   

15.
    
Sodium-based complex hydrides have recently gained interest as electrolytes for all-solid-state batteries due to their light weight and high electrochemical stability. Although their room temperature conductivities are not sufficiently high for battery application, nanocomposite formation with metal oxides has emerged as a promising approach to enhance the ionic conductivity of complex hydrides. This enhancement is generally attributed to the formation of a space charge layer at the hydride-oxide interface. However, in this study it is found that the conductivity enhancement results from interface reactions between the metal hydride and the oxide. Highly conductive NaBH4 and NaNH2/oxide nanocomposites are obtained by optimizing the interface reaction, which strongly depends on the interplay between the surface chemistry of the oxides and the reactivity of the metal hydrides. Notably, for NaBH4, the best performance is obtained with Al2O3, while NaNH2/SiO2 is the most conductive NaNH2/oxide nanocomposite with conductivities of, respectively, 4.7 × 10−5 and 2.1 × 10−5 S cm−1 at 80 °C. Detailed structural characterization reveals that this disparity originates from the formation of different tertiary interfacial compounds, and is not only a space charge effect. These results provide useful insights for the preparation of highly conductive nanocomposite electrolytes by optimizing interface interactions.  相似文献   

16.
    
It is well known that the piezoelectric performance of ferroelectric Pb(Zr,Ti)O3 (PZT) based ceramics is far inferior to that of ferroelectric single crystals due to ceramics' polycrystalline nature. Herein, it is reported that piezoelectric stress coefficient e33 = 39.24 C m?2 (induced electric displacement under applied strain) in the relaxor piezoelectric ceramic 0.55Pb(Ni1/3Nb2/3)O3–0.135PbZrO3–0.315PbTiO3 (PNN‐PZT) prepared by the solid state reaction method exhibits the highest value among various reported ferroelectric ceramic and single crystal materials. In addition, its piezoelectric coefficient d33* = 1753 pm V?1 is also comparable with that of the commercial Pb(Mg1/3Nb2/3)O3‐PbTiO3 (PMN‐PT) piezoelectric single crystal. The PNN‐PZT ceramic is then assembled into a cymbal energy harvester. Notably, its maximum output current at the acceleration of 3.5 g is 2.5 mApp, which is four times of the PMN‐PT single crystal due to the large piezoelectric e33 constants; while the maximum output power is 14.0 mW, which is almost the same as the PMN‐PT single crystal harvester. The theoretical analysis on force‐induced power output is also presented, which indicates PNN‐PZT ceramic has great potential for energy device application.  相似文献   

17.
Photosynthetic proteins transduce sunlight into biologically useful forms of energy through a photochemical charge separation that has a close to 100% quantum efficiency, and there is increasing interest in their use as sustainable materials in biohybrid devices for solar energy harvesting. This work explores a new strategy for boosting the open circuit voltage of photoelectrochemical cells based on a bacterial photosynthetic pigment‐protein by employing highly oxidizing redox electrolytes in conjunction with an n‐type silicon anode. Illumination generates electron–hole pairs in both the protein and the silicon electrode, the two being connected by the electrolyte which transfers electrons from the reducing terminal of the protein to photogenerated holes in the silicon valence band. A high open circuit voltage of 0.6 V is achieved with the most oxidizing electrolyte 2,2,6,6‐tetramethyl‐1‐piperidinyloxy, and this is further improved to 0.7 V on surface modification of the silicon electrode to increase its surface area and reduce reflection of incident light. The photovoltages produced by these biohybrid protein/silicon cells are comparable to those typical of silicon heterojunction and dye‐sensitized solar cells.  相似文献   

18.
    
Beta alumina ceramics are well-known fast-ionic conductors of Na-ion. The effect of Na2O content (8.00–13.19%) on properties of beta alumina solid electrolytes was studied in the paper by XRD, SEM and EIS. The results showed that in the Na2O–Al2O3 system, the β″-Al2O3 phase was formatted at the low temperature of 1250 °C, however the noticeable transformation from β″-Al2O3 to β-Al2O3 occurred in the higher temperature range. The β″-phase content of the precursor powders was independent of the Na2O content, but β″-phase content, the volume density and the bending strength of beta alumina sinters grew with the increase of the Na2O content. Samples with 10.84% Na2O possessed the optimum ionic conductivity and the most uniform microstructure. The ionic conductivity depends not only on the phase content, but also on the phase microstructure.  相似文献   

19.
    
Polar topological structures in ferroelectric materials have attracted significant interest due to their fascinating physical properties and promising applications in high-density, nonvolatile memories. Currently, most polar topological patterns are only observed in the bulky perovskite superlattices. In this work, a discovery of tunable ferroelectric polar topological structures is reported, designed, and achieved using topological strain engineering in two-dimensional (2D) PbX (X = S, Se, and Te) materials via integrating first-principles calculations, machine learning molecular dynamics simulations, and continuum modeling. First-principles calculations discover the strain-induced reversible ferroelectric phase transition with diverse polarization directions strongly correlated to the straining conditions. Taking advantage of the mechanical flexibility of 2D PbX, using molecular dynamics (MD) simulations, it is successfully demonstrated that the complex strain fields of 2D topological surfaces under mechanical indentation can generate unique skyrmion-like polar topological vortex patterns. Further continuum simulations for experimentally accessible larger-scale 2D topological surfaces uncover multiple skyrmion-like structures (i.e., vortex, anti-vortex, and flux-closure) and transition between them by adopting/designing different types of mechanical loadings (such as out-of-plane indention and air blowing). Topological surfaces with various designable reversible polar topological structures can be tailored by complex straining flexible 2D materials, which provides excellent opportunities for next-generation nanoelectronics and sensor devices.  相似文献   

20.
All-solid-state batteries (SSBs) represent one of the most promising avenues for surpassing the energy density limitations of conventional lithium-ion batteries. However, the unstable interfacial contact between the solid-state electrolyte and the electrode poses a critical challenge for practical applications. To tackle this issue, a hybrid system incorporating both liquid electrolytes (LEs) and sulfide solid-state electrolytes may serve as a viable alternative. In this hybrid system, the LE facilitates the in situ formation of a solid electrolyte interphase layer, thereby enhancing the physical interface contact. Consequently, the electrochemical lifetime of the hybrid all-SSBs is significantly improved, as evidenced by the stable lithium plating behavior observed through analytical techniques such as in situ X-ray imaging. Nonetheless, the hybrid system exhibits clear limitations, and several issues that need to be addressed for its practical implementation are identified. In conclusion, potential solutions that could be employed to overcome these challenges are proposed.  相似文献   

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