Lithium primary batteries are widely used in various fields where high energy densities and long storage times are in demand.However,studies on lithium primary batteries are currently focused on the gravimetric energy...Lithium primary batteries are widely used in various fields where high energy densities and long storage times are in demand.However,studies on lithium primary batteries are currently focused on the gravimetric energy densities of active materials and rarely account for the volumetric energy requirements of unmanned devices.Herein,CuF_(2)/CF_(x) composites are prepared via planetary ball milling(PBM)to improve the volumetric energy densities of lithium primary batteries using the high mass density of CuF_(2),achieving a maximum volumetric energy density of 4163.40 Wh L^(-1).The CuF_(2)/CF_(x) hybrid cathodes exhibit three distinct discharge plateaus rather than simple combinations of the discharge curves of their components.This phenomenon is caused by charge redistribution and lattice modulation on the contact surfaces of CuF_(2) and CF_(x) during PBM,which change the valence state of Cu and modify the electronic structures of the composites.As a result,CuF_(2)/CF_(x) hybrid cathodes exhibit unique discharge behaviors and improved rate capabilities,delivering a maximum power density of 11.16 kW kg^(-1)(25.56 kW L^(-1)).Therefore,it is a promising strategy to further improve the comprehensive performance of lithium primary batteries through the use of interfacial optimization among different fluoride cathodes.展开更多
The dynamics of negative surface discharges in c-C_(4)F_(8)/CF_(3)I/CO_(2) gas mixture is investigated here with a 2D fuid model.The distributions of ion concentration,electric field strength and photon flux during th...The dynamics of negative surface discharges in c-C_(4)F_(8)/CF_(3)I/CO_(2) gas mixture is investigated here with a 2D fuid model.The distributions of ion concentration,electric field strength and photon flux during the propagation of the streamer are obtained by solving the drift-diffusion equations of particles and Poisson's equation,and the photon flux variation function during the propagation is also fitted.It is found that the streamer branches occur when the streamer transitions from the upper surface of the insulator to the side surface,and then when the streamer approaches the plane electrode,the photon flux will increase significantly.On this basis,the positive and negative surface discharge models are compared in terms of streamer characteristics,particle characteristics and streamer branches.It is found that the streamer has a higher electron concentration and electric field in the positive model.The streamer develops“floating”in the positive surface discharge,while it is close to the surface of the insulator in the negative model.In addition,the negative streamer branch has a wider width and develops further.展开更多
Zn(CF_(3)SO_(3))_(2)as an electrolyte has been widely used to improve the electrochemical performance for ZIBs due to that the bulky CF_(3)SO_(3)-can reduce the solvation effect of Zn^(2+)and promote the ionic diffusi...Zn(CF_(3)SO_(3))_(2)as an electrolyte has been widely used to improve the electrochemical performance for ZIBs due to that the bulky CF_(3)SO_(3)-can reduce the solvation effect of Zn^(2+)and promote the ionic diffusion.Herein,we found that Zn(CF_(3)SO_(3))_(2)electrolyte can induce different electrochemical mechanisms from ZnSO_(4)electrolyte.Compared to the ZnSO^(4)electrolyte,the HNaV_(6)O_(16)·4H2_(O)electrode with Zn(CF_(3)SO_(3))_(2)electrolyte exhibits a high capacity of 444 mAh·g^(-1)at 500 mA·g^(-1)with a capacity retention of 92.3%after 80 cycles.Even,at a high rate of 5 Ag-1,the HNaV_(6)O_(16)·4H_(2)O electrode delivers an initial discharge capacity of 328 mAh·g^(-1)with a capacity retention of 93.7%after 1000 cycles.Differing from the mechanism with ZnSO4 electrolyte,the excellent cycle stability of HNaV_(6)O_(16)·4H_(2)Oelectrode can be attributed to the in-situ phase transformation to ZnxV_(2)O_(5)·nH_(2)O based on the co-intercalation of Zn^(2+)/H^(+).展开更多
A thermally-induced multi-component reaction of CF_(3)-substituted imidoyl sulfoxonium ylides(TFISYs),amines and(triphenylphosphonio)difluoroacetate(PDFA)has been developed,allowing a facile access to 2-trifluoromethy...A thermally-induced multi-component reaction of CF_(3)-substituted imidoyl sulfoxonium ylides(TFISYs),amines and(triphenylphosphonio)difluoroacetate(PDFA)has been developed,allowing a facile access to 2-trifluoromethyl-4-aminoquinolines in high yields.The reaction proceeds smoothly with or without the addition of sulfur and utilizes difluorocarbene as a C1 synthon under simply heating conditions.Mechanistic study reveals that in-situ generated thiocarbonyl fluoride,isothiocyanate or gem-difluoroalkene might act as the key reaction intermediates.展开更多
基金financially supported by the National Key R&D Program of China(No.2016YFA0202302)the State Key Program of National Natural Science Foundation of China(Nos.51633007 and 52130303)the National Natural Science Foundation of China(Nos.51773147 and 51973151).
文摘Lithium primary batteries are widely used in various fields where high energy densities and long storage times are in demand.However,studies on lithium primary batteries are currently focused on the gravimetric energy densities of active materials and rarely account for the volumetric energy requirements of unmanned devices.Herein,CuF_(2)/CF_(x) composites are prepared via planetary ball milling(PBM)to improve the volumetric energy densities of lithium primary batteries using the high mass density of CuF_(2),achieving a maximum volumetric energy density of 4163.40 Wh L^(-1).The CuF_(2)/CF_(x) hybrid cathodes exhibit three distinct discharge plateaus rather than simple combinations of the discharge curves of their components.This phenomenon is caused by charge redistribution and lattice modulation on the contact surfaces of CuF_(2) and CF_(x) during PBM,which change the valence state of Cu and modify the electronic structures of the composites.As a result,CuF_(2)/CF_(x) hybrid cathodes exhibit unique discharge behaviors and improved rate capabilities,delivering a maximum power density of 11.16 kW kg^(-1)(25.56 kW L^(-1)).Therefore,it is a promising strategy to further improve the comprehensive performance of lithium primary batteries through the use of interfacial optimization among different fluoride cathodes.
基金the National Natural Science Foundation of China(No.62075045)。
文摘The dynamics of negative surface discharges in c-C_(4)F_(8)/CF_(3)I/CO_(2) gas mixture is investigated here with a 2D fuid model.The distributions of ion concentration,electric field strength and photon flux during the propagation of the streamer are obtained by solving the drift-diffusion equations of particles and Poisson's equation,and the photon flux variation function during the propagation is also fitted.It is found that the streamer branches occur when the streamer transitions from the upper surface of the insulator to the side surface,and then when the streamer approaches the plane electrode,the photon flux will increase significantly.On this basis,the positive and negative surface discharge models are compared in terms of streamer characteristics,particle characteristics and streamer branches.It is found that the streamer has a higher electron concentration and electric field in the positive model.The streamer develops“floating”in the positive surface discharge,while it is close to the surface of the insulator in the negative model.In addition,the negative streamer branch has a wider width and develops further.
基金This study was financially supported by the National Natural Science Foundation of China(No.51772193)China Postdoctral Science Foundation(No.2019T250254).
文摘Zn(CF_(3)SO_(3))_(2)as an electrolyte has been widely used to improve the electrochemical performance for ZIBs due to that the bulky CF_(3)SO_(3)-can reduce the solvation effect of Zn^(2+)and promote the ionic diffusion.Herein,we found that Zn(CF_(3)SO_(3))_(2)electrolyte can induce different electrochemical mechanisms from ZnSO_(4)electrolyte.Compared to the ZnSO^(4)electrolyte,the HNaV_(6)O_(16)·4H2_(O)electrode with Zn(CF_(3)SO_(3))_(2)electrolyte exhibits a high capacity of 444 mAh·g^(-1)at 500 mA·g^(-1)with a capacity retention of 92.3%after 80 cycles.Even,at a high rate of 5 Ag-1,the HNaV_(6)O_(16)·4H_(2)O electrode delivers an initial discharge capacity of 328 mAh·g^(-1)with a capacity retention of 93.7%after 1000 cycles.Differing from the mechanism with ZnSO4 electrolyte,the excellent cycle stability of HNaV_(6)O_(16)·4H_(2)Oelectrode can be attributed to the in-situ phase transformation to ZnxV_(2)O_(5)·nH_(2)O based on the co-intercalation of Zn^(2+)/H^(+).
基金financial support from K.C.Wong Education Foundation(GJTD-2020-08).
文摘A thermally-induced multi-component reaction of CF_(3)-substituted imidoyl sulfoxonium ylides(TFISYs),amines and(triphenylphosphonio)difluoroacetate(PDFA)has been developed,allowing a facile access to 2-trifluoromethyl-4-aminoquinolines in high yields.The reaction proceeds smoothly with or without the addition of sulfur and utilizes difluorocarbene as a C1 synthon under simply heating conditions.Mechanistic study reveals that in-situ generated thiocarbonyl fluoride,isothiocyanate or gem-difluoroalkene might act as the key reaction intermediates.
