Dilute Aqueous-Aprotic Electrolyte Towards Robust Zn-Ion Hybrid Supercapacitor with High Operation Voltage and Long Lifespan

With the merits of the high energy density of batteries and power density of supercapacitors,the aqueous Zn-ion hybrid supercapacitors emerge as a promising candidate for applications where both rapid energy delivery and moderate energy storage are required.However,the narrow electrochemical window of aqueous electrolytes induces severe side reactions on the Zn metal anode and shortens its lifespan.It also limits the operation voltage and energy density of the Zn-ion hybrid supercapacitors.Using'water in salt'electrolytes can effectively broaden their electrochemical windows,but this is at the expense of high cost,low ionic conductivity,and narrow temperature compatibility,compromising the electrochemical performance of the Zn-ion hybrid supercapacitors.Thus,designing a new electrolyte to balance these factors towards high-performance Zn-ion hybrid supercapacitors is urgent and necessary.We developed a dilute water/acetonitrile electrolyte(0.5 m Zn(CF_(3)SO_(3))_(2)+1 m LiTFSI-H_(2)O/AN)for Zn-ion hybrid supercapacitors,which simultaneously exhibited expanded electrochemical window,decent ionic conductivity,and broad temperature compatibility.In this electrolyte,the hydration shells and hydrogen bonds are significantly modulated by the acetonitrile and TFSI-anions.As a result,a Zn-ion hybrid supercapacitor with such an electrolyte demonstrates a high operating voltage up to 2.2 V and long lifespan beyond 120,000 cycles.

共同体视域下民族院校应用化学专业虚拟教研室建设的理论与实践

虚拟教研室是“智能+”时代新型基层教学组织的重要探索,是推动高等教育高质量内涵式发展的必然要求和重要支撑。本文将共同体概念同高校教研室相结合,将教研室建设基于中华民族共同体意识的理论下进行建构。研究了由中南民族大学牵头的“民族院校应用化学专业虚拟教研室”的建设理论与实践,从微观把握到宏观调控,发挥教研室基层教学组织的重要作用,促进高等教育人才培养质量的提升。

Designing Advanced Aqueous Zinc-Ion Batteries:Principles,Strategies,and Perspectives

Aqueous zinc-ion batteries(AZIBs)are an appealing battery system due to their low cost,intrinsic safety,and environmental-friendliness,while their application is plagued by the obstacles from the cathode,electrolyte,and zinc anode.Summarizing the design principles and strategies toward the optimization of cathode,electrolyte,and zinc anode is crucial for the development of AZIBs.Herein,we present a comprehensive analysis of the design principles and promising strategies toward the improvement of AZIBs.Firstly,the various reaction mechanisms are summarized and the existing issues associated with the cathode,electrolyte,and zinc anode are discussed to guide the rational design of AZIBs.Subsequently,we provide an in-depth and comprehensive discussion on the design principles and strategies for the electrodes/electrolyte/separator optimization,and analyze the advantages and disadvantages of various strategies.Importantly,the design principles and strategies of the newly appeared conversion-type AZIBs,such as Zn-S battery and Zn-Se battery,are also discussed and analyzed.The effect of design strategies on the electrochemical performance and the relationship between the current issues and strategies are also unveiled in detail.Finally,some research trends and perspectives are provided for designing better AZIBs.

Solvothermal synthesis and characterization of nanocrystalline vanadium-chromium composite oxides and catalytic ammoxidation of 2,6-dichlorotoluene

Vanadium‐chromium oxides(VCrO)were usually prepared by high‐temperature solid‐state reactions;however,mixed phases were frequently produced and the morphology of the products was not well controlled.In this work,we prepared amorphous VCrO precursors by using V2O5 and CrO3 and alcohols or mixtures of alcohol and water via solvothermal reaction at 180°C.The precursors were then calcined under nitrogen at various temperatures.The products were characterized by powder X‐ray diffraction,transmission electron microscopy,and X‐ray photoelectron spectroscopy.It was revealed that pure‐phase nanocrystalline orthorhombic CrVO4 was obtained when methanol or methanol/water was used as the solvothermal medium and the precursor was calcined at 700°C.The size of the CrVO4 crystals was around 500 nm when methanol was used,whereas it reduced significantly to less than 50 nm when a mixture of methanol and water was used.The sizes could be effectively tuned from 10 to 50 nm by varying the methanol/water volume ratio.To the best of our knowledge,this is the first report on the synthesis of pure‐phase CrVO4 nanocrystals.The nano‐CrVO4 showed almost the highest catalytic activity for the ammoxidation of 2,6‐dichlorotoluene to 2,6‐dichlorobenzonitrile among the reported bi‐component composite oxides,owing to its smaller particle size,larger specific surface area,and more exposed active centers.

Effect of preparation method on halloysite supported cobalt catalysts for Fischer-Tropsch synthesis

Novel cobalt Fischer-Tropsch synthesis （FTS） catalysts were prepared from natural halloysite nanotubes （HNT） by double-solvent and wet- impregnation methods, and characterized by TEM, XRD, TPR and N2 adsorption-desorption. Comparing with the catalyst prepared by wet- impregnation method, the catalyst prepared by double-solvent method reduces Co3O4 particle migration and agglomeration due to size-induced effect, thus showing higher catalytic activity for Fischer-Tropsch synthesis.

从纳米酶的视角探究农业食品安全的奥秘

Global climate changes,such as extreme weather,sea levels rise,and biodiversity decline,have destructive impacts on the global agrofood system,in terms of crop yield,agrofood quality and consumer safety.Those stressed conditions and environmental pollution for crop and agrofood prompt us to take immediate action to develop a whole-new-era agrofood system from the perspective of sustainability[1].

High-performance flexible self-powered strain sensor based on carbon nanotube/ZnSe/CoSe_(2) nanocomposite film electrodes

High-performance energy storage and sensing devices have been undergoing rapid development to meet the demand for portable and wearable electronic products,which require flexibility,extensibility,small volume and lightweight.In this study,we construct a lightweight and flexible self-powered sensing system by integrating a highly stretchable strain sensor with a high-performance asymmetric supercapacitor based on ZnSe/CoSe_(2)//ECNT(ECNT:electrochemically activated carbon nanotube film).The ZnSe/CoSe_(2) two-dimentional nanosheets on carbon nanotube(CNT)films are synthesized through a simple and efficient strategy derived from ZnCo-based metal-organic frameworks(MOFs).The density functional theory(DFT)simulations show the higher conductivity of the ZnSe/CoSe_(2)/CNT electrode than the CoSe_(2)/CNT electrode.Due to the synergistic properties of self-supported two-dimentional ZnSe/CoSe_(2) nanosheets with high specific surface area and the high pathway of one-dimention CNTs,the nanocomposite electrode provides efficient transmission and short paths for electron/ion diffusion.The asymmetric supercapacitor provides a stable output power supply to the sensors that can precisely respond to strain and pressure changes.The sensor can also be attached to a garment for measuring a variety of joint movements.

Coupling N-doping and rich oxygen vacancies in mesoporous ZnMn_(2)O_(4)nanocages toward advanced aqueous zinc ion batteries

The development of a high specific capacity and stable manganese(Mn)-based cathode material is very attractive for aqueous zinc-ion(Zn^(2+))batteries(ZIBs).However,the inherent low electrical conductivity and volume expansion challenges limit its stability improvement.Here,a mesoporous ZnMn_(2)O_(4)(ZMO)nanocage(N-ZMO)coupled with nitrogen doping and oxygen vacancies is prepared by defect engineering and rational structural design as a high-performance cathode material for rechargeable ZIBs.The oxygen vacancies enhance the electrical conductivity of the material and the nitrogen doping releases the strong electrostatic force of the material to maintain a higher structural stability.Interestingly,N-ZMO exhibits excellent ability of Zn^(2+)storage(225.4 mAh·g^(−1)at 0.3 A·g^(−1)),good rate,and stable cycling performance(88.4 mAh·g^(−1)after 1,000 cycles at 3 A·g^(−1)).Furthermore,a flexible quasi-solid-state device with high energy density(261.6 Wh·kg^(−1))is assembled,demonstrating long-lasting durability.We believe that the strategy in this study can provide a new approach for developing aqueous ZIBs.

Enhancing the long-term Na-storage cyclability of conversion-type iron selenide composite by construction of 3D inherited hyperbranched polymer buffering matrix

Electrochemical conversion reactions provide more selections for Na-storage materials, but the reaction suffers from low reversibility and poor cyclability. Introducing an electrochemically inactive component is a common strategy, but the effect is quite limited since it could not stabilize the structure during long-term cycling. In this study, a new approach is developed using an amino group-functioned hyperbranched polymer (AHP) as a template and electrode additive for the design of high-performance FeSe2-AHP composite with chemical interaction. The assembled FeSe2-AHP composite nanoneedles were prepared by the selenylation of FeS-AHP composite microflowers and entirely inherit the polymer network from the precursor. The amino groups of AHP in composite coordinate with iron cations to achieve uniform polymer dispersion in the composite, and maintain the molecular level mixed state during the long-term cycling. Moreover, the in-situ constructed uniform 3D elastic polymer network effectively accommodates volume expansion and alleviates nanoparticle aggregation during sodiation/de-sodiation. FeSe2-AHP composite provides a superior rate capability (584.8 mAh·g−1 at 20 A·g−1) and a remarkable cyclability with a capacity retention rate of 93.3% after 2,000 cycles. FeSe2-AHP composite shows a high pseudocapacitive behavior for the abundant nanometer interface established by AHP, enhancing the solid-state Na+ diffusion. The FeSe2-AHP anode is also compatible with Na3V2(PO4)3/C cathode in a full Na-ion battery, which provides a high-power performance (powering 51 LEDs). The work herein highlights an innovative and efficient strategy for conversion-type material design and demonstrates the function of chemical interaction of polymer additive in the enhancement of long-term cyclability for conversion electrode.

人民政协在国家治理中的重要作用

人民政协在推进国家治理体系和治理能力现代化建设中位置特殊、优势独特,发挥着不可替代的作用,主要体现在:辅助决策,提高国家治理能力的科学化、民主化水平;促进和谐,不断汇聚推动国家治理的重要力量;畅通渠道,在国家治理体系中发挥桥梁纽带作用。面对国情、世情发生的深刻变化,人民政协应该以宪法、政协章程和相关政策为依据,继续拓展形式、拓宽渠道,为推进国家治理体系和治理能力现代化贡献力量。参政党要不断加强自身建设,通过政协平台积极建言献策,不断将新型政党制度在国家治理体系中的作用发挥到最大。