It is still a great challenge at present to combine the high rate capability of the electrochemical capacitor with the high electrochemical capacity feature of rechargeable battery in energy storage and transport devi...It is still a great challenge at present to combine the high rate capability of the electrochemical capacitor with the high electrochemical capacity feature of rechargeable battery in energy storage and transport devices. By studying the lithiation mechanism of Li_4Ti_5O_12 （LTO） using in-situ electron holography, we find that double charge layers are formed at the interface of the insulating Li_4Ti_5O_12 （Li_4） phase and the semiconducting Li_7Ti_5O_12 （Li_7） phase, and can greatly boost the lithiation kinetics. The electron wave phase of the LTO particle is found to gradually shrink with the interface movement, leaving a positive electric field from Li_7 to Li_4 phase. Once the capacitive interface charges are formed, the lithiation of the core/shell particle could be established within 10 s. The ultrafast kinetics is attributed to the built-in interface potential and the mixed Ti3＋/Ti4＋ sites at the interface that could be maximally lowering the thermodynamic barrier for Li ion migration.展开更多
由于正交相五氧化二铌(T-Nb_(2)O_(5))为ReO_(3)型层状结构,锂、钠离子可以在其(001)平面快速脱嵌,而在[001]方向的传输一般较难。本研究通过原位透射电子显微镜(Transmission Electron Microscope,TEM)方法研究钠在T-Nb_(2)O_(5)纳米片...由于正交相五氧化二铌(T-Nb_(2)O_(5))为ReO_(3)型层状结构,锂、钠离子可以在其(001)平面快速脱嵌,而在[001]方向的传输一般较难。本研究通过原位透射电子显微镜(Transmission Electron Microscope,TEM)方法研究钠在T-Nb_(2)O_(5)纳米片(001)面内及[001]方向的钠离子电化学嵌入行为,发现由于纳米片晶体存在大量的位错和畴界,钠离子可通过这些缺陷穿越(001)面扩散,并进而在深层的(001)面内快速扩散。同时,本研究还发现刚合成的T-Nb_(2)O_(5)纳米片在[001]方向上存在调制结构,存在交替分布的压应变和张应变区域,而钠离子的嵌入可以调节这些应变分布。展开更多
The defects in the ceria usually work as the active reaction sites in their industrial applications.In this article,we studied the formation and atomic process of the defects of ceria nanowires under heating by using ...The defects in the ceria usually work as the active reaction sites in their industrial applications.In this article,we studied the formation and atomic process of the defects of ceria nanowires under heating by using in situ aberration-corrected transmission electron microscopy(Cs-TEM)method.With the temperature elevating,ceria nanowires are reduced and defects begin to appear and grow up.When temperature reaches 1,023 K,the defect morphology exhibits the rhombus or hexagon patterns,which are surrounded by{111}and{200}planes with lower surface energy,and the heated ceria still maintain the same cubic fluorite structure as their parent.It is also indicated that the formation of defects originates from the release of lattice oxygen and the volatilization of surface Ce ions.This work provides an important insight into designing ceria-based catalysts and ionic conductors.展开更多
基金supported by the National Natural Science Foundation of China (Nos. 51501085, 11704019, 51522212 and 51421002)National Program on Key Basic Research Project (2014CB921002)the Strategic Priority Research Program of Chinese Academy of Sciences (No. XDB07030200)
文摘It is still a great challenge at present to combine the high rate capability of the electrochemical capacitor with the high electrochemical capacity feature of rechargeable battery in energy storage and transport devices. By studying the lithiation mechanism of Li_4Ti_5O_12 （LTO） using in-situ electron holography, we find that double charge layers are formed at the interface of the insulating Li_4Ti_5O_12 （Li_4） phase and the semiconducting Li_7Ti_5O_12 （Li_7） phase, and can greatly boost the lithiation kinetics. The electron wave phase of the LTO particle is found to gradually shrink with the interface movement, leaving a positive electric field from Li_7 to Li_4 phase. Once the capacitive interface charges are formed, the lithiation of the core/shell particle could be established within 10 s. The ultrafast kinetics is attributed to the built-in interface potential and the mixed Ti3＋/Ti4＋ sites at the interface that could be maximally lowering the thermodynamic barrier for Li ion migration.
文摘由于正交相五氧化二铌(T-Nb_(2)O_(5))为ReO_(3)型层状结构,锂、钠离子可以在其(001)平面快速脱嵌,而在[001]方向的传输一般较难。本研究通过原位透射电子显微镜(Transmission Electron Microscope,TEM)方法研究钠在T-Nb_(2)O_(5)纳米片(001)面内及[001]方向的钠离子电化学嵌入行为,发现由于纳米片晶体存在大量的位错和畴界,钠离子可通过这些缺陷穿越(001)面扩散,并进而在深层的(001)面内快速扩散。同时,本研究还发现刚合成的T-Nb_(2)O_(5)纳米片在[001]方向上存在调制结构,存在交替分布的压应变和张应变区域,而钠离子的嵌入可以调节这些应变分布。
基金supported by the Program from Chinese Academy of Sciences (ZDYZ2015-1, XDB30000000,XDB07030100, Y8K5261B11)the National Natural Science Foundation of China (21773303, 21872172, 51472267, 51672007, 221322304, 11290161, 51572233, 61574121, 51421002)+1 种基金the National Key Research and Development Program (2016YFA0300804, 2016YFA0300903)the National Program for Thousand Young Talents of China
文摘The defects in the ceria usually work as the active reaction sites in their industrial applications.In this article,we studied the formation and atomic process of the defects of ceria nanowires under heating by using in situ aberration-corrected transmission electron microscopy(Cs-TEM)method.With the temperature elevating,ceria nanowires are reduced and defects begin to appear and grow up.When temperature reaches 1,023 K,the defect morphology exhibits the rhombus or hexagon patterns,which are surrounded by{111}and{200}planes with lower surface energy,and the heated ceria still maintain the same cubic fluorite structure as their parent.It is also indicated that the formation of defects originates from the release of lattice oxygen and the volatilization of surface Ce ions.This work provides an important insight into designing ceria-based catalysts and ionic conductors.
