Artificial solid electrolyte interphase(SEI) is promising to inhibit uncontrollable lithium dendrites and enable long cycling stability for lithium metal batteries. However, the essential mechanical stability is limit...Artificial solid electrolyte interphase(SEI) is promising to inhibit uncontrollable lithium dendrites and enable long cycling stability for lithium metal batteries. However, the essential mechanical stability is limited since organic layers generally have low modulus whereas intrinsic brittleness for inorganic ones remains a great concern. Polymer-based SEIs with rigid and flexible chains in adequate mechanical properties are supposed to address this issue. Herein, a homogeneous and mechanically stable diffusion layer is achieved by blending rigid chains of polyphenylene sulfone(PPSU) with flexible chains of poly(vinylidene fluoride)(PVDF) in a hybrid membrane, enabling uniform diffusion and stabilizing the lithium metal anode. The Li||Cu cell with the protected electrode exhibits a long lifetime more than 450 cycles(0.5 m A cm^(-2), 1.0 m A h cm^(-2))(fourfold longer than the control group) with higher average Coulombic efficiency of 98.7%. Enhanced performances are also observed at Li||Li and full cell configurations. The improved performances are attributed to the controlled morphology and stable interphase, according to scanning electron microscopy(SEM) and electrochemical impedance. This research advances the idea of uniform lithium plating and provides a new insight on how to create a homogeneous and mechanically stable diffusion layer using rigid-flexible polymers.展开更多
A third-order KdV solution to the internal solitary wave is derived by a new method based on the weakly nonlinear assumptions in a rigid-lid two-layer system.The solution corrects an error by Mirie and Su(1984).A two-...A third-order KdV solution to the internal solitary wave is derived by a new method based on the weakly nonlinear assumptions in a rigid-lid two-layer system.The solution corrects an error by Mirie and Su(1984).A two-dimensional numerical wave tank has been established with the help of the open source CFD library OpenFOAM and the third-party software waves2Foam.Various analytical solutions,including the first-order to third-order KdV solutions,the eKdV solution and the MCC solution,have been used to initialise the flow fields in the CFD simulations of internal solitary waves.Two groups including 11 numerical cases have been carried out.In the same group,the initial wave amplitudes are the same but the implemented analytical solutions are different.The simulated wave profiles at different moments have been presented.The relative errors in terms of the wave amplitude between the last time step and the initial input have been analysed quantitatively.It is found that the third-order KdV solution results in the most stable internal solitary wave in the numerical wave tank for both small-amplitude and finite-amplitude cases.The finding is significant for the further simulations involving internal solitary waves.展开更多
According to the principle of effective stress action of rock and soil, we established a mechanical model of water flooding into roadways,analyzed the constitutive relation of hydrodynamic pressure and contact pressur...According to the principle of effective stress action of rock and soil, we established a mechanical model of water flooding into roadways,analyzed the constitutive relation of hydrodynamic pressure and contact pressure of rock and soil and discovered that the process of pre-grouting of a roadway curtain is a dynamically balancing process in which effective stress keeps gradually in- creasing and pore water pressure gradually declines. In such a grouting process, the initial water plugging effect is realized when the effective stress and total stress reaches equilibrium. A rigid-flexible packing layer is designed behind the brickwork to increase the effective stress and reduce pore water pressure in order to have a permanent water proof performance. This provides a theoretical basis for roadway driving and permanent water prevention. The monitoring and application results show that the initial and perma- nent waterproof theory has provided an effective method for roadway driving and making it waterproof.展开更多
基金supported by the National Natural Science Foundation of China (Grant No. 22109008)。
文摘Artificial solid electrolyte interphase(SEI) is promising to inhibit uncontrollable lithium dendrites and enable long cycling stability for lithium metal batteries. However, the essential mechanical stability is limited since organic layers generally have low modulus whereas intrinsic brittleness for inorganic ones remains a great concern. Polymer-based SEIs with rigid and flexible chains in adequate mechanical properties are supposed to address this issue. Herein, a homogeneous and mechanically stable diffusion layer is achieved by blending rigid chains of polyphenylene sulfone(PPSU) with flexible chains of poly(vinylidene fluoride)(PVDF) in a hybrid membrane, enabling uniform diffusion and stabilizing the lithium metal anode. The Li||Cu cell with the protected electrode exhibits a long lifetime more than 450 cycles(0.5 m A cm^(-2), 1.0 m A h cm^(-2))(fourfold longer than the control group) with higher average Coulombic efficiency of 98.7%. Enhanced performances are also observed at Li||Li and full cell configurations. The improved performances are attributed to the controlled morphology and stable interphase, according to scanning electron microscopy(SEM) and electrochemical impedance. This research advances the idea of uniform lithium plating and provides a new insight on how to create a homogeneous and mechanically stable diffusion layer using rigid-flexible polymers.
基金This work is supported by Lloyd’s Register Foundation(LRF)through the joint centre involving University College London,Shanghai Jiaotong University and Harbin Engineer-ing University,to which the authors are most grateful.Lloyd’s Register Foundation helps to protect life and property by sup-porting engineering-related education,public engagement and the application of researchThe first author acknowledges the scholarship sponsored by the Erasmus Mundus Europe Asia(EMEA)scholarship pro-gramme,Faculty of Engineering of University College Lon-don and the Henry Lester Trust LtdThe second author ac-knowledges the financial support by the China Scholarship Council(CSC)(no.201206680001).
文摘A third-order KdV solution to the internal solitary wave is derived by a new method based on the weakly nonlinear assumptions in a rigid-lid two-layer system.The solution corrects an error by Mirie and Su(1984).A two-dimensional numerical wave tank has been established with the help of the open source CFD library OpenFOAM and the third-party software waves2Foam.Various analytical solutions,including the first-order to third-order KdV solutions,the eKdV solution and the MCC solution,have been used to initialise the flow fields in the CFD simulations of internal solitary waves.Two groups including 11 numerical cases have been carried out.In the same group,the initial wave amplitudes are the same but the implemented analytical solutions are different.The simulated wave profiles at different moments have been presented.The relative errors in terms of the wave amplitude between the last time step and the initial input have been analysed quantitatively.It is found that the third-order KdV solution results in the most stable internal solitary wave in the numerical wave tank for both small-amplitude and finite-amplitude cases.The finding is significant for the further simulations involving internal solitary waves.
基金Projects 50774078 supported by the National Natural Science Foundation of China 2007CB209400 by the National Basic Research Program of China
文摘According to the principle of effective stress action of rock and soil, we established a mechanical model of water flooding into roadways,analyzed the constitutive relation of hydrodynamic pressure and contact pressure of rock and soil and discovered that the process of pre-grouting of a roadway curtain is a dynamically balancing process in which effective stress keeps gradually in- creasing and pore water pressure gradually declines. In such a grouting process, the initial water plugging effect is realized when the effective stress and total stress reaches equilibrium. A rigid-flexible packing layer is designed behind the brickwork to increase the effective stress and reduce pore water pressure in order to have a permanent water proof performance. This provides a theoretical basis for roadway driving and permanent water prevention. The monitoring and application results show that the initial and perma- nent waterproof theory has provided an effective method for roadway driving and making it waterproof.
