Direct methanol fuel cells(DMFCs) have attracted extensive attention as promising next-generation energy conversion devices. However, commercialized proton exchange membranes(PEMs) hardly fulfill the demand of methano...Direct methanol fuel cells(DMFCs) have attracted extensive attention as promising next-generation energy conversion devices. However, commercialized proton exchange membranes(PEMs) hardly fulfill the demand of methanol tolerance for DMFCs employing high-concentration methanol solutions.Herein, we report a series of semi-crystalline poly(arylene ether ketone) PEMs with ultra-densely sulfonic-acid-functionalized pendants linked by flexible alkyl chains, namely, SL-SPEK-x(where x represents the molar ratio of the novel monomer containing multiple phenyl side chain to the bisfluoride monomers). The delicate structural design rendered SL-SPEK-x membranes with high crystallinity and well-defined nanoscale phase separation between hydrophilic and hydrophobic phases. The reinforcement from poly(ether ketone) crystals enabled membranes with inhibited dimensional variation and methanol penetration. Furthermore, microphase separation significantly enhanced proton conductivity. The SL-SPEK-12.5 membrane achieved the optimum trade-off between proton conductivity(0.182 S cm^(-1), 80 ℃), water swelling(13.6%, 80 ℃), and methanol permeability(1.6 × 10^(-7)cm~2 s^(-1)). The DMFC assembled by the SL-SPEK-12.5 membrane operated smoothly with a 10 M methanol solution, outputting a maximum power density of 158.3 mW cm^(-2), nearly twice that of Nafion 117(94.2 mW cm^(-2)). Overall, the novel structural optimization strategy provides the possibility of PEMs surviving in high-concentration methanol solutions, thus facilitating the miniaturization and portability of DMFC devices.展开更多
Flexible joints are usually used to transfer velocities in robot systems and may lead to delays in motion transformation due to joint flexibility. In this paper, a linkrotor structure connected by a flexible joint or ...Flexible joints are usually used to transfer velocities in robot systems and may lead to delays in motion transformation due to joint flexibility. In this paper, a linkrotor structure connected by a flexible joint or shaft is firstly modeled to be a slow-fast delayed system when moment of inertia of the lightweight link is far less than that of the heavy rotor. To analyze the stability and oscillations of the slowfast system, the geometric singular perturbation method is extended, with both slow and fast manifolds expressed analytically. The stability of the slow manifold is investigated and critical boundaries are obtained to divide the stable and the unstable regions. To study effects of the transformation delay on the stability and oscillations of the link, two quantitatively different driving forces derived from the negative feedback of the link are considered. The results show that one of these two typical driving forces may drive the link to exhibit a stable state and the other kind of driving force may induce a relaxation oscillation for a very small delay. However, the link loses stability and undergoes regular periodic and bursting oscillation when the transformation delay is large. Basically, a very small delay does not affect the stability of the slow manifold but a large delay affects substantially.展开更多
This paper is mainly focused on the attitude dynamics and control of a fuel-filled flexible spacecraft sub- jected to the thermal payload during eclipse transitions. The flexible appendages are considered as Euler-Ber...This paper is mainly focused on the attitude dynamics and control of a fuel-filled flexible spacecraft sub- jected to the thermal payload during eclipse transitions. The flexible appendages are considered as Euler-Bernoulli beams, and the sloshing liquid is modeled as in two modes multi-spring-mass models; the governing equations of this coupled system are developed by using Hamilton＇s prin- ciple. Numerical results show that the spacecraft attitude responses consist of a quasi-static displacement and superim- posed vibration. Then, we design an adaptive sliding mode and use the Lyapunov approach control law to control the attitude disturbance and suppress the thermal jitter and liq- uid sloshing for the fuel filled flexible spacecraft subject to the thermal payload. Numerical results are presented to verify the efficiency of the hybrid control methods. The results show that the adaptive sliding mode method might be effective to handle the steady-state errors and the Lyapunov control algo- rithm would suppress the residual vibration.展开更多
The development of aqueous battery with dual mechanisms is now arousing more and more interest.The dual mechanisms of Zn^(2+)(de)intercalation and I^(-)/I_(2)redox bring unexpected effects.Herein,differing from previo...The development of aqueous battery with dual mechanisms is now arousing more and more interest.The dual mechanisms of Zn^(2+)(de)intercalation and I^(-)/I_(2)redox bring unexpected effects.Herein,differing from previous studies using Zn I_(2)additive,this work designs an aqueous Bi I_(3)-Zn battery with selfsupplied I^(-).Ex situ tests reveal the conversion of Bi I_(3)into Bi(discharge)and Bi OI(charge)at the 1st cycle and the dissolved I^(-)in electrolyte.The active I^(-)species enhances the specific capacity and discharge medium voltage of electrode as well as improves the generation of Zn dendrite and by-product.Furthermore,the porous hard carbon is introduced to enhance the electronic/ionic conductivity and adsorb iodine species,proven by experimental and theoretical studies.Accordingly,the well-designed Bi I_(3)-Zn battery delivers a high reversible capacity of 182 m A h g^(-1)at 0.2 A g^(-1),an excellent rate capability with 88 m A h g^(-1)at 10 A g^(-1),and an impressive cyclability with 63%capacity retention over 20 K cycles at 10 A g^(-1).An excellent electrochemical performance is obtained even at a high mass loading of 6 mg cm^(-2).Moreover,a flexible quasi-solid-state Bi I_(3)-Zn battery exhibits satisfactory battery performances.This work provides a new idea for designing high-performance aqueous battery with dual mechanisms.展开更多
The concept of the liquid Li17Pb83 and Helium gas dual-cooled Fuel Breeding Blanket (FBB) for the Fusion-Driven sub-critical System (FDS) is presented and analyzed. Taking self-sustaining tritium (TBR >1.05) and an...The concept of the liquid Li17Pb83 and Helium gas dual-cooled Fuel Breeding Blanket (FBB) for the Fusion-Driven sub-critical System (FDS) is presented and analyzed. Taking self-sustaining tritium (TBR >1.05) and annual output of 100 kg or more fissile 239Pu (FBR > 0.238) as objective parameters, and based on the three-dimensional Monte Carlo neutron-photon transport code MCNP/4A, a neutronics-optimizated calculation of different cases was carried out and the concept is proved feasible. In addition, the total breeding ratio ( BR = TBR + FBR ) is listed corresponding to different cases.展开更多
Mixed ionic-electronic conductors in the family of LaxSr1-xCoyFe1-y O3-δ have been widely studied as cathode materials for solid oxide fuel cells （SOFCs）. However, the long-term stability was a concern. Here we rep...Mixed ionic-electronic conductors in the family of LaxSr1-xCoyFe1-y O3-δ have been widely studied as cathode materials for solid oxide fuel cells （SOFCs）. However, the long-term stability was a concern. Here we report our findings on the effect of a thin film coating of La0.85Sr0.15MnO3-δ （LSM） on the performance of a porous La0.6Sr0.4Co0.2Feo.8O3-δ（LSCF） cathode. When the thicknesses of the LSM coatings are appropriate, an LSM-coated LSCF electrode showed better stability and lower polarization （or higher activity） than the blank LSCF cathode without LSM infiltration. An anode-supported cell with an LSM-infiltrated LSCF cathode demonstrated at 825 ℃ a peak power density of -1.07 W/cm2, about 24% higher than that of the same cell without LSM infiltration （-0.86 W/cm2）. Further, the LSM coating enhanced the stability of the electrode; there was little degradation in performance for the cell with an LSM-infiltrated LSCF cathode during 100 h operation.展开更多
A nitrate-citrate combustion route to synthesize La0.9Sr0.1Ga0.8Mg0.2O3-σ powder for solid oxide fuel cell application was presented. This route is based on the gelling of nitrate solutions by the addition of citric ...A nitrate-citrate combustion route to synthesize La0.9Sr0.1Ga0.8Mg0.2O3-σ powder for solid oxide fuel cell application was presented. This route is based on the gelling of nitrate solutions by the addition of citric acid and ammonium hydroxide, followed by an intense combustion process due to an exothermic redox reaction between nitrate and citrate ions. The optimum technical parameters are that the pH value is 5, and the molar ratio of citric acid to the total metallic ion is 1.5:1. X-ray diffraction characterization of calcined gel shows that pure phase was synthesized after calcination at 1400℃for 10 h, and the TEM result shovvs the calcined powder with average particle size is about 150 nm. The grain resistance contributes to the total resistance of sintered peliet below 500℃. The conductivity of the sintered peliet at 800℃ was 0.07 S-1·cm-1 higher than the conductivity of YSZ (0.05 S-1·cm-1 at 800℃)展开更多
This study investigates the transfer of the scrape-applied method from the electrodes of a lithium battery to the membrane-electrode assembly of fuel cells, including Proton Exchange Membrane Fuel Cells and Direct Met...This study investigates the transfer of the scrape-applied method from the electrodes of a lithium battery to the membrane-electrode assembly of fuel cells, including Proton Exchange Membrane Fuel Cells and Direct Methanol Fuel Cell. Three methods are commonly used to manufacture lithium battery electrodes： the roller-applied method, the spraying-applied method, and the scrape-applied method. This study develops novel scrape-applied equip- ment for lithium battery electrodes. This method is novel and suitable for producing fuel cell, better than other tradi- tional methods. In this study, the stability of coating process was tested by measuring the weight and thickness of a dry electrode. The stability and reproducibility of electrode fab- rication were examined by systematic data analysis. Finally, the study used a specially designed single cell composed of 16 conductive segments, which are insulated locally. The current passing through each segment was measured using Hall Effect sensors connected to the segment compartments. Based on the measured distribution of the local current in a segmented single cell, the influence of flooding and stoi- chiometry variation of feed gas was discussed in terms of electrochemical reaction rate. The experimental results serve as an important basis for future research in this field, which hold potential benefits to the academia and the industry.展开更多
Promoting the oxygen reduction reaction(ORR)is critical for commercialization of intermediate-temperature solid oxide fuel cells(IT-SOFCs),where Sr_(2)Fe_(1.5)Mo_(0.5)O_(6)−δ(SFM)is a promising cathode by working as ...Promoting the oxygen reduction reaction(ORR)is critical for commercialization of intermediate-temperature solid oxide fuel cells(IT-SOFCs),where Sr_(2)Fe_(1.5)Mo_(0.5)O_(6)−δ(SFM)is a promising cathode by working as a mixed ionic and electronic conductor.In this work,doping of In^(3+)greatly increases the oxygen vacancy concentration and the content of adsorbed oxygen species in Sr_(2)Fe_(1.5)Mo_(0.5−x)InxO_(6−δ)(SFMInx),and thus effectively promotes the ORR performance.As a typical example,SFMIn_(0.1)reduces the polarization resistance(R_(p))from 0.089 to 0.046Ω∙cm^(2)at 800°C,which is superior to those doped with other metal elements.In addition,SFMIn0.1 increases the peak power density from 0.92 to 1.47 W∙cm^(−2)at 800°C with humidified H_(2)as the fuel,indicating that In3+doping at the Mo site can effectively improve the performance of SOFC cathode material.展开更多
The FCSE controlling equation of pinned thinwalled curve box was derived and the indeterminate problem of continuous thin-walled curve box with diaphragm was solved based on flexibility theory. With Bayesian statistic...The FCSE controlling equation of pinned thinwalled curve box was derived and the indeterminate problem of continuous thin-walled curve box with diaphragm was solved based on flexibility theory. With Bayesian statistical theory,dynamic Bayesian error function of displacement parameters of indeterminate curve box was founded. The corresponding formulas of dynamic Bayesian expectation and variance were deduced. Combined with one-dimensional Fibonacci automatic search scheme of optimal step size,the Powell optimization theory was utilized to research the stochastic identification of displacement parameters of indeterminate thin-walled curve box. Then the identification steps were presented in detail and the corresponding calculation procedure was compiled. Through some classic examples,it is obtained that stochastic performances of systematic parameters and systematic responses are simultaneously deliberated in dynamic Bayesian error function. The one-dimensional optimization problem of the optimal step size is solved by adopting Fibonacci search method. And the Powell identification of displacement parameters of indeterminate thin-walled curve box has satisfied numerical stability and convergence,which demonstrates that the presented method and the compiled procedure are correct and reliable.During parameters鈥？iterative processes,the Powell theory is irrelevant with the calculation of finite curve strip element（FCSE） partial differentiation,which proves high computation effciency of the studied method.展开更多
Extracts are important components of fuels. Fatty-extracts with high heating value （HV） are hypothe- sized by researchers as positively related to the HV of fuels. The Soxhlet extractor is typically used to extract ...Extracts are important components of fuels. Fatty-extracts with high heating value （HV） are hypothe- sized by researchers as positively related to the HV of fuels. The Soxhlet extractor is typically used to extract fatty-extracts but it has shortcomings, including long processing time （8-10 h） and the requirement for large amounts of organic solvent. Supercritical extraction is an alternate and useful technique for extraction of natural products. However, published studies rarely discuss the relationship between extracts and HV. In this study, we assessed the supercritical extracts （SUE） of forest fuels in the Great Xing＇an Mountains. Our results indicated that the optimum conditions for extraction of SuEs were 40-60 mesh, 40-50 MPa, 45℃, 80 min and a CO2 flow rate of 1.5-2.0 dm3/min. The Soxhlet extracts contents and the SuE contents were all related to HV. However, R2 of the coniferous samples （0.8499） and needle samples （0.9722） demonstrated that the correlation between HV and the SuE content was closer. We conclude that supercritical fatty-extracts provide a useful index of the HV of fuels, especially coniferous fuels. SuE data can be used in fire management, for example to estimate the rate of fire spread or fire intensity.展开更多
Ba_(1.03)Ce_(0.8)Eu_(0.2)O_(3-α) solid electrolyte with nonstoichiometric composition was prepared by high temperature solid-state reaction. Phase composition, surface and fracture morphologies of the specimen were c...Ba_(1.03)Ce_(0.8)Eu_(0.2)O_(3-α) solid electrolyte with nonstoichiometric composition was prepared by high temperature solid-state reaction. Phase composition, surface and fracture morphologies of the specimen were characterized by using XRD and SEM, respectively. Ionic conduction was researched by gas concentration cell, the performance of hydrogen-air fuel cell was measured in the temperature range of 600～1000 ℃, and compared them with those of BaCe_(0.8)Eu_(0.2)O_(3-α) and Ba_(0.98)Ce_(0.8)Eu_(0.2)O_(3-α). The results indicate that Ba_(1.03)Ce_(0.8)Eu_(0.2)O_(3-α) is a single-phase perovskite-type orthorhombic system. It is a pure proton conductor in the temperature range of 600～1000 ℃ in hydrogen atmosphere, and its proton conduction is superior to that of BaCe_(0.8)Eu_(0.2)O_(3-α) and Ba_(0.98)Ce_(0.8)Eu_(0.2)O_(3-α). It is a mixed conductor of oxide ion and electron hole in oxygen atmosphere. At 1000 ℃, the performance of the fuel cell in which Ba_(1.03)Ce_(0.8)Eu_(0.2)O_(3-α) as electrolyte is higher than that of BaCe_(0.8)Eu_(0.2)O_(3-α) or Ba_(0.98)Ce_(0.8)Eu_(0.2)O_(3-α).展开更多
The precursors of La0.7Sr0.3-xCaxCo0.9Fe0.1O3-δ(LSCCF, x=0.05, 0.10, 0.15, 0.20) as the cathode materials for intermediate temperature solid oxide fuel cell (ITSOFC) were prepared by reverse titration co-precipitatio...The precursors of La0.7Sr0.3-xCaxCo0.9Fe0.1O3-δ(LSCCF, x=0.05, 0.10, 0.15, 0.20) as the cathode materials for intermediate temperature solid oxide fuel cell (ITSOFC) were prepared by reverse titration co-precipitation method with metal-nitrates as starting materials and mixed alkali (NaOH and Na2CO3) as a precipitating agent. The formation process of LSCCF from the precursors was monitored by TG-DSC, and the crystal structure and particles morphology of the precursors which were calcined at 600, 800, 1000 ℃ for 3 h were characterized using XRD, SEM technologies. Compared with the solid state reaction of constituent oxides, when the pH value of the precipitating solution was in the range of 9.1～9.5, the LSCCF powders from the precursors caclined at 800 ℃ for 3 h had high purity, homogeneous and single perovskite phase. The electrical conductivity of the LSCCF samples sintered at 1200 ℃ for 3 h, which was measured as a function of temperatures from 100 to 800 ℃ by DC four-probe method in air, decreased with x from 0.05 to 0.20. The value of electrical conductivity was almost equal because of Ca2+, Sr2+ co-dopant resulting in the 'mix effect' while x=0.10 or 0.15. The electrical conductivity of all doped samples was higher than 100 S·cm-1 at intermediate temperatures from 500 to 800 ℃, and there was good compatibility between the LSCCF cathode and Ce0.8Sm0.2O2 electrolyte.展开更多
基金supported by the program of Jilin Provincial Department of Science and Technology (YDZJ202301ZYTS320)。
文摘Direct methanol fuel cells(DMFCs) have attracted extensive attention as promising next-generation energy conversion devices. However, commercialized proton exchange membranes(PEMs) hardly fulfill the demand of methanol tolerance for DMFCs employing high-concentration methanol solutions.Herein, we report a series of semi-crystalline poly(arylene ether ketone) PEMs with ultra-densely sulfonic-acid-functionalized pendants linked by flexible alkyl chains, namely, SL-SPEK-x(where x represents the molar ratio of the novel monomer containing multiple phenyl side chain to the bisfluoride monomers). The delicate structural design rendered SL-SPEK-x membranes with high crystallinity and well-defined nanoscale phase separation between hydrophilic and hydrophobic phases. The reinforcement from poly(ether ketone) crystals enabled membranes with inhibited dimensional variation and methanol penetration. Furthermore, microphase separation significantly enhanced proton conductivity. The SL-SPEK-12.5 membrane achieved the optimum trade-off between proton conductivity(0.182 S cm^(-1), 80 ℃), water swelling(13.6%, 80 ℃), and methanol permeability(1.6 × 10^(-7)cm~2 s^(-1)). The DMFC assembled by the SL-SPEK-12.5 membrane operated smoothly with a 10 M methanol solution, outputting a maximum power density of 158.3 mW cm^(-2), nearly twice that of Nafion 117(94.2 mW cm^(-2)). Overall, the novel structural optimization strategy provides the possibility of PEMs surviving in high-concentration methanol solutions, thus facilitating the miniaturization and portability of DMFC devices.
基金supported by the National Natural Science Foundation of China(11032009 and 11272236)
文摘Flexible joints are usually used to transfer velocities in robot systems and may lead to delays in motion transformation due to joint flexibility. In this paper, a linkrotor structure connected by a flexible joint or shaft is firstly modeled to be a slow-fast delayed system when moment of inertia of the lightweight link is far less than that of the heavy rotor. To analyze the stability and oscillations of the slowfast system, the geometric singular perturbation method is extended, with both slow and fast manifolds expressed analytically. The stability of the slow manifold is investigated and critical boundaries are obtained to divide the stable and the unstable regions. To study effects of the transformation delay on the stability and oscillations of the link, two quantitatively different driving forces derived from the negative feedback of the link are considered. The results show that one of these two typical driving forces may drive the link to exhibit a stable state and the other kind of driving force may induce a relaxation oscillation for a very small delay. However, the link loses stability and undergoes regular periodic and bursting oscillation when the transformation delay is large. Basically, a very small delay does not affect the stability of the slow manifold but a large delay affects substantially.
基金supported by the National Natural Science Foundation of China(NNSFC)(Grant 11472041)the Research Fund for the Doctoral Program of Higher Education of China(Grant 20131101110002)
文摘This paper is mainly focused on the attitude dynamics and control of a fuel-filled flexible spacecraft sub- jected to the thermal payload during eclipse transitions. The flexible appendages are considered as Euler-Bernoulli beams, and the sloshing liquid is modeled as in two modes multi-spring-mass models; the governing equations of this coupled system are developed by using Hamilton＇s prin- ciple. Numerical results show that the spacecraft attitude responses consist of a quasi-static displacement and superim- posed vibration. Then, we design an adaptive sliding mode and use the Lyapunov approach control law to control the attitude disturbance and suppress the thermal jitter and liq- uid sloshing for the fuel filled flexible spacecraft subject to the thermal payload. Numerical results are presented to verify the efficiency of the hybrid control methods. The results show that the adaptive sliding mode method might be effective to handle the steady-state errors and the Lyapunov control algo- rithm would suppress the residual vibration.
基金funding from National Natural Science Foundation of China(52103053,52102312)Huxiang Young Talents of Hunan Province(2022RC1004)+1 种基金Macao Young Scholars Program(AM2021011)Foundation of State Key Laboratory of Utilization of Woody Oil Resource(GZKF202126)。
文摘The development of aqueous battery with dual mechanisms is now arousing more and more interest.The dual mechanisms of Zn^(2+)(de)intercalation and I^(-)/I_(2)redox bring unexpected effects.Herein,differing from previous studies using Zn I_(2)additive,this work designs an aqueous Bi I_(3)-Zn battery with selfsupplied I^(-).Ex situ tests reveal the conversion of Bi I_(3)into Bi(discharge)and Bi OI(charge)at the 1st cycle and the dissolved I^(-)in electrolyte.The active I^(-)species enhances the specific capacity and discharge medium voltage of electrode as well as improves the generation of Zn dendrite and by-product.Furthermore,the porous hard carbon is introduced to enhance the electronic/ionic conductivity and adsorb iodine species,proven by experimental and theoretical studies.Accordingly,the well-designed Bi I_(3)-Zn battery delivers a high reversible capacity of 182 m A h g^(-1)at 0.2 A g^(-1),an excellent rate capability with 88 m A h g^(-1)at 10 A g^(-1),and an impressive cyclability with 63%capacity retention over 20 K cycles at 10 A g^(-1).An excellent electrochemical performance is obtained even at a high mass loading of 6 mg cm^(-2).Moreover,a flexible quasi-solid-state Bi I_(3)-Zn battery exhibits satisfactory battery performances.This work provides a new idea for designing high-performance aqueous battery with dual mechanisms.
基金This work was supported by the Chinese Academy of Sciences and the National Natural Science Foundation of China No.10175068.
文摘The concept of the liquid Li17Pb83 and Helium gas dual-cooled Fuel Breeding Blanket (FBB) for the Fusion-Driven sub-critical System (FDS) is presented and analyzed. Taking self-sustaining tritium (TBR >1.05) and annual output of 100 kg or more fissile 239Pu (FBR > 0.238) as objective parameters, and based on the three-dimensional Monte Carlo neutron-photon transport code MCNP/4A, a neutronics-optimizated calculation of different cases was carried out and the concept is proved feasible. In addition, the total breeding ratio ( BR = TBR + FBR ) is listed corresponding to different cases.
基金supported by the Department of Energy (National Energy Technology Laboratory) SECA Core Technology Program under Award Number DE-NT0006557 and DE-FE0009652by NSFC under grant No.51002182
文摘Mixed ionic-electronic conductors in the family of LaxSr1-xCoyFe1-y O3-δ have been widely studied as cathode materials for solid oxide fuel cells （SOFCs）. However, the long-term stability was a concern. Here we report our findings on the effect of a thin film coating of La0.85Sr0.15MnO3-δ （LSM） on the performance of a porous La0.6Sr0.4Co0.2Feo.8O3-δ（LSCF） cathode. When the thicknesses of the LSM coatings are appropriate, an LSM-coated LSCF electrode showed better stability and lower polarization （or higher activity） than the blank LSCF cathode without LSM infiltration. An anode-supported cell with an LSM-infiltrated LSCF cathode demonstrated at 825 ℃ a peak power density of -1.07 W/cm2, about 24% higher than that of the same cell without LSM infiltration （-0.86 W/cm2）. Further, the LSM coating enhanced the stability of the electrode; there was little degradation in performance for the cell with an LSM-infiltrated LSCF cathode during 100 h operation.
基金The authors acknowledge financial support from 863 National Project(No.2003AA302440).
文摘A nitrate-citrate combustion route to synthesize La0.9Sr0.1Ga0.8Mg0.2O3-σ powder for solid oxide fuel cell application was presented. This route is based on the gelling of nitrate solutions by the addition of citric acid and ammonium hydroxide, followed by an intense combustion process due to an exothermic redox reaction between nitrate and citrate ions. The optimum technical parameters are that the pH value is 5, and the molar ratio of citric acid to the total metallic ion is 1.5:1. X-ray diffraction characterization of calcined gel shows that pure phase was synthesized after calcination at 1400℃for 10 h, and the TEM result shovvs the calcined powder with average particle size is about 150 nm. The grain resistance contributes to the total resistance of sintered peliet below 500℃. The conductivity of the sintered peliet at 800℃ was 0.07 S-1·cm-1 higher than the conductivity of YSZ (0.05 S-1·cm-1 at 800℃)
文摘This study investigates the transfer of the scrape-applied method from the electrodes of a lithium battery to the membrane-electrode assembly of fuel cells, including Proton Exchange Membrane Fuel Cells and Direct Methanol Fuel Cell. Three methods are commonly used to manufacture lithium battery electrodes： the roller-applied method, the spraying-applied method, and the scrape-applied method. This study develops novel scrape-applied equip- ment for lithium battery electrodes. This method is novel and suitable for producing fuel cell, better than other tradi- tional methods. In this study, the stability of coating process was tested by measuring the weight and thickness of a dry electrode. The stability and reproducibility of electrode fab- rication were examined by systematic data analysis. Finally, the study used a specially designed single cell composed of 16 conductive segments, which are insulated locally. The current passing through each segment was measured using Hall Effect sensors connected to the segment compartments. Based on the measured distribution of the local current in a segmented single cell, the influence of flooding and stoi- chiometry variation of feed gas was discussed in terms of electrochemical reaction rate. The experimental results serve as an important basis for future research in this field, which hold potential benefits to the academia and the industry.
基金acknowledge the Autonomous Region Key Research Project(No.2022D02D31)the Graduate Education Innovation Project(No.XJ2022G046)。
文摘Promoting the oxygen reduction reaction(ORR)is critical for commercialization of intermediate-temperature solid oxide fuel cells(IT-SOFCs),where Sr_(2)Fe_(1.5)Mo_(0.5)O_(6)−δ(SFM)is a promising cathode by working as a mixed ionic and electronic conductor.In this work,doping of In^(3+)greatly increases the oxygen vacancy concentration and the content of adsorbed oxygen species in Sr_(2)Fe_(1.5)Mo_(0.5−x)InxO_(6−δ)(SFMInx),and thus effectively promotes the ORR performance.As a typical example,SFMIn_(0.1)reduces the polarization resistance(R_(p))from 0.089 to 0.046Ω∙cm^(2)at 800°C,which is superior to those doped with other metal elements.In addition,SFMIn0.1 increases the peak power density from 0.92 to 1.47 W∙cm^(−2)at 800°C with humidified H_(2)as the fuel,indicating that In3+doping at the Mo site can effectively improve the performance of SOFC cathode material.
基金supported by the National Natural Science Foundation of China (10472045, 10772078 and 11072108)the Science Foundation of NUAA(S0851-013)
文摘The FCSE controlling equation of pinned thinwalled curve box was derived and the indeterminate problem of continuous thin-walled curve box with diaphragm was solved based on flexibility theory. With Bayesian statistical theory,dynamic Bayesian error function of displacement parameters of indeterminate curve box was founded. The corresponding formulas of dynamic Bayesian expectation and variance were deduced. Combined with one-dimensional Fibonacci automatic search scheme of optimal step size,the Powell optimization theory was utilized to research the stochastic identification of displacement parameters of indeterminate thin-walled curve box. Then the identification steps were presented in detail and the corresponding calculation procedure was compiled. Through some classic examples,it is obtained that stochastic performances of systematic parameters and systematic responses are simultaneously deliberated in dynamic Bayesian error function. The one-dimensional optimization problem of the optimal step size is solved by adopting Fibonacci search method. And the Powell identification of displacement parameters of indeterminate thin-walled curve box has satisfied numerical stability and convergence,which demonstrates that the presented method and the compiled procedure are correct and reliable.During parameters鈥？iterative processes,the Powell theory is irrelevant with the calculation of finite curve strip element（FCSE） partial differentiation,which proves high computation effciency of the studied method.
基金sponsored by the National Natural Science Foundation of China(Grant number:31170618)the National Key Technologies R&D Program of China(Grant number2011BAD32B05)
文摘Extracts are important components of fuels. Fatty-extracts with high heating value （HV） are hypothe- sized by researchers as positively related to the HV of fuels. The Soxhlet extractor is typically used to extract fatty-extracts but it has shortcomings, including long processing time （8-10 h） and the requirement for large amounts of organic solvent. Supercritical extraction is an alternate and useful technique for extraction of natural products. However, published studies rarely discuss the relationship between extracts and HV. In this study, we assessed the supercritical extracts （SUE） of forest fuels in the Great Xing＇an Mountains. Our results indicated that the optimum conditions for extraction of SuEs were 40-60 mesh, 40-50 MPa, 45℃, 80 min and a CO2 flow rate of 1.5-2.0 dm3/min. The Soxhlet extracts contents and the SuE contents were all related to HV. However, R2 of the coniferous samples （0.8499） and needle samples （0.9722） demonstrated that the correlation between HV and the SuE content was closer. We conclude that supercritical fatty-extracts provide a useful index of the HV of fuels, especially coniferous fuels. SuE data can be used in fire management, for example to estimate the rate of fire spread or fire intensity.
文摘Ba_(1.03)Ce_(0.8)Eu_(0.2)O_(3-α) solid electrolyte with nonstoichiometric composition was prepared by high temperature solid-state reaction. Phase composition, surface and fracture morphologies of the specimen were characterized by using XRD and SEM, respectively. Ionic conduction was researched by gas concentration cell, the performance of hydrogen-air fuel cell was measured in the temperature range of 600～1000 ℃, and compared them with those of BaCe_(0.8)Eu_(0.2)O_(3-α) and Ba_(0.98)Ce_(0.8)Eu_(0.2)O_(3-α). The results indicate that Ba_(1.03)Ce_(0.8)Eu_(0.2)O_(3-α) is a single-phase perovskite-type orthorhombic system. It is a pure proton conductor in the temperature range of 600～1000 ℃ in hydrogen atmosphere, and its proton conduction is superior to that of BaCe_(0.8)Eu_(0.2)O_(3-α) and Ba_(0.98)Ce_(0.8)Eu_(0.2)O_(3-α). It is a mixed conductor of oxide ion and electron hole in oxygen atmosphere. At 1000 ℃, the performance of the fuel cell in which Ba_(1.03)Ce_(0.8)Eu_(0.2)O_(3-α) as electrolyte is higher than that of BaCe_(0.8)Eu_(0.2)O_(3-α) or Ba_(0.98)Ce_(0.8)Eu_(0.2)O_(3-α).
基金the National High-Tech Development Plan (2006AA05Z417)the Natural Science Foundation of Lia-oning Province (20062145)the Education department of Liaoning Province (05L073)
文摘The precursors of La0.7Sr0.3-xCaxCo0.9Fe0.1O3-δ(LSCCF, x=0.05, 0.10, 0.15, 0.20) as the cathode materials for intermediate temperature solid oxide fuel cell (ITSOFC) were prepared by reverse titration co-precipitation method with metal-nitrates as starting materials and mixed alkali (NaOH and Na2CO3) as a precipitating agent. The formation process of LSCCF from the precursors was monitored by TG-DSC, and the crystal structure and particles morphology of the precursors which were calcined at 600, 800, 1000 ℃ for 3 h were characterized using XRD, SEM technologies. Compared with the solid state reaction of constituent oxides, when the pH value of the precipitating solution was in the range of 9.1～9.5, the LSCCF powders from the precursors caclined at 800 ℃ for 3 h had high purity, homogeneous and single perovskite phase. The electrical conductivity of the LSCCF samples sintered at 1200 ℃ for 3 h, which was measured as a function of temperatures from 100 to 800 ℃ by DC four-probe method in air, decreased with x from 0.05 to 0.20. The value of electrical conductivity was almost equal because of Ca2+, Sr2+ co-dopant resulting in the 'mix effect' while x=0.10 or 0.15. The electrical conductivity of all doped samples was higher than 100 S·cm-1 at intermediate temperatures from 500 to 800 ℃, and there was good compatibility between the LSCCF cathode and Ce0.8Sm0.2O2 electrolyte.
