驻极体声传感器及其储电材料的现状

综述了驻极体声传感器及其储电材料近年来的迅猛发展。传统的FEP(tetrafluoroethylene-hexa-fluoropropylenecopolymer)驻极体电容式声传感器及以铁电聚合物PVDF(polyvinylidenefluoride)家族为芯片的声传感器和超声换能器仍焕发着青春活力。Si基微型驻极体声传感器的理论和实验研究已经日趋成熟,而用空间电荷型多孔聚合物驻极体压电薄膜为芯片可望研制出新一代声电和电声传感器、压力传感器和驱动器。

Hydrogen storage properties of Mg-TiO_2 composite powder prepared by arc plasma method

Mg-based Mg-TiO2 composite powder was prepared by arc plasma evaporation of the Mg＋5%TiO2 mixture followed by passivation in air. ICP, XRD and SEM techniques were used to characterize the composition, phase components and microstructure of the composite powder. The hydrogen sorption properties of the composite powder were investigated by DSC and PCT techniques. According to the data from PCT measurements, the hydrogenation enthalpy and entropy changes of the composite powder are calculated to be-71.5 kJ/mol and-130.1 J/（K·mol）, respectively. Besides, the hydrogenation activation energy is determined to be 77.2 kJ/ mol. The results indicate that TiO2 added into Mg by arc plasma method can act as a catalyst to improve the hydrogen sorption kinetic properties of Mg.

Application of thermal electrochemical equation to metal-hydride half-cell system

Application of thermal electrochemical equation to metal-hydride half-cell system was investigated, and the influence of state of charge on the thermal electrochemical performance of hydrogen storage materials was studied. The results show that both the absolute value of the molar enthalpy change and the internal resistance of evolution hydrogen reaction are less than that of absorption hydrogen reaction at the same state of charge. The molar reaction enthalpy change of absorption and evolution of hydride electrode change contrarily with the enhancement of filling degree of hydrogen in hydride electrode. The relation curve of molar reaction enthslpy change to state of charge, both absorption and evolution hydrogen reaction, is close to a constant when the state of charge is 10%- 60%, and during state of charge below 10% or state of charge above 60%, the molar reaction enthalpy change varies sharply. Meanwhile, the internal resistance of electrode reaction has an ascending trend with the enhancement on filling degree of hydrogen in hydride electrode in both absorption and evolution hydrogen reaction.

Dissolution-regrowth synthesis of SiO_2 nanoplates and embedment into two carbon shells for enhanced lithium-ion storage

In this work, SiO2 nanoplates with opened macroporous structure on carbon layer （C-mSiO2） have been obtained by dissolving and subsequent ingrowing the outer solid SiO2 layer of the aerosol-based C-SiO2 double-shell hollow spheres. Subsequently, triple-shell C-mSiO2-C hollow spheres were successfully prepared after coating the C- mSiO2 templates by the carbon layer from the carbonization of sucrose. When being applied as the anode material fur lithium-ion batteries, the C-mSiO2-C triple-shell hollow spheres deliver a high capacity of 501 mA. h.g- 1 after 100 cycles at 500 mA.g-1 （based on the total mass of silica and the two carbon shells）, which is higher than those of C-mSiO2 （391 mA.h.g 1） spheres with an outer porous SiO2 layer, C-SiO2-C （370 mA-h.g-1） hollow spheres with a middle solid Si02 layer, and C-SiO2 （319.8 mA·h-g-1） spheres with an outer solid SiO2 layer. In addition, the battery still delivers a high capacity of 403 mA· h· g- 1 at a current density of 1000 mA· g- 1 after 400 cycles. The good electrochemical performance can be attributed to the high surface area （246.7 m2·g- 1 ） and pore volume （0.441 cm3· g-1） of the anode materials, as well as the unique structure of the outer and inner carbon layer which not only enhances electrical conductivity, structural stability, but buffers volume change of the intermediate SiO2 layer during repeated charge-discharge processes. Furthermore, the SiO2 nanoplates with opened macroporous structure facilitate the electrolyte transport and electrochemical reaction.

Investigation of Excessive Material on Insulating Properties Using Different Heat Transfer Fluid for Thermal Energy Storage Development

Though TES （thermal energy storage） is developed hugely in most of the solar power generation plants, it is less growth in implementing a modular type of TES in a solar plant, e.g., solar dish/stifling engine application. The main issue in designing the TES system is its thermal capacity of storage materials, e.g., insulator. This study is focusing on the potential waste material as an insulator for thermal energy storage applications. The insulator usage is to reduce the heat transfer between two mediums and the capability is measured by its resistance to heat flow. It is needed to obtain optimal materials to energy conversion at the same time reduce the waste generation. Therefore, a small-scale experimental testing of natural cooling process of an insulated tank within a confined room without any forced cooling system, e.g., fan. The testing is repeated by changing the insulator using the potential waste material from natural and industrial waste and also by changing the HTF （heat transfer fluid）. The analysis is performed on the relationship between heat loss and the reserved period by the insulator. The results indicate the percentage of period of the insulated tank withstands the heat compared to non-insulated tank, e.g., cotton reserved the period of 14% more than non-insulated tank to withstand the heat transfer of cooking oil to the surrounding. The paper finally justifies the most potential waste material as an insulator in different heat transfer fluids.

Graphene： a promising 2D material for electrochemical energy storage

Graphene, with unique two-dimensional form and numerous appealing properties, promises to remarkably increase the energy density and power density of electrochemical energy storage devices(EESDs),ranging from the popular lithium ion batteries and supercapacitors to next-generation high-energy batteries. Here, we review the recent advances of the state-of-the-art graphene-based materials for EESDs,including lithium ion batteries, supercapacitors, micro-supercapacitors, high-energy lithium-air and lithium-sulfur batteries, and discuss the importance of the pore, doping, assembly, hybridization and functionalization of different nano-architectures in improving electrochemical performance. The major roles of graphene are highlighted as(1) a superior active material,(2) ultrathin 2D flexible support,and(3) an inactive yet electrically conductive additive. Furthermore, we address the enormous potential of graphene for constructing new-concept emerging graphene-enabled EESDs with multiple functionalities of lightweight, ultra-flexibility, thinness, and novel cell configurations. Finally, future perspectives and challenges of graphene-based EESDs are briefly discussed.

Recent advancements in metal organic framework based electrodes for supercapacitors

Metal organic frameworks（MOFs） are considered as very promising candidates to build electrodes for electrochemical energy storage devices such as lithium ion batteries, fuel cells and supercapacitors, due to their diverse structure, adjustable aperture, large specific surface area and abundant active sites. Supercapacitor has been widely investigated in the past decades. Of critical importance in these devices is the electrode active materials, and this application has been intensively studied with the development of novel nanomaterials. In this review we summarize recent reports on MO Fs as electrode materials for super capacitors. Specifically,the synthesis of MOF materials for super capacitor electrodes and their performance in electrochemical energy storage are discussed. We aim to include supercapacitor electrode materials related to MOFs, such as carbon, metal and composite materials. It is proposed that MOFs play an important role in the development of a new generation of supercapacitor electrode materials. Finally, we discuss the current challenges in the field of supercapacitors, with a view towards how to address these challenges with the future development of MOFs and their derivatives.

Highlights on inorganic solid state chemistry and energy materials

This review highlights the recent research progress on inorganic solid state energy materials in China,from synthesis and fundamental properties to their applications.It describes the significant contributions of Chinese scholars in the field of inorganic solid state chemistry and energy materials including green catalysts,fuel cells,lithium batteries,solar cells,hydrogen storage materials,thermoelectric materials,luminescent materials and superconductors,and then outlines the ongoing rapid progress of novel inorganic solid state materials and the development of reliable and reproducible preparation methods for inorganic solid state materials in China.Finally,we conclude the paper by considering future developments of inorganic solid state chemistry and energy materials in China.

Electrochemical energy storage applications of “pristine” graphene produced by non-oxidative routes

Graphene is a promising material as both active components and additives in electrochemical energy storage devices. The properties of graphene strongly depend on the fabrication methods. The applications of reduced graphene oxide as electrode materials have been well studied and reviewed, but the using of "pristine" graphene as electrode material for energy storage is still a new topic. In this paper, we review state-of-the-art progress in the fabrication of "pristine" graphene by different methods and the electrochemical performance of graphene-based electrodes. The achievements in this area will be summarized and compared with the graphene oxide route in terms of cost, scalability, material properties and performances, and the challenges in these methods will be discussed as well.

Ni_(3)S_(2)@NiWO_(4)nanoarrays towards all-solid-state hybrid supercapacitor with record-high energy density

The rational design and synthesis of hybrid-type electrode nanomaterials are significant for their diverse applications,including their potential usage as high-efficiency nanoarchitectures for supercapacitors(SCs)as a class of promising energy-storage systems for powering next-generation electric vehicles and electronic devices.Here,we reported a facile and controllable synthesis of core-shell Ni_(3)S_(2)@NiWO_(4)nanoarrays to fabricate a freestanding electrode for hybrid SCs.Impressively,the as-prepared freestanding Ni_(3)S_(2)@NiWO_(4)electrode presents an ultrahigh areal capacity of 2032μA h cm^(-2)at 5 mA cm^(-2),and a capacity retention of 63.6%even when the current density increased up to 50 mA cm^(-2).Remarkably,the Ni_(3)S_(2)@NiWO_(4)nanoarraybased hybrid SC delivers a maximum energy density of 1.283 mW h cm^(-2)at 3.128 mW cm^(-2)and a maximum power density of 41.105 mW cm^(-2)at 0.753 mW h cm^(-2).Furthermore,the hybrid SC exhibits a capacity retention of 89.6%even after continuous 10,000 cycles,proving its superior stability.This study provides a facile pathway to rationally design a variety of core-shell metal nanostructures for high-performance energy storage devices.

One-pot facile fabrication of carbon-coated Bi2S3 nanomeshes with efficient Li-storage capability

Layered bismuth sulfide （Bi2S3） has emerged as an important type of Li-storage material due to its high theoretical capacity and intriguing reaction mechanism. The engineering and fabrication of Bi2S3 materials with large capacity and stable cyclability via a facile approach is essential, but still remains a great challenge. Herein, we employ a one-pot hydrothermal route to fabricate carbon-coated Bi2S3 nanomeshes （Bi2S3/C） as an efficient Li-storage material. The nanomeshes serve as a highly conducting and porous scaffold facilitating electron and ion transport, while the carbon coating layer provides flexible space for efficient reduction of mechanical strain upon electrochemical cycling. Consequently, the fabricated Bi2S3/C exhibits a high and stable capacity delivery in the 0.01-2.5 V region, notably outperforming previously reported Bi2S3 materials. It is able to discharge 472 mA·h·g^-1 at 120 mA.g^-1 over 50 full cycles, and to retain 301 mA·h·g^-1 in the 40th cycle at 600 mA.g^-l, demonstrating the potential of Bi2S3 as electrode materials for rechargeable batteries.

Catalytic effect of carbon-based electrode materials in energy storage devices

The catalytic effect of electrode materials is one of the most crucial factors for achieving efficient electrochemical energy conversion and storage.Carbon-based metal composites were widely synthesized and employed as electrode materials because of their inherited outstanding properties.Usually,electrode materials can provide a higher capacity than the anticipated values,even beyond the theoretical limit.The origin of the extra capacity has not yet been explained accurately,and its formation mechanism is still ambiguous.Herein,we first summarized the current research progress and drawbacks in energy storage devices(ESDs),and elaborated the role of catalytic effect in enhancing the performance of ESDs as follows:promoting the evolution of the solid electrolyte interphase(SEI),accelerating the reversible conversion of discharge/charge products,and improving the conversion speed of the intermediate and the utilization rate of the active materials,thereby avoiding the shuttling effect.Additionally,a particular focus was placed on the interaction between the catalytic effect and energy storage performance in order to highlight the efficacy and role of the catalytic effect.We hope that this review could provide innovative ideas for designing the electrode materials with an efficient catalytic effect for ESDs to promote the development of this research field.

Advances in flexible lithium metal batteries

Flexible energy storage devices are becoming indispensable new elements of wearable electronics to improve our living qualities.As the main energy storage devices,lithium-ion batteries(LIBs)are gradually approaching their theoretical limit in terms of energy density.In recent years,lithium metal batteries(LMBs)with metallic Li as the anode are revived due to the extremely high energy density,and are considered to be one of the ideal alternatives for the next generation of flexible power supply.In this review,key technologies and scientific problems to be overcome for flexible LMBs are discussed.Then,the recent advances in flexible LMBs,including the design of flexible Li metal anodes,electrolytes,cathodes and interlayers,are summarized.In addition,we have summed up the research progress of flexible device configurations,and emphasized the importance of flexibility evaluation and functionality integration to ensure the wearing safety in complex environment.Finally,the challenges and future development of flexible LMBs are summarized and prospected.

Highly densified carbon electrode materials towards practical supercapacitor devices

Supercapacitors are expected to bridge the gap between conventional electrostatic capacitors and batteries, but have not found significant application in primary energy devices, partly due to some unsolved problems in the elec- trode materials. A wide range of novel materials such as novel carbons have been investigated to increase the energy den- sity of the electrodes and the volumetric merits of the materi- als need to be specifically considered and evaluated, towards the practical application of these novel materials. In obser- vation of the intense research activity to improve the volu- metric performance of carbon electrodes, the density or mass loading is particularly important and shall be further opti- mized, both for commercially applied activated carbons and in novel carbon electrode materials such as graphene. In this review, we presented a brief overview of the recent progress in improving the volumetric performance of carbon-based su- percapacitor electrodes, particularly highlighting the devel- opment of densified electrodes by various technical strategies including the controlled assembly of carbon building blocks, developing carbon based hybrid composites and constructing micro- supercapacitors.

Novel MOF shell-derived surface modification of Li-rich layered oxide cathode for enhanced lithium storage

Li-rich layered oxide materials have attracted increasing attention because of their high specific capacity(>250 mAh g^(-1)). However, these materials typically suffer from poor cycling stability and low rate performance. Herein, we propose a facile and novel metal-organic-framework(MOF) shell-derived surface modification strategy to construct NiCo nanodots decorated(~5 nm in diameter) carbon-confined Li_(1.2)Mn_(0.54) Ni_(0.13)Co_(0.13)O_2 nanoparticles(LLO@C&NiCo). The MOF shell is firstly formed on the surface of as-prepared Li_(1.2)Mn_(0.54)Ni_(0.13)Co_(0.13)O_2 nanoparticles via low-pressure vapor superassembly and then is in situ converted to the NiCo nanodots decorated carbon shell after subsequent controlled pyrolysis.The obtained LLO@C&NiCo cathode exhibits enhanced cycling and rate capability with a capacity retention of 95% after 100 cycles at 0.4 C and a high capacity of 159 mAh g^(-1) at 5 C, respectively, compared with those of LLO(75% and 105 mAh g^(-1)). The electrochemical impedance spectroscopy and selected area electron diffraction analyses after cycling demonstrate that the thin C&NiCo shell can endow LLO with high electronic conductivity and structural stability, indicating the undesired formation of the spinel phase initiated from the particle surface is efficiently suppressed. Therefore, this presented strategy may open a new avenue on the design of high-performance electrode materials for energy storage.

Stimulus-responsive polymers for safe batteries and smart electronics

Stimulus-responsive energy storage devices,which can respond to external stimuli,such as heat,pH,moisture,pressure,or electric field,have recently attracted intensive attention,aiming at the ever-increasing demand for safe batteries and smart electronics.The most typical stimulus-responsive materials are polymers that can change their conformation by forming and destroying secondary forces,including hydrogen bonds and electrostatic interactions in response to external stimuli,accompanied by changes in the intrinsic properties such as conductivity and hydrophobicity.Although the applications of stimulus-responsive functions in rechargeable batteries are still in the early stage because of the complexity and compatibility of battery architectures,many new concepts of regulating the polymer structures upon applications of stimuli have already been developed.In this review,we discuss the recent progress of stimulus-responsive polymers on energy storage devices featuring thermal protection and intelligent scenarios,with a focus on the detailed structural transformations of polymers under a given stimulus and the corresponding changes in battery performance.Finally,we present perspectives on the current limitations and future research directions of stimulus-responsive polymers for energy storage devices.

Ferroelectric control of single-molecule magnetism in 2D limit

The electric control of magnetic properties based on magnetoelectric effect is crucial for the development of future data storage devices.Here,based on first-principles calculations,a strong magnetoelectric effect is proposed to effectively switch on/off the magnetic states as well as alter the in-plane/perpendicular easy axes of metal-phthalocyanine molecules(MPc)by reversing the electric polarization of the underlying two-dimensional(2D)ferroelectric a-In2Se3 substrate with the application of an external electric field.The mechanism originates from the different hybridization between the molecule and the ferroelectric substrate in which the different electronic states of surface Se layer play a dominant role.Moreover,the magnetic moments and magnetic anisotropy energies(MAE)of OsPc/In2Se3 can be further largely enhanced by a functionalized atom atop the OsPc molecule.The I-OsPc/In2Se3 system possesses large MAE up to 30 meV at both polarization directions,which is sufficient for room-temperature applications.These findings provide a feasible scheme to realize ferroelectric control of magnetic states in 2D limit,which have great potential for applications in nanoscale electronics and spintronics.

Two-dimensional SnO_2/graphene heterostructures for highly reversible electrochemical lithium storage

The ever-growing market demands for lithium ion batteries have stimulated numerous research efforts aiming at the exploration of novel electrode materials with higher capacity and long-term cycling stability.Two-dimensional (2D)nanomaterials and their heterostructures are an intense area of study and promise great potential in electrochemical lithium storage owing to their unique properties that result from structural planar confinement.Here we report a microwave chemistry strategy to integrate ultrathin SnO2 nanosheets into graphene layer to construct surface-to-surface 2D heterostructured architectures,which can provide unique structural planar confinement for highly reversible electrochemical lithium storage.The as-synthesized 2D SnO2/graphene heterostructures can exhibit high reversible capacity of 688.5mAh g^-1 over 500cycles with excellent long-term cycling stability and good rate capability when used as anode materials for lithium ion batteries.The present work definitely reveals the advantages of 2D heterostructures featured with a surface-to-surface stack between two different nanosheets in energy storage and conversion devices.

Lamella-like electrode with high Br_(2)-entrapping capability and activity enabled by adsorption and spatial confinement effects for brominebased flow battery

Bromine-based flow batteries(Br-FBs)are well suitable for stationary energy storage owing to their high energy density and low cost.However,their power density and lifespan are limited by relatively low reaction kinetics of Br_(2)/Br-couple and serious self-discharge caused by bromine migration.Herein,lamella-like porous carbon nitride nanosheets(PCNS)with adsorption and spatial confinement effects are used to modify cathodes for Br-FBs.The large specific surface area and plentiful N-containing groups enable PCNS with excellent adsorption capacity,which captures bromine species into the pores on PCNS layers.The captured bromine species is subsequently confined in PCNS interlayers due to the strong interaction between bromine species and N-containing groups,thus effectively depressing bromine diffusion/migration.Moreover,the strong bromine adsorption capacity significantly improves the electrochemical activity of PCNS.Consequently,a zinc-bromine flow battery(ZBFB)employing PCNS-modified cathode achieves a high current density of 180 m A cm^(-2),with an ultra-high coulombic efficiency of 99.22%.It also exhibits better self-discharge performance and a long cycle life of 500 cycles.Furthermore,a complexing agent-free ZBFB is successfully realized based on the superior bromineentrapping/retaining capacity of the PCNS-modified cathode.Consequently,this work provides a promising strategy toward electrode modifications for high-performance and long-lifespan Br-FBs.