The major problem with lithium-sulfur(Li-S)batteries is their poor cycling stability because of slow redox kinetics in the cathode and the growth of lithium dendrites on the anode.We report the production of 2D porous...The major problem with lithium-sulfur(Li-S)batteries is their poor cycling stability because of slow redox kinetics in the cathode and the growth of lithium dendrites on the anode.We report the production of 2D porous carbon nanosheets doped with both Fe and Ni(Fe/Ni-N-PCNSs)by an easy and template-free approach that solve this problem.Because of their ultrathin porous 2D structure and uniform distribution of Fe and Ni dopants,they capture polysulfides,speed up the sulfur redox reaction,and improve the material’s lithiophilicity,greatly suppressing the shuttling of polysulfides and dendrite growth on the lithium anode.As a result,it has an exceptional performance as a stable host for elemental sulfur and metallic lithium,producing a record long life of 1000 cycles with a very small capacity decay of 0.00025%per cycle in a Li-S battery and an excellent cycling stability of over 850 h with a small overpotential of>72 mV in a lithium metal battery.This work suggests the use of multifunctional-based 2D porous carbon nanosheets as a stable host for both elemental sulfur and metallic lithium to improve the Li-S battery per-formance.展开更多
In this work,a comprehensive comparison regarding the impacts of M(M=Cu,Co,Mn)substitution for Ni on the structures and the hydrogen storage kinetics of the nanocrystalline and amorphous Mg20Ni10-xMx(M=Cu,Co,Mn; x=0-4...In this work,a comprehensive comparison regarding the impacts of M(M=Cu,Co,Mn)substitution for Ni on the structures and the hydrogen storage kinetics of the nanocrystalline and amorphous Mg20Ni10-xMx(M=Cu,Co,Mn; x=0-4)alloys prepared by melt spinning has been carried out.The analysis of XRD and TEM reveals that the as-spun(M=None,Cu)alloys display an entire nanocrystalline structure,whereas the as-spun(M=Co,Mn)alloys hold a mixed structure of nanocrystalline and amorphous structure when M content x=4,indicating that the substitution of M(M=Co,Mn)for Ni facilitates the glass formation in the Mg2Ni-type alloy.Besides,all the as-spun alloys have a major phase of Mg2Ni but M(M=Co,Mn)substitution brings on the formation of some secondary phases,MgCo2 and Mg phases for M=Co as well as MnNi and Mg phases for M=Mn.Based upon the measurements of the automatic Sieverts apparatus and the automatic galvanostatic system,the impacts engendered by M(M=Cu,Co,Mn)substitution on the gaseous and electrochemical hydrogen storage kinetics of the alloys appear to be evident.The gaseous hydriding kinetics of the alloys first rises and then declines with the growing of M(M=Cu,Co,Mn)content.Particularly,the M(M= Mn)substitution results in a sharp drop in the hydriding kinetics when x=4.The M(M=Cu,Co,Mn)substitution ameliorates the dehydriding kinetics dramatically in the order(M=Co)>(M=Mn)>(M=Cu).The electrochemical kinetics of the alloys visibly grows with M content rising for(M=Cu,Co),while it first increases and then declines for(M=Mn).展开更多
Thiobacillus ferrooxidans might be the most important bacteria used in biometallurgy. The foundation way of its growth process is oxidizing ferrous in order to obtain energy needed for metabolism, but the variation of...Thiobacillus ferrooxidans might be the most important bacteria used in biometallurgy. The foundation way of its growth process is oxidizing ferrous in order to obtain energy needed for metabolism, but the variation of ferrous concentration and mixed potential of the culture media would have crucial effect on the bacteria growth. Based on the characteristics of Thiobacillus ferrooxidans growth and redox potential of ferric and ferrous, an electrochemical cell was designed conventionally to study growth rule and the relationship between redox potential and bacteria growth was built up, and some growth kinetics of Thiobacillus ferrooxidans were elucidated. It demonstrates that the variation of open potential of electrochemical cell Δ E shows the growth tendency of Thiobacillus ferrooxidans , at the initial growth stage, the value of Δ E increases slowly, when at logistic growth stage, it increases drastically, and the growth rate of bacteria is linear with the oxidation rate of ferrous. The bacteria growth kinetics model is proposed using Monod and Michealis-Menten equation, and the kinetics parameters are got. The consistence of the measured and the calculated results proves that it is proper to use the proposed kinetics model and the electrochemical cell method to describe the growth rule of Thiobacillus ferrooxidans .展开更多
Kinetic parameters of the electrode reactions were measured by investigating steady-state current-potential behaviors. The results show that the apparent transfer coefficient of anodic process is 0.0582, diffusion coe...Kinetic parameters of the electrode reactions were measured by investigating steady-state current-potential behaviors. The results show that the apparent transfer coefficient of anodic process is 0.0582, diffusion coefficient of thiourea gold complex is 6.04×10~ -6 cm^2/s,anodic reaction order of thiourea is 2.0183, and anodic reaction order of OH^- is 0.0166. The theoretical kinetics equation of gold dissolving in alkaline thiourea solution is deduced, which indicates that anodic reaction order of thiourea is 2, and anodic reaction order of OH^- is 0. The theoretical values of the kinetic parameters are consistent with experimental values very well. The correctness of the mechanism is further demonstrated using apparent transfer coefficient according to the electrochemical dynamic equation of multi-electron reaction.展开更多
The graphite was modified using pitch through dynamical melt-carbonization, and the effects of modification temperature and the amount of pitch on the characteristics of graphite were investigated. The structure and c...The graphite was modified using pitch through dynamical melt-carbonization, and the effects of modification temperature and the amount of pitch on the characteristics of graphite were investigated. The structure and characteristics of the graphite were determined by X-ray diffractometry(XRD), scanning electron microscopy(SEM), particle size analysis and electrochemical measurements. The results show that the modified graphite has a disordered carbon/graphite composite structure, larger average particle diameter, greater tap density, and better electrochemical characteristics than the untreated graphite. The sample coated with 10% pitch dynamical melt-carbonized at 400 ℃ for 3 h and heat-treated at 850 ℃ for 2 h has better electrochemical performances with a reversible capacity of 360.5 mA·h/g, a irreversible capacity of 41.0 mA·h/g, and an initial coulombic efficiency of 89.8% compared with natural graphite and disordered carbon. The cycling stability of the Li/C cell with modified graphite as anodes is improved, and its capacity retention ratio at the 30th cycle is up to 94.37%.展开更多
Based on electromagnetics and mechanics, electromechanical coupled dynamic equations for the drive were developed. Using method of perturbation, free vibrations of the mechanical system under electric disturbance were...Based on electromagnetics and mechanics, electromechanical coupled dynamic equations for the drive were developed. Using method of perturbation, free vibrations of the mechanical system under electric disturbance were investigated. The forced responses of the mechanical system to mechanical excitation under electric disturbance were also presented. It is known that for the system with electric disturbance, as time grows, beat occurs. When electric disturbing frequency is near to the natural frequencies of the mechanical system or their integer multiple, resonance vibrations occur. The forced responses of the mechanical system to mechanical excitation under electric disturbance are compound vibrations decided by mechanical excitation, electric disturbance and parameters of the system. The coupled resonance vibration caused by electric disturbance and mechanical excitation was discussed as well. The conditions under which above coupled resonance occurs were presented. The results show that when the difference of the excitation frequency and the perturbation frequency is equal to some order of natural frequency, coupled resonance vibrations occur.展开更多
The electric double layer with the transmission of particles was presented based on the principle of electrochemistry.In accordance with this theory,the cavitation catalysis removal mechanism of ultrasonic-pulse elect...The electric double layer with the transmission of particles was presented based on the principle of electrochemistry.In accordance with this theory,the cavitation catalysis removal mechanism of ultrasonic-pulse electrochemical compound machining(UPECM) based on particles was proposed.The removal mechanism was a particular focus and was thus validated by experiments.The principles and experiments of UPECM were introduced,and the removal model of the UPECM based on the principles of UPECM was established.Furthermore,the effects of the material removal rate for the main processing parameters,including the particles size,the ultrasonic vibration amplitude,the pulse voltage and the minimum machining gap between the tool and the workpiece,were also studied through UPECM.The results show that the particles promote ultrasonic-pulse electrochemical compound machining and thus act as the catalyzer of UPECM.The results also indicate that the processing speed,machining accuracy and surface quality can be improved under UPECM compound machining.展开更多
Anodic oxidation with different electrolyte was employed to improve the electrochemical properties of carbon paper as negative electrode for vanadium redox battery(VRB).The treated carbon paper exhibits enhanced elect...Anodic oxidation with different electrolyte was employed to improve the electrochemical properties of carbon paper as negative electrode for vanadium redox battery(VRB).The treated carbon paper exhibits enhanced electrochemical activity for V^2+/V^3+redox reaction.The sample(CP-NH3)treated in NH3 solution demonstrates superior performance in comparison with the sample(CP-NaOH)treated in NaOH solution.X-ray photoelectron spectroscopy results show that oxygen-and nitrogen-containing functional groups have been introduced on CP-NH3 surface by the treatment,and Raman spectra confirm the increased surface defect of CP-NH3.Energy storage performance of cell was evaluated by charge/discharge measurement by using CP-NH3.Usage of CP-NH3 can greatly improve the cell performance with energy efficiency increase of 4.8%at 60 mA/cm^2.The excellent performance of CP-NH3 mainly results from introduction of functional groups as active sites and improved wetting properties.This work reveals that anodic oxidation is a clean,simple,and efficient method for boosting the performance of carbon paper as negative electrode for VRB.展开更多
This paper studied a supervisory control system for a hybrid off-highway electric vehicle under the chargesustaining(CS)condition.A new predictive double Q-learning with backup models(PDQL)scheme is proposed to optimi...This paper studied a supervisory control system for a hybrid off-highway electric vehicle under the chargesustaining(CS)condition.A new predictive double Q-learning with backup models(PDQL)scheme is proposed to optimize the engine fuel in real-world driving and improve energy efficiency with a faster and more robust learning process.Unlike the existing“model-free”methods,which solely follow on-policy and off-policy to update knowledge bases(Q-tables),the PDQL is developed with the capability to merge both on-policy and off-policy learning by introducing a backup model(Q-table).Experimental evaluations are conducted based on software-in-the-loop(SiL)and hardware-in-the-loop(HiL)test platforms based on real-time modelling of the studied vehicle.Compared to the standard double Q-learning(SDQL),the PDQL only needs half of the learning iterations to achieve better energy efficiency than the SDQL at the end learning process.In the SiL under 35 rounds of learning,the results show that the PDQL can improve the vehicle energy efficiency by 1.75%higher than SDQL.By implementing the PDQL in HiL under four predefined real-world conditions,the PDQL can robustly save more than 5.03%energy than the SDQL scheme.展开更多
A new electro-hydraulic exciter that consists of rotary valve and micro-displacement double-functioned hydraulic cylinder was proposed to realize different kinds of waveforms.Calculated fluid dynamics(CFD) simulation ...A new electro-hydraulic exciter that consists of rotary valve and micro-displacement double-functioned hydraulic cylinder was proposed to realize different kinds of waveforms.Calculated fluid dynamics(CFD) simulation of rotary valve orifice reveals that orifice exists the two-throttle phenomenon.According to the finding,the revised flow area model was established.Vibration waveforms analysis was carried out by means of mathematic model and the related experiments were validated.Furthermore,as a new analysis indicator,saturation percentage was introduced first.The experimental results indicate that the revised flow area model is more accurate compared to the original one,and vibration waveforms can be optimized through suitable spool parameters and the revised cylinder structure.展开更多
基金supported by Basic and Applied Basic Research Fund Project of Guangdong(2022A1515011817,2023A1515030160)Research and Innovation Group of Guangdong University of Education(2024KYCXTD014)。
文摘The major problem with lithium-sulfur(Li-S)batteries is their poor cycling stability because of slow redox kinetics in the cathode and the growth of lithium dendrites on the anode.We report the production of 2D porous carbon nanosheets doped with both Fe and Ni(Fe/Ni-N-PCNSs)by an easy and template-free approach that solve this problem.Because of their ultrathin porous 2D structure and uniform distribution of Fe and Ni dopants,they capture polysulfides,speed up the sulfur redox reaction,and improve the material’s lithiophilicity,greatly suppressing the shuttling of polysulfides and dendrite growth on the lithium anode.As a result,it has an exceptional performance as a stable host for elemental sulfur and metallic lithium,producing a record long life of 1000 cycles with a very small capacity decay of 0.00025%per cycle in a Li-S battery and an excellent cycling stability of over 850 h with a small overpotential of>72 mV in a lithium metal battery.This work suggests the use of multifunctional-based 2D porous carbon nanosheets as a stable host for both elemental sulfur and metallic lithium to improve the Li-S battery per-formance.
基金Projects(51161015,51371094)supported by National Natural Science Foundations of ChinaProject(2011ZD10)supported by Natural Science Foundation of Inner Mongolia,China
文摘In this work,a comprehensive comparison regarding the impacts of M(M=Cu,Co,Mn)substitution for Ni on the structures and the hydrogen storage kinetics of the nanocrystalline and amorphous Mg20Ni10-xMx(M=Cu,Co,Mn; x=0-4)alloys prepared by melt spinning has been carried out.The analysis of XRD and TEM reveals that the as-spun(M=None,Cu)alloys display an entire nanocrystalline structure,whereas the as-spun(M=Co,Mn)alloys hold a mixed structure of nanocrystalline and amorphous structure when M content x=4,indicating that the substitution of M(M=Co,Mn)for Ni facilitates the glass formation in the Mg2Ni-type alloy.Besides,all the as-spun alloys have a major phase of Mg2Ni but M(M=Co,Mn)substitution brings on the formation of some secondary phases,MgCo2 and Mg phases for M=Co as well as MnNi and Mg phases for M=Mn.Based upon the measurements of the automatic Sieverts apparatus and the automatic galvanostatic system,the impacts engendered by M(M=Cu,Co,Mn)substitution on the gaseous and electrochemical hydrogen storage kinetics of the alloys appear to be evident.The gaseous hydriding kinetics of the alloys first rises and then declines with the growing of M(M=Cu,Co,Mn)content.Particularly,the M(M= Mn)substitution results in a sharp drop in the hydriding kinetics when x=4.The M(M=Cu,Co,Mn)substitution ameliorates the dehydriding kinetics dramatically in the order(M=Co)>(M=Mn)>(M=Cu).The electrochemical kinetics of the alloys visibly grows with M content rising for(M=Cu,Co),while it first increases and then declines for(M=Mn).
文摘Thiobacillus ferrooxidans might be the most important bacteria used in biometallurgy. The foundation way of its growth process is oxidizing ferrous in order to obtain energy needed for metabolism, but the variation of ferrous concentration and mixed potential of the culture media would have crucial effect on the bacteria growth. Based on the characteristics of Thiobacillus ferrooxidans growth and redox potential of ferric and ferrous, an electrochemical cell was designed conventionally to study growth rule and the relationship between redox potential and bacteria growth was built up, and some growth kinetics of Thiobacillus ferrooxidans were elucidated. It demonstrates that the variation of open potential of electrochemical cell Δ E shows the growth tendency of Thiobacillus ferrooxidans , at the initial growth stage, the value of Δ E increases slowly, when at logistic growth stage, it increases drastically, and the growth rate of bacteria is linear with the oxidation rate of ferrous. The bacteria growth kinetics model is proposed using Monod and Michealis-Menten equation, and the kinetics parameters are got. The consistence of the measured and the calculated results proves that it is proper to use the proposed kinetics model and the electrochemical cell method to describe the growth rule of Thiobacillus ferrooxidans .
基金Project(50004009) supported by the National Natural Science Foundation of China
文摘Kinetic parameters of the electrode reactions were measured by investigating steady-state current-potential behaviors. The results show that the apparent transfer coefficient of anodic process is 0.0582, diffusion coefficient of thiourea gold complex is 6.04×10~ -6 cm^2/s,anodic reaction order of thiourea is 2.0183, and anodic reaction order of OH^- is 0.0166. The theoretical kinetics equation of gold dissolving in alkaline thiourea solution is deduced, which indicates that anodic reaction order of thiourea is 2, and anodic reaction order of OH^- is 0. The theoretical values of the kinetic parameters are consistent with experimental values very well. The correctness of the mechanism is further demonstrated using apparent transfer coefficient according to the electrochemical dynamic equation of multi-electron reaction.
基金Project(50302016) supported by the National Natural Science Foundation of China
文摘The graphite was modified using pitch through dynamical melt-carbonization, and the effects of modification temperature and the amount of pitch on the characteristics of graphite were investigated. The structure and characteristics of the graphite were determined by X-ray diffractometry(XRD), scanning electron microscopy(SEM), particle size analysis and electrochemical measurements. The results show that the modified graphite has a disordered carbon/graphite composite structure, larger average particle diameter, greater tap density, and better electrochemical characteristics than the untreated graphite. The sample coated with 10% pitch dynamical melt-carbonized at 400 ℃ for 3 h and heat-treated at 850 ℃ for 2 h has better electrochemical performances with a reversible capacity of 360.5 mA·h/g, a irreversible capacity of 41.0 mA·h/g, and an initial coulombic efficiency of 89.8% compared with natural graphite and disordered carbon. The cycling stability of the Li/C cell with modified graphite as anodes is improved, and its capacity retention ratio at the 30th cycle is up to 94.37%.
基金Project(51075350)supported by the National Natural Science Foundation of China
文摘Based on electromagnetics and mechanics, electromechanical coupled dynamic equations for the drive were developed. Using method of perturbation, free vibrations of the mechanical system under electric disturbance were investigated. The forced responses of the mechanical system to mechanical excitation under electric disturbance were also presented. It is known that for the system with electric disturbance, as time grows, beat occurs. When electric disturbing frequency is near to the natural frequencies of the mechanical system or their integer multiple, resonance vibrations occur. The forced responses of the mechanical system to mechanical excitation under electric disturbance are compound vibrations decided by mechanical excitation, electric disturbance and parameters of the system. The coupled resonance vibration caused by electric disturbance and mechanical excitation was discussed as well. The conditions under which above coupled resonance occurs were presented. The results show that when the difference of the excitation frequency and the perturbation frequency is equal to some order of natural frequency, coupled resonance vibrations occur.
基金Project(51275116)supported by the National Natural Science Foundation of ChinaProject(2012ZE77010)supported by the Aero Science Foundation of ChinaProject(LBH-Q11090)supported by the Postdoctoral Science Research Development Foundation of Heilongjiang Province,China
文摘The electric double layer with the transmission of particles was presented based on the principle of electrochemistry.In accordance with this theory,the cavitation catalysis removal mechanism of ultrasonic-pulse electrochemical compound machining(UPECM) based on particles was proposed.The removal mechanism was a particular focus and was thus validated by experiments.The principles and experiments of UPECM were introduced,and the removal model of the UPECM based on the principles of UPECM was established.Furthermore,the effects of the material removal rate for the main processing parameters,including the particles size,the ultrasonic vibration amplitude,the pulse voltage and the minimum machining gap between the tool and the workpiece,were also studied through UPECM.The results show that the particles promote ultrasonic-pulse electrochemical compound machining and thus act as the catalyzer of UPECM.The results also indicate that the processing speed,machining accuracy and surface quality can be improved under UPECM compound machining.
基金Project(NCET-10-0946)supported by Program for New Century Excellent Talents in University of ChinaProject(2017JY0038)supported by Science and Technology Key Project of Sichuan Province,ChinaProject(2013TX8)supported by Titanium and Titanium Alloy Innovation Team of Panzhihua City,China
文摘Anodic oxidation with different electrolyte was employed to improve the electrochemical properties of carbon paper as negative electrode for vanadium redox battery(VRB).The treated carbon paper exhibits enhanced electrochemical activity for V^2+/V^3+redox reaction.The sample(CP-NH3)treated in NH3 solution demonstrates superior performance in comparison with the sample(CP-NaOH)treated in NaOH solution.X-ray photoelectron spectroscopy results show that oxygen-and nitrogen-containing functional groups have been introduced on CP-NH3 surface by the treatment,and Raman spectra confirm the increased surface defect of CP-NH3.Energy storage performance of cell was evaluated by charge/discharge measurement by using CP-NH3.Usage of CP-NH3 can greatly improve the cell performance with energy efficiency increase of 4.8%at 60 mA/cm^2.The excellent performance of CP-NH3 mainly results from introduction of functional groups as active sites and improved wetting properties.This work reveals that anodic oxidation is a clean,simple,and efficient method for boosting the performance of carbon paper as negative electrode for VRB.
基金Project(KF2029)supported by the State Key Laboratory of Automotive Safety and Energy(Tsinghua University),ChinaProject(102253)supported partially by the Innovate UK。
文摘This paper studied a supervisory control system for a hybrid off-highway electric vehicle under the chargesustaining(CS)condition.A new predictive double Q-learning with backup models(PDQL)scheme is proposed to optimize the engine fuel in real-world driving and improve energy efficiency with a faster and more robust learning process.Unlike the existing“model-free”methods,which solely follow on-policy and off-policy to update knowledge bases(Q-tables),the PDQL is developed with the capability to merge both on-policy and off-policy learning by introducing a backup model(Q-table).Experimental evaluations are conducted based on software-in-the-loop(SiL)and hardware-in-the-loop(HiL)test platforms based on real-time modelling of the studied vehicle.Compared to the standard double Q-learning(SDQL),the PDQL only needs half of the learning iterations to achieve better energy efficiency than the SDQL at the end learning process.In the SiL under 35 rounds of learning,the results show that the PDQL can improve the vehicle energy efficiency by 1.75%higher than SDQL.By implementing the PDQL in HiL under four predefined real-world conditions,the PDQL can robustly save more than 5.03%energy than the SDQL scheme.
基金Project(51275499)supported by the National Natural Science Foundation of ChinaProject(2013CB035404)supported by the National Basic Research Program("973" Program)of ChinaProject(51221004)supported by the Science Fund for Creative Research Groups,National Natural Science Foundation of China
文摘A new electro-hydraulic exciter that consists of rotary valve and micro-displacement double-functioned hydraulic cylinder was proposed to realize different kinds of waveforms.Calculated fluid dynamics(CFD) simulation of rotary valve orifice reveals that orifice exists the two-throttle phenomenon.According to the finding,the revised flow area model was established.Vibration waveforms analysis was carried out by means of mathematic model and the related experiments were validated.Furthermore,as a new analysis indicator,saturation percentage was introduced first.The experimental results indicate that the revised flow area model is more accurate compared to the original one,and vibration waveforms can be optimized through suitable spool parameters and the revised cylinder structure.
