As a national platform for global technological innovation and cooperation,the 2023 Exhibition of the ZGC Forum recently closed in Beijing.The forum witnessed many dark technologies including low-carbon cycling,space ...As a national platform for global technological innovation and cooperation,the 2023 Exhibition of the ZGC Forum recently closed in Beijing.The forum witnessed many dark technologies including low-carbon cycling,space interaction,data display across whole screens,and the metaverse.展开更多
The Cooperation Signing Ceremony of China Life and China 2009 World Philatelic Exhibition (‘China 2009’) was held in Luo Yang,August 25,2008. The following members attended the ceremony:Mr.Zhong Fan,GM Assistant of ...The Cooperation Signing Ceremony of China Life and China 2009 World Philatelic Exhibition (‘China 2009’) was held in Luo Yang,August 25,2008. The following members attended the ceremony:Mr.Zhong Fan,GM Assistant of Strategic Planning Department of China Life Insurance Company Lid,Mr.Kuai Tongwen,General Manager of He Nan Branch of China Life Insurance Company Ltd,Mr.Yang Haifu,Secretary-General of Executive Committee of World Philatelic Exhibition and General Manager of He Nan Postal Service Company,Mr.展开更多
Potassium-ion batteries(PIBs)are considered promising alternatives to lithium-ion batteries owing to cost-effective potassium resources and a suitable redox potential of-2.93 V(vs.-3.04 V for Li+/Li).However,the explo...Potassium-ion batteries(PIBs)are considered promising alternatives to lithium-ion batteries owing to cost-effective potassium resources and a suitable redox potential of-2.93 V(vs.-3.04 V for Li+/Li).However,the exploration of appro-priate electrode materials with the correct size for reversibly accommodating large K+ions presents a significant challenge.In addition,the reaction mecha-nisms and origins of enhanced performance remain elusive.Here,tetragonal FeSe nanoflakes of different sizes are designed to serve as an anode for PIBs,and their live and atomic-scale potassiation/depotassiation mechanisms are revealed for the first time through in situ high-resolution transmission electron micros-copy.We found that FeSe undergoes two distinct structural evolutions,sequen-tially characterized by intercalation and conversion reactions,and the initial intercalation behavior is size-dependent.Apparent expansion induced by the intercalation of K+ions is observed in small-sized FeSe nanoflakes,whereas unexpected cracks are formed along the direction of ionic diffusion in large-sized nanoflakes.The significant stress generation and crack extension originating from the combined effect of mechanical and electrochemical interactions are elucidated by geometric phase analysis and finite-element analysis.Despite the different intercalation behaviors,the formed products of Fe and K_(2)Se after full potassiation can be converted back into the original FeSe phase upon depotassiation.In particular,small-sized nanoflakes exhibit better cycling perfor-mance with well-maintained structural integrity.This article presents the first successful demonstration of atomic-scale visualization that can reveal size-dependent potassiation dynamics.Moreover,it provides valuable guidelines for optimizing the dimensions of electrode materials for advanced PIBs.展开更多
The Heavenly Stems and the Earthly Branches, used to indicate the sequence of years in the traditional Chinese calendar, have a long history and far-reaching influence. They are the crystallization of the wisdom of th...The Heavenly Stems and the Earthly Branches, used to indicate the sequence of years in the traditional Chinese calendar, have a long history and far-reaching influence. They are the crystallization of the wisdom of the ancient people of China. An oracle bone unearthed at展开更多
文摘As a national platform for global technological innovation and cooperation,the 2023 Exhibition of the ZGC Forum recently closed in Beijing.The forum witnessed many dark technologies including low-carbon cycling,space interaction,data display across whole screens,and the metaverse.
文摘The Cooperation Signing Ceremony of China Life and China 2009 World Philatelic Exhibition (‘China 2009’) was held in Luo Yang,August 25,2008. The following members attended the ceremony:Mr.Zhong Fan,GM Assistant of Strategic Planning Department of China Life Insurance Company Lid,Mr.Kuai Tongwen,General Manager of He Nan Branch of China Life Insurance Company Ltd,Mr.Yang Haifu,Secretary-General of Executive Committee of World Philatelic Exhibition and General Manager of He Nan Postal Service Company,Mr.
基金This work was supported by the National Key R&D Program of China(Grant No.2018YFB1304902)the National Natural Science Foundation of China(Grant Nos.12004034,U1813211,22005247,11904372,51502007,52072323,52122211,12174019,and 51972058)+1 种基金the Gen-eral Research Fund of Hong Kong(Project No.11217221)China Postdoctoral Science Foundation Funded Project(Grant No.2021M690386).
文摘Potassium-ion batteries(PIBs)are considered promising alternatives to lithium-ion batteries owing to cost-effective potassium resources and a suitable redox potential of-2.93 V(vs.-3.04 V for Li+/Li).However,the exploration of appro-priate electrode materials with the correct size for reversibly accommodating large K+ions presents a significant challenge.In addition,the reaction mecha-nisms and origins of enhanced performance remain elusive.Here,tetragonal FeSe nanoflakes of different sizes are designed to serve as an anode for PIBs,and their live and atomic-scale potassiation/depotassiation mechanisms are revealed for the first time through in situ high-resolution transmission electron micros-copy.We found that FeSe undergoes two distinct structural evolutions,sequen-tially characterized by intercalation and conversion reactions,and the initial intercalation behavior is size-dependent.Apparent expansion induced by the intercalation of K+ions is observed in small-sized FeSe nanoflakes,whereas unexpected cracks are formed along the direction of ionic diffusion in large-sized nanoflakes.The significant stress generation and crack extension originating from the combined effect of mechanical and electrochemical interactions are elucidated by geometric phase analysis and finite-element analysis.Despite the different intercalation behaviors,the formed products of Fe and K_(2)Se after full potassiation can be converted back into the original FeSe phase upon depotassiation.In particular,small-sized nanoflakes exhibit better cycling perfor-mance with well-maintained structural integrity.This article presents the first successful demonstration of atomic-scale visualization that can reveal size-dependent potassiation dynamics.Moreover,it provides valuable guidelines for optimizing the dimensions of electrode materials for advanced PIBs.
文摘The Heavenly Stems and the Earthly Branches, used to indicate the sequence of years in the traditional Chinese calendar, have a long history and far-reaching influence. They are the crystallization of the wisdom of the ancient people of China. An oracle bone unearthed at
