Spinel LiNi_(0.5)Mn_(1.5)O_(4)(LNMO)cathode material doped with Ti and La co-doping were synthesized through a solid-state method.The bi-functions of the Ti and La co-doping is realized.On the one hand,the stability o...Spinel LiNi_(0.5)Mn_(1.5)O_(4)(LNMO)cathode material doped with Ti and La co-doping were synthesized through a solid-state method.The bi-functions of the Ti and La co-doping is realized.On the one hand,the stability of the LiNi_(0.5)Mn_(1.5)O_(4)crystal structure is enhanced and the Mn3t interference inside the material is reduced by the Ti doping.On the other hand,the co-doped La contributes to the formation of Li_(0.5)La_(0.5)TiO_(3)(LLTO)superionic conductor incorporated in the bulk LiNi_(0.5)Mn_(1.5)O_(4)phase,thereby enhancing the Li diffusion.With the help of XRD,FTIR,SEM and STEM techniques,La and Ti in the crystallographic structure and the dispersion of the LLTO superionic conductor in the bulk LNMO spinel are discussed.At the optimized molar ratio of 20:1 between LNMO and LLTO,the composite exhibits the best electrochemical performances in terms of the reversible capacity,rate capability and cycling stability.The lithium ion diffusion coefficient in the bulk LNMO phase is tripled by the LLTO superionic conductor incorporation.展开更多
Lead-free double perovskite nanocrystals(NCs),such as Cs2AgInCl6,have attracted considerable attention as stable and non-toxic alternatives to lead-based perovskites.However,the low photoluminescence(PL)intensity of p...Lead-free double perovskite nanocrystals(NCs),such as Cs2AgInCl6,have attracted considerable attention as stable and non-toxic alternatives to lead-based perovskites.However,the low photoluminescence(PL)intensity of pristine Cs_(2)AgInCl_(6)limits its practical applications.In this study,a series of Cs_(2)AgIn_(1−γ−x)Bi_(x)La_(γ)Cl_(6)NCs were synthesized to break the parity-forbidden transition and modify the associated optical functionalities.A broadband bright warm-white emission in the visible region was achieved,with an excellent PL quantum yield of 60%.The dynamic mechanism,involving ultrafast transient absorption,suggests that high-efficiency PL is induced by triplet self-trapping exciton emission.The incorporation of La^(3+)-Bi^(3)+facilitated the singlet–triplet transition by increasing the lifetime and quickening the intersystem crossing process.This finding provides a reliable method for optimizing the optical properties of emerging lead-free halide perovskite NCs.展开更多
基金This work is financially supported by the National Natural Science Foundation of China(NSFC,contract no.21875154 and 21473120)The authors also thank the Ministry of Science and Technology of the People's Republic of China,China(Contract No.2015AA034601).
文摘Spinel LiNi_(0.5)Mn_(1.5)O_(4)(LNMO)cathode material doped with Ti and La co-doping were synthesized through a solid-state method.The bi-functions of the Ti and La co-doping is realized.On the one hand,the stability of the LiNi_(0.5)Mn_(1.5)O_(4)crystal structure is enhanced and the Mn3t interference inside the material is reduced by the Ti doping.On the other hand,the co-doped La contributes to the formation of Li_(0.5)La_(0.5)TiO_(3)(LLTO)superionic conductor incorporated in the bulk LiNi_(0.5)Mn_(1.5)O_(4)phase,thereby enhancing the Li diffusion.With the help of XRD,FTIR,SEM and STEM techniques,La and Ti in the crystallographic structure and the dispersion of the LLTO superionic conductor in the bulk LNMO spinel are discussed.At the optimized molar ratio of 20:1 between LNMO and LLTO,the composite exhibits the best electrochemical performances in terms of the reversible capacity,rate capability and cycling stability.The lithium ion diffusion coefficient in the bulk LNMO phase is tripled by the LLTO superionic conductor incorporation.
基金the National Key Research and Development Program of China(2017YFA0204800)the National Natural Science Foundation of China(21833009,21533010,and 21525315)+2 种基金the Scientific Instrument Developing Project of the Chinese Academy of Sciences(YJKYYQ20190003)Liaoning Revitalization Talents Program(XLYC1802126)Dalian City Foundation for Science and Technology Innovation(2019J12GX031).
文摘Lead-free double perovskite nanocrystals(NCs),such as Cs2AgInCl6,have attracted considerable attention as stable and non-toxic alternatives to lead-based perovskites.However,the low photoluminescence(PL)intensity of pristine Cs_(2)AgInCl_(6)limits its practical applications.In this study,a series of Cs_(2)AgIn_(1−γ−x)Bi_(x)La_(γ)Cl_(6)NCs were synthesized to break the parity-forbidden transition and modify the associated optical functionalities.A broadband bright warm-white emission in the visible region was achieved,with an excellent PL quantum yield of 60%.The dynamic mechanism,involving ultrafast transient absorption,suggests that high-efficiency PL is induced by triplet self-trapping exciton emission.The incorporation of La^(3+)-Bi^(3)+facilitated the singlet–triplet transition by increasing the lifetime and quickening the intersystem crossing process.This finding provides a reliable method for optimizing the optical properties of emerging lead-free halide perovskite NCs.
