Electrospinning techniques for Li,Na and K-ion batteries

In this current outlook, we critically review the most vital new outcomes in the field of rechargeable Li, Na and K-ion batteries. We deliberate current discoveries like the progress of electrospinning and their applications in future. Mainly, we discuss freestanding and binder-free electrodes structural and morphological effect when it undergoes long term cycling. Finally, this short review grants the up-to-date advancement on novel processing strategies of various carbon-based electrospun composites as anodes whose performance are similar with or even can beat that of the commercial anode material system.     

Next-generation aqueous flow battery chemistries

The battery industry is seeking solutions for large-scale energy storage that are affordable, durable, and safe. Aqueous redox flow batteries (RFBs) have the inherent properties to meet these requirements. While much has been learned over the past decade on the properties of redox materials, the focus of next-generation systems must be primarily on lowering redox material cost and increasing durability. In this context, in addition to inexpensive materials such as iron salts, redox couples based on small organic molecules have shown significant promise. A considerable level of understanding has been gained on the factors affecting the durability of aqueous RFB systems, specifically relating to molecular stability and crossover. New molecular classes, substituent strategies, and cell configurations have been identified to enhance the durability of systems in the future. Next-generation systems will also need to focus on designing molecules for achieving high energy efficiency and power density as well. Furthermore, the application of computational methods for screening of chemical stability could accelerate discovery of new molecular architectures.     

The development and demonstration status of practical flow battery systems

In recent years, the introduction of energy storage batteries has gained in importance from the viewpoint of the stabilization of electric power systems, with global promotion for the introduction of renewable energy sources. Redox flow batteries (RFBs) offer excellent features, including suitability to large capacity, a long lifetime, and a high level of safety. It has already been 40 years since its basic principle was proposed by NASA in 1974. At present, RFBs adopting vanadium (V) electrolytes have been aggressively developed and operated in various parts of the world. Hokkaido Electric Power Company in Japan has started practical operation of a RFB system with a capacity of 15 MW × 4 h. This review will describe development trends and some operation case examples from the viewpoint of RFB systems.     

Constructing an unbalanced structure toward high working voltage for improving energy density of non-aqueous carbon-based electrochemical capacitors

The energy density of non-aqueous carbon-based electrochemical capacitors(cEC)is mainly determined by the specific capacitance and operational voltage range.In this study,we propose to construct an unbalanced structure to make full use of stable voltage range for improving energy density.The stable voltage range is firstly carefully explored using cyclic voltammetry.Then an unbalanced carbon-based electrochemical capacitor(ucEC)is constructed with an optimized positive electrode to negative electrode weight ratio and voltage range.Its electrochemical performance is comprehensively investigated,including energy density,power density as well as cycle life.The ucEC is capable to deliver an improved energy density up to 64.9 Wh/kg(1.4 times as high as a general cEC)without sacrificing the power density and cycle life.The electrode properties after cycling are also analyzed,illustrating the change of electrode potential caused by unbalanced structure.The proposed structure demonstrates a great potential for improving the energy density at little cost of electrode design and cell configuration.     

Recent advances of newly designed in-situ polymerized electrolyte for high energy density/safe solid Li metal batteries

It is revealed that the application of commercial liquid organic electrolytes encountered increasing safety hazards to achieve higher energy density. The replace of solid electrolytes could eliminate most safety issues induced by liquid electrolytes. However, both solo polymer electrolyte and inorganic electrolyte have difficulty to simultaneously acquire high ionic conductivity and good interfacial compatibility. At this circumstance, in-situ polymerization is developed to construct a compatible interface with high ionic conductivity and improved safety performances. In this review, recent advances of newly designed electrolyte are summarized and discussed. It is realized that the polymerization conversion of monomer and construction of 3D inorganic structure are the factors deserve consideration for high security and energy density. Finally, the challenges and future perspectives are outlined to foresee the development of in-situ polymerized electrolytes.     

Role of MXene surface terminations in electrochemical energy storage: A review

MXenes are a group of recently discovered 2D materials and have attracted extensive attention since their first report in 2011; they have shown excellent prospects for energy storage applications owing to their unique layered microstructure and tunable electrical properties. One major feature of MXenes is their tailorable surface terminations (e.g., −F, −O, −OH). Numerous studies have indicated that the composition of the surface terminations can significantly impact the electrochemical properties of MXenes. Nonetheless, the underlying mechanisms are still poorly understood, mainly because of the difficulties in quantitative analysis and characterization. This review summarizes the latest research progress on MXene terminations. First, a systematic introduction to the approaches for preparing MXenes is presented, which generally dominates the surface terminations. Then, theoretical and experimental efforts regarding the surface terminations are discussed, and the influence of surface terminations on the electronic and electrochemical properties of MXenes are generalized. Finally, we present the significance and research prospects of MXene terminations. We expect this review to encourage research on MXenes and provide guidance for usingthese materials for batteries and supercapacitors.     

Sulfone-based high-voltage electrolytes for high energy density rechargeable lithium batteries:Progress and perspective

Further enhancement in the energy density of rechargeable lithium batteries calls for high-voltage cathode materials and stable anodes,as well as matched high-voltage electrolytes without compromising the overall property of batteries.Sulfone-based electrolytes have aroused great interest in recent years owing to their wide electrochemical window and high safety.However,significant challenges such as the complexity of synthesis,high melting point(typically above room temperature),high viscosity,and their poor compatibility with graphite-based anodes have drastically impeded their practical applications.In this review,recent progress of sulfone solvents in high energy density rechargeable lithium batteries is summarized theoretically and experimentally.More importantly,general improvement methods of sulfone-based electrolytes,such as adding additives and cosolvents,structural modifications of sulfo ne,superconcentrated salt strategy are briefly discussed.We expect that this review provides inspiration for the future developments of sulfone-based high-voltage electrolytes(SHVEs) and their widespread applications in high specific energy lithium batteries.     

A symmetric aqueous redox flow battery based on viologen derivative

Due to the diversity and feasibility of structural modification for organic molecules,organic-based redox flow batteries(ORFBs) have been widely investigated,especially in aqueous solution under neutral circumstance.In this work,a symmetric aqueous redox flow battery(SARFB) was rationally designed by employing a bipolar redox active molecule(N,N'-dimethyl-4,4-bipyridinium diiodide,MVI_2) as both cathode and anode materials and combining with an anion exchange membrane.For one MVI_2 flow battery,MV~(2+)/MV~(·+) and I~-/I_3~-serve as the redox couples of anode and cathode,respectively.The MVI_2 battery with a working voltage of 1.02 V exhibited a high voltage efficiency of 90.30% and energy efficiency of 89.44% after 450 cycles,and crossover problem was prohibited.The comparable conductivity of MVI_2 water solution enabled to construct a battery even without using supporting electrolyte.Besides,the bipolar character of MVI_2 battery with/without supporting electrolyte was investigated in the voltage range between-1.2 V and 1.2 V,showing excellent stable cycling stability during the polarity-reversal test.     

High-performance Na1.25V3O8 nanosheets for aqueous zinc-ion battery by electrochemical induced de-sodium at high voltage

Aqueous rechargeable zinc-ion batteries (ARZIBs) are expected to replace organic electrolyte batteries owing to its low price, safe and environmentally friendly characteristics. Herein, we fabricated vanadium-based Na_1.25V₃O₈ nanosheets as a cathode material for ARZIBs, which present a high performance by electrochemical de-sodium at high voltage to form Na₂V₆O₁₆ phase in the first cycle: high capacity of 390 mAh/g at 0.1 A/g, high rate performance (162 mAh/g at 10 A/g) and superior cycle stability (179 mAh/g with a high capacity retention of 88.2% of the maximum capacity after 2000 cycles). In addition, the cell exhibits a high energy density of 416.9 Wh/kg at 143.6 W/kg, suggesting great potential of the as-prepared Na_1.25V₃O₈ nanosheets for ARZIBs     

Li/SOCl2、BCX电池放电电压滞后研究

应用交流阻抗法研究Li/SOCl2、BCX电池放电过程碳、锂电极阻抗变化并测试外加电压和并联超电容对电池放电初期电压的影响.测试表明,锂电极阻抗在放电初期迅速减小了80%~90%,直到放电末期,阻抗几乎不变;碳电极阻抗至放电末期才迅速增大;BCX电池有较高开路电压可改善放电电压滞后;电池并联超级电容器可抑制放电电压滞后.     

Recent developments in sol-gel based polymer electrolyte membranes for vanadium redox flow batteries – A review

The current importance of energy production from renewable sources stimulated interest in energy storage systems. Recent research has focused on developing vanadium redox flow batteries (VRFB) for large scale energy storage owing to their cost-effectiveness, flexible design, energy efficiency and long cycle life. Nafion the preferred membrane in VRFB systems has an overall cost of more than 11% in these systems. However, due to its drawbacks of high permeability and high cost limit its suitability for commercial use. Many researchers are therefore keen to develop new chemical designs for synthetic membranes, such as perfluorinated, partially fluorinated, hydrocarbon based and organic-inorganic composite membrane. The sol-gel process, which is mainly based on hydrolysis and condensation reaction offers the possibility of homogeneous preparation of membranes, leading to high proton conductivity and reduced vanadium ion permeability, thereby greatly increasing the cell efficiency. This review summarizes recent development in the synthesis and applications of sol-gel based proton exchange membranes for VRFB system, on which many researchers have been working in recent years. We also discuss critical research areas and the future development of cost-effective sol-gel based membranes for attractive energy storage systems.     

基于多层结构设计的高储能密度氧化石墨烯/聚酰亚胺复合材料

采用逐层涂布、 分层控制固化程度的方法, 利用聚酰胺酸(PAA, 聚酰亚胺前体)溶液和含有氧化石墨烯（GO）的PAA溶液制备了一系列由高绝缘性PI层与GO@PI介电层交替组合而成的界面清晰且紧密衔接的多层复合薄膜. 通过调控介电层中GO含量及分层结构, 使多层复合薄膜兼具高介电常数和高击穿强度特征. 结果表明, 三层复合薄膜PI/1.0GO@PI/PI的击穿强度为261.5 kV/mm, 储能密度达到1.27 J/cm³, 与相同介电层厚度的单层薄膜相比, 击穿强度和储能密度分别提高了97%和144%, 同时, 其介电损耗也保持在较低水平(tanδ=0.0079). 绝缘层和高介电常数层的协同作用提升了氧化石墨烯/聚酰亚胺复合薄膜的储能密度. 这种简单的多层结构设计有利于氧化石墨烯/聚合物复合材料在介质储能领域的应用.     

Synthesis of porous biocarbon supported Ni3S4/CeO2 nanocomposite as high-efficient electrode materials for asymmetric supercapacitors

Biocarbon-supported polymetallic composites (CAS@Ni₃S₄/CeO₂) were fabricated by a facile hydrothermal process. The as-prepared CAS@Ni₃S₄/CeO₂ materials integrated the advantages of transition metal sulfides (good conductivity), rare-earth metal oxides (excellent stability), as well as porous carbon with high surface area, thus exhibiting promising electrochemical performance in supercapacitor applications. Indeed, the optimal CAS@Ni₃S₄/CeO₂-150 composite displayed a high specific capacitance of 1364 F g^?1 and impressive cycle performance with capacitance retention of 93.81 % after 10,000 cycles. The calculation of capacitance contribution showed that the satisfying behavior of the electrode was a combination of the diffusion process and the surface capacitance characteristics. Furthermore, the assembled asymmetric supercapacitor (CAS@Ni₃S₄/CeO₂-150//CAS) delivered an ultrahigh energy density of 102.76 Wh kg^?1, which was better than that of the commercial activated carbon-based ASC device. This novel strategy might provide a new perspective for transition metal sulfide/rare earth metal oxide composite in the electrochemical energy storage field.     

A novel polyaniline/mesoporous carbon nano-composite electrode for asymmetric supercapacitor

<正>A novel nano-composite of polyaniline/mesoporous carbon(PANI/CMK-3) was prepared with mesoporous carbon(CMK-3) serving as the support.Electrochemical asymmetric capacitors have been successfully designed by using PANI/CMK-3 composite and CMK-3 as positive and negative electrode,respectively.The results showed that the discharge capacity of the asymmetric capacitor could reach 87.4 F/g under the current density of 5 mA/cm~2 and cell voltage of 1.4 V.The energy density of the asymmetric capacitor was up to 23.8 Wh/kg with a power density of 206 W/kg.Furthermore,PANI/CMK-3-CMK-3 asymmetric capacitor using this PANI/CMK-3 nano-composite could be activated quickly and possess high charge-discharge efficiency.     

能量最低构型Ca2B4团簇的储氢性能

基于密度泛函理论,研究了Ca₂B₄团簇的几何结构、电子特征和储氢性能。前2个与第4个能量最低构型Ca₂B₄ 01、Ca₂B₄02和Ca₂B₄ 04有很高的热力学稳定性,分别最多可以吸附12、12和10个氢分子,达到16.3%、16.3%和14.0%的储氢量,超过了美国能源部提出的目标(5.5%）。Ca₂B₄ 01(H₂)₁₂、Ca₂B₄ 02(H₂)₁₂和Ca₂B₄ 04(H₂)₁₀的平均每个氢分子吸附能量分别为0.58~4.21 eV、0.54~3.69 eV和0.10~0.12 eV。玻恩-奥本海默分子动力学模拟表明,Ca₂B₄ 01和Ca₂B₄ 02可作为潜在吸附氢气的候选目标,而Ca₂B₄ 04不行。吉布斯自由能校正的氢吸附能结果表明,在101 325 Pa下,Ca₂B₄ 01和Ca₂B₄ 02吸附12个氢气分子有较大的可调节的温度范围。     

A High-Performance Asymmetric Supercapacitor Based on Tungsten Oxide Nanoplates and Highly Reduced Graphene Oxide Electrodes

Tungsten oxide/graphene hybrid materials are attractive semiconductors for energy-related applications. Herein, we report an asymmetric supercapacitor (ASC, HRG//m-WO₃ ASC), fabricated from monoclinic tungsten oxide (m-WO₃) nanoplates as a negative electrode and highly reduced graphene oxide (HRG) as a positive electrode material. The supercapacitor performance of the prepared electrodes was evaluated in an aqueous electrolyte (1 m H₂SO₄) using three- and two-electrode systems. The HRG//m-WO₃ ASC exhibits a maximum specific capacitance of 389 F g⁻¹ at a current density of 0.5 A g⁻¹, with an associated high energy density of 93 Wh kg⁻¹ at a power density of 500 W kg⁻¹ in a wide 1.6 V operating potential window. In addition, the HRG//m-WO₃ ASC displays long-term cycling stability, maintaining 92 % of the original specific capacitance after 5000 galvanostatic charge–discharge cycles. The m-WO₃ nanoplates were prepared hydrothermally while HRG was synthesized by a modified Hummers method.     

An aqueous zinc-ion hybrid super-capacitor for achieving ultrahigh-volumetric energy density

Zinc-ion hybrid super-capacitors are regarded as promising safe energy storage systems. However, the relatively low volumetric energy density has become the main bottlenecks in practical applications of portable electronic devices. In this work, the zinc-ion hybrid super-capacitor with high volumetric energy density and superb cycle stability had been constructed which employing the high-density three-dimensional graphene hydrogel as cathode and Zn foil used as anode in 1 mol/L ZnSO₄ electrolyte. Benefiting from the abundant ion transport paths and the abundant active sites for graphene hydrogel with high density and porous structure, the zinc-ion hybrid super-capacitor exhibited an extremely high volumetric energy density of 118.42 Wh/L and a superb power density of 24.00 kW/L, as well as an excellent long cycle life (80% retention after 30,000 cycles at 10 A/g), which was superior to the volumetric energy density of the reported zinc-ion hybrid super-capacitors. This device, based on the fast ion adsorption/desorption on the capacitor-type graphene cathode and reversible Zn²⁺ plating/stripping on the battery-type Zn anode, which will inspire the development of zinc-ion hybrid super-capacitor in miniaturized devices.     

A STUDY ON MECHANICAL PROPERTIES OF γ-RAY IRRADIATED HDPE FILLED WITH SERICITE-TRIDYMITE-CRISTOBALITE*

The effect of γ-ray irradiation on the mechanical properties of high densitypolyethylene(HDPE) filled with sericite-tridymite-cristobalite(STC) was studied. The ex-perimental results show that γ-ray irradiation can improve the affinity between HDPE andSTC, and the dispersion of STC in HDPE matrix. Compared with HDPE/STC (80/20)blend, the yield stress and impact strength of irradiated HDPE (10kGy)/STC (80/20) blendare increased from 22.8 MPa and 70J/m to 28.5 MPa and 144J/m. The yield stress andimpact strength of HDPE/irradiated HDPE/STC (48/32/20) are 27.8MPa and 210J/m,respectively.     

Al3Li4(BH4)13: A Complex Double‐Cation Borohydride with a New Structure

The new double‐cation Al–Li–borohydride is an attractive candidate material for hydrogen storage due to a very low hydrogen desorption temperature (～70 °C) combined with a high hydrogen density (17.2 wt %). It was synthesised by high‐energy ball milling of AlCl₃ and LiBH₄. The structure of the compound was determined from image‐plate synchrotron powder diffraction supported by DFT calculations. The material shows a unique 3D framework structure within the borohydrides (space group=P‐43n, a=11.3640(3) Å). The unexpected composition Al₃Li₄(BH₄)₁₃ can be rationalized on the basis of a complex cation [(BH₄)Li₄]³⁺ and a complex anion [Al(BH₄)₄]^?. The refinements from synchrotron powder diffraction of different samples revealed the presence of limited amounts of chloride ions replacing the borohydride on one site. In situ Raman spectroscopy, differential scanning calorimetry (DSC), thermogravimetry (TG) and thermal desorption measurements were used to study the decomposition pathway of the compound. Al–Li–borohydride decomposes at ～70 °C, forming LiBH₄. The high mass loss of about 20 % during the decomposition indicates the release of not only hydrogen but also diborane.     

高密度聚乙烯与EPDM磺酸锌盐共混物结构与性能的研究

本文研究了高密度聚乙烯(HDPE)/EPDM磺酸锌盐(Zn-SEPDM)共混物的机械性能、流变行为、形态和相容性。结果表明:加入Zn-SEPDM可使HDPE的熔点和结晶度降低,熔程变窄。当Zn-SEPDM含量超过20％,共混物中Zn-SEPDM呈连续相,冲击强度突增。