The understanding of reaction mechanisms of electrode materials is of significant importance for the development of advanced batteries.The LiMn2O4 cathode has a voltage plateau around 2.8 V(vs.Li^+/Li),which can provi...The understanding of reaction mechanisms of electrode materials is of significant importance for the development of advanced batteries.The LiMn2O4 cathode has a voltage plateau around 2.8 V(vs.Li^+/Li),which can provide an additional capacity for Li storage,but it suffers from a severe capacity degradation.In this study,operando X-ray diffraction is carried out to investigate the structural evolutions and degradation mechanisms of LiMn2O4 in different voltage ranges.In the range of 3.0-4.3 V(vs.Li^+/Li),the LiMn2O4 cathode exhibits a low capacity but good cycling stability with cycles up to 100 cycles and the charge/discharge processes are associated with the reversible extraction/insertion of Li^+from/into LixMn2O4(0≤x≤1).In the range of 1.4-4.4 V(vs.Li^+/Li),a capacity higher than 200 mAh/g is achieved,but it rapidly decays during the cycling.The voltage plateau around 2.8 V(vs.Li^+/Li)is related to the transformation of the cubic LiMn2O4 phase to the tetragonal Li2Mn2O4 phase,which leads to the formation of cracks as well as the performance degradation.展开更多
Transient change of the operating parameters has a serious influence on the stability of liquid annular seals.Take the liquid annular seals as a research object,a numerical method based on six-degree-of-freedom(6DOF)t...Transient change of the operating parameters has a serious influence on the stability of liquid annular seals.Take the liquid annular seals as a research object,a numerical method based on six-degree-of-freedom(6DOF)to analyze the dynamic response of liquid annular seals under gravity impact load.The variations of the force of liquid seal and pressure as well as the axis trajectory in time history are investigated.The influence of different sealing clearance,different liquid viscosity and different rotor speed is also studied.The results show that the maximum sealing pressure and sealing force of gravity direction will increase greatly in a very short time and then reduce rapidly.When sealing clearance increases,the displacement response amplitudes of axis trajectory,the maximum sealing force of gravity direction and maximum sealing pressure also increase.When liquid viscosity increases,the displacement response amplitudes of axis trajectory,the maximum sealing force of gravity direction and maximum sealing pressure decrease.We also found that different rotor speed has almost no influence on the maximum sealing force of gravity direction and maximum sealing pressure.展开更多
Magnesium ion batteries are emerging as promising alternatives to lithium ion batteries because of their advantages including high energydensity,dendrite-free features and low cost.Nevertheless,one of the major challe...Magnesium ion batteries are emerging as promising alternatives to lithium ion batteries because of their advantages including high energydensity,dendrite-free features and low cost.Nevertheless,one of the major challenges for magnesium ion batteries is the kinetically sluggishmagnesium insertion/extraction and diffusion in electrode materials.Aiming at this issue,biphase eutectic-like bismuth-tin film is designedherein to construct a self-supporting anode with interdigitated phase distribution and hierarchically porous structure,and further fabricated bya facile one-step magnetron cosputtering route.As benchmarked with single-phase bismuth or tin film,the biphase bismuth-tin film delivershigh specific capacity (538 mAh/g at 50 mA/g),excellent rate performance (417 mAh/g at 1,000 mA/g) and good cycling stability (233 mAh/gat the 200th cycle).The superior magnesium storage performance of the sputtered bismuth-tin film could be attributed to the synergetic effectof the interdigitated bismuth/tin phase distribution,hierarchically porous structure and biphase buffering matrices,which could increase ionictransport channels,shorten diffusion lengths and reduce total volume changes.展开更多
Engineering of carbon/metal nanocomposites with small metal particles is promising for the development of alloy-type anodes.Herein,an Sb@C composite was developed from a commercial potassium antimony tartrate precurso...Engineering of carbon/metal nanocomposites with small metal particles is promising for the development of alloy-type anodes.Herein,an Sb@C composite was developed from a commercial potassium antimony tartrate precursor using a scalable pyrolysis method.Ultrafine Sb nanoparticles are confined within a porous carbon framework,which substantially facilitates the diffusion of Na-ion/electrons and effectively alleviates the charg-ing/discharging induced volume change.The obtained Sb@C material displays excellent electrochemical perfor-mance for Na^(+) storage.The Na^(+) diffusion behavior of Sb@C was comprehensively investigated using various methods,and its gas evolution during the discharge/charge was monitored via online mass spectrometry.Then,Sb@C was assembled into full cells.During discharge/charge processes,the Na_(3)V_(2)(PO_(4))_(2)F_(3)/Sb@C full cells de-livered a competitive working voltage of 2.95 V and a capacity retention of 93.4%(50 cycles@0.2 A g^(−1)).Considering its facile preparation method from a commercial precursor,the Sb@C composite can potentially realize a large-scale application of sodium-ion batteries.展开更多
Bi-Sb alloys are appealing anode materials for potassium ion batteries(PIBs)but challenged by their enormous volumetric variation during operation.Herein,a facile one-step dealloying protocol was devised and utilized ...Bi-Sb alloys are appealing anode materials for potassium ion batteries(PIBs)but challenged by their enormous volumetric variation during operation.Herein,a facile one-step dealloying protocol was devised and utilized to prepare the Bi-Sb alloys that manifest an exotic bicontinuous hierarchical nanoporous(np)microstructure ideal for volume-change mitigation and K+transport percolation.The growth mechanism fostering the peculiar morphology of the np-(Bi,Sb)alloys was investigated and clarified via operando X-ray(XRD)and ex-situ scanning electron microscopy(SEM).In particular,the np-Bi6Sb2 electrode,optimized for comprehensive electrochemical performance,achieves decent reversible capacities and a superior lifespan,as benchmarked with the monometallic references and other Bi-Sb alloy electrodes.The(de)potassiation mechanism of the np-(Bi,Sb)alloys was studied by operando XRD and further rationalized by density functional theory(DFT)calculations,whereby a homogeneous(segregation-free)and robust two-step electrochemically-driven phase transformations’catenation of(Bi,Sb)↔K(Bi,Sb)2↔K3(Bi,Sb)was reliably established to substantiate the outstanding reversibility of the np-(Bi,Sb)anodes in PIBs.展开更多
This paper is concerned with the active control of thermomechanical buckling of composite laminated plates using piezoelectric facesheets as actuators.The four-variable trigonometric shear deformation theory and Hamil...This paper is concerned with the active control of thermomechanical buckling of composite laminated plates using piezoelectric facesheets as actuators.The four-variable trigonometric shear deformation theory and Hamilto's principle are applied to formulate the governing equation of structural system.The temperature feedback control strategy is proposed to conduct the active control of thermal-mechanical buckling.The simulation results show that the thermo-mechanical buckling of composite laminated plates can be effectively controlled by the presented control method.With a specific control gain,the critical mechanical buckling load can remain constant at different temperatures.The effects of geometric parameters,fiber angle,stacking sequence,position of piezoelectric layer and boundary conditions on the active control of thermo-mechanical buckling are also investigated.展开更多
基金the financial support by the National Natural Science Foundation of China (51871133, 51671115)support by the Department of Science and Technology of the Shandong Province for the Young Tip-Top Talent Support Project.
文摘The understanding of reaction mechanisms of electrode materials is of significant importance for the development of advanced batteries.The LiMn2O4 cathode has a voltage plateau around 2.8 V(vs.Li^+/Li),which can provide an additional capacity for Li storage,but it suffers from a severe capacity degradation.In this study,operando X-ray diffraction is carried out to investigate the structural evolutions and degradation mechanisms of LiMn2O4 in different voltage ranges.In the range of 3.0-4.3 V(vs.Li^+/Li),the LiMn2O4 cathode exhibits a low capacity but good cycling stability with cycles up to 100 cycles and the charge/discharge processes are associated with the reversible extraction/insertion of Li^+from/into LixMn2O4(0≤x≤1).In the range of 1.4-4.4 V(vs.Li^+/Li),a capacity higher than 200 mAh/g is achieved,but it rapidly decays during the cycling.The voltage plateau around 2.8 V(vs.Li^+/Li)is related to the transformation of the cubic LiMn2O4 phase to the tetragonal Li2Mn2O4 phase,which leads to the formation of cracks as well as the performance degradation.
基金Key projects of technological innovation and application development of Chongqing,China(Grant NO.cstc2018jszx-cyzd0729).
文摘Transient change of the operating parameters has a serious influence on the stability of liquid annular seals.Take the liquid annular seals as a research object,a numerical method based on six-degree-of-freedom(6DOF)to analyze the dynamic response of liquid annular seals under gravity impact load.The variations of the force of liquid seal and pressure as well as the axis trajectory in time history are investigated.The influence of different sealing clearance,different liquid viscosity and different rotor speed is also studied.The results show that the maximum sealing pressure and sealing force of gravity direction will increase greatly in a very short time and then reduce rapidly.When sealing clearance increases,the displacement response amplitudes of axis trajectory,the maximum sealing force of gravity direction and maximum sealing pressure also increase.When liquid viscosity increases,the displacement response amplitudes of axis trajectory,the maximum sealing force of gravity direction and maximum sealing pressure decrease.We also found that different rotor speed has almost no influence on the maximum sealing force of gravity direction and maximum sealing pressure.
基金National Natural Science Foundation of China (Nos. 51671115 and 51871133)Department of Science and Technology of Shandong Province for Young Tip-top Talent Support ProjectYoung Tip-top Talent Support Project (the Organization Department of the Central Committee of the CPC).
文摘Magnesium ion batteries are emerging as promising alternatives to lithium ion batteries because of their advantages including high energydensity,dendrite-free features and low cost.Nevertheless,one of the major challenges for magnesium ion batteries is the kinetically sluggishmagnesium insertion/extraction and diffusion in electrode materials.Aiming at this issue,biphase eutectic-like bismuth-tin film is designedherein to construct a self-supporting anode with interdigitated phase distribution and hierarchically porous structure,and further fabricated bya facile one-step magnetron cosputtering route.As benchmarked with single-phase bismuth or tin film,the biphase bismuth-tin film delivershigh specific capacity (538 mAh/g at 50 mA/g),excellent rate performance (417 mAh/g at 1,000 mA/g) and good cycling stability (233 mAh/gat the 200th cycle).The superior magnesium storage performance of the sputtered bismuth-tin film could be attributed to the synergetic effectof the interdigitated bismuth/tin phase distribution,hierarchically porous structure and biphase buffering matrices,which could increase ionictransport channels,shorten diffusion lengths and reduce total volume changes.
基金Taishan Scholar Founda-tion of Shandong Province and Jinan Science and Technology Bureau(2019GXRC001).
文摘Engineering of carbon/metal nanocomposites with small metal particles is promising for the development of alloy-type anodes.Herein,an Sb@C composite was developed from a commercial potassium antimony tartrate precursor using a scalable pyrolysis method.Ultrafine Sb nanoparticles are confined within a porous carbon framework,which substantially facilitates the diffusion of Na-ion/electrons and effectively alleviates the charg-ing/discharging induced volume change.The obtained Sb@C material displays excellent electrochemical perfor-mance for Na^(+) storage.The Na^(+) diffusion behavior of Sb@C was comprehensively investigated using various methods,and its gas evolution during the discharge/charge was monitored via online mass spectrometry.Then,Sb@C was assembled into full cells.During discharge/charge processes,the Na_(3)V_(2)(PO_(4))_(2)F_(3)/Sb@C full cells de-livered a competitive working voltage of 2.95 V and a capacity retention of 93.4%(50 cycles@0.2 A g^(−1)).Considering its facile preparation method from a commercial precursor,the Sb@C composite can potentially realize a large-scale application of sodium-ion batteries.
基金The authors gratefully acknowledge financial support by National Natural Science Foundation of China(51871133,92045302,21972055,21825202,21733012 and 21972133)the support of Taishan Scholar Foundation of Shandong Province,the program of Jinan Science and Technology Bureau(2019GXRC001)+1 种基金National Key R&D Program of China(2018YFB0104400)the Newton Advanced Fellowships(NAF/R2/180603).
文摘Bi-Sb alloys are appealing anode materials for potassium ion batteries(PIBs)but challenged by their enormous volumetric variation during operation.Herein,a facile one-step dealloying protocol was devised and utilized to prepare the Bi-Sb alloys that manifest an exotic bicontinuous hierarchical nanoporous(np)microstructure ideal for volume-change mitigation and K+transport percolation.The growth mechanism fostering the peculiar morphology of the np-(Bi,Sb)alloys was investigated and clarified via operando X-ray(XRD)and ex-situ scanning electron microscopy(SEM).In particular,the np-Bi6Sb2 electrode,optimized for comprehensive electrochemical performance,achieves decent reversible capacities and a superior lifespan,as benchmarked with the monometallic references and other Bi-Sb alloy electrodes.The(de)potassiation mechanism of the np-(Bi,Sb)alloys was studied by operando XRD and further rationalized by density functional theory(DFT)calculations,whereby a homogeneous(segregation-free)and robust two-step electrochemically-driven phase transformations’catenation of(Bi,Sb)↔K(Bi,Sb)2↔K3(Bi,Sb)was reliably established to substantiate the outstanding reversibility of the np-(Bi,Sb)anodes in PIBs.
基金This work was supported by the National Natural Science Foundation of China(Nos.12072084 and 11761131006)the Fundamental Research Funds for the Central Universities,the Ph.D.Student ResearchInnovation Fund of the Fundamental Research Funds for the Central Universities(No.3072020GIP0206).
文摘This paper is concerned with the active control of thermomechanical buckling of composite laminated plates using piezoelectric facesheets as actuators.The four-variable trigonometric shear deformation theory and Hamilto's principle are applied to formulate the governing equation of structural system.The temperature feedback control strategy is proposed to conduct the active control of thermal-mechanical buckling.The simulation results show that the thermo-mechanical buckling of composite laminated plates can be effectively controlled by the presented control method.With a specific control gain,the critical mechanical buckling load can remain constant at different temperatures.The effects of geometric parameters,fiber angle,stacking sequence,position of piezoelectric layer and boundary conditions on the active control of thermo-mechanical buckling are also investigated.