With exceptional capacity during high-voltage cycling,P3-type Nadeficient layered oxide cathodes have captured substantial attention.Nevertheless,they are plagued by severe capacity degradation over cycling.In this st...With exceptional capacity during high-voltage cycling,P3-type Nadeficient layered oxide cathodes have captured substantial attention.Nevertheless,they are plagued by severe capacity degradation over cycling.In this study,tuning and optimizing the phase composition in layered oxides through Li incorporation are proposed to enhance the high-voltage stability.The structural dependence of layered Na_(2/3)LixNi_(0.25)Mn_(0.75)O_(2)þδoxides on the lithium content(0.0≤x≤1.0)offered during synthesis is investigated systematically on an atomic scale.Surprisingly,increasing the Li content triggers the formation of mixed P2/O3-type or P3/P2/O3-type layered phases.As the voltage window is 1.5-4.5 V,P3-type Na2/3Ni_(0.25)Mn_(0.75)O_(2)(NL0.0NMO,R3m)material exhibits a sequence of phase transformations throughout the process of(de)sodiation,that is,O3⇌P3⇌O30⇌O3″.Such complicated phase transitions can be effectively suppressed in the Na2/3Li_(0.7)Ni_(0.25)Mn_(0.75)O_(2.4)(NL_(0.7)NMO)oxide with P2/P3/O3-type mixed phases.Consequently,cathodes made of NL0.7NMO exhibit a substantially enhanced cyclic performance at high voltages compared to that of the P3-type layered NL0.0NMO cathode.Specifically,NL0.7NMO demonstrates an outstanding capacity retention of 98%after 10 cycles at 1 C within 1.5-4.5 V,much higher than that of NL0.0NMO(83%).This work delves into the intricate realm of bolstering the high-voltage durability of layered oxide cathodes,paving the way for advanced sodium-ion battery technologies.展开更多
Stimuli responsive materials have recently been the subject of tremendous research efforts owing to their numerous potential applications. Although there currently exist many different types of ＂smart＂ materials, th...Stimuli responsive materials have recently been the subject of tremendous research efforts owing to their numerous potential applications. Although there currently exist many different types of ＂smart＂ materials, those based on photoresponsive transformations are especially attractive. In this review, we focus on a relatively new class of photochromic molecules based on the photochemistry of chelate organoborates, which form intensely colored, base-stabilized boriranes.Recent efforts to exploit the reactivity of these systems are summarized, and future prospects in materials science discussed.展开更多
Layered alkali-containing 3d transition-metal oxides are of the utmost importance in the use of electrode materials for advanced energy storage applications such as Li-,Na-,or K-ion batteries.A significant challenge i...Layered alkali-containing 3d transition-metal oxides are of the utmost importance in the use of electrode materials for advanced energy storage applications such as Li-,Na-,or K-ion batteries.A significant challenge in the field of materials chemistry is understanding the dynamics of the chemical reactions between alkali-free precursors and alkali species during the synthesis of these compounds.In this study,in situ high-resolution synchrotron-based X-ray diffraction was applied to reveal the Li/Na/K-ion insertion-induced structural transformation mechanism during high-temperature solid-state reaction.The in situ diffraction results demonstrate that the chemical reaction pathway strongly depends on the alkali-free precursor type,which is a structural matrix enabling phase transi-tions.Quantitative phase analysis identifies for the first time the decomposition of lithium sources as the most critical factor for the formation of metastable intermediates or impurities during the entire process of Li-rich layered Li[Li_(0.2)Ni_(0.2)Mn_(0.6)]O_(2) formation.Since the alkali ions have different ionic radii,Na/K ions tend to be located on prismatic sites in the defective layered structure(Na_(2/3-x)[Ni_(0.25)Mn_(0.75)]O_(2) or K_(2/3-x)[Ni_(0.25)Mn_(0.75)]O_(2))during calcination,whereas the Li ions prefer to be localized on the tetrahedral and/or octahedral sites,forming O-type structures.展开更多
基金Distinguished Young Foundation of Sichuan Province,Grant/Award Number:2020JDJQ0027National Natural Science Foundation of China,Grant/Award Numbers:22108218,20A20145,21878195+2 种基金German Research Foundation,Grant/Award Number:390874152“Young Talent Support Plan”of Xi'an Jiaotong University,Grant/Award Number:HG6J016Qinchuangyuan Innovative Talent Project,Grant/Award Number:QCYRCXM-2022-137。
文摘With exceptional capacity during high-voltage cycling,P3-type Nadeficient layered oxide cathodes have captured substantial attention.Nevertheless,they are plagued by severe capacity degradation over cycling.In this study,tuning and optimizing the phase composition in layered oxides through Li incorporation are proposed to enhance the high-voltage stability.The structural dependence of layered Na_(2/3)LixNi_(0.25)Mn_(0.75)O_(2)þδoxides on the lithium content(0.0≤x≤1.0)offered during synthesis is investigated systematically on an atomic scale.Surprisingly,increasing the Li content triggers the formation of mixed P2/O3-type or P3/P2/O3-type layered phases.As the voltage window is 1.5-4.5 V,P3-type Na2/3Ni_(0.25)Mn_(0.75)O_(2)(NL0.0NMO,R3m)material exhibits a sequence of phase transformations throughout the process of(de)sodiation,that is,O3⇌P3⇌O30⇌O3″.Such complicated phase transitions can be effectively suppressed in the Na2/3Li_(0.7)Ni_(0.25)Mn_(0.75)O_(2.4)(NL_(0.7)NMO)oxide with P2/P3/O3-type mixed phases.Consequently,cathodes made of NL0.7NMO exhibit a substantially enhanced cyclic performance at high voltages compared to that of the P3-type layered NL0.0NMO cathode.Specifically,NL0.7NMO demonstrates an outstanding capacity retention of 98%after 10 cycles at 1 C within 1.5-4.5 V,much higher than that of NL0.0NMO(83%).This work delves into the intricate realm of bolstering the high-voltage durability of layered oxide cathodes,paving the way for advanced sodium-ion battery technologies.
基金financially supported by the Natural Science and Engineering Research Council of Canada (RGPIN:1193993-2013)the National Natural Science Foundation of China (21501017)
文摘Stimuli responsive materials have recently been the subject of tremendous research efforts owing to their numerous potential applications. Although there currently exist many different types of ＂smart＂ materials, those based on photoresponsive transformations are especially attractive. In this review, we focus on a relatively new class of photochromic molecules based on the photochemistry of chelate organoborates, which form intensely colored, base-stabilized boriranes.Recent efforts to exploit the reactivity of these systems are summarized, and future prospects in materials science discussed.
基金the National Natural Science Foundation of China(grant no.22108218)“Young Talent Support Plan”of Xi'an Jiaotong University(71211201010723)+6 种基金This work was financially supported by the China Postdoctoral Science Foundation(Grant No.2021M693813)Guangxi Science and Technology Base and Talents Special Project(Grant No.AD21159007)the Natural Science Foundation of Guangxi(Grant No.2020GXNSFBA297029)the Foundation of Key Laboratory of New Processing Technology for Nonferrous Metal&Materials,Ministry of Education/Guangxi Key Laboratory of Optical and Electronic Materials and Devices,Guilin University of Technology(Contract No.20AA-13)the Foundation of Guilin University of Tech-nology(GLUTQDJJ2020003)High Level Innovation Team and Outstanding Scholar Program of Guangxi Institutes.We acknowledge DESY(Hamburg,Germany),a member of the Helmholtz Association HGF,and Paul Scherrer Institut(Villigen PSI,Switzerland)for the provision of experimental facilitiescontributes to the research performed at CELEST(Center for Electro-chemical Energy Storage Ulm-Karlsruhe)and was supported by the German Research Foundation(DFG)under Project ID 390874152(POLiS Cluster of Excellence).
文摘Layered alkali-containing 3d transition-metal oxides are of the utmost importance in the use of electrode materials for advanced energy storage applications such as Li-,Na-,or K-ion batteries.A significant challenge in the field of materials chemistry is understanding the dynamics of the chemical reactions between alkali-free precursors and alkali species during the synthesis of these compounds.In this study,in situ high-resolution synchrotron-based X-ray diffraction was applied to reveal the Li/Na/K-ion insertion-induced structural transformation mechanism during high-temperature solid-state reaction.The in situ diffraction results demonstrate that the chemical reaction pathway strongly depends on the alkali-free precursor type,which is a structural matrix enabling phase transi-tions.Quantitative phase analysis identifies for the first time the decomposition of lithium sources as the most critical factor for the formation of metastable intermediates or impurities during the entire process of Li-rich layered Li[Li_(0.2)Ni_(0.2)Mn_(0.6)]O_(2) formation.Since the alkali ions have different ionic radii,Na/K ions tend to be located on prismatic sites in the defective layered structure(Na_(2/3-x)[Ni_(0.25)Mn_(0.75)]O_(2) or K_(2/3-x)[Ni_(0.25)Mn_(0.75)]O_(2))during calcination,whereas the Li ions prefer to be localized on the tetrahedral and/or octahedral sites,forming O-type structures.
