以五氧化二钒干凝胶、碳酸锰、磷酸二氢铵、碳酸锂、乙炔黑为原料,采用固相法在相对较低的温度条件下合成了x Li Mn PO4·y Li3V2(PO4)3锂离子电池复合正极材料。采用X射线衍射(XRD)、扫描电镜(SEM)对其晶体结构和表面形貌进行表征...以五氧化二钒干凝胶、碳酸锰、磷酸二氢铵、碳酸锂、乙炔黑为原料,采用固相法在相对较低的温度条件下合成了x Li Mn PO4·y Li3V2(PO4)3锂离子电池复合正极材料。采用X射线衍射(XRD)、扫描电镜(SEM)对其晶体结构和表面形貌进行表征。结果表明,750℃下烧结15 h合成的3Li Mn PO4·Li3V2(PO4)3为结晶良好的两相结构,颗粒粒径较小且分布比较均匀,其在室温、0.2 C倍率下首次充放电容量分别为144.8 m Ah/g和139.8 m Ah/g,循环50次后容量为130.5 m Ah/g。展开更多
Single-atomic site catalysts have drawn considerable attention because of their maximum atom-utilization efficiency and excellent catalytic activity.In this work,a highly active single-atomic Pt site photocatalyst was...Single-atomic site catalysts have drawn considerable attention because of their maximum atom-utilization efficiency and excellent catalytic activity.In this work,a highly active single-atomic Pt site photocatalyst was synthesized through employing defective Ti0_(2) nanosheets as solid support for photo-catalytic water splitting.It indicated that the surface oxygen vacancies on defective Ti0_(2) nanosheets could effectively stabilize the single-atomic Pt sites through constructing a three-center Ti-Pt-Ti structure.The Ti-Pt-Ti structure can hold the stability of isolated single-atomic Pt sites and facilitate the separation and transfer of photoinduced charge carriers,thereby greatly improving the photocatalytic H2 evolution.Notably,our synthesized photocatalyst exhibited a remarkably enhanced H2 evolution performance,and the H2 production rate is up to 13460.7μmol h^(-1)·g^(-1),which is up to around 29.0 and 4.7 times higher than those of Ti0_(2) nanosheets and Pt nanoparticles-Ti0_(2).In addition,a plausible enhanced reaction mechanism was also proposed combining with photo-electrochemical characterizations and density functional theoiy(DFT)calculation results.Ultimately,it is believed that this work highlights the benefits of a single-site catalyst and paves the way to rationally design the highly active and stable single-atomic site photocatalysts on metal oxide support.展开更多
Fast charging and high-power delivering batteries are highly demanded in mobile electronics,electric vehicles and grid energy storage,but there are full of challenges.The star-material Li_(3)V_(2)(PO_(4))_(3) is demon...Fast charging and high-power delivering batteries are highly demanded in mobile electronics,electric vehicles and grid energy storage,but there are full of challenges.The star-material Li_(3)V_(2)(PO_(4))_(3) is demonstrated as a promising high-rate cathode material meeting the above requirements.Herein,we report the carbon decorated Li_(3)V_(2)(PO_(4))_(3) (LVP/C) cathode prepared via a facile method,which displays a remarkable high-rate capability and long-term cycling performance.Briefly,the prepared LVP/C delivers a high discharge capacity of 122 mAh g^(-1)(-93% of the theoretical capacity) at a high rate up to 20 C and a superior capacity retention of 87.1% after 1000 cycles.Importantly,by applying a combination of X-ray absorption spectroscopy and full-range mapping of resonant inelastic X-ray scattering,we clearly elucidate the structural and chemical evolutions of LVP upon various potentials and cycle numbers.We show unambiguous spectroscopic evidences that the evolution of the hybridization strength between V and O in LVP/C as a consequence of lithiation/delithiation is highly reversible both in the bulk and on the surface during the discharge-charge processes even over extended cycles,which should be responsible for the remarkable electrochemical performance of LVP/C.Our present study provides not only an effective synthesis strategy but also deeper insights into the surface and bulk electrochemical reaction mechanism of LVP,which should be beneficial for the further design of high-performance LVP electrode materials.展开更多
Li_(1.3)Al_(0.3)Ti_(1.7)(PO_(4))_(3)(LATP),of much interest owing to its high ionic conductivity,superior air stability,and low cost,has been regarded as one of the most promising solid-state electrolytes for next-gen...Li_(1.3)Al_(0.3)Ti_(1.7)(PO_(4))_(3)(LATP),of much interest owing to its high ionic conductivity,superior air stability,and low cost,has been regarded as one of the most promising solid-state electrolytes for next-generation solid-state lithium batteries(SSLBs).Unfortunately,the commercialization of SSLBs is still impeded by severe interfacial issues,such as high interfacial impedance and poor chemical stability.Herein,we proposed a simple and convenient in-situ approach to constructing a tight and robust interface between the Li anode and LATP electrolyte via a SnO_(2)gradient buffer layer.It is firmly attached to the surface of LATP pellets due to the volume expansion of SnO_(2)when in-situ reacting with Li metal,and thus effectively alleviates the physical contact loosening during cycling,as confirmed by the mitigated impedance rising.Meanwhile,the as-formed SnO_(2)/Sn/LixSn gradient buffer layer with low electronic conductivity successfully protects the LATP electrolyte surface from erosion by the Li metal anode.Additionally,the LixSn alloy formed at the Li surface can effectively regulate uniform lithium deposition and suppress Li dendrite growth.Therefore,this work paves a new way to simultaneously address the chemical instability and poor physical contact of LATP with Li metal in developing low-cost and highly stable SSLBs.展开更多
Lithium(Li)-rich manganese(Mn)-based cathode Li_(1.2)Ni_(0.13)Co_(0.13)Mn_(0.54)O_(2)(LRNCM)has attracted considerable attention owing to its high specific discharge capacity and low cost.However,unsatisfactory cycle ...Lithium(Li)-rich manganese(Mn)-based cathode Li_(1.2)Ni_(0.13)Co_(0.13)Mn_(0.54)O_(2)(LRNCM)has attracted considerable attention owing to its high specific discharge capacity and low cost.However,unsatisfactory cycle performance and poor rate property hinder its large-scale application.The fast ionic conductor has been widely used as the cathode coating material because of its superior stability and excellent lithium-ion conductivity rate.In this study,Li_(1.2)Ni_(0.13)Co_(0.13)Mn_(0.54)O_(2) is modified by using Li_(1.4)Al_(0.4)Ti_(1.6)(PO_(4))_(3)(LATP)ionic conductor.The electrochemical test results show that the discharge capacity of the resulting LRNCM@LATP1 sample is 198 mA·h/g after 100 cycles at 0.2C,with a capacity retention of 81%.Compared with the uncoated pristine LRNCM(188.4 m A·h/g and 76%),LRNCM after the LATP modification shows superior cycle performance.Moreover,the lithium-ion diffusion coefficient D_(Li+)is a crucial factor affecting the rate performance,and the D_(Li+)of the LRNCM material is improved from 4.94×10^(-13) to 5.68×10^(-12)cm^(2)/s after modification.The specific capacity of LRNCM@LATP1 reaches 102.5 mA·h/g at 5C,with an improved rate performance.Thus,the modification layer can considerably enhance the electrochemical performance of LRNCM.展开更多
As the major source of air pollution,sulfur dioxide(S0_(2))emissions have become the focus of global attention.However,existing studies rarely consider spatial effects when discussing the relationship between foreign ...As the major source of air pollution,sulfur dioxide(S0_(2))emissions have become the focus of global attention.However,existing studies rarely consider spatial effects when discussing the relationship between foreign direct investment(FDI)and S0_(2) emissions.This study took the Yangtze River Delta as the research area and used the spatial panel data of 26 cities in this region for 2004-2017.The study investigated the spatial agglomeration effects and dynamics at work in FDI and S0_(2) emissions by using global and local measures of spatial autocorrelation.Then,based on regression analysis using a results of traditional ordinary least squares(OLS)model and a spatial econometric model,the spatial Durbin model(SDM)with spatial-time effects was adopted to quantify the impact of FDI on S0_(2) emissions,so as to avoid the regression results bias caused by ignoring the spatial effects.The results revealed a significant spatial autocorrelation between FDI and S0_(2) emissions,both of which displayed obvious path dependence characteristics in their geographical distribution.A series of agglomeration regions were observed on the spatial scale.The estimation results of the SDM showed that FDI inflow promoted S0_(2) emissions,which supports the pollution haven hypothesis.The findings of this study are significant in the prevention and control of air pollution in the Yangtze River Delta.展开更多
Magnetic susceptibility,specific heat,and neutron powder diffraction measurements have been performed on polycrystalline Li_(2)Co(WO_4)_(2)samples.Under zero magnetic field,two successive magnetic transitions at T_(N1...Magnetic susceptibility,specific heat,and neutron powder diffraction measurements have been performed on polycrystalline Li_(2)Co(WO_4)_(2)samples.Under zero magnetic field,two successive magnetic transitions at T_(N1)~9.4 K and T_(N2)~7.4 K are observed.The magnetic ordering temperatures gradually decrease as the magnetic field increases.Neutron diffraction reveals that Li_(2)Co(WO_4)_(2)enters an incommensurate magnetic state with a temperature dependent k between T_(N1)and T_(N2).The magnetic propagation vector locks-in to a commensurate value k=(1/2,1/4,1/4)below T_(N2).The antiferromagnetic structure is refined at 1.7 K with Co2+magnetic moment 2.8(1),μ_B,consistent with our first-principles calculations.展开更多
文摘以五氧化二钒干凝胶、碳酸锰、磷酸二氢铵、碳酸锂、乙炔黑为原料,采用固相法在相对较低的温度条件下合成了x Li Mn PO4·y Li3V2(PO4)3锂离子电池复合正极材料。采用X射线衍射(XRD)、扫描电镜(SEM)对其晶体结构和表面形貌进行表征。结果表明,750℃下烧结15 h合成的3Li Mn PO4·Li3V2(PO4)3为结晶良好的两相结构,颗粒粒径较小且分布比较均匀,其在室温、0.2 C倍率下首次充放电容量分别为144.8 m Ah/g和139.8 m Ah/g,循环50次后容量为130.5 m Ah/g。
基金This research was funded by the Canadian Centre for Clean Coal/Carbon and Mineral Processing Technologies(C5MPT),the National Key R&D Program of China(2017YFB0310803)and the China Scholarship Council(CSC).We thank the NanoFAB at the University of Alberta for the convenience of instruments use,and the kindly help of Nanqi Duan and Chao Qi on sample characterization.
文摘Single-atomic site catalysts have drawn considerable attention because of their maximum atom-utilization efficiency and excellent catalytic activity.In this work,a highly active single-atomic Pt site photocatalyst was synthesized through employing defective Ti0_(2) nanosheets as solid support for photo-catalytic water splitting.It indicated that the surface oxygen vacancies on defective Ti0_(2) nanosheets could effectively stabilize the single-atomic Pt sites through constructing a three-center Ti-Pt-Ti structure.The Ti-Pt-Ti structure can hold the stability of isolated single-atomic Pt sites and facilitate the separation and transfer of photoinduced charge carriers,thereby greatly improving the photocatalytic H2 evolution.Notably,our synthesized photocatalyst exhibited a remarkably enhanced H2 evolution performance,and the H2 production rate is up to 13460.7μmol h^(-1)·g^(-1),which is up to around 29.0 and 4.7 times higher than those of Ti0_(2) nanosheets and Pt nanoparticles-Ti0_(2).In addition,a plausible enhanced reaction mechanism was also proposed combining with photo-electrochemical characterizations and density functional theoiy(DFT)calculation results.Ultimately,it is believed that this work highlights the benefits of a single-site catalyst and paves the way to rationally design the highly active and stable single-atomic site photocatalysts on metal oxide support.
基金supported by Collaborative Innovation Center of Suzhou Nano Science & Technologythe Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)+5 种基金the 111 roject, Joint International Research Laboratory of Carbon-Based Functional Materials and Devicesthe National Natural Science Foundation of China (11905154)the Natural Science Foundation of the Jiangsu Higher Education Institutions of China (19KJA550004)the Natural Science Foundation of Jiangsu Province (BK20190814)the National Key R&D Program of China (No. 2016YFA0202600)supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231。
文摘Fast charging and high-power delivering batteries are highly demanded in mobile electronics,electric vehicles and grid energy storage,but there are full of challenges.The star-material Li_(3)V_(2)(PO_(4))_(3) is demonstrated as a promising high-rate cathode material meeting the above requirements.Herein,we report the carbon decorated Li_(3)V_(2)(PO_(4))_(3) (LVP/C) cathode prepared via a facile method,which displays a remarkable high-rate capability and long-term cycling performance.Briefly,the prepared LVP/C delivers a high discharge capacity of 122 mAh g^(-1)(-93% of the theoretical capacity) at a high rate up to 20 C and a superior capacity retention of 87.1% after 1000 cycles.Importantly,by applying a combination of X-ray absorption spectroscopy and full-range mapping of resonant inelastic X-ray scattering,we clearly elucidate the structural and chemical evolutions of LVP upon various potentials and cycle numbers.We show unambiguous spectroscopic evidences that the evolution of the hybridization strength between V and O in LVP/C as a consequence of lithiation/delithiation is highly reversible both in the bulk and on the surface during the discharge-charge processes even over extended cycles,which should be responsible for the remarkable electrochemical performance of LVP/C.Our present study provides not only an effective synthesis strategy but also deeper insights into the surface and bulk electrochemical reaction mechanism of LVP,which should be beneficial for the further design of high-performance LVP electrode materials.
基金financially supported by the China Postdoctoral Science Foundation(2021M700396)the National Natural Science Foundation of China(52102206)the research grants from the National Research Foundation(2022K1A3A1A20014496 and 2022R1F1A1074707)funded by the government of the Republic of Korea。
文摘Li_(1.3)Al_(0.3)Ti_(1.7)(PO_(4))_(3)(LATP),of much interest owing to its high ionic conductivity,superior air stability,and low cost,has been regarded as one of the most promising solid-state electrolytes for next-generation solid-state lithium batteries(SSLBs).Unfortunately,the commercialization of SSLBs is still impeded by severe interfacial issues,such as high interfacial impedance and poor chemical stability.Herein,we proposed a simple and convenient in-situ approach to constructing a tight and robust interface between the Li anode and LATP electrolyte via a SnO_(2)gradient buffer layer.It is firmly attached to the surface of LATP pellets due to the volume expansion of SnO_(2)when in-situ reacting with Li metal,and thus effectively alleviates the physical contact loosening during cycling,as confirmed by the mitigated impedance rising.Meanwhile,the as-formed SnO_(2)/Sn/LixSn gradient buffer layer with low electronic conductivity successfully protects the LATP electrolyte surface from erosion by the Li metal anode.Additionally,the LixSn alloy formed at the Li surface can effectively regulate uniform lithium deposition and suppress Li dendrite growth.Therefore,this work paves a new way to simultaneously address the chemical instability and poor physical contact of LATP with Li metal in developing low-cost and highly stable SSLBs.
基金Project(51772333) supported by the National Natural Science Foundation of China。
文摘Lithium(Li)-rich manganese(Mn)-based cathode Li_(1.2)Ni_(0.13)Co_(0.13)Mn_(0.54)O_(2)(LRNCM)has attracted considerable attention owing to its high specific discharge capacity and low cost.However,unsatisfactory cycle performance and poor rate property hinder its large-scale application.The fast ionic conductor has been widely used as the cathode coating material because of its superior stability and excellent lithium-ion conductivity rate.In this study,Li_(1.2)Ni_(0.13)Co_(0.13)Mn_(0.54)O_(2) is modified by using Li_(1.4)Al_(0.4)Ti_(1.6)(PO_(4))_(3)(LATP)ionic conductor.The electrochemical test results show that the discharge capacity of the resulting LRNCM@LATP1 sample is 198 mA·h/g after 100 cycles at 0.2C,with a capacity retention of 81%.Compared with the uncoated pristine LRNCM(188.4 m A·h/g and 76%),LRNCM after the LATP modification shows superior cycle performance.Moreover,the lithium-ion diffusion coefficient D_(Li+)is a crucial factor affecting the rate performance,and the D_(Li+)of the LRNCM material is improved from 4.94×10^(-13) to 5.68×10^(-12)cm^(2)/s after modification.The specific capacity of LRNCM@LATP1 reaches 102.5 mA·h/g at 5C,with an improved rate performance.Thus,the modification layer can considerably enhance the electrochemical performance of LRNCM.
基金Under the auspices of National Natural Science Foundation of China(No.41771140)National Key R&D Program of China(No.2018YFE0105900)。
文摘As the major source of air pollution,sulfur dioxide(S0_(2))emissions have become the focus of global attention.However,existing studies rarely consider spatial effects when discussing the relationship between foreign direct investment(FDI)and S0_(2) emissions.This study took the Yangtze River Delta as the research area and used the spatial panel data of 26 cities in this region for 2004-2017.The study investigated the spatial agglomeration effects and dynamics at work in FDI and S0_(2) emissions by using global and local measures of spatial autocorrelation.Then,based on regression analysis using a results of traditional ordinary least squares(OLS)model and a spatial econometric model,the spatial Durbin model(SDM)with spatial-time effects was adopted to quantify the impact of FDI on S0_(2) emissions,so as to avoid the regression results bias caused by ignoring the spatial effects.The results revealed a significant spatial autocorrelation between FDI and S0_(2) emissions,both of which displayed obvious path dependence characteristics in their geographical distribution.A series of agglomeration regions were observed on the spatial scale.The estimation results of the SDM showed that FDI inflow promoted S0_(2) emissions,which supports the pollution haven hypothesis.The findings of this study are significant in the prevention and control of air pollution in the Yangtze River Delta.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11834002,12074111,and 11704109)the National Key R&D Project of China(Grant No.2016YFA0300101)。
文摘Magnetic susceptibility,specific heat,and neutron powder diffraction measurements have been performed on polycrystalline Li_(2)Co(WO_4)_(2)samples.Under zero magnetic field,two successive magnetic transitions at T_(N1)~9.4 K and T_(N2)~7.4 K are observed.The magnetic ordering temperatures gradually decrease as the magnetic field increases.Neutron diffraction reveals that Li_(2)Co(WO_4)_(2)enters an incommensurate magnetic state with a temperature dependent k between T_(N1)and T_(N2).The magnetic propagation vector locks-in to a commensurate value k=(1/2,1/4,1/4)below T_(N2).The antiferromagnetic structure is refined at 1.7 K with Co2+magnetic moment 2.8(1),μ_B,consistent with our first-principles calculations.
