Surface electropositivity and low internal resistance are important factors to improve the anode performance in microbial fuel cells (MFCs). Nitrogen doping is an effective way for the modification of traditional carb...Surface electropositivity and low internal resistance are important factors to improve the anode performance in microbial fuel cells (MFCs). Nitrogen doping is an effective way for the modification of traditional carbon materials. In this work, heat treatment and melamine were used to modify carbon felts to enhance electrogenesis capacity of MFCs. The modified carbon felts were characterized using X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), atomic force microscopy (AFM) and malvern zeta potentiometer. Results show that the maximum power densities under heat treatment increase from 276.1 to 423.4 mW/m(2) (700 degrees C) and 461.5 mW/m(2) (1200 degrees C) and further increase to 472.5 mW/m(2) (700 degrees C) and 515.4 mW/m(2) (1200 degrees C) with the co-carbonization modification of melamine. The heat treatment reduces the material resistivity, improves the zeta potential which is beneficial to microbial adsorption and electron transfer. The addition of melamine leads to the higher content of surface pyridinic and quaternary nitrogen and higher zeta potential. It is related to higher MFCs performance. Generally, the melamine modification at high temperature increases the feasibility of carbon felt as MFCs's anode materials. (C) 2016 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.展开更多
The recent development of portable electronics promotes the growing demand for flexible energy storage devices. Supercapacitors are promising candidates due to their high power density. Therefore, flexible supercapaci...The recent development of portable electronics promotes the growing demand for flexible energy storage devices. Supercapacitors are promising candidates due to their high power density. Therefore, flexible supercapacitors are desired. Here, the porous activated carbon felts(ACFs) with exfoliated graphene nanosheets and rich oxygen-containing groups were fabricated by a facile thermal treatment strategy.Such ACFs can act as the flexible electrodes of all-solid-state supercapacitors directly without the use of binder and conductive materials. They exhibit excellent electrochemical properties, such as high specific areal capacitance, superior rate ability and long-term cycling stability. Moreover, the fabricated flexible all-solid-state supercapacitors based on ACFs deliver stable electrochemical performance under different bending states.展开更多
The cerium-based redox flow battery(RFB)is regarded as a compelling gridscale energy storage technology to revolutionize the utilization of renewable energy by storing the energy in liquid electrolytes.However,its wid...The cerium-based redox flow battery(RFB)is regarded as a compelling gridscale energy storage technology to revolutionize the utilization of renewable energy by storing the energy in liquid electrolytes.However,its widespread implementation is impeded by the cerium redox reactions that exhibit slow kinetics on commercial graphite felt(GF)electrodes.Surface functionalization may be an available activation strategy to achieve a significant boost in the electrochemical performance of GFs.However,conventional chemical and/or electrochemical routes for the surface functionalization of GFs suffer from the issues of complication,and the deterioration of the resulting modified electrode surface over long-term cycle processes leads to catalytic activity decline.Here,we develop a facile and general strategy for introducing the functional groups to the electrode through the addition of L-cysteine into electrolytes.The-COOH,-NH_(2),and-SH groups in L-cysteine can induce oxygen/nitrogen/sulfur trifunctional doping on GF surfaces with lower deterioration rates,which enables the activated GFs to demonstrate a promising electrocatalytic activity toward cerium redox reactions and excellent durability when used as a cerium-based RFB electrode.This study proposes a rational strategy to overcome the intrinsic limitations of existing modification techniques for GFs and provides a potential pathway toward high-performance RFBs.展开更多
An optimization method for sound absorption of gradient(multi-layered) sintered metal fiber felts is presented. The theoretical model based on dynamic flow resistivity is selected to calculate the sound absorption coe...An optimization method for sound absorption of gradient(multi-layered) sintered metal fiber felts is presented. The theoretical model based on dynamic flow resistivity is selected to calculate the sound absorption coefficient of the sintered metal fiber felts since it only requires three key morphological parameters: fiber diameter, porosity and layer thickness. The model predictions agree well with experimental measurements. Objective functions and constraint conditions are then set up to optimize separately the distribution of porosity, fiber diameter, and simultaneous porosity and fiber diameter in the metal fiber. The optimization problem for either a sole frequency or a pre-specified frequency range is solved using a genetic algorithm method. Acoustic performance comparison between optimized and non-optimized metal fibers is presented to confirm the effectiveness of the optimization method. Gradient sintered metal fiber felts hold great potential for noise control applications particularly when stringent restriction is placed on the total volume and/or weight of sound absorbing material allowed to use.展开更多
Hydrogen energy, as one of the cleanest energy sources, has emerged as a leading candidate for replacing nonrenewable energy. However, hydrogen is not directly available from nature. Challenges such as high production...Hydrogen energy, as one of the cleanest energy sources, has emerged as a leading candidate for replacing nonrenewable energy. However, hydrogen is not directly available from nature. Challenges such as high production costs and the need for efficient large-scale production technologies remain significant obstacles. Among the various hydrogen production methods, water electrolysis stands out due to its environmentally friendly nature and the high purity of hydrogen produced. Proton exchange membrane(PEM) electrolyzers are promising devices for hydrogen production. They exhibit the superiorities in high operational current densities exceeding 2 A cm^(-2), greater resistance to fluctuations, and improved electrolysis efficiency. A critical component of PEM water electrolyzers is the porous transport layer(PTL), which serves as an electron conductor between the membrane electrode assembly and the bipolar plate, ensuring efficient mass transport between gas and liquid phases. This review provides a comprehensive examination of PTL materials,structural configurations, surface treatments, and the resulting performance of electrolytic cells. These insights aim to guide researchers in selecting appropriate PTL materials and treatments tailored to specific practical applications. Additionally, this paper analyzes operational conditions—such as compaction pressure, temperature,water flow rate, and oxygen saturation within the electrolyzer—that influence PTL performance. These factors are crucial for researchers to holistically design and optimize PEM electrolyzer systems.展开更多
The effective thermal management of lithium-ion batteries is the key to ensuring their fast charging-discharging,safe and efficient operation.Herein,inspired by transpiration-driven water transport in plants,we report...The effective thermal management of lithium-ion batteries is the key to ensuring their fast charging-discharging,safe and efficient operation.Herein,inspired by transpiration-driven water transport in plants,we report a highly hygroscopic needle-punched carbon fiber felt(HS/CFF)with high evaporative cooling efficiency and fire resistance for the safe operation of lithium-ion batteries working at ultrahigh-rate conditions.The three-dimensional fiber skeleton structure constructed by needle punching in the carbon fiber felt enables effective water transport and storage in HS/CFF,without any water leakage.At an ultra-high discharge rate of 10 C,HS/CFF can reduce the maximum temperature of commercial lithium-ion batteries by 18°C,and can keep the battery temperature below 60°C.During 500 cycles of charge-discharge,HS/CFF maintains stable evaporative heat dissipation performance,which helps to improve the safety of lithium-ion batteries and extend their service life.Moreover,HS/CFF remains non-combustible even under exposure to a flame(600-700°C)for 10 min,and the HS/CFF can be reused after the burning test,with the original excellent heat dissipation effect unchanged.This flexible,fire-resistant cooling material offers a promising avenue for low-energy intelligent thermal management of lithium-ion batteries and other heat-generating electronic devices.展开更多
Vanadium redox flow batteries(VRFBs)hold significant promise for large-scale energy storage applications.However,the sluggish reaction kinetics on the electrode surface considerably limit their performance.Implementat...Vanadium redox flow batteries(VRFBs)hold significant promise for large-scale energy storage applications.However,the sluggish reaction kinetics on the electrode surface considerably limit their performance.Implementation of efficient surface modification on carbon electrodes through an economically viable production method is crucial for the practical application of VRFBs.Herein,a nano-carbon layer with morphology of fine nanoparticles(<90 nm)and rich oxygen functional groups was constructed on carbon felts by unbalanced magnetron sputtering coupled with thermal treatment.This modified carbon felt served as both anode and cathode in cell,enabling an improved wettability of electrolyte and high reversibility of the active mass,and promoted kinetics of redox reactions.The optimized carbon felt,achieved through one hour of deposition(1C-CF),demonstrated outstanding electrochemical performance in a single cell.The cell exhibited a high energy efficiency of 82.4%at a current density of 100 m A cm^(-2)and maintained 71.8%at a high current density of 250 mA cm^(-2).Furthermore,the energy efficiency remained at 77.2%during long-term cycling(450 cycles)at a current density of 150 mA cm^(-2),indicating good electrode stability.Our results shed light on the surface design of carbon felt electrodes for the broad application interest of VRFB energy storage systems.展开更多
Vanadium redox flow battery(VRFB)exhibits a great potential for application in large-scale and long-term energy storage systems due to its high safety,longevity,and environmental friendliness.However,the poor electroc...Vanadium redox flow battery(VRFB)exhibits a great potential for application in large-scale and long-term energy storage systems due to its high safety,longevity,and environmental friendliness.However,the poor electrocatalytic activity of the pristine graphite felt electrode seriously hinders the energy density and efficiency of VRFB.To address the issue,in this work,the rich active site-NiMoO_(4)nanorods were used to in situ modify graphite felt for high-performance VRFB.The rod-to-diameter ratio and deposition of NiMoO_(4)were controlled by adjusting the ratio of water/ethanol and concentration of the precursor solution to obtain the optimal length of NiMoO_(4)nanorods uniformly deposited on the graphite felt surface.This abundant micropores,dual active sites of Mo-O-Ni,and additional oxygen vacancies effectively increase the specific surface area,the number of active sites,and the hydrophilicity for graphite felt,which boosts the charge transfer and mass transfer for VO^(2+)/VO_(2)^(+)and V^(3+)/V^(2+)redox reactions.The modified battery exhibits an energy efficiency of 71.1%at 150 mA·cm^(-2),which is 19.8%higher than the blank battery.Furthermore,the modified battery shows excellent stability during 100 cycles.This work will promote the development and application of binary metal oxides with rich active sites in VRFB.展开更多
Fabrication, characterization and performance of a porous metal-fiber sintered felt （PMFSF） based on multi-tooth cutting and solid-phase sintering were studied. The PMFSF was used as the anodic methanol barrier in a...Fabrication, characterization and performance of a porous metal-fiber sintered felt （PMFSF） based on multi-tooth cutting and solid-phase sintering were studied. The PMFSF was used as the anodic methanol barrier in a passive air-breathing direct methanol fuel cell to mitigate the effects of methanol crossover. Compared with the commercial SUS316L felt made of bundle-drawn fibers, this self-made PMFSF has larger pore diameter, polarized pore distribution, irregular fiber shape, rougher surface, lower mass flow resistance and evident hydrophobicity. The results reveal that the use of a PMFSF significantly enhances the cell performance since it helps to maintain a balance between the reactant and product management while depressing methanol crossover. The PMFSF with a porosity of 70% yields the highest cell performance at a methanol concentration of 4 mol/L.展开更多
Fabricating of high performance electrodes by a sustainable and cost effective method is essential to the development of vanadium redox flow batteries(VRFBs).In this work,an effective strategy is proposed to deposit c...Fabricating of high performance electrodes by a sustainable and cost effective method is essential to the development of vanadium redox flow batteries(VRFBs).In this work,an effective strategy is proposed to deposit carbon nanoparticles on graphite felts by hydrothermal carbonization method.This in-situ method minimizes the drop off and aggregation of carbon nanoparticles during electrochemical testing.Such integration of felts and hydrothermal carbons(HTC)produces a new electrode that combines the outstanding electrical conductivity of felts with the effective redox active sites provided by the HTC coating layer.The presence of the amorphous carbon layers on the felts is found to be able to promote the mass/charge transfer,and create oxygenated/nitrogenated active sites and hence enhances wettability.Consequently,the most optimized electrode based on a rational approach delivers an impressive electrochemical performance toward VRFBs in wide range of current densities from 200 to 500 mAcm^-2.The voltage efficiency(VE)of GFs-HTC is much higher than the VEs of the pristine GFs,especially at high current densities.It exhibits a 4.18 times increase in discharge capacity over the pristine graphite felt respectively,at a high current density of 400 mAcm^-2.The enhanced performance is attributed to the abundant active sites from amorphous hydrothermal carbon,which facilitates the fast electrochemical kinetics of vanadium redox reactions.This work evidences that the glucose-derived hydrothermal carbons as energy storage booster hold great promise in practical VRFBs application.展开更多
Developing non-noble-metal oxygen evolution reaction(OER) electrocatalysts with high performance is critical to electrocatalytic water splitting. In this work, we fabricated Co Fe-layered double hydroxide(LDH) nanowir...Developing non-noble-metal oxygen evolution reaction(OER) electrocatalysts with high performance is critical to electrocatalytic water splitting. In this work, we fabricated Co Fe-layered double hydroxide(LDH) nanowire arrays on graphite felt(Co Fe-LDH/GF) via a hydrothermal method. The Co Fe-LDH/GF, as a robust integrated 3 D OER anode, exhibits excellent catalytic activity with the need of low overpotential of 252 and 285 mV to drive current densities of 10 and 100 mA/cm^(2) in 1.0 mol/L KOH, respectively. In addition, it also maintains electrochemical durability for at least 24 h. This work would open up avenues for the development of GF like attractive catalyst supports for oxygen evolution applications.展开更多
Advanced zinc-cerium redox flow battery（ZCRFB） is a large-scale energy storage system which plays a significant role in the application of new energy sources. The requirement of superior cathode with high acitivity ...Advanced zinc-cerium redox flow battery（ZCRFB） is a large-scale energy storage system which plays a significant role in the application of new energy sources. The requirement of superior cathode with high acitivity and fast ion diffusion is a hierarchical porous structure, which was synthesized in this work by a method in which both hard template and soft template were used. The structure and the performance of the cathode prepared here were characterized and evaluated by a variety of techniques such as scanning electron microscopy（SEM）, transmission electron microscopy（TEM）, X-ray photoelectron spectroscopy（XPS）, cyclic voltammetry（CV）, linear sweep voltammetry（LSV）, and chronoamperometry（CA）. There were mainly three types of pore size within the hierarchical porous carbon： 2 μm, 80 nm, and 10 nm. The charge capacity of the cell using hierarchical porous carbon（HPC） as positive electrode was obviously larger than that using carbon felt; the former was 665.5 mAh with a coulombic efficiency of 89.0% and an energy efficiency of 79.0%, whereas the latter was 611.1 mAh with a coulombic efficiency of 81.5% and an energy efficiency of 68.6%. In addition, performance of the ZCRFB using HPC as positive electrode showed a good stability over 50 cycles.These results showed that the hierarchical porous carbon was superior over the carbon felt for application in ZCRFB.展开更多
Electro-oxidation of Ce （ Ⅲ ） to Ce （ Ⅳ ） in parallel plate flow type electrolyzer divided with cation exchange membrane was carried out in nitric acid media at carbon felt anode under galvanostatic conditions. ...Electro-oxidation of Ce （ Ⅲ ） to Ce （ Ⅳ ） in parallel plate flow type electrolyzer divided with cation exchange membrane was carried out in nitric acid media at carbon felt anode under galvanostatic conditions. Carbon felt was used as an anode for its high specific surface area and high oxygen evolution overpotential. Pt coated Ti plates were used as cathode and anode current feeder. The oxidation of 1 mol· L^-1 Ce（ Ⅲ ） solution in 2 mol· L^- 1 HNO3 was proceeding with a high current efficiency （92%） until about 80% of Ce（ Ⅲ ） was oxidized. Then, oxygen evolution, accompanied by terminal voltage jump, took place, lowering current efficiency. Ce（ Ⅲ ） was oxidized up to 90% with current efficiency of 62%. In this mode, strong carbon felt anode oxidation was observed. The wear out of carbon felt was 46% in six consequent runs （6 h of operation）. After each run, carbon felt surface had to be renewed with slightly alkaline solution to remove carbon oxidation products and ensure regular operational conditions. When anode surface was blocked, oxygen evolution took place from the beginning of electrolysis due to higher actual current density. The wear out of carbon felt anode could be minimized by means of oxygen evolution prevention. In the case when electrolysis had been stopped before oxygen evolution started （at Ce（ Ⅳ ） conversion of about 80% ）, the wear out of anode was less than 2% during 6 consequent runs （4 h of operation）.展开更多
A phosphorous-doped graphite felt(PGF) is fabricated and examined as electrode for vanadium flow battery(VFB). P doping improves the electrolyte wettability of GF and induces more defect sites on its surface, resultin...A phosphorous-doped graphite felt(PGF) is fabricated and examined as electrode for vanadium flow battery(VFB). P doping improves the electrolyte wettability of GF and induces more defect sites on its surface, resulting in significantly enhanced activity and reversibility towards VO2^+/VO2^+ and V^2+/V3^+couples. VFB with PGF electrode demonstrates outstanding performance such as high-rate capability under 50–400 mA cm^-2, wide-temperature tolerance at-20 °C–60 °C, and excellent durability over 1000 charge–discharge cycles. These merits enable PGF a promising electrode for the next-generation VFB,which can operate at high-power and all-climate conditions.展开更多
Developing excellent absorption-dominant electromagnetic interference(EMI)shielding composites is an urgent demand for the rapid development of 5 G technology and electronic equipment.Herein,a simple strategy is emplo...Developing excellent absorption-dominant electromagnetic interference(EMI)shielding composites is an urgent demand for the rapid development of 5 G technology and electronic equipment.Herein,a simple strategy is employed to fabricate carbon nanotubes-polypropylene fibers(CP)/polypropylene-glass fibers felt(PGFF)/Fe 3 O 4 composites with superior EMI shielding effectiveness and low reflection due to the magnetic-conductive bi-gradient structure which is naturally formed by deposition during the vacuum-assisted filtration process.The difference in dimensionality between one-dimensional CNT with outstand-ing electrical conductivity and zero-dimensional magnetic Fe 3 O 4 nanoparticles is the theoretical basis for the successful construction of the magnetic-conductive bi-gradient structure in a gap-rich PGFF matrix that endows the composites with“absorb-reflect-reabsorb”EMI shieldingmechanism.Whentheelectro-magnetic waves are incident from the magnetic layer,the EMI shielding effectiveness(SE)reaches 48.9 dB as the weight percentage of the conductive layer increases,more importantly,the reflection coefficients are reduced by more than 0.32 compared with that of another incident pattern.What’s more,the re-sultant composites exhibit an outstanding signal shielding function in the application.This work paves a convenient pathway for designing a magnetic-conductive bi-gradient structure and efficient absorbing EMI shielding composites applied in the next-generated electronic information and communication field.展开更多
Electrode materials with good redox kinetics,excellent mass transfer characteristics and ultra-high stability play a crucial role in reducing the life-cycle cost and prolonging the maintenance-free time of the vanadiu...Electrode materials with good redox kinetics,excellent mass transfer characteristics and ultra-high stability play a crucial role in reducing the life-cycle cost and prolonging the maintenance-free time of the vanadium flow batteries(VFB).Herein,a nitrogen-doped porous graphite felt electrode(N-PGF)is proposed by growing ZIF-67 nanoparticles on carbon fibers and then calcinating and acid etching.The multi-scale structure of“carbon fiber gap(electrolyte flow),micro/nano pore(active species diffusion)and Nitrogen active center(reaction site)”in N-PGF electrode effectively increases the catalytic sites and promotes mass transfer characteristics.Reasonable electrode design makes the battery show excellent rate performance and ultra-high cycling stability.The peak power density of the battery reaches 1006 mW cm^(-2).During 1000 cycles at 150 mA cm^(-2),the average discharge capacity and average discharge energy of N-PGF increase substantially by 11.6%and 23.4%compared with the benchmark thermal activated graphite felt,respectively.More excitingly,after ultra-long term(5000 cycles)operation at an ultra-high current density(300 mA cm^(-2)),N-PGF exhibits an unprecedented energy efficiency retention(99.79%)and electrochemical performance stability.展开更多
Vanadium flow battery （VFB） is a fast going and promising system for large-scale stationary energy stor- age. However, drawbacks such as low power density and narrow temperature window caused by poor catalytic activ...Vanadium flow battery （VFB） is a fast going and promising system for large-scale stationary energy stor- age. However, drawbacks such as low power density and narrow temperature window caused by poor catalytic activity of graphite felt （GF） electrodes limit its worldwide application. In this paper, bismuth, as a low-cost, no-toxic and high-activity electrocatalyst, is used to modify the thermal activated GF （TGF） via a facile hydrothermal method. Bismuth can effectively inhibit the side reaction of hydrogen evolution in wide temperature range, while promoting the V2＋/V3＋ redox reaction. As a result, the VFB assembled with Bi/TGF as negative electrode demonstrates outstanding rate performance under the current density up to 400 mAcm-2, as well as a long-term stability over 600 charging/discharging cycles at a high cur- rent density of 150mA cm-2. Moreover, it also shows excellent temperature adaptability from -10 ℃ to 50 ℃ and high durability for life test at the temperature of 50 ℃.展开更多
The scarcity of wettability,insufficient active sites,and low surface area of graphite felt(GF)have long been suppressing the performance of vanadium redox flow batteries(VRFBs).Herein,an ultra-homogeneous multipledim...The scarcity of wettability,insufficient active sites,and low surface area of graphite felt(GF)have long been suppressing the performance of vanadium redox flow batteries(VRFBs).Herein,an ultra-homogeneous multipledimensioned defect,including nano-scale etching and atomic-scale N,O codoping,was used to modify GF by the molten salt system.NH_(4)Cl and KClO_(3) were added simultaneously to the system to obtain porous N/O co-doped electrode(GF/ON),where KClO_(3) was used to ultra-homogeneously etch,and O-functionalize electrode,and NH4Cl was used as N dopant,respectively.GF/ON presents better electrochemical catalysis for VO_(2)+/VO_(2)+ and V3+/V2+ reactions than only O-functionalized electrodes(GF/O)and GF.The enhanced electrochemical properties are attributed to an increase in active sites,surface area,and wettability,as well as the synergistic effect of N and O,which is also supported by the density functional theory calculations.Further,the cell using GF/ON shows higher discharge capacity,energy efficiency,and stability for cycling performance than the pristine cell at 140 mA cm^(−2) for 200 cycles.Moreover,the energy efficiency of the modified cell is increased by 9.7% from 55.2% for the pristine cell at 260 mA cm^(−2).Such an ultra-homogeneous etching with N and O co-doping through“boiling”molten salt medium provides an effective and practical application potential way to prepare superior electrodes for VRFB.展开更多
Vanadium redox flow batteries(VRFBs)are one of the most promising energy storage systems owing to their safety,efficiency,flexibility and scalability.However,the commercial viability of VRFBs is still hindered by the ...Vanadium redox flow batteries(VRFBs)are one of the most promising energy storage systems owing to their safety,efficiency,flexibility and scalability.However,the commercial viability of VRFBs is still hindered by the low electrochemical performance of the available carbon-based electrodes.Defect engineering is a powerful strategy to enhance the redox catalytic activity of carbon-based electrodes for VRFBs.In this paper,uniform carbon defects are introduced on the surfaces of carbon felt(CF)electrode by Ar plasma etching.Together with a higher specific surface area,the Ar plasma treated CF offers additional catalytic sites,allowing faster and more reversible oxidation/reduction reactions of vanadium ions.As a result,the VRFB using plasma treated electrode shows a power density of 1018.3 mW/cm^(2),an energy efficiency(EE)of 84.5%,and the EE remains stable over 1000 cycles.展开更多
文摘Surface electropositivity and low internal resistance are important factors to improve the anode performance in microbial fuel cells (MFCs). Nitrogen doping is an effective way for the modification of traditional carbon materials. In this work, heat treatment and melamine were used to modify carbon felts to enhance electrogenesis capacity of MFCs. The modified carbon felts were characterized using X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), atomic force microscopy (AFM) and malvern zeta potentiometer. Results show that the maximum power densities under heat treatment increase from 276.1 to 423.4 mW/m(2) (700 degrees C) and 461.5 mW/m(2) (1200 degrees C) and further increase to 472.5 mW/m(2) (700 degrees C) and 515.4 mW/m(2) (1200 degrees C) with the co-carbonization modification of melamine. The heat treatment reduces the material resistivity, improves the zeta potential which is beneficial to microbial adsorption and electron transfer. The addition of melamine leads to the higher content of surface pyridinic and quaternary nitrogen and higher zeta potential. It is related to higher MFCs performance. Generally, the melamine modification at high temperature increases the feasibility of carbon felt as MFCs's anode materials. (C) 2016 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.
基金supported by National Natural Science Foundation of China (Nos. 21573116, 51822205 and 21875121)Ministry of Science and Technology of China (No. 2017YFA0206701)+1 种基金Ministry of Education of China (No. B12015)the Young Thousand Talents Program
文摘The recent development of portable electronics promotes the growing demand for flexible energy storage devices. Supercapacitors are promising candidates due to their high power density. Therefore, flexible supercapacitors are desired. Here, the porous activated carbon felts(ACFs) with exfoliated graphene nanosheets and rich oxygen-containing groups were fabricated by a facile thermal treatment strategy.Such ACFs can act as the flexible electrodes of all-solid-state supercapacitors directly without the use of binder and conductive materials. They exhibit excellent electrochemical properties, such as high specific areal capacitance, superior rate ability and long-term cycling stability. Moreover, the fabricated flexible all-solid-state supercapacitors based on ACFs deliver stable electrochemical performance under different bending states.
基金Natural Science Foundation of Liaoning Province,Grant/Award Number:2020-MZLH-40High-Level Talent Innovation Support Program of Dalian City,Grant/Award Number:2019RQ076National Natural Science Foundation of China,Grant/Award Numbers:21801034,51732007,51872033。
文摘The cerium-based redox flow battery(RFB)is regarded as a compelling gridscale energy storage technology to revolutionize the utilization of renewable energy by storing the energy in liquid electrolytes.However,its widespread implementation is impeded by the cerium redox reactions that exhibit slow kinetics on commercial graphite felt(GF)electrodes.Surface functionalization may be an available activation strategy to achieve a significant boost in the electrochemical performance of GFs.However,conventional chemical and/or electrochemical routes for the surface functionalization of GFs suffer from the issues of complication,and the deterioration of the resulting modified electrode surface over long-term cycle processes leads to catalytic activity decline.Here,we develop a facile and general strategy for introducing the functional groups to the electrode through the addition of L-cysteine into electrolytes.The-COOH,-NH_(2),and-SH groups in L-cysteine can induce oxygen/nitrogen/sulfur trifunctional doping on GF surfaces with lower deterioration rates,which enables the activated GFs to demonstrate a promising electrocatalytic activity toward cerium redox reactions and excellent durability when used as a cerium-based RFB electrode.This study proposes a rational strategy to overcome the intrinsic limitations of existing modification techniques for GFs and provides a potential pathway toward high-performance RFBs.
基金supported by the National Natural Science Foundation of China(Grant No.51528501)the Fundamental Research Funds for Central Universities(Grant No.2014qngz12)Xin is supported by China Scholarship Council as a visiting scholar to Harvard University
文摘An optimization method for sound absorption of gradient(multi-layered) sintered metal fiber felts is presented. The theoretical model based on dynamic flow resistivity is selected to calculate the sound absorption coefficient of the sintered metal fiber felts since it only requires three key morphological parameters: fiber diameter, porosity and layer thickness. The model predictions agree well with experimental measurements. Objective functions and constraint conditions are then set up to optimize separately the distribution of porosity, fiber diameter, and simultaneous porosity and fiber diameter in the metal fiber. The optimization problem for either a sole frequency or a pre-specified frequency range is solved using a genetic algorithm method. Acoustic performance comparison between optimized and non-optimized metal fibers is presented to confirm the effectiveness of the optimization method. Gradient sintered metal fiber felts hold great potential for noise control applications particularly when stringent restriction is placed on the total volume and/or weight of sound absorbing material allowed to use.
基金financial supports provided by the National Key R&D Program of China(No.2022YFB4002002)China Grinm Group Youth FundGrinm Industrial Research Institute Innovation Fund
文摘Hydrogen energy, as one of the cleanest energy sources, has emerged as a leading candidate for replacing nonrenewable energy. However, hydrogen is not directly available from nature. Challenges such as high production costs and the need for efficient large-scale production technologies remain significant obstacles. Among the various hydrogen production methods, water electrolysis stands out due to its environmentally friendly nature and the high purity of hydrogen produced. Proton exchange membrane(PEM) electrolyzers are promising devices for hydrogen production. They exhibit the superiorities in high operational current densities exceeding 2 A cm^(-2), greater resistance to fluctuations, and improved electrolysis efficiency. A critical component of PEM water electrolyzers is the porous transport layer(PTL), which serves as an electron conductor between the membrane electrode assembly and the bipolar plate, ensuring efficient mass transport between gas and liquid phases. This review provides a comprehensive examination of PTL materials,structural configurations, surface treatments, and the resulting performance of electrolytic cells. These insights aim to guide researchers in selecting appropriate PTL materials and treatments tailored to specific practical applications. Additionally, this paper analyzes operational conditions—such as compaction pressure, temperature,water flow rate, and oxygen saturation within the electrolyzer—that influence PTL performance. These factors are crucial for researchers to holistically design and optimize PEM electrolyzer systems.
基金supported by the Key Laboratory of Flame Retardancy Finishing of Textile Materials,CNTAC(No.Q811580421)the Qianjiang Talent Plan of Zhejiang Province(No.QJD1902018).
文摘The effective thermal management of lithium-ion batteries is the key to ensuring their fast charging-discharging,safe and efficient operation.Herein,inspired by transpiration-driven water transport in plants,we report a highly hygroscopic needle-punched carbon fiber felt(HS/CFF)with high evaporative cooling efficiency and fire resistance for the safe operation of lithium-ion batteries working at ultrahigh-rate conditions.The three-dimensional fiber skeleton structure constructed by needle punching in the carbon fiber felt enables effective water transport and storage in HS/CFF,without any water leakage.At an ultra-high discharge rate of 10 C,HS/CFF can reduce the maximum temperature of commercial lithium-ion batteries by 18°C,and can keep the battery temperature below 60°C.During 500 cycles of charge-discharge,HS/CFF maintains stable evaporative heat dissipation performance,which helps to improve the safety of lithium-ion batteries and extend their service life.Moreover,HS/CFF remains non-combustible even under exposure to a flame(600-700°C)for 10 min,and the HS/CFF can be reused after the burning test,with the original excellent heat dissipation effect unchanged.This flexible,fire-resistant cooling material offers a promising avenue for low-energy intelligent thermal management of lithium-ion batteries and other heat-generating electronic devices.
基金supported by National Natural Science Foundation of China(U21B2057)。
文摘Vanadium redox flow batteries(VRFBs)hold significant promise for large-scale energy storage applications.However,the sluggish reaction kinetics on the electrode surface considerably limit their performance.Implementation of efficient surface modification on carbon electrodes through an economically viable production method is crucial for the practical application of VRFBs.Herein,a nano-carbon layer with morphology of fine nanoparticles(<90 nm)and rich oxygen functional groups was constructed on carbon felts by unbalanced magnetron sputtering coupled with thermal treatment.This modified carbon felt served as both anode and cathode in cell,enabling an improved wettability of electrolyte and high reversibility of the active mass,and promoted kinetics of redox reactions.The optimized carbon felt,achieved through one hour of deposition(1C-CF),demonstrated outstanding electrochemical performance in a single cell.The cell exhibited a high energy efficiency of 82.4%at a current density of 100 m A cm^(-2)and maintained 71.8%at a high current density of 250 mA cm^(-2).Furthermore,the energy efficiency remained at 77.2%during long-term cycling(450 cycles)at a current density of 150 mA cm^(-2),indicating good electrode stability.Our results shed light on the surface design of carbon felt electrodes for the broad application interest of VRFB energy storage systems.
基金financially supported by National Natural Science Foundation of China(Nos.51872090 and 51772097)Hebei Natural Science Fund for Distinguished Young Scholar(No.E2019209433)+4 种基金Youth Talent Program of Hebei Provincial Education Department(No.BJ2018020)Natural Science Foundation of Hebei Province(Nos.E2020209151 and E2024209029)National Key R&D Plan Project(No.2022YFB4200305)Research Projects of CNPC(Nos.2024ZG50 and 2023DQ03-04)Innovation Capacity Enhancement Projects of Hebei Province(No.22567608H)
文摘Vanadium redox flow battery(VRFB)exhibits a great potential for application in large-scale and long-term energy storage systems due to its high safety,longevity,and environmental friendliness.However,the poor electrocatalytic activity of the pristine graphite felt electrode seriously hinders the energy density and efficiency of VRFB.To address the issue,in this work,the rich active site-NiMoO_(4)nanorods were used to in situ modify graphite felt for high-performance VRFB.The rod-to-diameter ratio and deposition of NiMoO_(4)were controlled by adjusting the ratio of water/ethanol and concentration of the precursor solution to obtain the optimal length of NiMoO_(4)nanorods uniformly deposited on the graphite felt surface.This abundant micropores,dual active sites of Mo-O-Ni,and additional oxygen vacancies effectively increase the specific surface area,the number of active sites,and the hydrophilicity for graphite felt,which boosts the charge transfer and mass transfer for VO^(2+)/VO_(2)^(+)and V^(3+)/V^(2+)redox reactions.The modified battery exhibits an energy efficiency of 71.1%at 150 mA·cm^(-2),which is 19.8%higher than the blank battery.Furthermore,the modified battery shows excellent stability during 100 cycles.This work will promote the development and application of binary metal oxides with rich active sites in VRFB.
基金Projects(50930005,51075155)supported by the National Natural Science Foundation of ChinaProject(20100172110001)supported by PhD Programs Foundation of Ministry of Education of China
文摘Fabrication, characterization and performance of a porous metal-fiber sintered felt （PMFSF） based on multi-tooth cutting and solid-phase sintering were studied. The PMFSF was used as the anodic methanol barrier in a passive air-breathing direct methanol fuel cell to mitigate the effects of methanol crossover. Compared with the commercial SUS316L felt made of bundle-drawn fibers, this self-made PMFSF has larger pore diameter, polarized pore distribution, irregular fiber shape, rougher surface, lower mass flow resistance and evident hydrophobicity. The results reveal that the use of a PMFSF significantly enhances the cell performance since it helps to maintain a balance between the reactant and product management while depressing methanol crossover. The PMFSF with a porosity of 70% yields the highest cell performance at a methanol concentration of 4 mol/L.
基金supported by the Award Program for Fujian Minjiang Scholar Professorshipthe National Natural Science Foundation of China(21571035)。
文摘Fabricating of high performance electrodes by a sustainable and cost effective method is essential to the development of vanadium redox flow batteries(VRFBs).In this work,an effective strategy is proposed to deposit carbon nanoparticles on graphite felts by hydrothermal carbonization method.This in-situ method minimizes the drop off and aggregation of carbon nanoparticles during electrochemical testing.Such integration of felts and hydrothermal carbons(HTC)produces a new electrode that combines the outstanding electrical conductivity of felts with the effective redox active sites provided by the HTC coating layer.The presence of the amorphous carbon layers on the felts is found to be able to promote the mass/charge transfer,and create oxygenated/nitrogenated active sites and hence enhances wettability.Consequently,the most optimized electrode based on a rational approach delivers an impressive electrochemical performance toward VRFBs in wide range of current densities from 200 to 500 mAcm^-2.The voltage efficiency(VE)of GFs-HTC is much higher than the VEs of the pristine GFs,especially at high current densities.It exhibits a 4.18 times increase in discharge capacity over the pristine graphite felt respectively,at a high current density of 400 mAcm^-2.The enhanced performance is attributed to the abundant active sites from amorphous hydrothermal carbon,which facilitates the fast electrochemical kinetics of vanadium redox reactions.This work evidences that the glucose-derived hydrothermal carbons as energy storage booster hold great promise in practical VRFBs application.
基金supported by the National Natural Science Foundation of China (No.22072015)。
文摘Developing non-noble-metal oxygen evolution reaction(OER) electrocatalysts with high performance is critical to electrocatalytic water splitting. In this work, we fabricated Co Fe-layered double hydroxide(LDH) nanowire arrays on graphite felt(Co Fe-LDH/GF) via a hydrothermal method. The Co Fe-LDH/GF, as a robust integrated 3 D OER anode, exhibits excellent catalytic activity with the need of low overpotential of 252 and 285 mV to drive current densities of 10 and 100 mA/cm^(2) in 1.0 mol/L KOH, respectively. In addition, it also maintains electrochemical durability for at least 24 h. This work would open up avenues for the development of GF like attractive catalyst supports for oxygen evolution applications.
基金supported by National Program on Key Basic Research Project of China(973 Program,2012CB215500)National Natural Science Foundation of China(21361010)
文摘Advanced zinc-cerium redox flow battery（ZCRFB） is a large-scale energy storage system which plays a significant role in the application of new energy sources. The requirement of superior cathode with high acitivity and fast ion diffusion is a hierarchical porous structure, which was synthesized in this work by a method in which both hard template and soft template were used. The structure and the performance of the cathode prepared here were characterized and evaluated by a variety of techniques such as scanning electron microscopy（SEM）, transmission electron microscopy（TEM）, X-ray photoelectron spectroscopy（XPS）, cyclic voltammetry（CV）, linear sweep voltammetry（LSV）, and chronoamperometry（CA）. There were mainly three types of pore size within the hierarchical porous carbon： 2 μm, 80 nm, and 10 nm. The charge capacity of the cell using hierarchical porous carbon（HPC） as positive electrode was obviously larger than that using carbon felt; the former was 665.5 mAh with a coulombic efficiency of 89.0% and an energy efficiency of 79.0%, whereas the latter was 611.1 mAh with a coulombic efficiency of 81.5% and an energy efficiency of 68.6%. In addition, performance of the ZCRFB using HPC as positive electrode showed a good stability over 50 cycles.These results showed that the hierarchical porous carbon was superior over the carbon felt for application in ZCRFB.
文摘Electro-oxidation of Ce （ Ⅲ ） to Ce （ Ⅳ ） in parallel plate flow type electrolyzer divided with cation exchange membrane was carried out in nitric acid media at carbon felt anode under galvanostatic conditions. Carbon felt was used as an anode for its high specific surface area and high oxygen evolution overpotential. Pt coated Ti plates were used as cathode and anode current feeder. The oxidation of 1 mol· L^-1 Ce（ Ⅲ ） solution in 2 mol· L^- 1 HNO3 was proceeding with a high current efficiency （92%） until about 80% of Ce（ Ⅲ ） was oxidized. Then, oxygen evolution, accompanied by terminal voltage jump, took place, lowering current efficiency. Ce（ Ⅲ ） was oxidized up to 90% with current efficiency of 62%. In this mode, strong carbon felt anode oxidation was observed. The wear out of carbon felt was 46% in six consequent runs （6 h of operation）. After each run, carbon felt surface had to be renewed with slightly alkaline solution to remove carbon oxidation products and ensure regular operational conditions. When anode surface was blocked, oxygen evolution took place from the beginning of electrolysis due to higher actual current density. The wear out of carbon felt anode could be minimized by means of oxygen evolution prevention. In the case when electrolysis had been stopped before oxygen evolution started （at Ce（ Ⅳ ） conversion of about 80% ）, the wear out of anode was less than 2% during 6 consequent runs （4 h of operation）.
基金supported by the National Natural Science Foundation of China(No.21576154)the Shenzhen Basic Research Project(Nos.JCYJ20170818115018000,JCYJ20170307154206288,JCYJ20170412170756603)
文摘A phosphorous-doped graphite felt(PGF) is fabricated and examined as electrode for vanadium flow battery(VFB). P doping improves the electrolyte wettability of GF and induces more defect sites on its surface, resulting in significantly enhanced activity and reversibility towards VO2^+/VO2^+ and V^2+/V3^+couples. VFB with PGF electrode demonstrates outstanding performance such as high-rate capability under 50–400 mA cm^-2, wide-temperature tolerance at-20 °C–60 °C, and excellent durability over 1000 charge–discharge cycles. These merits enable PGF a promising electrode for the next-generation VFB,which can operate at high-power and all-climate conditions.
基金supported by the Key Research Pro-gram of Zhejiang Province(No.2020C01010)the Natural Science Foundation of Zhejiang Province(No.LY20E030008)the Na-tional Natural Science Foundation of China(No.21504078).
文摘Developing excellent absorption-dominant electromagnetic interference(EMI)shielding composites is an urgent demand for the rapid development of 5 G technology and electronic equipment.Herein,a simple strategy is employed to fabricate carbon nanotubes-polypropylene fibers(CP)/polypropylene-glass fibers felt(PGFF)/Fe 3 O 4 composites with superior EMI shielding effectiveness and low reflection due to the magnetic-conductive bi-gradient structure which is naturally formed by deposition during the vacuum-assisted filtration process.The difference in dimensionality between one-dimensional CNT with outstand-ing electrical conductivity and zero-dimensional magnetic Fe 3 O 4 nanoparticles is the theoretical basis for the successful construction of the magnetic-conductive bi-gradient structure in a gap-rich PGFF matrix that endows the composites with“absorb-reflect-reabsorb”EMI shieldingmechanism.Whentheelectro-magnetic waves are incident from the magnetic layer,the EMI shielding effectiveness(SE)reaches 48.9 dB as the weight percentage of the conductive layer increases,more importantly,the reflection coefficients are reduced by more than 0.32 compared with that of another incident pattern.What’s more,the re-sultant composites exhibit an outstanding signal shielding function in the application.This work paves a convenient pathway for designing a magnetic-conductive bi-gradient structure and efficient absorbing EMI shielding composites applied in the next-generated electronic information and communication field.
基金supported by the National Natural Science Foundation of China(21576154)the Natural Science Foundation of Guangdong Province(2022A1515011999 and 2019A1515011955)the Shenzhen Basic Research Project(20200829101039001 and GXWD20201231165806004)。
文摘Electrode materials with good redox kinetics,excellent mass transfer characteristics and ultra-high stability play a crucial role in reducing the life-cycle cost and prolonging the maintenance-free time of the vanadium flow batteries(VFB).Herein,a nitrogen-doped porous graphite felt electrode(N-PGF)is proposed by growing ZIF-67 nanoparticles on carbon fibers and then calcinating and acid etching.The multi-scale structure of“carbon fiber gap(electrolyte flow),micro/nano pore(active species diffusion)and Nitrogen active center(reaction site)”in N-PGF electrode effectively increases the catalytic sites and promotes mass transfer characteristics.Reasonable electrode design makes the battery show excellent rate performance and ultra-high cycling stability.The peak power density of the battery reaches 1006 mW cm^(-2).During 1000 cycles at 150 mA cm^(-2),the average discharge capacity and average discharge energy of N-PGF increase substantially by 11.6%and 23.4%compared with the benchmark thermal activated graphite felt,respectively.More excitingly,after ultra-long term(5000 cycles)operation at an ultra-high current density(300 mA cm^(-2)),N-PGF exhibits an unprecedented energy efficiency retention(99.79%)and electrochemical performance stability.
基金financial support from the National Natural Science Foundation of China (No. 21576154)the Open Fund of The State Key Laboratory of Refractories and Metallurgy (No. G201809)the Shenzhen Basic Research Project (Nos. JCYJ20170412170756603 and JCYJ20170307152754218)
文摘Vanadium flow battery （VFB） is a fast going and promising system for large-scale stationary energy stor- age. However, drawbacks such as low power density and narrow temperature window caused by poor catalytic activity of graphite felt （GF） electrodes limit its worldwide application. In this paper, bismuth, as a low-cost, no-toxic and high-activity electrocatalyst, is used to modify the thermal activated GF （TGF） via a facile hydrothermal method. Bismuth can effectively inhibit the side reaction of hydrogen evolution in wide temperature range, while promoting the V2＋/V3＋ redox reaction. As a result, the VFB assembled with Bi/TGF as negative electrode demonstrates outstanding rate performance under the current density up to 400 mAcm-2, as well as a long-term stability over 600 charging/discharging cycles at a high cur- rent density of 150mA cm-2. Moreover, it also shows excellent temperature adaptability from -10 ℃ to 50 ℃ and high durability for life test at the temperature of 50 ℃.
基金supported by the National Natural Science Foundation of China(No.51872090)Natural Science Foundation of Hebei Province(No.E2019209433,E2022209158)Colleges and Universities in Hebei Province Science and Technology Research Project(No.JZX2024026).
文摘The scarcity of wettability,insufficient active sites,and low surface area of graphite felt(GF)have long been suppressing the performance of vanadium redox flow batteries(VRFBs).Herein,an ultra-homogeneous multipledimensioned defect,including nano-scale etching and atomic-scale N,O codoping,was used to modify GF by the molten salt system.NH_(4)Cl and KClO_(3) were added simultaneously to the system to obtain porous N/O co-doped electrode(GF/ON),where KClO_(3) was used to ultra-homogeneously etch,and O-functionalize electrode,and NH4Cl was used as N dopant,respectively.GF/ON presents better electrochemical catalysis for VO_(2)+/VO_(2)+ and V3+/V2+ reactions than only O-functionalized electrodes(GF/O)and GF.The enhanced electrochemical properties are attributed to an increase in active sites,surface area,and wettability,as well as the synergistic effect of N and O,which is also supported by the density functional theory calculations.Further,the cell using GF/ON shows higher discharge capacity,energy efficiency,and stability for cycling performance than the pristine cell at 140 mA cm^(−2) for 200 cycles.Moreover,the energy efficiency of the modified cell is increased by 9.7% from 55.2% for the pristine cell at 260 mA cm^(−2).Such an ultra-homogeneous etching with N and O co-doping through“boiling”molten salt medium provides an effective and practical application potential way to prepare superior electrodes for VRFB.
基金Project(Xiang Zu [2016] 91) supported by the “100 Talented Teams” of Hunan Province,ChinaProject(2018RS3077) supported by the Huxiang High-level Talents Program,China+2 种基金Project(22002009) supported by the National Natural Science Foundation of ChinaProject(2021JJ40565) supported by the Natural Science Foundation of Hunan Province,ChinaProject(19C0054) supported by the Scientific Research Foundation of Hunan Provincial Education Department,China。
文摘Vanadium redox flow batteries(VRFBs)are one of the most promising energy storage systems owing to their safety,efficiency,flexibility and scalability.However,the commercial viability of VRFBs is still hindered by the low electrochemical performance of the available carbon-based electrodes.Defect engineering is a powerful strategy to enhance the redox catalytic activity of carbon-based electrodes for VRFBs.In this paper,uniform carbon defects are introduced on the surfaces of carbon felt(CF)electrode by Ar plasma etching.Together with a higher specific surface area,the Ar plasma treated CF offers additional catalytic sites,allowing faster and more reversible oxidation/reduction reactions of vanadium ions.As a result,the VRFB using plasma treated electrode shows a power density of 1018.3 mW/cm^(2),an energy efficiency(EE)of 84.5%,and the EE remains stable over 1000 cycles.
