Polycrystalline La-doped CaMnO3 ceramics have been prepared by a solid-state sintering method. Analysis of microstructure and phase composition indicates that the addition of La can prohibit the further growth of grai...Polycrystalline La-doped CaMnO3 ceramics have been prepared by a solid-state sintering method. Analysis of microstructure and phase composition indicates that the addition of La can prohibit the further growth of grain, and no impurity phase appears. The results revealed that the La doping can lead to a large change of the activation energy (from 0.2:2 to 0.02 eV), and thus result in a marked increase in electric conductivity of 2-4 orders of magnitude. The power factor can reach about 1.5×10-4 W.m-1.K-2 in a wide temperature range, which potentially make them attractive for n-type high-temperature thermoelectric materials.展开更多
A breakthrough in advancing power density and stability of carbon-based supercapacitors is trapped by inefficient pore structures of electrode materials.Herein,an ultramicroporous carbon with ultrahigh integrated capa...A breakthrough in advancing power density and stability of carbon-based supercapacitors is trapped by inefficient pore structures of electrode materials.Herein,an ultramicroporous carbon with ultrahigh integrated capacitance fabricated via one-step carbonization/activation of dense bacterial cellulose(BC)precursor followed by nitrogen/sulfur dual doping is reported.The microporous carbon possesses highly concentrated micropores(~2 nm)and a considerable amount of sub-micropores(<1 nm).The unique porous structure provides high specific surface area(1554 m^2 g^-1)and packing density(1.18 g cm^-3).The synergistic effects from the particular porous structure and optimal doping effectively enhance ion storage and ion/electron transport.As a result,the remarkable specific capacitances,including ultrahigh gravimetric and volumetric capacitances(430 F g^-1 and 507 F cm^-3 at 0.5 A g^-1),and excellent cycling and rate stability even at a high current density of 10 A g^-1(327 F g^-1 and 385 F cm^-3)are realized.Via compositing the porous carbon and BC skeleton,a robust all-solid-state cellulose-based supercapacitor presents super high areal energy density(~0.77 mWh cm^-2),volumetric energy density(~17.8 W L^-1),and excellent cyclic stability.展开更多
Oxide-based ceramics could be promising thermoelectric materials because of their thermal and chemical stability at high temperature.However,their mediocre electrical conductivity or high thermal conductivity is still...Oxide-based ceramics could be promising thermoelectric materials because of their thermal and chemical stability at high temperature.However,their mediocre electrical conductivity or high thermal conductivity is still a challenge for the use in commercial devices.Here,we report significantly suppressed thermal conductivity in SrTiO_(3)-based thermoelectric ceramics via high-entropy strategy for the first time,and optimized electrical conductivity by defect engineering.In high-entropy(Ca_(0.2)Sr_(0.2)Ba_(0.2)Pb_(0.2)La_(0.2))TiO_(3)bulks,the minimum thermal conductivity can be 1.17 W/(m·K)at 923 K,which should be ascribed to the large lattice distortion and the huge mass fluctuation effect.The power factor can reach about 295μW/(m·K^(2))by inducing oxygen vacancies.Finally,the ZT value of 0.2 can be realized at 873 K in this bulk sample.This approach proposed a new concept of high entropy into thermoelectric oxides,which could be generalized for designing high-performance thermoelectric oxides with low thermal conductivity.展开更多
Ca3Co409/polyaniline bulk composites have been successfully fabricated by ball-milling and hot-pressing method. Our results indicate that the Seebeck coefficient can be increased nearly by 400% with adding 15 wt% 0a3C...Ca3Co409/polyaniline bulk composites have been successfully fabricated by ball-milling and hot-pressing method. Our results indicate that the Seebeck coefficient can be increased nearly by 400% with adding 15 wt% 0a3Co409 to the polyaniline. The thermal conductivity changes slightly with increasing filler content. The highest figure of merit, ZT can reach 5× 10-4 at 329 K for these bulk composites, which is almost 50 times larger than that of pure polyaniline, suggesting that the polymer-thermoelectric oxide composites are promising candidates for light-weight, low-cost and non-toxic thermoelectric applications.展开更多
Dy-doped CaMnO3 ceramics have been synthesized by co-precipitation method combined with the solid-state reaction.Phase composition and microstructure analysis indicate that high density and pure CaMnO3 phase can be ac...Dy-doped CaMnO3 ceramics have been synthesized by co-precipitation method combined with the solid-state reaction.Phase composition and microstructure analysis indicate that high density and pure CaMnO3 phase can be achieved.The electric conductivity can be enhanced by Dy doping,and result in a slight increase of the thermal conductivity.The highest dimensionless figure of merit ZT of 0.15 has been obtained at 973 K for x = 0.02 sample,which is about 4 times larger than that of the pure CaMnO3,which indicate that CaMnO3can be a promising candidate for n-type thermoelectric material at high temperature.展开更多
Inl.9aZn0.03Ge0.0303 and Sr2RuEr06 composite ceramics have been prepared by the spark plasma sintering (SPS) technique. Microstructure studies show that the Sr2RuErO6 phases are randomly dispersed in the In1.94Zn0.0...Inl.9aZn0.03Ge0.0303 and Sr2RuEr06 composite ceramics have been prepared by the spark plasma sintering (SPS) technique. Microstructure studies show that the Sr2RuErO6 phases are randomly dispersed in the In1.94Zn0.03Ge0.03O3 matrix. The results show that the Seebeck coefficient increases with increasing the amount of Sr2RuErO6, while the thermal conductivity of the composite samples is lower than that of the Inl.9aZno.03Ge0.03O3 ceramic. The thermal conductivity of the 7 vol.% Sr2RuErO6 sample can decrease to 2.15 W.m-1.K-1 at 973 K, and the evaluated maximum ZT value is 0.23 for 3 vol.% Sr2RuErO6 samples at 973 K, which makes them promising materials for the thermoelectric devices.展开更多
基金supported by the National Program on Key Basic Research Project ("973 Program")under grant No.2007CB607505the National High Technology Research and Development Program of China under grant No.2009AAO3Z216
文摘Polycrystalline La-doped CaMnO3 ceramics have been prepared by a solid-state sintering method. Analysis of microstructure and phase composition indicates that the addition of La can prohibit the further growth of grain, and no impurity phase appears. The results revealed that the La doping can lead to a large change of the activation energy (from 0.2:2 to 0.02 eV), and thus result in a marked increase in electric conductivity of 2-4 orders of magnitude. The power factor can reach about 1.5×10-4 W.m-1.K-2 in a wide temperature range, which potentially make them attractive for n-type high-temperature thermoelectric materials.
文摘A breakthrough in advancing power density and stability of carbon-based supercapacitors is trapped by inefficient pore structures of electrode materials.Herein,an ultramicroporous carbon with ultrahigh integrated capacitance fabricated via one-step carbonization/activation of dense bacterial cellulose(BC)precursor followed by nitrogen/sulfur dual doping is reported.The microporous carbon possesses highly concentrated micropores(~2 nm)and a considerable amount of sub-micropores(<1 nm).The unique porous structure provides high specific surface area(1554 m^2 g^-1)and packing density(1.18 g cm^-3).The synergistic effects from the particular porous structure and optimal doping effectively enhance ion storage and ion/electron transport.As a result,the remarkable specific capacitances,including ultrahigh gravimetric and volumetric capacitances(430 F g^-1 and 507 F cm^-3 at 0.5 A g^-1),and excellent cycling and rate stability even at a high current density of 10 A g^-1(327 F g^-1 and 385 F cm^-3)are realized.Via compositing the porous carbon and BC skeleton,a robust all-solid-state cellulose-based supercapacitor presents super high areal energy density(~0.77 mWh cm^-2),volumetric energy density(~17.8 W L^-1),and excellent cyclic stability.
基金financially supported by Basic Science Center Project of the National Natural Science Foundation of China under Grant No.51788104National Key Research Program of China under Grant No.2016YFA0201003the National Natural Science Foundation of China under Grant No.51729201。
文摘Oxide-based ceramics could be promising thermoelectric materials because of their thermal and chemical stability at high temperature.However,their mediocre electrical conductivity or high thermal conductivity is still a challenge for the use in commercial devices.Here,we report significantly suppressed thermal conductivity in SrTiO_(3)-based thermoelectric ceramics via high-entropy strategy for the first time,and optimized electrical conductivity by defect engineering.In high-entropy(Ca_(0.2)Sr_(0.2)Ba_(0.2)Pb_(0.2)La_(0.2))TiO_(3)bulks,the minimum thermal conductivity can be 1.17 W/(m·K)at 923 K,which should be ascribed to the large lattice distortion and the huge mass fluctuation effect.The power factor can reach about 295μW/(m·K^(2))by inducing oxygen vacancies.Finally,the ZT value of 0.2 can be realized at 873 K in this bulk sample.This approach proposed a new concept of high entropy into thermoelectric oxides,which could be generalized for designing high-performance thermoelectric oxides with low thermal conductivity.
基金supported by the National Basic Research Program of China("973 Program",No.2013CB632506)the National Natural Science Foundation of China(No.51025205)the Specialized Research Fund for the Doctoral Program of Higher Education(No.20120002110006)
文摘Ca3Co409/polyaniline bulk composites have been successfully fabricated by ball-milling and hot-pressing method. Our results indicate that the Seebeck coefficient can be increased nearly by 400% with adding 15 wt% 0a3Co409 to the polyaniline. The thermal conductivity changes slightly with increasing filler content. The highest figure of merit, ZT can reach 5× 10-4 at 329 K for these bulk composites, which is almost 50 times larger than that of pure polyaniline, suggesting that the polymer-thermoelectric oxide composites are promising candidates for light-weight, low-cost and non-toxic thermoelectric applications.
基金financially supported by the Ministry of Sci & Tech of China through a 973 Project,under grant No. 2013CB632506the National Natural Science Foundation of China under Grant Nos.51025205 and 11234012the Specialized Research Fund for the Doctoral Program of Higher Education,under grant No.20120002110006
文摘Dy-doped CaMnO3 ceramics have been synthesized by co-precipitation method combined with the solid-state reaction.Phase composition and microstructure analysis indicate that high density and pure CaMnO3 phase can be achieved.The electric conductivity can be enhanced by Dy doping,and result in a slight increase of the thermal conductivity.The highest dimensionless figure of merit ZT of 0.15 has been obtained at 973 K for x = 0.02 sample,which is about 4 times larger than that of the pure CaMnO3,which indicate that CaMnO3can be a promising candidate for n-type thermoelectric material at high temperature.
基金supported by the National Basic Research Program of China under Crant No.2007CB607504supported by the National High Technology Research and Development Program of China,under grant No.2009AA03Z216
文摘Inl.9aZn0.03Ge0.0303 and Sr2RuEr06 composite ceramics have been prepared by the spark plasma sintering (SPS) technique. Microstructure studies show that the Sr2RuErO6 phases are randomly dispersed in the In1.94Zn0.03Ge0.03O3 matrix. The results show that the Seebeck coefficient increases with increasing the amount of Sr2RuErO6, while the thermal conductivity of the composite samples is lower than that of the Inl.9aZno.03Ge0.03O3 ceramic. The thermal conductivity of the 7 vol.% Sr2RuErO6 sample can decrease to 2.15 W.m-1.K-1 at 973 K, and the evaluated maximum ZT value is 0.23 for 3 vol.% Sr2RuErO6 samples at 973 K, which makes them promising materials for the thermoelectric devices.