为降低Li_(1+x)Al_(x)Ti_(2-x)(PO_(4))_(3)(LATP)电解质膜与锂金属负极之间的界面阻抗,抑制LATP与锂金属之间的副反应以及锂枝晶的生长,提高LATP电解质膜的性能,使用PVDF对LATP基电解质膜界面进行修饰,并研究其电化学性能。将LATP陶瓷...为降低Li_(1+x)Al_(x)Ti_(2-x)(PO_(4))_(3)(LATP)电解质膜与锂金属负极之间的界面阻抗,抑制LATP与锂金属之间的副反应以及锂枝晶的生长,提高LATP电解质膜的性能,使用PVDF对LATP基电解质膜界面进行修饰,并研究其电化学性能。将LATP陶瓷粉末与聚氧化乙烯、LIFSI混合均匀后浇筑成膜,将PVDF溶液均匀涂覆在电解质膜表面,干燥得到修饰后的电解质膜。通过电化学实验、充放电实验、表面表征等方法,研究PVDF修饰后电解质膜的性能。结果显示,PVDF影响了LATP的晶体结构,优化了锂离子迁移通道。修饰后电解质膜的室温离子电导率提升,室温下电化学窗口由3.74 V增加到4.10 V,锂离子迁移数由0.915提升到0.978,组装锂金属对称电池在0.05 m A/cm^(2)电流密度下的循环时间从45 h提升到280 h以上,有效抑制了锂枝晶的生长,提升了电解质膜与锂金属界面稳定性。在电流密度0.025、0.050、0.100、0.200 m A/cm^(2)下的极化电压分别为27、60、110、220 m V。在LFP|SSCEs-1|Li全电池中循环超过25圈后形成了良好的SEI界面。从第25圈到第100圈容量保持率为87%,库仑效率始终保持在95%以上。PVDF修饰层提升了LATP电解质膜的电化学性能以及和锂金属界面的稳定性,对全固态锂电池的应用具有积极意义。展开更多
Ruthenium(Ru)-based chalcogenide(S,Se)is a promising material in various fields,such as optics,photoelectrodes,and electrocatalysis,owing to its suitable bandgap for generating charge carriers under light illumination...Ruthenium(Ru)-based chalcogenide(S,Se)is a promising material in various fields,such as optics,photoelectrodes,and electrocatalysis,owing to its suitable bandgap for generating charge carriers under light illumination ranging from visible to near-infrared(NIR)and its high absorption coefficient.In this study,we report the synthesis of Ru Se_(2)thin films by chemical vapor deposition(CVD)with a bandgap matching the NIR region at 0.52 e V.Further,we demonstrated Ru S_(2x)Se_(2-2x)alloy films using the post-sulfurization process after CVD Ru Se_(2)with a tunable bandgap from 0.52 to 1.39 e V depending on sulfur composition.Remarkably,Ru S_(2x)Se_(2-2x)alloy film metal–semiconductor–metal(MSM)photodetector sulfurized at 500°C,with a 0.75 e V bandgap,exhibits enhanced broad absorption across NIR spectral ranges,suppressed dark current and high photoresponsivity in NIR wavelengths range even at zero-bias.We believe the bandgaptunable Ru S_(2x)Se_(2-2x)thin film through an efficient deposition method could be suitable for various optoelectronic applications.展开更多
NASICON type solid electrolyte Li_(1+x)Al_(x)Ge_(2-x)(PO_(4))_(3)(LAGP)is one of the most potential candidates in view of their high ionic conductivity,high oxidation resistance and excellent air stability.However,ine...NASICON type solid electrolyte Li_(1+x)Al_(x)Ge_(2-x)(PO_(4))_(3)(LAGP)is one of the most potential candidates in view of their high ionic conductivity,high oxidation resistance and excellent air stability.However,inevitable interface issues often cause severe performance degradation,seriously affecting its commercial application.Herein,a lithiophilic carbon buffer layer is constructed on the LAGP surface adjacent to the Li electrode side by a facile pyrolysis reaction,then the LiC_(x) interlayer is generated in situ between the carbon buffer layer and lithium metal,which can guide uniform ion transport while improving interface contact.Thus,the LiC_(x)-LAGP showed excellent ionic conductivity,high flexibility and lithiophilic interphase.Specially,the Li|LiC_(x)-LAGP|Li battery has achieved a 1000 h stable cycles at 0.1 mA/cm^(2),remarkably,the Li|LiC_(x)-LAGP|LFP battery retains 85%of their initial capacity after 200 cycles under 1 C,even for the NCM811 cathode,the battery still has a good cycle performance.展开更多
A series of solid solutions with high content of Tb_(2)O_(3)-(Tb_(x)Ti_(1−x))4O_(8−2x)(x=0.667-0.830)are synthesized in the Tb_(2)O_(3)-TiO_(2)system via co-precipitation and/or mechanical activation.This is followed ...A series of solid solutions with high content of Tb_(2)O_(3)-(Tb_(x)Ti_(1−x))4O_(8−2x)(x=0.667-0.830)are synthesized in the Tb_(2)O_(3)-TiO_(2)system via co-precipitation and/or mechanical activation.This is followed by high-temperature annealing for 4-22 h.The X-ray diffrac-tion method showed that the fluorite structure was realized for(Tb_(x)Ti_(1−x))4O_(8−2x)(x=0.75-0.817).The solid solution Tb_(3.12)Ti_(0.88)O_(6.44)(64mol%Tb_(2)O_(3)(x=0.78))with a fluorite structure exhibited a maximum hole conductivity of~22 S/cm at 600℃.To separate the ionic component of the conductivity in the electronic conductor Tb_(3.12)Ti_(0.88)O_(6.44),its high entropy analogue,(La_(0.2)Gd_(0.2)Tm_(0.2)Lu_(0.2)Y_(0.2))_(3.12)Ti_(0.88)O_(6.44),was synthesized in which all rare-earth elements(REE)cations exhibited valency of+3.Consequently,the contribution of ionic(proton)conductivity(~7×10^(−6)S/cm at 600℃)was revealed with respect to the background of dominant hole conductivity.The proton conduct-ivity of high-entropy oxide(HEО)(La_(0.2)Gd_(0.2)Tm_(0.2)Lu_(0.2)Y_(0.2))_(3.12)Ti_(0.88)O_(6.44)was confirmed by the detection of the isotope effect,where the mobility of the heavier O-D ions was lower than that of the O-H hydroxyls,resulting in lower conductivity in D_(2)O vapors when com-pared to H_(2)O.展开更多
To satisfy the demands of modern society for high-energy–density sulfide-based all-solid-state lithium batteries(ASSLBs),Ni-rich cathode materials have gained much attention for their high capacity and energy density...To satisfy the demands of modern society for high-energy–density sulfide-based all-solid-state lithium batteries(ASSLBs),Ni-rich cathode materials have gained much attention for their high capacity and energy density.However,their practical deployment is hindered by accelerated interface degradation and capacity decay originating from surface oxygen release and lattice oxygen activation during prolonged cycling.In this study,Ti_(x)NbB_((1−x))C_(2)was successfully coated on the surface of LiNi_(0.94)Co_(0.05)Mn_(0.01)O_(2).Density functional theory(DFT)calculations first elucidate a“point-to-point”anchoring mechanism where each surface oxygen atom coordinates with single species(Ti/Nb/B)offered by Ti_(x)NbB_((1−x))C_(2),which forms robust O–M bonds and sustain a stable interface structure.The electron energy loss spectroscopy(EELS)reveals the segregation of Ti/Nb toward subsurface layers during cycling,creating an optimized lattice oxygen coordination environment and suppressing oxygen activation.The dual oxygen stabilization mechanism dramatically improves the reversibility of phase transition and the structural stability of the Ni-rich cathode materials.Moreover,Ti_(x)NbB_((1−x))C_(2)as the protective layer decreases mechanical strain and suppresses the parasitic reactions.Consequently,the engineered cathode delivers 91%capacity retention after 1000 cycles at 0.3 C,suggesting excellent cycling stability.The research delivers a new design philosophy for the coating layer that can stabilize surface oxygen.Furthermore,the atomistic understanding of the structure–property relationship of the Ni-rich cathode materials provides valuable guidance for the future design of new cathode materials with superior structural stability in ASSLBs.展开更多
Barium metaborate (BaB 2O 4) exists in two forms the high temperature for m α phase and the low temperature form β phase,with the phase transition poi nt at around 925℃.The low temperature phase (β BBO) is an exce...Barium metaborate (BaB 2O 4) exists in two forms the high temperature for m α phase and the low temperature form β phase,with the phase transition poi nt at around 925℃.The low temperature phase (β BBO) is an excellent NLO cryst al for UV region,while the high temperature one (α BBO) is known as a good bir efringent material.α BBO crystal possesses better transparency in the ultravio let region compared with commonly used YVO 4 and CaCO 3 crystals.However,due t o phase transition problem,it is difficult to grow single α BBO crystals by D CZ method,which restricts its wider application.α BBO crystal usually cracks upon cooling resulted from phase transition to β phase.Therefore,it is difficult to grow β BBO single crystals directly from pure BaB 2O 4 mel t;however,to grow single crystals of α BBO is not easy,either. Our recent experiments showed that one could avoid cracking of α BBO cryst als by Sr 2+ doping.This minute amount of Sr 2+ plays the role of structure stabilizer,which inhibits structural reconstruction. In this way,Sr 2+ d op ed BBO single crystals do not subject to phase transition from 925℃ down to roo m temperature. We have mow successfully grown out α BBO single crystals 30mm in diameter by D CZ method from Sr x Ba 1- x BO 4 melt with Sr concentration 0.3 0 .5%.The ratation rate is 10 15r/min,pulling speed is 1 2mm/h.Preliminary tests revealed that its structure and physic chemical properties were almost identic al to those grown from pure melts.These Sr 2+ doped α BBO crystals are no w being widely used in optical isolators.展开更多
文摘为降低Li_(1+x)Al_(x)Ti_(2-x)(PO_(4))_(3)(LATP)电解质膜与锂金属负极之间的界面阻抗,抑制LATP与锂金属之间的副反应以及锂枝晶的生长,提高LATP电解质膜的性能,使用PVDF对LATP基电解质膜界面进行修饰,并研究其电化学性能。将LATP陶瓷粉末与聚氧化乙烯、LIFSI混合均匀后浇筑成膜,将PVDF溶液均匀涂覆在电解质膜表面,干燥得到修饰后的电解质膜。通过电化学实验、充放电实验、表面表征等方法,研究PVDF修饰后电解质膜的性能。结果显示,PVDF影响了LATP的晶体结构,优化了锂离子迁移通道。修饰后电解质膜的室温离子电导率提升,室温下电化学窗口由3.74 V增加到4.10 V,锂离子迁移数由0.915提升到0.978,组装锂金属对称电池在0.05 m A/cm^(2)电流密度下的循环时间从45 h提升到280 h以上,有效抑制了锂枝晶的生长,提升了电解质膜与锂金属界面稳定性。在电流密度0.025、0.050、0.100、0.200 m A/cm^(2)下的极化电压分别为27、60、110、220 m V。在LFP|SSCEs-1|Li全电池中循环超过25圈后形成了良好的SEI界面。从第25圈到第100圈容量保持率为87%,库仑效率始终保持在95%以上。PVDF修饰层提升了LATP电解质膜的电化学性能以及和锂金属界面的稳定性,对全固态锂电池的应用具有积极意义。
基金supported by TANAKA KIKINZOKU KOGYO K.Kfinancially supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(No.NRF-2022R1A2C2006764)the Materials and Components Technology Development Program of MOTIE/KEIT(No.[20012460])。
文摘Ruthenium(Ru)-based chalcogenide(S,Se)is a promising material in various fields,such as optics,photoelectrodes,and electrocatalysis,owing to its suitable bandgap for generating charge carriers under light illumination ranging from visible to near-infrared(NIR)and its high absorption coefficient.In this study,we report the synthesis of Ru Se_(2)thin films by chemical vapor deposition(CVD)with a bandgap matching the NIR region at 0.52 e V.Further,we demonstrated Ru S_(2x)Se_(2-2x)alloy films using the post-sulfurization process after CVD Ru Se_(2)with a tunable bandgap from 0.52 to 1.39 e V depending on sulfur composition.Remarkably,Ru S_(2x)Se_(2-2x)alloy film metal–semiconductor–metal(MSM)photodetector sulfurized at 500°C,with a 0.75 e V bandgap,exhibits enhanced broad absorption across NIR spectral ranges,suppressed dark current and high photoresponsivity in NIR wavelengths range even at zero-bias.We believe the bandgaptunable Ru S_(2x)Se_(2-2x)thin film through an efficient deposition method could be suitable for various optoelectronic applications.
基金financially supported by the National Natural Science Foundation of China(Nos.52372188,51902090)Henan Key Research Project Plan for Higher Education Institutions(Nos.24A150019,23A150038)+4 种基金Key Scientific Research Project of Education Department of Henan Province(No.22A150042)the National students’platform for innovation and entrepreneurship training program(No.201910476010)CAS Henan Industrial Technology Innovation&Incubation Center(No.2024121)2023 Introduction of studying abroad talent program,the China Postdoctoral Science Foundation(No.2019 M652546)the Henan Province Postdoctoral Start-Up Foundation(No.1901017).
文摘NASICON type solid electrolyte Li_(1+x)Al_(x)Ge_(2-x)(PO_(4))_(3)(LAGP)is one of the most potential candidates in view of their high ionic conductivity,high oxidation resistance and excellent air stability.However,inevitable interface issues often cause severe performance degradation,seriously affecting its commercial application.Herein,a lithiophilic carbon buffer layer is constructed on the LAGP surface adjacent to the Li electrode side by a facile pyrolysis reaction,then the LiC_(x) interlayer is generated in situ between the carbon buffer layer and lithium metal,which can guide uniform ion transport while improving interface contact.Thus,the LiC_(x)-LAGP showed excellent ionic conductivity,high flexibility and lithiophilic interphase.Specially,the Li|LiC_(x)-LAGP|Li battery has achieved a 1000 h stable cycles at 0.1 mA/cm^(2),remarkably,the Li|LiC_(x)-LAGP|LFP battery retains 85%of their initial capacity after 200 cycles under 1 C,even for the NCM811 cathode,the battery still has a good cycle performance.
基金the state assignment on the topic“Interdisciplinary approaches to the creation and study of micro-/nanostructured systems”(No.125012200595-8)Conductivity measurements of the samples were performed in accordance with the state task for FRC PCP and MC RAS(No.124013000692-4).
文摘A series of solid solutions with high content of Tb_(2)O_(3)-(Tb_(x)Ti_(1−x))4O_(8−2x)(x=0.667-0.830)are synthesized in the Tb_(2)O_(3)-TiO_(2)system via co-precipitation and/or mechanical activation.This is followed by high-temperature annealing for 4-22 h.The X-ray diffrac-tion method showed that the fluorite structure was realized for(Tb_(x)Ti_(1−x))4O_(8−2x)(x=0.75-0.817).The solid solution Tb_(3.12)Ti_(0.88)O_(6.44)(64mol%Tb_(2)O_(3)(x=0.78))with a fluorite structure exhibited a maximum hole conductivity of~22 S/cm at 600℃.To separate the ionic component of the conductivity in the electronic conductor Tb_(3.12)Ti_(0.88)O_(6.44),its high entropy analogue,(La_(0.2)Gd_(0.2)Tm_(0.2)Lu_(0.2)Y_(0.2))_(3.12)Ti_(0.88)O_(6.44),was synthesized in which all rare-earth elements(REE)cations exhibited valency of+3.Consequently,the contribution of ionic(proton)conductivity(~7×10^(−6)S/cm at 600℃)was revealed with respect to the background of dominant hole conductivity.The proton conduct-ivity of high-entropy oxide(HEО)(La_(0.2)Gd_(0.2)Tm_(0.2)Lu_(0.2)Y_(0.2))_(3.12)Ti_(0.88)O_(6.44)was confirmed by the detection of the isotope effect,where the mobility of the heavier O-D ions was lower than that of the O-H hydroxyls,resulting in lower conductivity in D_(2)O vapors when com-pared to H_(2)O.
基金supported by the National Natural Science Foundation of China(21203008,21975025,12274025,22372008,and 22179007)Hainan Province Science and Technology Special Fund(ZDYF2021SHFZ232 and ZDYF2023GXJS022)Hainan Province Postdoctoral Science Foundation(300333)。
文摘To satisfy the demands of modern society for high-energy–density sulfide-based all-solid-state lithium batteries(ASSLBs),Ni-rich cathode materials have gained much attention for their high capacity and energy density.However,their practical deployment is hindered by accelerated interface degradation and capacity decay originating from surface oxygen release and lattice oxygen activation during prolonged cycling.In this study,Ti_(x)NbB_((1−x))C_(2)was successfully coated on the surface of LiNi_(0.94)Co_(0.05)Mn_(0.01)O_(2).Density functional theory(DFT)calculations first elucidate a“point-to-point”anchoring mechanism where each surface oxygen atom coordinates with single species(Ti/Nb/B)offered by Ti_(x)NbB_((1−x))C_(2),which forms robust O–M bonds and sustain a stable interface structure.The electron energy loss spectroscopy(EELS)reveals the segregation of Ti/Nb toward subsurface layers during cycling,creating an optimized lattice oxygen coordination environment and suppressing oxygen activation.The dual oxygen stabilization mechanism dramatically improves the reversibility of phase transition and the structural stability of the Ni-rich cathode materials.Moreover,Ti_(x)NbB_((1−x))C_(2)as the protective layer decreases mechanical strain and suppresses the parasitic reactions.Consequently,the engineered cathode delivers 91%capacity retention after 1000 cycles at 0.3 C,suggesting excellent cycling stability.The research delivers a new design philosophy for the coating layer that can stabilize surface oxygen.Furthermore,the atomistic understanding of the structure–property relationship of the Ni-rich cathode materials provides valuable guidance for the future design of new cathode materials with superior structural stability in ASSLBs.
文摘Barium metaborate (BaB 2O 4) exists in two forms the high temperature for m α phase and the low temperature form β phase,with the phase transition poi nt at around 925℃.The low temperature phase (β BBO) is an excellent NLO cryst al for UV region,while the high temperature one (α BBO) is known as a good bir efringent material.α BBO crystal possesses better transparency in the ultravio let region compared with commonly used YVO 4 and CaCO 3 crystals.However,due t o phase transition problem,it is difficult to grow single α BBO crystals by D CZ method,which restricts its wider application.α BBO crystal usually cracks upon cooling resulted from phase transition to β phase.Therefore,it is difficult to grow β BBO single crystals directly from pure BaB 2O 4 mel t;however,to grow single crystals of α BBO is not easy,either. Our recent experiments showed that one could avoid cracking of α BBO cryst als by Sr 2+ doping.This minute amount of Sr 2+ plays the role of structure stabilizer,which inhibits structural reconstruction. In this way,Sr 2+ d op ed BBO single crystals do not subject to phase transition from 925℃ down to roo m temperature. We have mow successfully grown out α BBO single crystals 30mm in diameter by D CZ method from Sr x Ba 1- x BO 4 melt with Sr concentration 0.3 0 .5%.The ratation rate is 10 15r/min,pulling speed is 1 2mm/h.Preliminary tests revealed that its structure and physic chemical properties were almost identic al to those grown from pure melts.These Sr 2+ doped α BBO crystals are no w being widely used in optical isolators.
