The growth of γ-In_(2)Se_(3) thin films on mica by molecular beam epitaxy is studied. Single-crystalline γ-In_(2)Se_(3) is achieved at a relatively low growth temperature. An ultrathin β-In_(2)Se_(3) buffer layer i...The growth of γ-In_(2)Se_(3) thin films on mica by molecular beam epitaxy is studied. Single-crystalline γ-In_(2)Se_(3) is achieved at a relatively low growth temperature. An ultrathin β-In_(2)Se_(3) buffer layer is observed to nucleate and grow through a process of self-organization at initial deposition, which facilitates subsequent monolithic epitaxy of single-crystallineγ-In_(2)Se_(3) at low temperature. Strong room-temperature photoluminescence and moderate optoelectronic response are observed in the achieved γ-In_(2)Se_(3) thin films.展开更多
FeSO_(4) has the characteristics of low cost and theoretical high energy density(799 W·h·kg^(-1) with a two-electron reaction),which can meet the demand for next-generation lithium-ion batteries.Herein,FeSO_...FeSO_(4) has the characteristics of low cost and theoretical high energy density(799 W·h·kg^(-1) with a two-electron reaction),which can meet the demand for next-generation lithium-ion batteries.Herein,FeSO_(4) as a novel highperformance conversion-reaction type cathode is investigated.We use dopamine as a carbon coating source to increase its electronic conductivity.FeSO_(4)@C demonstrates a high reversible specific capacity(512 mA·h·g^(-1))and a superior cycling performance(482 mA·h·g^(-1) after 250 cycles).In addition,we further study its reaction mechanism.The FeSO_(4) is converted to Fe and Li2SO_(4) during lithium ion insertion and the Fe-Li_(2)SO_(4) grain boundaries further store additional lithium ions.Our findings are valuable in exploring other new conversion-type lithium ion battery cathodes.展开更多
随着金属锂电池和全固态锂电池的发展,具有高能量密度无锂/少锂正极材料逐渐受到大家的广泛关注。该文通过一步固相法合成了结晶良好的微米颗粒少锂正极材料β-Li0.3V2O5,电子电导率为2.20×10-4 S/cm。该材料具有良好的循环性能,在...随着金属锂电池和全固态锂电池的发展,具有高能量密度无锂/少锂正极材料逐渐受到大家的广泛关注。该文通过一步固相法合成了结晶良好的微米颗粒少锂正极材料β-Li0.3V2O5,电子电导率为2.20×10-4 S/cm。该材料具有良好的循环性能,在2.2~4.0 V区间,0.5C电流下可逆容量为247 m A·h/g,循环100周仍有204 mA·h/g;同时倍率性能优异,在10C下容量为160 m A·h/g。利用非原位XRD,研究了该材料在1.5~4.0 V区间锂的嵌入/脱出过程的相变化,具体过程为:β(0<x<0.27)→β’(0.57<x<0.75)→β1(0.57<x<1.92)→β2(0.75<x<1.92)→β3(1.92<x<2.52)。整个充放电过程中,体积形变较小,晶胞参数a最大形变为3.1%(β2),晶胞参数c最大形变为4.5%(β3)。展开更多
Pyrite FeS_(2)exhibits an ultrahigh energy density(1671 W·h·kg^(-1),for the reaction of FeS_(2)+4Li=Fe+2Li_(2)S)in secondary lithium-ion batteries,but its poor cycling stability,huge volume expansion,the shu...Pyrite FeS_(2)exhibits an ultrahigh energy density(1671 W·h·kg^(-1),for the reaction of FeS_(2)+4Li=Fe+2Li_(2)S)in secondary lithium-ion batteries,but its poor cycling stability,huge volume expansion,the shuttle effect of polysulfides,and slow kinetic properties limit its practical application.In this work,we synthesize a composite structure material CoS on FeS_(2)surface(FeSx@CoS,1<x≤2)by using a cobalt-containing MOF to improve its cycle stability.It is found that CoS inhibits the side reactions and adsorbs polysulfides.As a result,the modified FeS_(2)shows a higher discharge capacity of 577 mA·h·g^(-1)(919 W·h·kg^(-1))after 60 cycles than 484 mA·h·g^(-1)(778 W·h·kg^(-1))of bare pyrite FeS_(2).This efficient strategy provides a valuable step toward the realization of high cycling stability FeS_(2)cathode materials for secondary lithium-ion batteries and enriches the basic understanding of the influence of FeS_(2)interfacial stability on its electrochemical performances.展开更多
Epitaxial growth and structural characteristics of metastableβ-In2Se3 thin films on H-terminated Si(111)substrates are studied.The In2Se3 thin films grown below theβ-to-αphase transition temperature(453 K)are chara...Epitaxial growth and structural characteristics of metastableβ-In2Se3 thin films on H-terminated Si(111)substrates are studied.The In2Se3 thin films grown below theβ-to-αphase transition temperature(453 K)are characterized to be strainedβ-In2Se3 mixed with significantγ-In2Se3 phases.The pure-phased single-crystallineβ-In2Se3 can be reproducibly achieved by in situ annealing the as-deposited poly-crystalline In2Se3 within the phase equilibrium temperature window ofβ-In2Se3.It is suggeted that the observedγ-to-βphase transition triggered by quite a low annealing temperature should be a rather lowered phase transition barrier of the epitaxy-stabilized In2Se3 thin-film system at a state far from thermodynamic equilibrium.展开更多
基金Project supported by the National Key R&D Program of China(Grant Nos.2018YFA0306102 and 2018YFA0306703)the National Natural Science Foundation of China(Grant No.61474014)+1 种基金the Sichuan Science and Technology Program,China(Grant No.2019YJ0202)the University Program for Elaborate Courses of Postgraduates。
文摘The growth of γ-In_(2)Se_(3) thin films on mica by molecular beam epitaxy is studied. Single-crystalline γ-In_(2)Se_(3) is achieved at a relatively low growth temperature. An ultrathin β-In_(2)Se_(3) buffer layer is observed to nucleate and grow through a process of self-organization at initial deposition, which facilitates subsequent monolithic epitaxy of single-crystallineγ-In_(2)Se_(3) at low temperature. Strong room-temperature photoluminescence and moderate optoelectronic response are observed in the achieved γ-In_(2)Se_(3) thin films.
基金Supported by the Fundamental Research Funds for the Central Universities,China(Grant No.ZYGX2019Z008)the National Natural Science Foundation of China(Grant No.52072061)。
文摘FeSO_(4) has the characteristics of low cost and theoretical high energy density(799 W·h·kg^(-1) with a two-electron reaction),which can meet the demand for next-generation lithium-ion batteries.Herein,FeSO_(4) as a novel highperformance conversion-reaction type cathode is investigated.We use dopamine as a carbon coating source to increase its electronic conductivity.FeSO_(4)@C demonstrates a high reversible specific capacity(512 mA·h·g^(-1))and a superior cycling performance(482 mA·h·g^(-1) after 250 cycles).In addition,we further study its reaction mechanism.The FeSO_(4) is converted to Fe and Li2SO_(4) during lithium ion insertion and the Fe-Li_(2)SO_(4) grain boundaries further store additional lithium ions.Our findings are valuable in exploring other new conversion-type lithium ion battery cathodes.
文摘随着金属锂电池和全固态锂电池的发展,具有高能量密度无锂/少锂正极材料逐渐受到大家的广泛关注。该文通过一步固相法合成了结晶良好的微米颗粒少锂正极材料β-Li0.3V2O5,电子电导率为2.20×10-4 S/cm。该材料具有良好的循环性能,在2.2~4.0 V区间,0.5C电流下可逆容量为247 m A·h/g,循环100周仍有204 mA·h/g;同时倍率性能优异,在10C下容量为160 m A·h/g。利用非原位XRD,研究了该材料在1.5~4.0 V区间锂的嵌入/脱出过程的相变化,具体过程为:β(0<x<0.27)→β’(0.57<x<0.75)→β1(0.57<x<1.92)→β2(0.75<x<1.92)→β3(1.92<x<2.52)。整个充放电过程中,体积形变较小,晶胞参数a最大形变为3.1%(β2),晶胞参数c最大形变为4.5%(β3)。
基金Project supported by the Fundamental Research Funds for the Central Universities,China(Grant No.ZYGX2019Z008)the National Natural Science Foundation of China(Grant No.52072061).
文摘Pyrite FeS_(2)exhibits an ultrahigh energy density(1671 W·h·kg^(-1),for the reaction of FeS_(2)+4Li=Fe+2Li_(2)S)in secondary lithium-ion batteries,but its poor cycling stability,huge volume expansion,the shuttle effect of polysulfides,and slow kinetic properties limit its practical application.In this work,we synthesize a composite structure material CoS on FeS_(2)surface(FeSx@CoS,1<x≤2)by using a cobalt-containing MOF to improve its cycle stability.It is found that CoS inhibits the side reactions and adsorbs polysulfides.As a result,the modified FeS_(2)shows a higher discharge capacity of 577 mA·h·g^(-1)(919 W·h·kg^(-1))after 60 cycles than 484 mA·h·g^(-1)(778 W·h·kg^(-1))of bare pyrite FeS_(2).This efficient strategy provides a valuable step toward the realization of high cycling stability FeS_(2)cathode materials for secondary lithium-ion batteries and enriches the basic understanding of the influence of FeS_(2)interfacial stability on its electrochemical performances.
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2018YFA0306102 and 2018YFA0306703)the National Natural Science Foundation of China(Grant Nos.61474014 and U1601208)the Sichuan Science and Technology Program,China(Grant Nos.2019YJ0202 and 20GJHZ0229).
文摘Epitaxial growth and structural characteristics of metastableβ-In2Se3 thin films on H-terminated Si(111)substrates are studied.The In2Se3 thin films grown below theβ-to-αphase transition temperature(453 K)are characterized to be strainedβ-In2Se3 mixed with significantγ-In2Se3 phases.The pure-phased single-crystallineβ-In2Se3 can be reproducibly achieved by in situ annealing the as-deposited poly-crystalline In2Se3 within the phase equilibrium temperature window ofβ-In2Se3.It is suggeted that the observedγ-to-βphase transition triggered by quite a low annealing temperature should be a rather lowered phase transition barrier of the epitaxy-stabilized In2Se3 thin-film system at a state far from thermodynamic equilibrium.
