Self-Rolling-Up Enabled Ultrahigh-Density Information Storage in Freestanding Single-Crystalline Ferroic Oxide Films

Ferroelectric memory is one of the most attractive emerging nonvolatile memory. Conventional methods to increase storage density in ferroelectrics include reducing the storage bit size or fabricating 3D stacks. However, the former will face a physical limit finally, and the integration of single-crystalline ferroelectric oxide following the latter still remains a great challenge. Here, a new method is introduced to construct a scroll-like 3D memory structure by self-rolling-up single-crystalline ferroelectric oxides. PbZr_0.3Ti_0.7O₃ single-crystalline thin film is chosen as a prototype and epitaxially grown on another oxide stressor layer with a few lattice-mismatch. Releasing such “Pb(Zr, Ti)O₃/stressor” bilayered structure from the substrate induces self-rolling-up due to the internal stress from the lattice-mismatch. High-density information can be written in the form of switched ferroelectric domains on those flat “Pb(Zr, Ti)O₃/stressor” membranes via piezoelectric force microscopy. In self-rolling-up membranes, information density can be experimentally enhanced up to 45 times. Theoretically, the freestanding “Pb(Zr, Ti)O₃/stressor” membranes have a strongly driven force to self-rolling-up, and the area ratio can enhance 100–450 times, corresponding to an ultra-high density information storage of 10² Tbit In⁻². This study provides a new and general method to develop compact, high-density, and 3D memories from oxide materials.     

Antiferroelectric Anisotropy of Epitaxial PbHfO3 Films for Flexible Energy Storage

Dielectric capacitors are widely studied for power supply systems because they can quickly store and release electrical energy. Among various kinds of dielectric materials, antiferroelectrics show promising features of high energy-storage density and efficiency. In this study, epitaxial antiferroelectric PbHfO₃ films with different orientations are fabricated, in which remarkable anisotropies of polarization and energy storage properties are discovered. With the optimization of film orientation, much-improved energy density and excellent high-temperature efficiency are achieved in the PbHfO₃ films. Moreover, the PbHfO₃ films are fabricated onto flexible mica substrates, which exhibit excellent property robustness against mechanical bending. This study provides a fundamental understanding of the anisotropic antiferroelectric behaviors of epitaxial PbHfO₃ films and provides a generalizable pathway for flexible energy-storage dielectric capacitors.     

Ultrahigh Energy Density of Antiferroelectric PbZrO3-Based Films at Low Electric Field

Dielectric capacitors play a vital role in advanced electronics and power systems as a medium of energy storage and conversion. Achieving ultrahigh energy density at low electric field/voltage, however, remains a challenge for insulating dielectric materials. Taking advantage of the phase transition in antiferroelectric (AFE) film PbZrO₃ (PZO), a small amount of isovalent (Sr²⁺) / aliovalent (La³⁺) dopants are introduced to form a hierarchical domain structure to increase the polarization and enhance the backward switching field E_A simultaneously, while maintaining a stable forward switching field E_F. An ultrahigh energy density of 50 J cm⁻³ is achieved for the nominal Pb_0.925La_0.05ZrO₃ (PLZ5) films at low electric fields of 1 MV cm⁻¹, exceeding the current dielectric energy storage films at similar electric field. This study opens a new avenue to enhance energy density of AFE materials at low field/voltage based on a gradient-relaxor AFE strategy, which has significant implications for the development of new dielectric materials that can operate at low field/voltage while still delivering high energy density.     

2D Antiferroelectric Hybrid Perovskite with a Large Breakdown Electric Field And Energy Storage Density

Energy conversion and storage devices are highly desirable for the sustainable development of human society. Hybrid organic–inorganic perovskites have shown great potential in energy conversion devices including solar cells and photodetectors. However, its potential in energy storage has seldom been explored. Here the crystal structure and electrical properties of the 2D hybrid perovskite (benzylammonium)₂PbBr₄ (PVK-Br) are investigated, and the consecutive ferroelectric-I (FE1) to ferroelectric-II (FE2) then to antiferroelectric (AFE) transitions that are driven by the orderly alignment of benzylamine and the distortion of [PbBr₆] octahedra are found. Furthermore, accompanied by field-induced AFE to FE transition near room temperature, a large energy storage density of ≈1.7 J cm⁻³ and a wide working temperature span of ≈70 K are obtained; both of which are among the best in hybrid AFEs. This good energy storage performance is attributed to the large polarization of ≈7.6 µC cm⁻² and the high maximum electric field of over 1000 kV cm⁻¹, which, as revealed by theoretical calculations, originate from the cooperative coupling between the [PbBr₆] octahedral framework and the benzylamine molecules. The research clarifies the discrepancy in the phase transition character of PVK-Br and shed light on developing high-performance energy storage devices based on 2D hybrid perovskite.     

Nonvolatile Random Access Memory and Energy Storage Based on Antiferroelectric Like Hysteresis in ZrO2

To date antiferroelectrics have not been considered as nonvolatile memory elements because a removal of the external field causes a depolarization, resulting in a loss of the stored information. In comparison to ferroelectrics, antiferroelectrics are known for their enhanced fatigue resistance. Therefore, the main scope of this study is the development of a new memory device concept that would enable the usage of antiferroelectrics as a nonvolatile material with improved wake‐up and enhanced endurance properties. Recent studies have shown antiferroelectric behavior in ZrO₂, a material that is widely used in semiconductor industry, especially in dynamic random access memories. The basis of the new concept is the antiferroelectric hysteresis combined with the use of different workfunction electrodes that induce an internal bias field. Utilizing this approach, the field cycling endurance is drastically improved. Combining a comprehensive material study and electrical trap spectroscopy together with Landau–Ginzburg–Devonshire formalism, a proof of concept for a novel antiferroelectric random access memory is presented. For implementing a nonvolatile random access memory, the capacitors have to be realized in a 3D integrated version. These 3D integrated ZrO₂ capacitors can be used as energy storage devices as well, showing record high energy storage density and very high energy efficiency values.     

Ultrahigh Energy‐Storage Density in Antiferroelectric Ceramics with Field‐Induced Multiphase Transitions

The excellent energy‐storage performance of ceramic capacitors, such as high‐power density, fast discharge speed, and the ability to operate over a broad temperature range, gives rise to their wide applications in different energy‐storage devices. In this work, the (Pb_0.98La_0.02)(Zr_0.55Sn_0.45)_0.995O₃ (PLZS) antiferroelectric (AFE) ceramics are prepared via a unique rolling machine approach. The field‐induced multiphase transitions are observed in polarization–electric field (P–E) hysteresis loops. All the PLZS AFE ceramics possess high energy‐storage densities and discharge efficiency (above 80%) with different sintering temperatures. Of particular significance is that an ultrahigh recoverable energy‐storage density of 10.4 J cm^‐3 and a high discharge efficiency of 87% are achieved at 40 kV mm^‐1 for PLZS ceramic with a thickness of 0.11 mm, sintered at 1175 °C, which are by far the highest values ever reported in bulk ceramics. Moreover, the corresponding ceramics exhibit a superior discharge current density of 1640 A cm^‐2 and ultrafast discharge speed (75 ns discharge period). This great improvement in energy‐storage performance is expected to expand the practical applications of dielectric ceramics in numerous electronic devices.     

Ultrahigh Energy‐Storage Density in NaNbO3‐Based Lead‐Free Relaxor Antiferroelectric Ceramics with Nanoscale Domains

Dielectric energy‐storage capacitors have received increasing attention in recent years due to the advantages of high voltage, high power density, and fast charge/discharge rates. Here, a new environment‐friendly 0.76NaNbO₃–0.24(Bi_0.5Na_0.5)TiO₃ relaxor antiferroelectric (AFE) bulk ceramic is studied, where local orthorhombic Pnma symmetry (R phase) and nanodomains are observed based on high‐resolution transmission electron microscopy, selected area electron diffraction, and in/ex situ synchrotron X‐ray diffraction. The orthorhombic AFE R phase and relaxor characteristics synergistically contribute to the record‐high energy‐storage density W_rec of ≈12.2 J cm^?3 and acceptable energy efficiency η ≈ 69% at 68 kV mm^?1, showing great advantages over currently reported bulk dielectric ceramics. In comparison with normal AFEs, the existence of large random fields in the relaxor AFE matrix and intrinsically high breakdown strength of NaNbO₃‐based compositions are thought to be responsible for the observed energy‐storage performances. Together with the good thermal stability of W_rec (>7.4 J cm^?3) and η (>73%) values at 45 kV mm^?1 up to temperature of 200 °C, it is demonstrated that NaNbO₃‐based relaxor AFE ceramics will be potential lead‐free dielectric materials for next‐generation pulsed power capacitor applications.     

Asymmetric Trilayer All-Polymer Dielectric Composites with Simultaneous High Efficiency and High Energy Density: A Novel Design Targeting Advanced Energy Storage Capacitors

Polymeric dielectrics have attracted intensive attention worldwide because of their huge potential for advanced energy storage capacitors. Thus far, various effective strategies have been developed to improve the inherent low energy densities of polymer dielectrics. However, enhanced energy density is always accompanied by suppressed discharge efficiency, which is detrimental to practical applications and deserves considerable concern. Targeting at achieving simultaneous high energy density and high discharge efficiency, the unique design of asymmetric all-polymer trilayer composite consisting of a transition layer sandwiched by a linear dielectric layer and a nonlinear dielectric layer is herein reported. It is demonstrated that the nonlinear dielectric layer offers high energy density, while the linear dielectric layer provides high discharge efficiency. Especially, the transition layer can effectively homogenize the electric field distribution, resulting in greatly elevated breakdown strength and improved energy density. In particular, a high efficiency of 89.9% along with a high energy density of 12.15 J cm⁻³ are concurrently obtained. The asymmetric trilayer all-polymer design strategy represents a new way to achieve high-performance dielectric energy storage materials.     

Superior High-Temperature Energy Density in Molecular Semiconductor/Polymer All-Organic Composites

High-temperature dielectric polymers are in constant demand for the multitude of high-power electronic devices employed in hybrid vehicles, grid-connected photovoltaic and wind power generation, to name a few. There is still a lack, however, of dielectric polymers that can work at high temperature (> 150 °C). Herein, a series of all-organic dielectric polymer composites have been fabricated by blending the n-type molecular semiconductor 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTCDA) with polyetherimide (PEI). Electron traps are created by the introduction of trace amounts of n-type small molecule semiconductor NTCDA into PEI, which effectively reduces the leakage current and improves the breakdown strength and energy storage properties of the composite at high temperature. Especially, excellent energy storage performance is achieved in 0.5 vol.% NTCDA/PEI at the high temperatures of 150 and 200 °C, e.g., ultrahigh discharge energy density of 5.1 J cm⁻³ at 150 °C and 3.2 J cm⁻³ at 200 °C with high discharge efficiency of 85–90%, which is superior to its state-of-the-art counterparts. This study provides a facile and effective strategy for the design of high-temperature dielectric polymers for advanced electronic and electrical systems.     

High‐Performance Ferroelectric–Dielectric Multilayered Thin Films for Energy Storage Capacitors

Herein, the effect of the insertion of a thin dielectric HfO₂:Al₂O₃ (HAO) layer at different positions in the Pt/0.5Ba(Zr_0.2Ti_0.8)O₃–0.5(Ba_0.7Ca_0.3)TiO₃ (BCZT)/Au structure on the energy storage performance of the capacitors is investigated. A high storage performance is achieved through the insertion of a HAO layer between BCZT and Au layers. The insertion of the dielectric layer causes a depolarization field which results in a high linearity hysteresis loop with low energy dissipation. The Pt/BCZT/HAO/Au capacitors show an impressive energy storage density of 99.8 J cm^?3 and efficiency of 71.0%, at an applied electric field of 750 kV cm^?1. Further, no significant change in the energy storage properties is observed after passing 10⁸ switching cycles through the capacitor. The presence of resistive switching (RS) in leakage current characteristics confirms the strong charge coupling between ferroelectric and insulator layers. The same trend of the RS ratio and the energy storage performance with the variation of the architecture of the devices suggests that the energy storage properties can be improved through the charge coupling between the layers. By combining ferroelectrics and dielectrics into one single structure, the proposed strategy provides an efficient way for developing highly efficient energy storage capacitors.     

3D HfO2 Thin Film MEMS Capacitor with Superior Energy Storage Properties

Capacitors are ubiquitous and crucial components in modern technologies. Future microelectronic devices require novel dielectric capacitors with higher energy storage density, higher efficiency, better frequency and temperature stabilities, and compatibility with integrated circuit (IC) processes. Here, in order to overcome these challenges, a novel 3D HfO₂ thin film capacitor is designed and fabricated by an integrated microelectromechanical system (MEMS) process. The energy storage density (ESD) of the capacitor reaches 28.94 J cm⁻³, and the energy storage efficiency of the capacitor is up to 91.3% under an applied electric field of 3.5 MV cm⁻¹. The ESD can be further improved by reducing the minimum period structure size of the 3D capacitor. Moreover, the 3D capacitor exhibits excellent temperature stability (up to 150 °C) and charge-discharge endurance (10⁷ cycles). The results indicate that the 3D HfO₂ thin film MEMS capacitor has enormous potential in energy storage applications in harsh environments, such as pulsed discharge and power conditioning electronics.     

Metal–Organic Framework (MOF) Derived Electrodes with Robust and Fast Lithium Storage for Li‐Ion Hybrid Capacitors

Hybrid metal–organic frameworks (MOFs) demonstrate great promise as ideal electrode materials for energy‐related applications. Herein, a well‐organized interleaved composite of graphene‐like nanosheets embedded with MnO₂ nanoparticles (MnO₂@C‐NS) using a manganese‐based MOF and employed as a promising anode material for Li‐ion hybrid capacitor (LIHC) is engineered. This unique hybrid architecture shows intriguing electrochemical properties including high reversible specific capacity 1054 mAh g^?1 (close to the theoretical capacity of MnO₂, 1232 mAh g^?1) at 0.1 A g^?1 with remarkable rate capability and cyclic stability (90% over 1000 cycles). Such a remarkable performance may be assigned to the hierarchical porous ultrathin carbon nanosheets and tightly attached MnO₂ nanoparticles, which provide structural stability and low contact resistance during repetitive lithiation/delithiation processes. Moreover, a novel LIHC is assembled using a MnO₂@C‐NS anode and MOF derived ultrathin nanoporous carbon nanosheets (derived from other potassium‐based MOFs) cathode materials. The LIHC full‐cell delivers an ultrahigh specific energy of 166 Wh kg^?1 at 550 W kg^?1 and maintained to 49.2 Wh kg^?1 even at high specific power of 3.5 kW kg^?1 as well as long cycling stability (91% over 5000 cycles). This work opens new opportunities for designing advanced MOF derived electrodes for next‐generation energy storage devices.     

Sub-Nanowires Boost Superior Capacitive Energy Storage Performance of Polymer Composites at High Temperatures

Polymer dielectrics with high breakdown strength (E_b) and high efficiency are urgently demanded in advanced electrical and electronic systems, yet their energy density (U_e) is limited due to low dielectric constant (ε_r) and high loss at elevated temperatures. Conventional inorganic fillers with diameters from nano to micrometers can only increase ε_r at the cost of compromised E_b and U_e due to their poor compatibility with polymer matrix. Herein, hydroxyapatite (HAP) sub-nanowires with a diameter of ≈0.9 nm are incorporated in polyetherimide (PEI) matrix to form HAP/PEI sub-nanocomposites. ε_r and E_b of the composites are concomitantly enhanced with only 0.5 wt.% of HAP sub-nanowires, leading to high U_e of 5.14 (@150 °C) and 3.1 J cm⁻³ (@200 °C) with efficiency of 90% and high-temperature stability up to 3 × 10⁵ charge-discharge cycles at 200 °C. Microstructural analysis and molecular dynamics simulations indicate that the sub-nanowires with comparable diameter as polymer chains induce enormous interfacial area, substantially increase mobility of polymer chains and form dense traps for charge carriers. This work extends the current research scope of polymer-inorganics composite dielectrics to the sub-nano-level incorporation and provides a novel strategy for fabricating high performance polymer dielectrics at elevated temperatures.     

Cactus‐Like NiCoP/NiCo‐OH 3D Architecture with Tunable Composition for High‐Performance Electrochemical Capacitors

To effectively enhance the energy density and overall performance of electrochemical capacitors (ECs), a new strategy is demonstrated to increase both the intrinsic activity of the reaction sites and their density. Herein, nickel cobalt phosphides (NiCoP) with high activity and nickel cobalt hydroxides (NiCo‐OH) with good stability are purposely combined in a hierarchical cactus‐like structure. The hierarchical electrode integrates the advantages of 1D nanospines for effective charge transport, 2D nanoflakes for mechanical stability, and 3D carbon cloth substrate for flexibility. The NiCoP/NiCo‐OH 3D electrode delivers a high specific capacitance of ≈1100 F g^?1, which is around seven times higher than that of bare NiCo‐OH. It also possesses ≈90% capacitance retention after 1000 charge–discharge cycles. An asymmetric supercapacitor composed of NiCoP/NiCo‐OH cathode and metal–organic framework‐derived porous carbon anode achieves a specific capacitance of ≈100 F g^?1, high energy density of ≈34 Wh kg^?1, and excellent cycling stability. The cactus‐like NiCoP/NiCo‐OH 3D electrode presents a great potential for ECs and is promising for other functional applications such as catalysts and batteries.     

激光能量密度对纳米Al2O3/PS复合材料致密度和显微结构的影响

当扫描间距一定时,选区激光烧结(SLS)成型的激光能量密度和激光功率(P)与扫描速度(V)的比值(P/V)成正比。为了研究激光能量密度对烧结试件致密度和显微结构的影响,分别对不同P/V比值及相同P/V比值但不同P值和V值条件下激光烧结试件的致密度进行了研究,并利用扫描电镜(SEM)分析研究了烧结试件的表面形貌和显微结构的变化。研究发现,在P/V值达到1 W/37.7 mm.s-1以前时,烧结试件的体积密度随着P/V值的增加而提高,试件表面越来越光滑,气孔数量及尺寸减小;随着P/V值进一步地提高,由于聚苯乙烯的降解,产生了大量的烟气,体积密度基本上没有提高,反而有可能会出现下降的趋势,气孔未见明显减少;在P/V值等于1 W/32 mm.s-1时,随着P和V值的同时增加,烧结试件的体积密度有下降的趋势,内部气孔增多,气孔尺寸变大。综合考虑激光器使用寿命及加工效率等因素,较佳的成型工艺参数选择为激光烧结功率28 W,扫描速度1120 mm/s,铺粉厚度0.1 mm,扫描间距0.2 mm,预热温度95℃。     

一种基于超级电容器储能的光伏控制器的实现

近年来,由于能源和环境问题,太阳能的利用得到了快速的发展。超级电容器也是近几年来发展起来的一种专门用于储能的特殊电容器,相对于普通蓄电池和电容器,有其独特的优势。基于超级电容器设计,此控制器运用单片机软件实现了最大功率跟踪控制,并具有防反充,防过充以及防止过放的功能。实验结果证明控制器达到了最大功率跟踪的功能。     

基于MATLAB的集成电路储能焊封装能量分布研究

气密性是集成电路封装中的一项重要技术指标,对于集成电路的可靠性使用具有重要作用。就气密性封装工艺中的储能焊封装技术进行了讨论,通过对储能焊设备放电过程进行分析及建模,得到了气密性焊接能量与各个工艺参数之间的关系,并利用MATLAB软件进行了模拟计算。结合具体实验,验证了理论建模及模拟的正确性,对于储能焊焊接的工艺参数设定及优化具有一定的指导意义。     

Micro‐Supercapacitors Based on Interdigital Electrodes of Reduced Graphene Oxide and Carbon Nanotube Composites with Ultrahigh Power Handling Performance

A novel method for fabricating micro‐patterned interdigitated electrodes based on reduced graphene oxide (rGO) and carbon nanotube (CNT) composites for ultra‐high power handling micro‐supercapacitor application is reported. The binder‐free microelectrodes were developed by combining electrostatic spray deposition (ESD) and photolithography lift‐off methods. Without typically used thermal or chemical reduction, GO sheets are readily reduced to rGO during the ESD deposition. Electrochemical measurements show that the in‐plane interdigital design of the microelectrodes is effective in increasing accessibility of electrolyte ions in‐between stacked rGO sheets through an electro‐activation process. Addition of CNTs results in reduced restacking of rGO sheets and improved energy and power density. Cyclic voltammetry (CV) measurements show that the specific capacitance of the micro‐supercapacitor based on rGO–CNT composites is 6.1 mF cm^?2 at 0.01 V s^?1. At a very high scan rate of 50 V s^?1, a specific capacitance of 2.8 mF cm^?2 (stack capacitance of 3.1 F cm^?3) is recorded, which is an unprecedented performance for supercapacitors. The addition of CNT, electrolyte‐accessible and binder‐free microelectrodes, as well as an interdigitated in‐plane design result in a high‐frequency response of the micro‐supercapacitors with resistive‐capacitive time constants as low as 4.8 ms. These characteristics suggest that interdigitated rGO–CNT composite electrodes are promising for on‐chip energy storage application with high power demands.     

一种基于蚁群算法的WSN能效均衡路由

为了解决无线传感器网络的能耗不均衡问题,提出了一种基于蚁群算法(ACO)的自适应能量均衡路由算法(EBEA).该算法将节点的能量密度融入到启发因子中,利用蚂蚁的动态适应性在全局范围内寻求最优路径让网络达能量均衡的效果.仿真实验结果表明,与LEACH算法相比,该算法能够均衡整个网络的能耗,并有效的避免了网络分割或者"能量空洞"现象,延长网络的生命周期.