Potassium-selenium(K-Se)batteries have attracted significant attention as one of the most promising alternatives of lithium-ion storage systems owing to high energy density and low cost.In the design of Se-based catho...Potassium-selenium(K-Se)batteries have attracted significant attention as one of the most promising alternatives of lithium-ion storage systems owing to high energy density and low cost.In the design of Se-based cathode materials,however,the low utilization rate of active Se and the rapid dissolution of polyselenides seriously weaken the capacity and cycle stability.Therefore,how to make full use of Se species without loss during the charge and discharge process is the key to design high-performance Se-based cathode.In this paper,a 3 D"water cube"-like Se/C hybrid(denoted as Se-O-PCS)is constructed with the assistance of Na_(2)CO_(3) templates.Thanks to the abundant carbonate groups(CO_(3)^(2-))originated from the Na_(2)CO_(3) templates,the molten Se species are firmly anchored into the pore of carbon skeleton by strong C-O-Se bonding.Thus,this unique Se-O-PCS model not only improves the utilization of active Se species,but also can reduce the contact with the electrolyte to inhibit the shuttle effect of polyselenides.Moreover,flexible carbon skeleton gives Se-O-PCS hybrid a good electrical conductivity and excellent structural robustness.Consequently,the resultant Se-O-PCS hybrid is endowed with an obviously enhanced K-ions storage property.展开更多
Potassium-selenium(K-Se)batteries have attracted more and more attention because of their high theoretical specific capacity and natural abundance of K resources.However,dissolution of polyselenides,large volume expan...Potassium-selenium(K-Se)batteries have attracted more and more attention because of their high theoretical specific capacity and natural abundance of K resources.However,dissolution of polyselenides,large volume expansion during cycling and low utilization of Se remain great challenges,leading to poor rate capability and cycle life.Herein,N/O dual-doped carbon nanofibers with interconnected micro/mesopores(MMCFs)are designed as hosts to manipulate Se molecular configuration for advanced flexible K-Se batteries.The micropores play a role in confining small Se molecule(Se_(2–3)),which could inhibit the formation of polyselenides and work as physical barrier to stabilize the cycle performance.While the mesopores can confine long-chain Se(Se_(4–7)),promising sufficient Se loading and contributing to higher discharge voltage of the whole Se@MMCFs composite.The N/O co-doping and the 3D interpenetrating nanostructure improve electrical conductivity and keep the structure integrity after cycling.The obtained Se_(2–3)/Se_(4–7)@MMCFs electrode exhibits an unprecedented cycle life(395 mA h g^(−1) at 1 A g^(−1) after 2000 cycles)and high specific energy density(400 Wh kg^(−1),nearly twice the specific energy density of the Se_(2–3)@MMCFs).This study offers a rational design for the realization of a high energy density and long cycle life chalcogen cathode for energy storage.展开更多
Iron-chalcogenide compounds with FeSe（Te, S） layers did not attract much attention until the discovery of high-Tc superconductivity （SC） in the iron-pnictide compounds at the begining of 2008. Compared with FeAs-b...Iron-chalcogenide compounds with FeSe（Te, S） layers did not attract much attention until the discovery of high-Tc superconductivity （SC） in the iron-pnictide compounds at the begining of 2008. Compared with FeAs-based superconductors, iron-chalcogenide superconductors have aroused enormous enthusiasm to study the relationship between SC and magnetisms with several distinct features, such as different antiferromagnetic ground states with relatively large moments in the parents, indicating possibly different superconducting mechanisms, the existence of the excess Fe atoms or Fe vacancies in the crystal lattice. Another reason is that the large single crystals are easily grown for the iron-chalcogenide compounds. This review will focus on our exploration for the iron-chalcogenide superconductors and discussion on several issues, including the crystal structure, magnetic properties, superconductivity, and phase separation. Some of them reach a consensus but some important questions still remain to be answered.展开更多
Selenium cathode has been demonstrated as a promising candidate of cathode material for low-cost and high-energy density potassium ion batteries(PIBs).Nevertheless,their applica tions are prevented by poor electrochem...Selenium cathode has been demonstrated as a promising candidate of cathode material for low-cost and high-energy density potassium ion batteries(PIBs).Nevertheless,their applica tions are prevented by poor electrochemical perfor-mance due to the shuttle effect of high-order polyselenides,the sluggish diffu-sion of bigger K+,and the huge volumetric expansion during cycling.In this work,we design a multifunctional Se host(N-HCNS)by grafting ZIF-8 derived microporous carbon onto the surface of N-doped porous carbon nanosheets.The obtained N-HCNS carbon matrix integrates conductivity,captivity,and immobility abilities,which inhibits the polyselenides shuttle,improves the Se utilization,and buffers the volume change during cycling.The 3D hollow car-bon skeleton enhances the infiltration of electrolytes.As an cathode for PIBs,the Se@N-HCNS electrode delivers an unprecedented life-span(260 mAh g1 at 1.0 Ag-1 after 2000 cycles)and exhibits a remarkable rate capacity(339 mAh g at 5.0 Ag-l).Density functional theory(DFT)calculation reveals the effective adsorption of K2Se with pyridine and pyrrole nitrogen dop-ing in carbon matrix.The unique synergetic design of electrode not only gives insight into the reaction mechanism but also highly emphasi zes the potential capabilities of N doped carbon in K-Se batteries.展开更多
基金financially supported by the National Natural Science Foundation of China(51877216)the Natural Science Foundation of Shandong Province(ZR2020MB078)+3 种基金the Taishan Scholar Foundation(tsqn20161017)the Major Program of Shandong Province Natural Science Foundation(ZR201801280009)the Fundamental Research Funds for the Central Universities(18CX05007A,19CX05001A,19CX05002A,20CX06101A)the Postdoctoral Applied Research Program of Qingdao。
文摘Potassium-selenium(K-Se)batteries have attracted significant attention as one of the most promising alternatives of lithium-ion storage systems owing to high energy density and low cost.In the design of Se-based cathode materials,however,the low utilization rate of active Se and the rapid dissolution of polyselenides seriously weaken the capacity and cycle stability.Therefore,how to make full use of Se species without loss during the charge and discharge process is the key to design high-performance Se-based cathode.In this paper,a 3 D"water cube"-like Se/C hybrid(denoted as Se-O-PCS)is constructed with the assistance of Na_(2)CO_(3) templates.Thanks to the abundant carbonate groups(CO_(3)^(2-))originated from the Na_(2)CO_(3) templates,the molten Se species are firmly anchored into the pore of carbon skeleton by strong C-O-Se bonding.Thus,this unique Se-O-PCS model not only improves the utilization of active Se species,but also can reduce the contact with the electrolyte to inhibit the shuttle effect of polyselenides.Moreover,flexible carbon skeleton gives Se-O-PCS hybrid a good electrical conductivity and excellent structural robustness.Consequently,the resultant Se-O-PCS hybrid is endowed with an obviously enhanced K-ions storage property.
基金This work was supported by the National Key R&D Research Program of China(Nos.2018YFA0209600,2017YFA0208300)the National Natural Science Foundation of China(Nos.51925207,U1910210,51872277,52002083,22005292,51802302)+4 种基金the DNL cooperation Fund,CAS(DNL180310)the Fundamental Research Funds for the Central Universities(WK2060140026,WK3430000006,WK2060000009)the National Synchrotron Radiation Laboratoi-y(KY2060000173)the National Postdoctoral Program for Innovative Talents(BX20200318)the China Postdoctoral Science Foundation(Nos.2020M672533,2019TQ0296,2020M682012).
文摘Potassium-selenium(K-Se)batteries have attracted more and more attention because of their high theoretical specific capacity and natural abundance of K resources.However,dissolution of polyselenides,large volume expansion during cycling and low utilization of Se remain great challenges,leading to poor rate capability and cycle life.Herein,N/O dual-doped carbon nanofibers with interconnected micro/mesopores(MMCFs)are designed as hosts to manipulate Se molecular configuration for advanced flexible K-Se batteries.The micropores play a role in confining small Se molecule(Se_(2–3)),which could inhibit the formation of polyselenides and work as physical barrier to stabilize the cycle performance.While the mesopores can confine long-chain Se(Se_(4–7)),promising sufficient Se loading and contributing to higher discharge voltage of the whole Se@MMCFs composite.The N/O co-doping and the 3D interpenetrating nanostructure improve electrical conductivity and keep the structure integrity after cycling.The obtained Se_(2–3)/Se_(4–7)@MMCFs electrode exhibits an unprecedented cycle life(395 mA h g^(−1) at 1 A g^(−1) after 2000 cycles)and high specific energy density(400 Wh kg^(−1),nearly twice the specific energy density of the Se_(2–3)@MMCFs).This study offers a rational design for the realization of a high energy density and long cycle life chalcogen cathode for energy storage.
基金supported by the National Basic Research Program of China(Grant Nos.2011CBA00103,2012CB821404,and 2009CB929104)the National Natural Science Foundation of China(Grant Nos.10974175,10934005,and 11204059)+1 种基金the Natural Science Foundation of Zhejiang Province,China(Grant No.Q12A040038)the Fundamental Research Funds for the Central Universities of China
文摘Iron-chalcogenide compounds with FeSe（Te, S） layers did not attract much attention until the discovery of high-Tc superconductivity （SC） in the iron-pnictide compounds at the begining of 2008. Compared with FeAs-based superconductors, iron-chalcogenide superconductors have aroused enormous enthusiasm to study the relationship between SC and magnetisms with several distinct features, such as different antiferromagnetic ground states with relatively large moments in the parents, indicating possibly different superconducting mechanisms, the existence of the excess Fe atoms or Fe vacancies in the crystal lattice. Another reason is that the large single crystals are easily grown for the iron-chalcogenide compounds. This review will focus on our exploration for the iron-chalcogenide superconductors and discussion on several issues, including the crystal structure, magnetic properties, superconductivity, and phase separation. Some of them reach a consensus but some important questions still remain to be answered.
基金China Postdoctoral Science Foundation,Grant/Award Number:2020M682031National Postdoctoral Program for Innovative Talents,Grant/Award Number:BX20200318+3 种基金National Synchrotron Radiation Laboratory,Grant/Award Num ber.KY2060000173Fundamental Research Funds for Central Universities,Grant/Award Number:WK 2060140026Dalian National Laboratory(DNL)Cooperation Fund for Clean Energy,Grant/Award Num ber:DNL 180310National Natural Science Foundation of China,Grant/Award Numbers:51972067,52002083,5187277,51925207,U1910210。
文摘Selenium cathode has been demonstrated as a promising candidate of cathode material for low-cost and high-energy density potassium ion batteries(PIBs).Nevertheless,their applica tions are prevented by poor electrochemical perfor-mance due to the shuttle effect of high-order polyselenides,the sluggish diffu-sion of bigger K+,and the huge volumetric expansion during cycling.In this work,we design a multifunctional Se host(N-HCNS)by grafting ZIF-8 derived microporous carbon onto the surface of N-doped porous carbon nanosheets.The obtained N-HCNS carbon matrix integrates conductivity,captivity,and immobility abilities,which inhibits the polyselenides shuttle,improves the Se utilization,and buffers the volume change during cycling.The 3D hollow car-bon skeleton enhances the infiltration of electrolytes.As an cathode for PIBs,the Se@N-HCNS electrode delivers an unprecedented life-span(260 mAh g1 at 1.0 Ag-1 after 2000 cycles)and exhibits a remarkable rate capacity(339 mAh g at 5.0 Ag-l).Density functional theory(DFT)calculation reveals the effective adsorption of K2Se with pyridine and pyrrole nitrogen dop-ing in carbon matrix.The unique synergetic design of electrode not only gives insight into the reaction mechanism but also highly emphasi zes the potential capabilities of N doped carbon in K-Se batteries.
