为进一步提高动力电池正极材料锰酸锂(LiMn_2O_4)的循环稳定性,通过溶胶-凝胶法用快离子导体La_(0.8)Sr_(0.2)MnO_3作为包覆材料对LiMn_2O_4进行表面修饰,探讨了不同包覆量对复合材料电化学性能的影响。采用X射线衍射仪(XRD)、场发射扫...为进一步提高动力电池正极材料锰酸锂(LiMn_2O_4)的循环稳定性,通过溶胶-凝胶法用快离子导体La_(0.8)Sr_(0.2)MnO_3作为包覆材料对LiMn_2O_4进行表面修饰,探讨了不同包覆量对复合材料电化学性能的影响。采用X射线衍射仪(XRD)、场发射扫描电镜(FESEM)和透射电子显微镜(TEM)对样品的微观结构以及形貌进行表征。结果表明:La_(0.8)Sr_(0.2)MnO_3的包覆并没有改变LiMn_2O_4晶体结构及空间构型;相比纯的LiMn_2O_4样品,La_(0.8)Sr_(0.2)MnO_3包覆后的样品颗粒表面较为粗糙;涂层为薄膜状结构,均匀且完全包覆在LiMn_2O_4颗粒的表面。利用电化学测试方法测试其电化学性能,测试结果表明,当La_(0.8)Sr_(0.2)MnO_3包覆量为5%时,具有较好的电化学性能,首次放电比容量为127.4 m A·h/g(0.1 C),25℃循环400次后容量保持率为91.2%,55℃循环100次后容量保持率为91.1%;与未经表面修饰的样品相比,其首次放电比容量为119.1 m A·h/g(0.1 C),400次的容量保持率为61.9%,100次容量保持率为77.9%,La_(0.8)Sr_(0.2)MnO_3包覆后的样品的电化学性能尤其是循环性能得到明显的提高。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
Direct carbon solid oxide fuel cells(DC-SOFCs)are promising,green,and efficient power-generating devices that are fueled by solid carbons and comprise all-solid-state structures.Developing suitable anode materials for...Direct carbon solid oxide fuel cells(DC-SOFCs)are promising,green,and efficient power-generating devices that are fueled by solid carbons and comprise all-solid-state structures.Developing suitable anode materials for DC-SOFCs is a substantial scientific challenge.Herein we investigated the use of La_(0.75)Sr_(0.25)Cr_(0.5)Mn_(0.5)O_(3)-δ−Ce_(0.8)Gd_(0.2)O_(1.9)(LSCM−GDC)composite electrodes as anodes for La_(0.9)Sr_(0.1)Ga_(0.8)Mg_(0.2)O_(3)-δelectrolyte-based DC-SOFCs,with Camellia oleifera shell char as the carbon fuel.The LSCM−GDC-anode DC-SOFC delivered a maximum power density of 221 mW/cm^(2) at 800℃ and it significantly improved to 425 mW/cm^(2) after Ni nanoparticles were introduced into the LSCM−GDC anode through wet impregnation.The microstructures of the prepared anodes were characterized,and the stability of the anode in a DC-SOFC and the influence of catalytic activity on open circuit voltage were studied.The above results indicate that LSCM–GDC anode is promising to be applied in DC-SOFCs.展开更多
Combustion catalyst La_(0.8)Sr_(0.2)CoO_3 (LSC) is expected to possess relatively high activity for the oxidation of carbon monoxide and many hydrocarbons. If γ-Al_2O_3 is used as its support, cobalt ions can easily ...Combustion catalyst La_(0.8)Sr_(0.2)CoO_3 (LSC) is expected to possess relatively high activity for the oxidation of carbon monoxide and many hydrocarbons. If γ-Al_2O_3 is used as its support, cobalt ions can easily react with γ-Al_2O_3 at not very high temperature to form spinel CoAl_2O_4 or spinel-like, which decreases the activity of the combustion catalyst. In this paper, MgAl_2O_4 and CaAl_2O_4 were pre-coated on γ-Al_2O_3 by impregnation respectively, which formed compound support for LSC. It is shown that, when MgAl_2O_4 layer is covered on the surface of MgAl_2O_4 by impregnation, the entering of cobalt ions into γ-Al_2O_3 lattice is restrained, then LSC formed on the surface of MgAl_2O_4, which leads to a good catalytic activity of xylene complete oxidation. But the layer of MgAl_2O_4 should be thick enough to reach 30% (mass fraction) MgO in the support due to large size particle of MgAl_2O_4 crystalline. If polyvinyl alcohol (PVA) is added into the impregnation solution adequately, MgAl_2O_4 particles formed on the surface of γ-Al_2O_3 are getting smaller, and less amount of MgAl_2O_4 is needed to cover up the surface of γ-Al_2O_3. If CaAl_2O_4 layer substituted for MgAl_2O_4, more closed cover is obtained in virtue of fine particles of CaAl_2O_4. The activity examination shows that smaller particles of MgAl_2O_4 or CaAl_2O_4 can be more effective to hinder cobalt ions entering the lattice of γ-Al_2O_3, and better activities will be obtained.展开更多
La0.8Sr0.2Co1-yFeyO3-δ (y=0.2, 0.4, 0.6, 0.8) powders were synthesized by ethylenediamine tetraacetic acid (EDTA) complexing sol-gel process. The powders were characterized via X-ray diffraction (XRD) and scanning el...La0.8Sr0.2Co1-yFeyO3-δ (y=0.2, 0.4, 0.6, 0.8) powders were synthesized by ethylenediamine tetraacetic acid (EDTA) complexing sol-gel process. The powders were characterized via X-ray diffraction (XRD) and scanning electron microscope and energy dispersive X-ray spectroscopy (SEM-EDS). The results showed that single-phased perovskite-type oxide powders with small particle size were obtained by the process, and the compositions of the productions agreed with the designed molar ratio. The electronic conductivity and ionic conductivity of La0.8Sr0.2Co1-yFeyO3-δ were investigated by DC four-terminal method and AC impedance spectroscopy, respectively. The electronic conductivity of La0.8Sr0.2Co1-yFeyO3-δ is approximately 2～4 orders of magnitude higher than the ionic conductivity. It was confirmed that the conductivities of the materials were strongly influenced by the composition anions, temperature and sample preparing process.展开更多
To promote the electrocatalytic activity and stability of traditional(a_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.8)O_(3-δ)(LSCF)oxygen electrodes in reversible solid oxide cells(RSOCs),conventional physical mixed method was used t...To promote the electrocatalytic activity and stability of traditional(a_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.8)O_(3-δ)(LSCF)oxygen electrodes in reversible solid oxide cells(RSOCs),conventional physical mixed method was used to prepare the Pd-LSCF composite oxygen electrode.The cell with Pd-LSCF|GDC|YSZ|Ni-YSZ configuration shows perfect electrochemical performance in both solid oxide fuel cell(SOFC)mode and solid oxide electrolysis cell(SOEC)mode.In the SOFC mode,the cell achieves a power density of 1.73 W/cm^(2)at800℃higher than that of the LSCF oxygen electrode with 1.38 W/cm^(2).In the SOEC mode,the current density at 1.5 V is 1.67 A/cm^(2)at 800℃under 50 vol%steam concentration.Moreover,the reversibility and stability of the RSOCs were tested during 192 h long-term reversible operation.The degradation rate of the cell is only 2.2%/100 h and 2.5%/100 h in the SOEC and the SOFC modes,respectively.These results confirm that compositing Pd with the LSCF oxygen electrode can considerably boost the electrochemical performance of LSCF electrode in RSOCs field.展开更多
La_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.8)O_(3-δ)(LSCF)is recognized as one of the most promising cathode materials for the highly-desired intermediatetemperature solid oxide fuel cell(IT-SOFC)technology.However,it is still ch...La_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.8)O_(3-δ)(LSCF)is recognized as one of the most promising cathode materials for the highly-desired intermediatetemperature solid oxide fuel cell(IT-SOFC)technology.However,it is still challenged by polarization losses due to reduced operation temperatures.In this work,a series of Ba^(2+)-doped La0.6-xBaxSr0.4Co0.2Fe0.8O3-δ(LBSCFx,x=0.05,0.10,0.15,and 0.20)materials are successfully synthesized and their electrochemical performances are evaluated as a cathode for IT-SOFC technology.The study shows that,compared to the un-doped LSCF,the Ba^(2+)-doped LBSCF possess higher electrical conductivities at 500-800℃ and display lower polarization resistances to oxygen adsorption/dissociation.As a result,the Ni-SDC|SDC|LBSCF0.20 cell(SDC=samarium-doped cerium,Sm_(0.2)Ce_(0.8)O_(1.9))delivers a high maximum power density of 0.704 W/cm^(2)at 750℃,which is>30%higher than the Ni-SDC|SDC|LSCF cell.This work reveals that Ba^(2+)-doping is effective in enhancing oxygen catalytic activity of LSCF-based cathode materials,demonstrating a new and commercial-feasible strategy in developing high performance cathode materials for the IT-SOFC technology.展开更多
The perovskite-type La_(0.8)Sr_(0.2)CoO_(3) supported on the mullite fiber porous ceramics was prepared by means of the impregnating method,and was then characterized by scanning electron microscopy(SEM)and X-ray diff...The perovskite-type La_(0.8)Sr_(0.2)CoO_(3) supported on the mullite fiber porous ceramics was prepared by means of the impregnating method,and was then characterized by scanning electron microscopy(SEM)and X-ray diffraction(XRD);thus we can come to the conclusion that the perovskite-type composite oxidant can disperse on the surface of mullite fiber ceramics.The catalytic activity of the La_(0.8)Sr_(0.2)CoO_(3) for NO and CO was evaluated.The effect of the doped 0.1 wt-%PdCl_(2) on the catalytic activity of the perovskite-type La_(0.8)Sr_(0.2)CoO_(3) was also discussed.The results show that the conversion rates of NO and CO respectively reaches 74.5% and 99% at 601℃ without doped Pd,and both reach 100%at 350℃ with a little doped Pd.展开更多
Efficient electrocatalysis at the cathode is essential for overcoming the limitations of Li-O_(2) batteries such as poor stability and low rate capability.Herein,we systematically studied the kinetic behavior of a Li-...Efficient electrocatalysis at the cathode is essential for overcoming the limitations of Li-O_(2) batteries such as poor stability and low rate capability.Herein,we systematically studied the kinetic behavior of a Li-O_(2) battery comprising perovskite La_(0.8)Sr_(0.2)VO_(3) nanofibers formed by partial Sr-cation doping and V cations with multiple oxidation states.Compared with undoped LaVO_(3) and La_(0.8)Sr_(0.2)VO_(4) nanofibers,perovskite La_(0.8)Sr_(0.2)VO_(3) nanofibers exhibited an improved capacity of 2000 mA g^(-1),and a 20-times-longer cycle life in Li-O_(2) batteries.X-ray photoelectron spectroscopy,electron paramagnetic resonance spectroscopy,and photoluminescence analyses revealed that the performance variations mainly originated from crystal defects,which modulate oxygen reduction/evolution kinetics.Through in situ Raman analysis,we showed that these structural defects are closely related to the oxygen reduction/evolution behavior of La_(0.8)Sr_(0.2)VO_(3) nanofibers and result in fewer parasitic reactions.This study offers insights into the potential rate capability of Li-O_(2) batteries and related devices.展开更多
文摘为进一步提高动力电池正极材料锰酸锂(LiMn_2O_4)的循环稳定性,通过溶胶-凝胶法用快离子导体La_(0.8)Sr_(0.2)MnO_3作为包覆材料对LiMn_2O_4进行表面修饰,探讨了不同包覆量对复合材料电化学性能的影响。采用X射线衍射仪(XRD)、场发射扫描电镜(FESEM)和透射电子显微镜(TEM)对样品的微观结构以及形貌进行表征。结果表明:La_(0.8)Sr_(0.2)MnO_3的包覆并没有改变LiMn_2O_4晶体结构及空间构型;相比纯的LiMn_2O_4样品,La_(0.8)Sr_(0.2)MnO_3包覆后的样品颗粒表面较为粗糙;涂层为薄膜状结构,均匀且完全包覆在LiMn_2O_4颗粒的表面。利用电化学测试方法测试其电化学性能,测试结果表明,当La_(0.8)Sr_(0.2)MnO_3包覆量为5%时,具有较好的电化学性能,首次放电比容量为127.4 m A·h/g(0.1 C),25℃循环400次后容量保持率为91.2%,55℃循环100次后容量保持率为91.1%;与未经表面修饰的样品相比,其首次放电比容量为119.1 m A·h/g(0.1 C),400次的容量保持率为61.9%,100次容量保持率为77.9%,La_(0.8)Sr_(0.2)MnO_3包覆后的样品的电化学性能尤其是循环性能得到明显的提高。
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℃)
基金Project(2019YFC1907405)supported by the National Key R&D Program of ChinaProject(GJJ200809)supported by the Education Department Project Fund of Jiangxi Province,ChinaProject(2020BAB214021)supported by the Natural Science Foundation of Jiangxi Province,China。
文摘Direct carbon solid oxide fuel cells(DC-SOFCs)are promising,green,and efficient power-generating devices that are fueled by solid carbons and comprise all-solid-state structures.Developing suitable anode materials for DC-SOFCs is a substantial scientific challenge.Herein we investigated the use of La_(0.75)Sr_(0.25)Cr_(0.5)Mn_(0.5)O_(3)-δ−Ce_(0.8)Gd_(0.2)O_(1.9)(LSCM−GDC)composite electrodes as anodes for La_(0.9)Sr_(0.1)Ga_(0.8)Mg_(0.2)O_(3)-δelectrolyte-based DC-SOFCs,with Camellia oleifera shell char as the carbon fuel.The LSCM−GDC-anode DC-SOFC delivered a maximum power density of 221 mW/cm^(2) at 800℃ and it significantly improved to 425 mW/cm^(2) after Ni nanoparticles were introduced into the LSCM−GDC anode through wet impregnation.The microstructures of the prepared anodes were characterized,and the stability of the anode in a DC-SOFC and the influence of catalytic activity on open circuit voltage were studied.The above results indicate that LSCM–GDC anode is promising to be applied in DC-SOFCs.
文摘Combustion catalyst La_(0.8)Sr_(0.2)CoO_3 (LSC) is expected to possess relatively high activity for the oxidation of carbon monoxide and many hydrocarbons. If γ-Al_2O_3 is used as its support, cobalt ions can easily react with γ-Al_2O_3 at not very high temperature to form spinel CoAl_2O_4 or spinel-like, which decreases the activity of the combustion catalyst. In this paper, MgAl_2O_4 and CaAl_2O_4 were pre-coated on γ-Al_2O_3 by impregnation respectively, which formed compound support for LSC. It is shown that, when MgAl_2O_4 layer is covered on the surface of MgAl_2O_4 by impregnation, the entering of cobalt ions into γ-Al_2O_3 lattice is restrained, then LSC formed on the surface of MgAl_2O_4, which leads to a good catalytic activity of xylene complete oxidation. But the layer of MgAl_2O_4 should be thick enough to reach 30% (mass fraction) MgO in the support due to large size particle of MgAl_2O_4 crystalline. If polyvinyl alcohol (PVA) is added into the impregnation solution adequately, MgAl_2O_4 particles formed on the surface of γ-Al_2O_3 are getting smaller, and less amount of MgAl_2O_4 is needed to cover up the surface of γ-Al_2O_3. If CaAl_2O_4 layer substituted for MgAl_2O_4, more closed cover is obtained in virtue of fine particles of CaAl_2O_4. The activity examination shows that smaller particles of MgAl_2O_4 or CaAl_2O_4 can be more effective to hinder cobalt ions entering the lattice of γ-Al_2O_3, and better activities will be obtained.
基金the National Natural Science Foundation of China (50204007)the Talent Foundation of Yunnan Province (2005PY01-33)Programfor New Century Excellent Talents in University (NCET-07-0387)
文摘La0.8Sr0.2Co1-yFeyO3-δ (y=0.2, 0.4, 0.6, 0.8) powders were synthesized by ethylenediamine tetraacetic acid (EDTA) complexing sol-gel process. The powders were characterized via X-ray diffraction (XRD) and scanning electron microscope and energy dispersive X-ray spectroscopy (SEM-EDS). The results showed that single-phased perovskite-type oxide powders with small particle size were obtained by the process, and the compositions of the productions agreed with the designed molar ratio. The electronic conductivity and ionic conductivity of La0.8Sr0.2Co1-yFeyO3-δ were investigated by DC four-terminal method and AC impedance spectroscopy, respectively. The electronic conductivity of La0.8Sr0.2Co1-yFeyO3-δ is approximately 2～4 orders of magnitude higher than the ionic conductivity. It was confirmed that the conductivities of the materials were strongly influenced by the composition anions, temperature and sample preparing process.
基金Project supported by the National Key Research&Development Project(2020YFB1506304)the National Natural Science Foundation of China(52172199,52072135,52002121)。
文摘To promote the electrocatalytic activity and stability of traditional(a_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.8)O_(3-δ)(LSCF)oxygen electrodes in reversible solid oxide cells(RSOCs),conventional physical mixed method was used to prepare the Pd-LSCF composite oxygen electrode.The cell with Pd-LSCF|GDC|YSZ|Ni-YSZ configuration shows perfect electrochemical performance in both solid oxide fuel cell(SOFC)mode and solid oxide electrolysis cell(SOEC)mode.In the SOFC mode,the cell achieves a power density of 1.73 W/cm^(2)at800℃higher than that of the LSCF oxygen electrode with 1.38 W/cm^(2).In the SOEC mode,the current density at 1.5 V is 1.67 A/cm^(2)at 800℃under 50 vol%steam concentration.Moreover,the reversibility and stability of the RSOCs were tested during 192 h long-term reversible operation.The degradation rate of the cell is only 2.2%/100 h and 2.5%/100 h in the SOEC and the SOFC modes,respectively.These results confirm that compositing Pd with the LSCF oxygen electrode can considerably boost the electrochemical performance of LSCF electrode in RSOCs field.
基金The project was supported by the National Natural Science Foundation of China(No.51974167)XRD,SEM and TEM examinations were assisted by the Center of Laboratory,Inner Monglia University of Science and Technology.
文摘La_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.8)O_(3-δ)(LSCF)is recognized as one of the most promising cathode materials for the highly-desired intermediatetemperature solid oxide fuel cell(IT-SOFC)technology.However,it is still challenged by polarization losses due to reduced operation temperatures.In this work,a series of Ba^(2+)-doped La0.6-xBaxSr0.4Co0.2Fe0.8O3-δ(LBSCFx,x=0.05,0.10,0.15,and 0.20)materials are successfully synthesized and their electrochemical performances are evaluated as a cathode for IT-SOFC technology.The study shows that,compared to the un-doped LSCF,the Ba^(2+)-doped LBSCF possess higher electrical conductivities at 500-800℃ and display lower polarization resistances to oxygen adsorption/dissociation.As a result,the Ni-SDC|SDC|LBSCF0.20 cell(SDC=samarium-doped cerium,Sm_(0.2)Ce_(0.8)O_(1.9))delivers a high maximum power density of 0.704 W/cm^(2)at 750℃,which is>30%higher than the Ni-SDC|SDC|LSCF cell.This work reveals that Ba^(2+)-doping is effective in enhancing oxygen catalytic activity of LSCF-based cathode materials,demonstrating a new and commercial-feasible strategy in developing high performance cathode materials for the IT-SOFC technology.
基金The work was supported by the National Natural Science Foundation of China(Grant No.50276017)the Natural Science Foundation of Guangdong Province,China(Grant No.2005B10301026).
文摘The perovskite-type La_(0.8)Sr_(0.2)CoO_(3) supported on the mullite fiber porous ceramics was prepared by means of the impregnating method,and was then characterized by scanning electron microscopy(SEM)and X-ray diffraction(XRD);thus we can come to the conclusion that the perovskite-type composite oxidant can disperse on the surface of mullite fiber ceramics.The catalytic activity of the La_(0.8)Sr_(0.2)CoO_(3) for NO and CO was evaluated.The effect of the doped 0.1 wt-%PdCl_(2) on the catalytic activity of the perovskite-type La_(0.8)Sr_(0.2)CoO_(3) was also discussed.The results show that the conversion rates of NO and CO respectively reaches 74.5% and 99% at 601℃ without doped Pd,and both reach 100%at 350℃ with a little doped Pd.
基金work was supported by the National Research Foun-dation of Korea(NRF)Grant funded by the Ministry of Science and ICT(2019R1A2B5B02070203)by the Creative Materials Discovery Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Science and ICT(2018M3D1A1058744).
文摘Efficient electrocatalysis at the cathode is essential for overcoming the limitations of Li-O_(2) batteries such as poor stability and low rate capability.Herein,we systematically studied the kinetic behavior of a Li-O_(2) battery comprising perovskite La_(0.8)Sr_(0.2)VO_(3) nanofibers formed by partial Sr-cation doping and V cations with multiple oxidation states.Compared with undoped LaVO_(3) and La_(0.8)Sr_(0.2)VO_(4) nanofibers,perovskite La_(0.8)Sr_(0.2)VO_(3) nanofibers exhibited an improved capacity of 2000 mA g^(-1),and a 20-times-longer cycle life in Li-O_(2) batteries.X-ray photoelectron spectroscopy,electron paramagnetic resonance spectroscopy,and photoluminescence analyses revealed that the performance variations mainly originated from crystal defects,which modulate oxygen reduction/evolution kinetics.Through in situ Raman analysis,we showed that these structural defects are closely related to the oxygen reduction/evolution behavior of La_(0.8)Sr_(0.2)VO_(3) nanofibers and result in fewer parasitic reactions.This study offers insights into the potential rate capability of Li-O_(2) batteries and related devices.
