Selective and durable fixed‐bed catalysts are highly desirable for developing eco‐efficient HPPO(hydrogen peroxide propylene oxide)process.The powder titanosilicate catalysts must be shaped before being applied in i...Selective and durable fixed‐bed catalysts are highly desirable for developing eco‐efficient HPPO(hydrogen peroxide propylene oxide)process.The powder titanosilicate catalysts must be shaped before being applied in industrial processes.As the essential additives for preparing formed catalysts,binders are usually the catalytically inert components,but they would cover the surface and pore mouth of zeolite,thereby declining the accessibility of active sites.By recrystallizing the binder(silica)/Ti‐MWW extrudates with the assistance of dual organic structure‐directing agents,the silica binder was converted into MWW zeolite phase to form a structured binder‐free Ti‐MWW zeolite with Si‐rich shell,which enhanced the diffusion efficiency and maintained the mechanical strength.Meanwhile,due to the partial dissolution of Si in the Ti‐MWW matrix,abundant silanol nests formed and part of framework TiO4 species were transferred into open TiO_(6)ones,improving the accumulation and activation ability of H_(2)O_(2)inside the monolith.Successive piperidine treatment and fluoridation of the binder‐free Ti‐MWW further enhanced the H_(2)O_(2)activation and oxygen transfer ability of the active Ti sites,and stabilized the Ti‐OOH intermediate through hydrogen bond formed between the end H in Ti‐OOH and the adjacent Si‐F species,thus achieving a more efficient epoxidation process.Additionally,the side reaction of PO hydrolysis was inhibited because the modification effectively quenched numerous Si‐OH groups.The lifetime of the modified binder‐free Ti‐MWW catalyst was 2400 h with the H_(2)O_(2)conversion and PO selectivity both above 99.5%.展开更多
Three-dimensional(3D) ultra-tiny Fe_(2)O_(3) nanoparticles/graphene hydrogels were prepared using a facile and efficient solvothermal reaction, by which the phase of iron oxide, particle size and the morphology of hyd...Three-dimensional(3D) ultra-tiny Fe_(2)O_(3) nanoparticles/graphene hydrogels were prepared using a facile and efficient solvothermal reaction, by which the phase of iron oxide, particle size and the morphology of hydrogels can be precisely controlled by simply adjusting the solvothermal reaction time. Accordingly, the effect of the microstructures of hydrogels on electrochemical performance was systematically studied. It was found that Fe_(2)O_(3)/r GO-50 hydrogels(with a solvothermal reaction time of 50 min) possessed a desirable crystallinity, suitable particle size, decent porous structure, large specific surface area and high electrical conductivity, thus exhibiting a superior electrochemical performance as binder-free anode of supercapacitors: a large potential range of 1.15 V, an ultrahigh specific capacitance of 1090 F·g^(-1) at a current density of 2A·g^(-1) and excellent rate capability (531 F·g^(-1) at 10 A·g^(-1)). The rational design and systematic research of electrode materials will provide new lights for the preparation of advanced electrochemical energy storage devices.展开更多
The demands for better energy storage devices due to fast development of electric vehicles(EVs) have raised increasing attention on lithium ion batteries(LIBs) with high power and energy densities. In this paper, we p...The demands for better energy storage devices due to fast development of electric vehicles(EVs) have raised increasing attention on lithium ion batteries(LIBs) with high power and energy densities. In this paper, we provide an overview of recent progress in graphene-based electrode materials. Graphene with its great electrical conductivity and mechanical properties have apparently improved the performance of traditional electrode materials. The methods and electrochemical properties of advanced graphene composite as cathode and anode for LIBs are reviewed. Two novel kinds of graphene hybrid materials are specially highlighted: three-dimensional porous and flexible binder-free graphene-based materials. Challenges for LIBs and future research trend in the development of high-performance electrode materials are further discussed.展开更多
A facile synthesis of the hierarchically porous cathode with Mo2C nanoparticles through the electrospinning technique and heat treatment is proposed. The carbonization temperature of the precursors is the key factor f...A facile synthesis of the hierarchically porous cathode with Mo2C nanoparticles through the electrospinning technique and heat treatment is proposed. The carbonization temperature of the precursors is the key factor for the formation of M02C nanoparticles on the carbon nanofibers （MCNFs）. Compared with the Mo2N nanoparticles embedded into N-doped carbon nanofibers film （MNNFs） and N-doped carbon nanofibers film （NFs）, the battery with MCNFs cathode is capable of operation with a high-capacity （10,509 mAhg-1 at 100 mAg-l）, a much reduced discharge-charge voltage gap, and a long-term life （124 cycles at 200 mA g-1 with a specific capacity limit of 500 mAh g -1）. These excellent performances are derived from the synergy of the following advantageous factors： （1） the hierarchically self-standing and binder-free structure of MCNFs could ensure the high diffusion flux of Li＋ and O2 as well as avoid clogging of the discharge product, bulk Li202; （2） the well dispersed M02C nanoparticles not only afford rich active sites, but also facilitate the electronic transfer for catalysis.展开更多
Extending the potential window of aqueous supercapacitors (SCs) up to 2.0 V is still a great challenge.Based on their good dynamic structural reversibility and open framework structure,the coordination superamolecular...Extending the potential window of aqueous supercapacitors (SCs) up to 2.0 V is still a great challenge.Based on their good dynamic structural reversibility and open framework structure,the coordination superamolecular networks (CSNs) exhibit rapid charge/discharge ability and excellent cycle stability.As a typical coordination superamolecular network (CSN),Prussian blue (denoted as CSN-PB),which self-assembled by the CN-ligand and iron ions is firstly in-situ grown on carbon cloth,followed by electro-deposition of MnO2 to form CSN-PB/MnO2 composite electrode.Benefiting from synergistic effect of the constituent components,as well as the open framework structure of CSN-PB,this composite electrode reaches a high potential window of 1.4 V (vs.Ag/AgCl) and delivers a good specific capacitance of 315.3 F·g^-1 in aqueous electrolyte.An aqueous asymmetric device,constructed with CSN-PB/MnO2 composite as cathode and activated carbon as anode,can work in a stable potential window of 2.4 V,exhibits a high energy density of 46.13 Wh·kg^-1 and excellent cycling stability with 85.5% capacitance retention after 20,000 cycles.This work provides a new concept of high dynamic structural reversibility from CSNs to increase the cell voltage of asymmetric SCs for further boosting energy density.展开更多
As the anode active substance of lithium ions battery(LIB),the low conductivity/ion diffusivity and large volume changes of tungsten oxide(WO_(3))lead to its serious polarization during the lithiation/delithiation pro...As the anode active substance of lithium ions battery(LIB),the low conductivity/ion diffusivity and large volume changes of tungsten oxide(WO_(3))lead to its serious polarization during the lithiation/delithiation process,decreasing the cycling stability.To address these challenges,a binder-free anode consisting of nitrogen-doped tungsten oxide nanosheets,encapsulated in carbon layers(N-doped WO_(3)@CL)and entangled with carbon nanotubes macro-films(CMF),was successfully synthesized through a combination of hydrothermal and online assembly method.Compared with the pristine tungsten oxide entangled with carbon nanotubes macro-films(WO_(3)@CMF),the synthesized N-doped WO_(3)@CL@CMF as a binder-free LIB anode demonstrated better electrochemical performance,which could be attributed to(1)surface defects of WO_(3)created by N dopant providing more channels to improve Li^(+)diffusion,(2)the N-doped WO_(3)@CL with a flower-like structure shortening the diffusion length of Li^(+)ions and further leading to high Li^(+)incorporation,and(3)carbon layers and carbon nanotubes synergistically alleviating the large volume change of the N-doped WO_(3)@CL@CMF electrode during the charging and discharging process.The present study offers insights into employing nitrogen dopant and a carbon matrix to mediate the conductivity and wrapped structure in the WO_(3)semiconductor powder,which provides an important strategy for large-scale design of the binder-free LIB anode with high performance.展开更多
WS2 has been considered as a promising anode material due to its high lithium storage capacity as well as fascinating physical properties. However, the insufficient electrical and ionic conductivities deteriorate the ...WS2 has been considered as a promising anode material due to its high lithium storage capacity as well as fascinating physical properties. However, the insufficient electrical and ionic conductivities deteriorate the rate per- formance of the batteries. Herein, we report a simple synthetic approach towards graphene-WS2 hybrids by rolling graphene into a hollow nanotube in which WSz nanoplates are en- capsulated. This new electrode design strategy facilitates the fabrication of integrated and binder-free lithium ion battery and sodium ion battery electrodes by combining electrospin- ning and chemical vapor deposition （CVD） methods. Bene- fiting from their confined growth and the interconnected in- situ graphitic carbon coating nanocable web, the WS2@G with nano-level WS2 dispersion not only provides an efficiently conductive and electrolyte accessible framework, but effec- tively alleviates the volume change during the cycling, en- abling a mechanically robust binder-free electrode along with the outstanding electrochemical Li＋ and Na＋ storage proper- ties.展开更多
本工作通过低成本、简单、快速的真空过滤方法首次成功制备了一种独立的、无粘合剂的柔性聚吡咯:聚磺苯乙烯/纤维素纳米纸电极(PPy:PSS/CNP).多层结构的纤维素纳米纸具有较高的表面积和良好的机械强度,不仅提供了高的电活性区域,缩短了...本工作通过低成本、简单、快速的真空过滤方法首次成功制备了一种独立的、无粘合剂的柔性聚吡咯:聚磺苯乙烯/纤维素纳米纸电极(PPy:PSS/CNP).多层结构的纤维素纳米纸具有较高的表面积和良好的机械强度,不仅提供了高的电活性区域,缩短了电解质离子的扩散距离,而且还阻止了PPy在充电/放电过程中的体积膨胀/收缩.优化后的PPy:PSS/CNP在10 mV s-1时表现出3.8 F cm-2(对应于475 F cm-3和240 F g-1)的高比电容和良好的循环稳定性(在5000次循环后有80.9%的电容保持率).PPy:PSS/CNP在不同弯曲角度下的循环伏安曲线表明电极具有突出的柔韧性和电化学稳定性.此外,组装的对称超级电容器器件在功率密度为4.4 m W cm-2(550 m W c m-3)的情况下,提供了122μW h cm-2(15 W h cm-3)的高面积能量密度,这个值优于其他基于纤维素电极材料制备的器件.PPy:PSS/CNP电极结合了高电容性能、灵活性、易于制造和廉价多个优势,为开发下一代绿色、经济便携式和可穿戴电子产品提供了巨大潜力.展开更多
Binder-free electrospining approach for fabricating bimetallic chalcogen electrodes is essential for cost-and time-cutting but challenging.Herein,we propose a novel direct spray technique in electrospinning method to ...Binder-free electrospining approach for fabricating bimetallic chalcogen electrodes is essential for cost-and time-cutting but challenging.Herein,we propose a novel direct spray technique in electrospinning method to fabricate binder-free electrospun nickel cerium selenide nanofiber(NCSNF)structured materials.The effect of the applied electrospinning voltage on the average fiber diameter is analyzed.Electrospinning voltage of 25 kV is applied for obtaining an average fiber diameter of<100 nm(87 nm)with rough interconnected nanofibers.The optimized NCSNF electrode exhibits remarkable longterm cycling stability over 50,000 galvanostatic charge-discharge(GCD)cycles.Furthermore,radish-derived nanolayered carbon(RDNLC)is synthesized via pyrolysis and its electrochemical properties are evaluated.The optimized NCSNF and RDNLC electrodes are employed to fabricate a polyvinyl alcohol-potassium hydroxide gel electrolyte-based quasi-solid-state asymmetric supercapacitor(ASC).The quasi-solid-state ASC delivers a high energy density value of 22 Wh kg−1 with 85%capacitance retention and 95%Coulombic efficiency over 40,000 GCD cycles,and upon being extended to the 50,000 GCD cycles,the capacitance retention and Coulombic efficiency reached 71%and 95%,respectively.A solar-charged wristbandlike device is designed as a wearable supercapacitor,and the integrated device is attached to the human hand for powering electronic gadgets in contorted states,thus demonstrating its potential for wearable applications.展开更多
Silver-zinc(Ag-Zn)batteries are a promising battery system for flexible electronics owing to their high safety,high energy density,and stable output voltage.However,poor cycling performance,low areal capacity,and infe...Silver-zinc(Ag-Zn)batteries are a promising battery system for flexible electronics owing to their high safety,high energy density,and stable output voltage.However,poor cycling performance,low areal capacity,and inferior flexibility limit the practical application of Ag-Zn batteries.Herein,we develop a flexible quasi-solid-state Ag-Zn battery system with superior performance by using mild electrolyte and binder-free electrodes.Copper foam current collector is introduced to impede the growth of Zn dendrite,and the structure of Ag cathode is engineered by electrodeposition and chloridization process to improve the areal capacity.This novel battery demonstrates a remarkable cycle retention of 90%for 200 cycles at 3 mA cm^(-2).More importantly,this binder-free battery can afford a high capacity of 3.5 mAh cm^(-2)at 3 mA cm^(-2),an outstanding power density of 2.42 mW cm^(-2),and a maximum energy density of 3.4 mWh cm^(-2).An energy management circuit is adopted to boost the output voltage of a single battery,which can power electronic ink display and Bluetooth temperature and humidity sensor.The developed battery can even operate under the extreme conditions,such as being bent and sealed in solid ice.This work offers a path for designing electrodes and electrolyte toward high-performance flexible Ag-Zn batteries.展开更多
Oxygen electrocatalysis,exemplified by the oxygen reduction reaction(ORR)and oxygen evolution reaction(OER),is central to energy storage and conversion technologies such as fuel cells,metal-air batteries,and water ele...Oxygen electrocatalysis,exemplified by the oxygen reduction reaction(ORR)and oxygen evolution reaction(OER),is central to energy storage and conversion technologies such as fuel cells,metal-air batteries,and water electrolysis.However,highly effective and inexpensive earth-abundant materials are sought after to replace the noble metal-based electrocatalysts currently in use.Recently,metal-organic frameworks(MOFs)and carbon-based MOF derivatives have attracted considerable attention as efficient catalysts due to their exceedingly tunable morphologies,structures,compositions,and functionalization.Here,we report two-dimensional(2D)MOF/MOF derivative coupled arrays on nickel foam as binder-free bifunctional ORR/OER catalysts with enhanced electrocatalytic activity and stability.Their remarkable electrochemical properties are primarily attributed to fully exposed active sites and facilitated charge-transfer kinetics.The coupled and hierarchical nanosheet arrays produced via our growth-pyrolysis-regrowth strategy offer promise in the development of highly active electrodes for energy-related electrochemical devices.展开更多
Durable and cost-effective electrode materials are essential for practical application of supercapacitors.Herein,large area NiCo_(2)O_(4)/reduced graphene oxide(NiCo_(2)O_(4)/rGO)composites with hierarchical structure...Durable and cost-effective electrode materials are essential for practical application of supercapacitors.Herein,large area NiCo_(2)O_(4)/reduced graphene oxide(NiCo_(2)O_(4)/rGO)composites with hierarchical structure were fabricated by a facile one-step ultrasonic spray on Ni foam and directly used as the binder-free electrodes for supercapacitors in aqueous KOH electrolyte.Owing to high electrical conductivity of rGO,hierarchical and layered structure of the electrode,as well as tight adhesion of active materials on the current collector,the as-obtained hybrid electrodes show a high specific capacitance of 871 F g^(-1)at current density of 1 A g^(-1),good rate performance and remarkable cycling stability with a capacitance retention of 134%after 30000 cycles.Besides,the assembled NiCo_(2)O_(4)/rGO//AC asymmetric supercapacitor(ASC)displays the maximum energy density of 29.3 Wh kg^(-1)at a power density of 790.8 W kg^(-1).Significantly,an ultralong cycling life of 102%capacitance retention is achieved for the ASC device after 30,000 charge/discharge cycles at 20 A g^(-1).The scalable fabrication route and excellent electrochemical performance of the NiCo_(2)O_(4)/rGO composites open the door for making novel hybrid electrodes of advanced supercapacitors.展开更多
Considering the intrinsic advantages of natural copiousness and cost-effectiveness of potassium resource,potassium-ion batteries(KIBs) are booming as prospective alternatives to lithium-ion batteries(LIBs) in large-sc...Considering the intrinsic advantages of natural copiousness and cost-effectiveness of potassium resource,potassium-ion batteries(KIBs) are booming as prospective alternatives to lithium-ion batteries(LIBs) in large-scale energy storage scenarios. Nevertheless, lacking desirable electrodes for reversibly hosting the bulky K+hinders the widespread application of KIBs, and it needs to be urgently solved. Hereon, the porous S-doped Sb_(2)O_(3)-graphene-carbon(SAGC) nanofibers are manufactured through an adjustable and facile approach, which involves electrospinning, in situ etching and sulfuration. The synthesized SAGC is featured by the ultra-small amorphous Sb_(2)O_(3) homogeneously wrapped inside the carbon matrix, as well as the co-incorporation of graphene and sulfur. Tentatively,the SAGC nanofiber sheets are applied as binder-free anodes for KIBs, exhibiting a prominent cycling life(256.72 m Ah·g^(-1) over 150 cycles at 100 m A·g^(-1)) and rate·g^(-1) over 100 cycles at 1 A·g^(-1)). The positive synergy among all the active components accounts for the distinguished performances of the SAGC. By reinforcing the tolerability to the swelling stress, producing the valid electrochemical active sites, and promoting the charge transferring for reversible K+uptake, the SAGC finally renders the excellent cyclability, capacity, and rate capability. Moreover, the extrinsic electrochemical pseudocapacitance characteristics induced by the porous carbon substrate elevate the K-storage capacity of the SAGC as well. It is hoped that the conclusions drawn may offer new insights into a direction for the high-performance binderfree KIB anodes.展开更多
文摘Selective and durable fixed‐bed catalysts are highly desirable for developing eco‐efficient HPPO(hydrogen peroxide propylene oxide)process.The powder titanosilicate catalysts must be shaped before being applied in industrial processes.As the essential additives for preparing formed catalysts,binders are usually the catalytically inert components,but they would cover the surface and pore mouth of zeolite,thereby declining the accessibility of active sites.By recrystallizing the binder(silica)/Ti‐MWW extrudates with the assistance of dual organic structure‐directing agents,the silica binder was converted into MWW zeolite phase to form a structured binder‐free Ti‐MWW zeolite with Si‐rich shell,which enhanced the diffusion efficiency and maintained the mechanical strength.Meanwhile,due to the partial dissolution of Si in the Ti‐MWW matrix,abundant silanol nests formed and part of framework TiO4 species were transferred into open TiO_(6)ones,improving the accumulation and activation ability of H_(2)O_(2)inside the monolith.Successive piperidine treatment and fluoridation of the binder‐free Ti‐MWW further enhanced the H_(2)O_(2)activation and oxygen transfer ability of the active Ti sites,and stabilized the Ti‐OOH intermediate through hydrogen bond formed between the end H in Ti‐OOH and the adjacent Si‐F species,thus achieving a more efficient epoxidation process.Additionally,the side reaction of PO hydrolysis was inhibited because the modification effectively quenched numerous Si‐OH groups.The lifetime of the modified binder‐free Ti‐MWW catalyst was 2400 h with the H_(2)O_(2)conversion and PO selectivity both above 99.5%.
基金financially supported by the National Natural Science Foundation of China (Nos. 21603019,51772034 and 12075224)the Opening Project of State Key Laboratory of High Performance Ceramics and Superfine Microstructure(No. SKL201807SIC)The Fundamental Research Funds for the Central Universities (No. 2019CDJGFCL004)。
文摘Three-dimensional(3D) ultra-tiny Fe_(2)O_(3) nanoparticles/graphene hydrogels were prepared using a facile and efficient solvothermal reaction, by which the phase of iron oxide, particle size and the morphology of hydrogels can be precisely controlled by simply adjusting the solvothermal reaction time. Accordingly, the effect of the microstructures of hydrogels on electrochemical performance was systematically studied. It was found that Fe_(2)O_(3)/r GO-50 hydrogels(with a solvothermal reaction time of 50 min) possessed a desirable crystallinity, suitable particle size, decent porous structure, large specific surface area and high electrical conductivity, thus exhibiting a superior electrochemical performance as binder-free anode of supercapacitors: a large potential range of 1.15 V, an ultrahigh specific capacitance of 1090 F·g^(-1) at a current density of 2A·g^(-1) and excellent rate capability (531 F·g^(-1) at 10 A·g^(-1)). The rational design and systematic research of electrode materials will provide new lights for the preparation of advanced electrochemical energy storage devices.
基金supported by the National Hi-Tech Research and Development Program of China("863"Project)(Grant No.2012CB932303)Shanghai Municipal Natural Science Foundation(Grant Nos.13ZR1463600&13XD1403900)
文摘The demands for better energy storage devices due to fast development of electric vehicles(EVs) have raised increasing attention on lithium ion batteries(LIBs) with high power and energy densities. In this paper, we provide an overview of recent progress in graphene-based electrode materials. Graphene with its great electrical conductivity and mechanical properties have apparently improved the performance of traditional electrode materials. The methods and electrochemical properties of advanced graphene composite as cathode and anode for LIBs are reviewed. Two novel kinds of graphene hybrid materials are specially highlighted: three-dimensional porous and flexible binder-free graphene-based materials. Challenges for LIBs and future research trend in the development of high-performance electrode materials are further discussed.
基金supported by the National Key Research and Development Program of China(2017YFA0206704 and 2016YFB0100103)the National Basic Research Program of China(2014CB932300)+3 种基金Strategic Priority Research Program of the Chinese Academy of Sciences(XDA09010404)Technology and Industry for National Defence of China(JCKY2016130B010)the National Natural Science Foundation of China(51771177,21422108,51472209,and 51472232)Jilin Province Science and Technology Development Program(20160101289JC)
文摘A facile synthesis of the hierarchically porous cathode with Mo2C nanoparticles through the electrospinning technique and heat treatment is proposed. The carbonization temperature of the precursors is the key factor for the formation of M02C nanoparticles on the carbon nanofibers （MCNFs）. Compared with the Mo2N nanoparticles embedded into N-doped carbon nanofibers film （MNNFs） and N-doped carbon nanofibers film （NFs）, the battery with MCNFs cathode is capable of operation with a high-capacity （10,509 mAhg-1 at 100 mAg-l）, a much reduced discharge-charge voltage gap, and a long-term life （124 cycles at 200 mA g-1 with a specific capacity limit of 500 mAh g -1）. These excellent performances are derived from the synergy of the following advantageous factors： （1） the hierarchically self-standing and binder-free structure of MCNFs could ensure the high diffusion flux of Li＋ and O2 as well as avoid clogging of the discharge product, bulk Li202; （2） the well dispersed M02C nanoparticles not only afford rich active sites, but also facilitate the electronic transfer for catalysis.
基金the National Natural Science Foundation of China (Nos.51472275,20973203 and 91022012)Guangdong Natural Science Foundation (No.2014A030313207)as well as Laboratory Open Fund Project of Sun Yat-sen University (No.201610310003).
文摘Extending the potential window of aqueous supercapacitors (SCs) up to 2.0 V is still a great challenge.Based on their good dynamic structural reversibility and open framework structure,the coordination superamolecular networks (CSNs) exhibit rapid charge/discharge ability and excellent cycle stability.As a typical coordination superamolecular network (CSN),Prussian blue (denoted as CSN-PB),which self-assembled by the CN-ligand and iron ions is firstly in-situ grown on carbon cloth,followed by electro-deposition of MnO2 to form CSN-PB/MnO2 composite electrode.Benefiting from synergistic effect of the constituent components,as well as the open framework structure of CSN-PB,this composite electrode reaches a high potential window of 1.4 V (vs.Ag/AgCl) and delivers a good specific capacitance of 315.3 F·g^-1 in aqueous electrolyte.An aqueous asymmetric device,constructed with CSN-PB/MnO2 composite as cathode and activated carbon as anode,can work in a stable potential window of 2.4 V,exhibits a high energy density of 46.13 Wh·kg^-1 and excellent cycling stability with 85.5% capacitance retention after 20,000 cycles.This work provides a new concept of high dynamic structural reversibility from CSNs to increase the cell voltage of asymmetric SCs for further boosting energy density.
基金This study was financially supported by the National Natural Science Foundation of China[Grant No.22062008]Supported by the program of Qingjiang Excellent Young Talents,Jiangxi University of Science and Technology[Grant No.JXUSTQJBJ2020008]+2 种基金the Special Fund for Postgraduate Innovation of Jiangxi Province[Grant No.YC2020-S458 and YC2021-S569]National Training Program for College Students’Innovation and Entrepreneurship[Grant No.202110407005X]the Postdoctoral Science Foundation of Jiangxi Province[Grant No.2019KY56 and 2018RC02].
文摘As the anode active substance of lithium ions battery(LIB),the low conductivity/ion diffusivity and large volume changes of tungsten oxide(WO_(3))lead to its serious polarization during the lithiation/delithiation process,decreasing the cycling stability.To address these challenges,a binder-free anode consisting of nitrogen-doped tungsten oxide nanosheets,encapsulated in carbon layers(N-doped WO_(3)@CL)and entangled with carbon nanotubes macro-films(CMF),was successfully synthesized through a combination of hydrothermal and online assembly method.Compared with the pristine tungsten oxide entangled with carbon nanotubes macro-films(WO_(3)@CMF),the synthesized N-doped WO_(3)@CL@CMF as a binder-free LIB anode demonstrated better electrochemical performance,which could be attributed to(1)surface defects of WO_(3)created by N dopant providing more channels to improve Li^(+)diffusion,(2)the N-doped WO_(3)@CL with a flower-like structure shortening the diffusion length of Li^(+)ions and further leading to high Li^(+)incorporation,and(3)carbon layers and carbon nanotubes synergistically alleviating the large volume change of the N-doped WO_(3)@CL@CMF electrode during the charging and discharging process.The present study offers insights into employing nitrogen dopant and a carbon matrix to mediate the conductivity and wrapped structure in the WO_(3)semiconductor powder,which provides an important strategy for large-scale design of the binder-free LIB anode with high performance.
基金supported by the Ministry of Science and Technology of China (2012CB933403)the National Natural Science Foundation of China (51425302, 51302045 and 5170021056)+2 种基金Beijing Municipal Science and Technology Commission (Z121100006812003)the Opening Project of State Key Laboratory of Advanced Technology for Float Glassthe Chinese Academy of Sciences
文摘WS2 has been considered as a promising anode material due to its high lithium storage capacity as well as fascinating physical properties. However, the insufficient electrical and ionic conductivities deteriorate the rate per- formance of the batteries. Herein, we report a simple synthetic approach towards graphene-WS2 hybrids by rolling graphene into a hollow nanotube in which WSz nanoplates are en- capsulated. This new electrode design strategy facilitates the fabrication of integrated and binder-free lithium ion battery and sodium ion battery electrodes by combining electrospin- ning and chemical vapor deposition （CVD） methods. Bene- fiting from their confined growth and the interconnected in- situ graphitic carbon coating nanocable web, the WS2@G with nano-level WS2 dispersion not only provides an efficiently conductive and electrolyte accessible framework, but effec- tively alleviates the volume change during the cycling, en- abling a mechanically robust binder-free electrode along with the outstanding electrochemical Li＋ and Na＋ storage proper- ties.
基金supported by the National Science Foundation(CMMI-2113948)Liang Y acknowledges the financial support from China Scholarship Council(201708510080).
文摘本工作通过低成本、简单、快速的真空过滤方法首次成功制备了一种独立的、无粘合剂的柔性聚吡咯:聚磺苯乙烯/纤维素纳米纸电极(PPy:PSS/CNP).多层结构的纤维素纳米纸具有较高的表面积和良好的机械强度,不仅提供了高的电活性区域,缩短了电解质离子的扩散距离,而且还阻止了PPy在充电/放电过程中的体积膨胀/收缩.优化后的PPy:PSS/CNP在10 mV s-1时表现出3.8 F cm-2(对应于475 F cm-3和240 F g-1)的高比电容和良好的循环稳定性(在5000次循环后有80.9%的电容保持率).PPy:PSS/CNP在不同弯曲角度下的循环伏安曲线表明电极具有突出的柔韧性和电化学稳定性.此外,组装的对称超级电容器器件在功率密度为4.4 m W cm-2(550 m W c m-3)的情况下,提供了122μW h cm-2(15 W h cm-3)的高面积能量密度,这个值优于其他基于纤维素电极材料制备的器件.PPy:PSS/CNP电极结合了高电容性能、灵活性、易于制造和廉价多个优势,为开发下一代绿色、经济便携式和可穿戴电子产品提供了巨大潜力.
基金supported by the National Research Foundation of Korea Grant funded by the Korean government(MSIP)(no.2018R1A6A1A03025708).
文摘Binder-free electrospining approach for fabricating bimetallic chalcogen electrodes is essential for cost-and time-cutting but challenging.Herein,we propose a novel direct spray technique in electrospinning method to fabricate binder-free electrospun nickel cerium selenide nanofiber(NCSNF)structured materials.The effect of the applied electrospinning voltage on the average fiber diameter is analyzed.Electrospinning voltage of 25 kV is applied for obtaining an average fiber diameter of<100 nm(87 nm)with rough interconnected nanofibers.The optimized NCSNF electrode exhibits remarkable longterm cycling stability over 50,000 galvanostatic charge-discharge(GCD)cycles.Furthermore,radish-derived nanolayered carbon(RDNLC)is synthesized via pyrolysis and its electrochemical properties are evaluated.The optimized NCSNF and RDNLC electrodes are employed to fabricate a polyvinyl alcohol-potassium hydroxide gel electrolyte-based quasi-solid-state asymmetric supercapacitor(ASC).The quasi-solid-state ASC delivers a high energy density value of 22 Wh kg−1 with 85%capacitance retention and 95%Coulombic efficiency over 40,000 GCD cycles,and upon being extended to the 50,000 GCD cycles,the capacitance retention and Coulombic efficiency reached 71%and 95%,respectively.A solar-charged wristbandlike device is designed as a wearable supercapacitor,and the integrated device is attached to the human hand for powering electronic gadgets in contorted states,thus demonstrating its potential for wearable applications.
基金financial support from the Australian Research Council(LP1900113)
文摘Silver-zinc(Ag-Zn)batteries are a promising battery system for flexible electronics owing to their high safety,high energy density,and stable output voltage.However,poor cycling performance,low areal capacity,and inferior flexibility limit the practical application of Ag-Zn batteries.Herein,we develop a flexible quasi-solid-state Ag-Zn battery system with superior performance by using mild electrolyte and binder-free electrodes.Copper foam current collector is introduced to impede the growth of Zn dendrite,and the structure of Ag cathode is engineered by electrodeposition and chloridization process to improve the areal capacity.This novel battery demonstrates a remarkable cycle retention of 90%for 200 cycles at 3 mA cm^(-2).More importantly,this binder-free battery can afford a high capacity of 3.5 mAh cm^(-2)at 3 mA cm^(-2),an outstanding power density of 2.42 mW cm^(-2),and a maximum energy density of 3.4 mWh cm^(-2).An energy management circuit is adopted to boost the output voltage of a single battery,which can power electronic ink display and Bluetooth temperature and humidity sensor.The developed battery can even operate under the extreme conditions,such as being bent and sealed in solid ice.This work offers a path for designing electrodes and electrolyte toward high-performance flexible Ag-Zn batteries.
文摘Oxygen electrocatalysis,exemplified by the oxygen reduction reaction(ORR)and oxygen evolution reaction(OER),is central to energy storage and conversion technologies such as fuel cells,metal-air batteries,and water electrolysis.However,highly effective and inexpensive earth-abundant materials are sought after to replace the noble metal-based electrocatalysts currently in use.Recently,metal-organic frameworks(MOFs)and carbon-based MOF derivatives have attracted considerable attention as efficient catalysts due to their exceedingly tunable morphologies,structures,compositions,and functionalization.Here,we report two-dimensional(2D)MOF/MOF derivative coupled arrays on nickel foam as binder-free bifunctional ORR/OER catalysts with enhanced electrocatalytic activity and stability.Their remarkable electrochemical properties are primarily attributed to fully exposed active sites and facilitated charge-transfer kinetics.The coupled and hierarchical nanosheet arrays produced via our growth-pyrolysis-regrowth strategy offer promise in the development of highly active electrodes for energy-related electrochemical devices.
基金financially supported by the Science and Technology Commission of Shanghai Municipality(No.18060502300)the Natural Science Foundation of Shanghai(21ZR1445700)+1 种基金the Innovation Program of Shanghai Municipal Education Commission(No.2019-01-07-00-07-E00015)the Medical Engineering Cross Project of USST(No.10-20-310-402)
文摘Durable and cost-effective electrode materials are essential for practical application of supercapacitors.Herein,large area NiCo_(2)O_(4)/reduced graphene oxide(NiCo_(2)O_(4)/rGO)composites with hierarchical structure were fabricated by a facile one-step ultrasonic spray on Ni foam and directly used as the binder-free electrodes for supercapacitors in aqueous KOH electrolyte.Owing to high electrical conductivity of rGO,hierarchical and layered structure of the electrode,as well as tight adhesion of active materials on the current collector,the as-obtained hybrid electrodes show a high specific capacitance of 871 F g^(-1)at current density of 1 A g^(-1),good rate performance and remarkable cycling stability with a capacitance retention of 134%after 30000 cycles.Besides,the assembled NiCo_(2)O_(4)/rGO//AC asymmetric supercapacitor(ASC)displays the maximum energy density of 29.3 Wh kg^(-1)at a power density of 790.8 W kg^(-1).Significantly,an ultralong cycling life of 102%capacitance retention is achieved for the ASC device after 30,000 charge/discharge cycles at 20 A g^(-1).The scalable fabrication route and excellent electrochemical performance of the NiCo_(2)O_(4)/rGO composites open the door for making novel hybrid electrodes of advanced supercapacitors.
基金financially supported by the National Natural Science Foundation of China (Nos.51404103,51574117 and 61376073)Hunan Provincial Education Department(No.20C0613)the College Student Innovation and Entrepreneurship Training Program of Hunan Province (No.S2022115350874)。
文摘Considering the intrinsic advantages of natural copiousness and cost-effectiveness of potassium resource,potassium-ion batteries(KIBs) are booming as prospective alternatives to lithium-ion batteries(LIBs) in large-scale energy storage scenarios. Nevertheless, lacking desirable electrodes for reversibly hosting the bulky K+hinders the widespread application of KIBs, and it needs to be urgently solved. Hereon, the porous S-doped Sb_(2)O_(3)-graphene-carbon(SAGC) nanofibers are manufactured through an adjustable and facile approach, which involves electrospinning, in situ etching and sulfuration. The synthesized SAGC is featured by the ultra-small amorphous Sb_(2)O_(3) homogeneously wrapped inside the carbon matrix, as well as the co-incorporation of graphene and sulfur. Tentatively,the SAGC nanofiber sheets are applied as binder-free anodes for KIBs, exhibiting a prominent cycling life(256.72 m Ah·g^(-1) over 150 cycles at 100 m A·g^(-1)) and rate·g^(-1) over 100 cycles at 1 A·g^(-1)). The positive synergy among all the active components accounts for the distinguished performances of the SAGC. By reinforcing the tolerability to the swelling stress, producing the valid electrochemical active sites, and promoting the charge transferring for reversible K+uptake, the SAGC finally renders the excellent cyclability, capacity, and rate capability. Moreover, the extrinsic electrochemical pseudocapacitance characteristics induced by the porous carbon substrate elevate the K-storage capacity of the SAGC as well. It is hoped that the conclusions drawn may offer new insights into a direction for the high-performance binderfree KIB anodes.
