In recent years,manganese-based oxides as an advanced class of cathode materials for zinc-ion batteries(ZIBs)have attracted a great deal of attentions from numerous researchers.However,their slow reaction kinetics,lim...In recent years,manganese-based oxides as an advanced class of cathode materials for zinc-ion batteries(ZIBs)have attracted a great deal of attentions from numerous researchers.However,their slow reaction kinetics,limited active sites and poor electrical conductivity inevitably give rise to the severe performance degradation.To solve these problems,herein,we introduce abundant oxygen vacancies into the flower-likeδ-MnO_(2)nanostructure and effectively modulate the vacancy defects to reach the optimal level(δ-MnO_(2)-x-2.0).The smart design intrinsically tunes the electronic structure,guarantees ion chemisorption-desorption equilibrium and increases the electroactive sites,which not only effectively accelerates charge transfer rate during reaction processes,but also endows more redox reactions,as verified by first-principle calculations.These merits can help the fabricatedδ-MnO_(2)-x-2.0 cathode to present a large specific capacity of 551.8 mAh g^(-1) at 0.5 A g^(-1),high-rate capability of 262.2 mAh g^(-1) at 10 A g^(-1) and an excellent cycle lifespan(83%of capacity retention after 1500 cycles),which is far superior to those of the other metal compound cathodes.In addition,the charge/discharge mechanism of theδ-MnO_(2)-x-2.0 cathode has also been elaborated through ex situ techniques.This work opens up a new pathway for constructing the next-generation high-performance ZIBs cathode materials.展开更多
In this work, we have studied the vacancy formation energy of TiN alloy of structure B2 of size 10 × 10 × 10 for nitrogen percentages of 45%, 50% and 55% under the influence of temperature at 1320 K, 1420 K ...In this work, we have studied the vacancy formation energy of TiN alloy of structure B2 of size 10 × 10 × 10 for nitrogen percentages of 45%, 50% and 55% under the influence of temperature at 1320 K, 1420 K and 1520 K using the Modified Embedded Atom Method MEAM under the calculation code LAMMPS version 2020. This study has enabled us to understand the behavior of the TiN alloy under different nitrogen percentages in terms of total energy, vacancy formation energy, crystalline parameter, occupancy rate and order parameter. For total energy, we have shown that as temperature increases, total energy decreases, making it easier to obtain TiN at higher temperatures;reaching the value of -7344.9169 eV for the 55% nitrogen structure for the temperature of 1420 K. For the energy of formation, we have shown that the compounds obtained at 1320 K and 1520 K have a more considerable energy of formation than that obtained at 1420 K. The study of fractions and the order parameter showed us that the structure of TiN with 55% nitrogen is less likely, as the composition obtained is at most 53.35%.展开更多
The housing vacancy rate(HVR)is an important index in assessing the healthiness of residential real estate market.In China,it is hardly to take advantage of the basic data of real estate information due to the opaque ...The housing vacancy rate(HVR)is an important index in assessing the healthiness of residential real estate market.In China,it is hardly to take advantage of the basic data of real estate information due to the opaque of those data.In this paper,the HVR is estimated to two scales.At the grid level,urban area ratio was calculated by nighttime images after eliminating outliers of nighttime images and night light intensity of non-residential pixels in mixed pixels by a proposed modified optimal threshold method,and built-up areas in each pixel were extracted from the land-cover data.Then,the HVR is calculated by comparing the light intensity of specific grid with the light intensity of full occupancy rate regions.At the administrative scale,the GCI(‘ghost city’index)is constructed by calculating the ratio of the total light radiation intensity of a city to the total construction land area of the city.The overall spatial differentiation pattern of the vacant houses in the national prefecture level administrative regions is analyzed.The following conclusions were drawn:vacant housing is rare in certain eastern coastal cities and regions in China with relatively fast economic development.Cities based on exhausted resources,some mountainous cities,and cities with relatively backward economic development more typically showed high levels of housing vacancy.The GCI of prefecture-level administrative units gradually declined from north to south,whereas the east-west distribution showed a parabolic shape.As city level decreased,the GCI registered a gradual upward trend.China’s urban housing vacancy can be divided into five categories:industry or resources driven,government planned,epitaxy expansionary,environmental constraint and speculative activate by combining the spatial distribution of housing vacancy with the factors of natural environment,social economic development level,and population density into consideration.展开更多
Oxygen vacancies (V_(o)) engineering has been deemed to an effective tactic for enhancing Li-ion storage kinetics and reversibility of SnO_(2)-based anode materials.Herein,we demonstrated the confinement of ultrahigh ...Oxygen vacancies (V_(o)) engineering has been deemed to an effective tactic for enhancing Li-ion storage kinetics and reversibility of SnO_(2)-based anode materials.Herein,we demonstrated the confinement of ultrahigh V_(o)SnO_(2) nanocrystals into N-doped carbon frameworks to boost their high-rate and cycle life.Density functional theory (DFT) calculations reveal that abundant V_(o) in SnO_(2) facilitates the adsorption to Li-ion with remarkably increased carrier concentration.The 6.0 nm-sized SnO_(2) particles and the embedded design effectively stabilize the structural integrity during de-/lithiation.Meantime,the as-formed large hetero-interface also expedites the electron transfer.These merits guarantee its high-rate performance and superior cycling stability.Consequently,this sample exhibits a high capacity of 1368.9m Ah g^(-1)at 0.1 A g^(-1),and can still maintain 488.5 mAh g^(-1)at 10 A g^(-1)and a long life over 400 cycles at 5 A g^(-1)with 96.6%capacity retention,which is among the best report for Sn-contained anode materials.This work sheds light on ultrahigh Vo and structural design in conversion-type oxides for highperformance lithium-ion batteries (LIBs).展开更多
Sodium-ion storage devices are highly desirable for large-scale energy storage applications owing to the wide availability of sodium resources and low cost.Transition metal nitrides(TMNs)are promising anode materials ...Sodium-ion storage devices are highly desirable for large-scale energy storage applications owing to the wide availability of sodium resources and low cost.Transition metal nitrides(TMNs)are promising anode materials for sodium-ion storage,while their detailed reaction mechanism remains unexplored.Herein,we synthesize the mesoporous Mo3N2 nanowires(Meso-Mo_(3)N_(2)-NWs).The sodium-ion storage mechanism of Mo3N2 is systematically investigated through in-situ XRD,ex-situ experimental characterizations and detailed kinetics analysis.Briefly,the Mo_(3)N_(2) undergoes a surface pseudocapacitive redox charge storage process.Benefiting from the rapid surface redox reaction,the Meso-Mo_(3)N_(2)-NWs anode delivers high specific capacity(282 m Ah g^(-1) at 0.1 A g^(-1)),excellent rate capability(87 m Ah g^(-1) at 16 A g^(-1))and long cycling stability(a capacity retention of 78.6%after 800 cycles at 1 A g^(-1)).The present work highlights that the surface pseudocapacitive sodium-ion storage mechanism enables to overcome the sluggish sodium-ion diffusion process,which opens a new direction to design and synthesize high-rate sodiumion storage materials.展开更多
基金supported by the National Natural Science Foundation of China under Grant Nos. 52072196, 52002200, 52102106 and 52002199Major Basic Research Program of the Natural Science Foundation of Shandong Province under Grant No. ZR2020ZD09+2 种基金the Natural Science Foundation of Shandong Province under Grant No. ZR2020QE063the Innovation and Technology Program of Shandong Province under Grant No. 2020KJA004the Taishan Scholars Program of Shandong Province under Grant No. ts201511034
文摘In recent years,manganese-based oxides as an advanced class of cathode materials for zinc-ion batteries(ZIBs)have attracted a great deal of attentions from numerous researchers.However,their slow reaction kinetics,limited active sites and poor electrical conductivity inevitably give rise to the severe performance degradation.To solve these problems,herein,we introduce abundant oxygen vacancies into the flower-likeδ-MnO_(2)nanostructure and effectively modulate the vacancy defects to reach the optimal level(δ-MnO_(2)-x-2.0).The smart design intrinsically tunes the electronic structure,guarantees ion chemisorption-desorption equilibrium and increases the electroactive sites,which not only effectively accelerates charge transfer rate during reaction processes,but also endows more redox reactions,as verified by first-principle calculations.These merits can help the fabricatedδ-MnO_(2)-x-2.0 cathode to present a large specific capacity of 551.8 mAh g^(-1) at 0.5 A g^(-1),high-rate capability of 262.2 mAh g^(-1) at 10 A g^(-1) and an excellent cycle lifespan(83%of capacity retention after 1500 cycles),which is far superior to those of the other metal compound cathodes.In addition,the charge/discharge mechanism of theδ-MnO_(2)-x-2.0 cathode has also been elaborated through ex situ techniques.This work opens up a new pathway for constructing the next-generation high-performance ZIBs cathode materials.
文摘In this work, we have studied the vacancy formation energy of TiN alloy of structure B2 of size 10 × 10 × 10 for nitrogen percentages of 45%, 50% and 55% under the influence of temperature at 1320 K, 1420 K and 1520 K using the Modified Embedded Atom Method MEAM under the calculation code LAMMPS version 2020. This study has enabled us to understand the behavior of the TiN alloy under different nitrogen percentages in terms of total energy, vacancy formation energy, crystalline parameter, occupancy rate and order parameter. For total energy, we have shown that as temperature increases, total energy decreases, making it easier to obtain TiN at higher temperatures;reaching the value of -7344.9169 eV for the 55% nitrogen structure for the temperature of 1420 K. For the energy of formation, we have shown that the compounds obtained at 1320 K and 1520 K have a more considerable energy of formation than that obtained at 1420 K. The study of fractions and the order parameter showed us that the structure of TiN with 55% nitrogen is less likely, as the composition obtained is at most 53.35%.
基金Under the auspices of National Natural Science Foundation of China(No.2071216,41661025)Research Capacity Promotion Program for Young Teachers of Northwest Normal University(No.NWNU-LKQN-16-7)。
文摘The housing vacancy rate(HVR)is an important index in assessing the healthiness of residential real estate market.In China,it is hardly to take advantage of the basic data of real estate information due to the opaque of those data.In this paper,the HVR is estimated to two scales.At the grid level,urban area ratio was calculated by nighttime images after eliminating outliers of nighttime images and night light intensity of non-residential pixels in mixed pixels by a proposed modified optimal threshold method,and built-up areas in each pixel were extracted from the land-cover data.Then,the HVR is calculated by comparing the light intensity of specific grid with the light intensity of full occupancy rate regions.At the administrative scale,the GCI(‘ghost city’index)is constructed by calculating the ratio of the total light radiation intensity of a city to the total construction land area of the city.The overall spatial differentiation pattern of the vacant houses in the national prefecture level administrative regions is analyzed.The following conclusions were drawn:vacant housing is rare in certain eastern coastal cities and regions in China with relatively fast economic development.Cities based on exhausted resources,some mountainous cities,and cities with relatively backward economic development more typically showed high levels of housing vacancy.The GCI of prefecture-level administrative units gradually declined from north to south,whereas the east-west distribution showed a parabolic shape.As city level decreased,the GCI registered a gradual upward trend.China’s urban housing vacancy can be divided into five categories:industry or resources driven,government planned,epitaxy expansionary,environmental constraint and speculative activate by combining the spatial distribution of housing vacancy with the factors of natural environment,social economic development level,and population density into consideration.
基金supported by the National Natural Science Foundation of China (21975074, 91834301 and 51621002)the Innovation Program of Shanghai Municipal Education Commissionthe Fundamental Research Funds for the Central Universities (222201718002)。
文摘Oxygen vacancies (V_(o)) engineering has been deemed to an effective tactic for enhancing Li-ion storage kinetics and reversibility of SnO_(2)-based anode materials.Herein,we demonstrated the confinement of ultrahigh V_(o)SnO_(2) nanocrystals into N-doped carbon frameworks to boost their high-rate and cycle life.Density functional theory (DFT) calculations reveal that abundant V_(o) in SnO_(2) facilitates the adsorption to Li-ion with remarkably increased carrier concentration.The 6.0 nm-sized SnO_(2) particles and the embedded design effectively stabilize the structural integrity during de-/lithiation.Meantime,the as-formed large hetero-interface also expedites the electron transfer.These merits guarantee its high-rate performance and superior cycling stability.Consequently,this sample exhibits a high capacity of 1368.9m Ah g^(-1)at 0.1 A g^(-1),and can still maintain 488.5 mAh g^(-1)at 10 A g^(-1)and a long life over 400 cycles at 5 A g^(-1)with 96.6%capacity retention,which is among the best report for Sn-contained anode materials.This work sheds light on ultrahigh Vo and structural design in conversion-type oxides for highperformance lithium-ion batteries (LIBs).
基金supported by the National Natural Science Foundation of China(51832004,51521001)the National Key Research and Development Program of China(2016YFA0202603)+2 种基金the Program of Introducing Talents of Discipline to Universities(B17034)the Foshan Xianhu Laboratory of the Advanced Energy Science and Technology Guangdong Laboratory(XHT2020-003)the “Double-First Class”Foundation of Materials and Intelligent Manufacturing Discipline of Xiamen University。
文摘Sodium-ion storage devices are highly desirable for large-scale energy storage applications owing to the wide availability of sodium resources and low cost.Transition metal nitrides(TMNs)are promising anode materials for sodium-ion storage,while their detailed reaction mechanism remains unexplored.Herein,we synthesize the mesoporous Mo3N2 nanowires(Meso-Mo_(3)N_(2)-NWs).The sodium-ion storage mechanism of Mo3N2 is systematically investigated through in-situ XRD,ex-situ experimental characterizations and detailed kinetics analysis.Briefly,the Mo_(3)N_(2) undergoes a surface pseudocapacitive redox charge storage process.Benefiting from the rapid surface redox reaction,the Meso-Mo_(3)N_(2)-NWs anode delivers high specific capacity(282 m Ah g^(-1) at 0.1 A g^(-1)),excellent rate capability(87 m Ah g^(-1) at 16 A g^(-1))and long cycling stability(a capacity retention of 78.6%after 800 cycles at 1 A g^(-1)).The present work highlights that the surface pseudocapacitive sodium-ion storage mechanism enables to overcome the sluggish sodium-ion diffusion process,which opens a new direction to design and synthesize high-rate sodiumion storage materials.
