The super volume changes and severe mechanical degradation have been a hindrance in the wide application of silicon based composite electrodes in commercial lithium-ion batteries(LIBs).Calendering,one procedure in pro...The super volume changes and severe mechanical degradation have been a hindrance in the wide application of silicon based composite electrodes in commercial lithium-ion batteries(LIBs).Calendering,one procedure in producing LIBs'electrodes,is indispensable to ensure low porosity and energy density.However,the repercussions of the calendering process on the physical characteristics related to the behavior of silicon(Si)based electrodes during the electrochemical reaction have not been well understood.Thus,on account of the deformation characteristic of cantilever electrodes,an in-situ technique is employed to analyze the repercussions of calendering status on the coupled electro-chemo-mechanical performances.During the electrochemical cycling,Young's modulus and diffusion-induced stress in composite electrodes are quantified.The results show that the swelling strain,the stress and the modulus of the Si-based electrode and the calendering degree are positively correlated.Meanwhile,the stress induced by diffusion in the active layer tends to increase in the stage of lithiation and reverses during the delithiation process.Accompany with the SEM analysis,we conclude that the calendering process can induce larger stress,driving the formation of cracks in electrodes.These findings can help understand how the calendering process could affect the capacity dissipating and lifetime of Si based electrodes.展开更多
The free piston shock tunnel is a type of shock tunnel with high performance. For this type of tunnel, the influence mechanism of shock wave attenuation on tailored operation is explored by numerical simulation and th...The free piston shock tunnel is a type of shock tunnel with high performance. For this type of tunnel, the influence mechanism of shock wave attenuation on tailored operation is explored by numerical simulation and theoretical analysis. By introducing the normalized velocity, the simple constraint equation for shock wave under the tailored operation is deduced. Moreover, the real gas effect is also taken into account in this equation. Based on the equation, the tailored operation of shock tunnels can be predicted with very few calculations. The present study shows that the change rate of the thermodynamic state of the gas behind the shock wave is inconsistent with the attenuation rate of the shock wave, which is the fundamental reason why the wind tunnel achieves tailored operation at a lower Mach number of shock waves. This lower Mach number of shock waves differs from the corresponding ideal value by a factor, which is about the square root of shock attenuation rate.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.12102264).
文摘The super volume changes and severe mechanical degradation have been a hindrance in the wide application of silicon based composite electrodes in commercial lithium-ion batteries(LIBs).Calendering,one procedure in producing LIBs'electrodes,is indispensable to ensure low porosity and energy density.However,the repercussions of the calendering process on the physical characteristics related to the behavior of silicon(Si)based electrodes during the electrochemical reaction have not been well understood.Thus,on account of the deformation characteristic of cantilever electrodes,an in-situ technique is employed to analyze the repercussions of calendering status on the coupled electro-chemo-mechanical performances.During the electrochemical cycling,Young's modulus and diffusion-induced stress in composite electrodes are quantified.The results show that the swelling strain,the stress and the modulus of the Si-based electrode and the calendering degree are positively correlated.Meanwhile,the stress induced by diffusion in the active layer tends to increase in the stage of lithiation and reverses during the delithiation process.Accompany with the SEM analysis,we conclude that the calendering process can induce larger stress,driving the formation of cracks in electrodes.These findings can help understand how the calendering process could affect the capacity dissipating and lifetime of Si based electrodes.
基金supported by the National Natural Science Foundation of China (No. 11572303)。
文摘The free piston shock tunnel is a type of shock tunnel with high performance. For this type of tunnel, the influence mechanism of shock wave attenuation on tailored operation is explored by numerical simulation and theoretical analysis. By introducing the normalized velocity, the simple constraint equation for shock wave under the tailored operation is deduced. Moreover, the real gas effect is also taken into account in this equation. Based on the equation, the tailored operation of shock tunnels can be predicted with very few calculations. The present study shows that the change rate of the thermodynamic state of the gas behind the shock wave is inconsistent with the attenuation rate of the shock wave, which is the fundamental reason why the wind tunnel achieves tailored operation at a lower Mach number of shock waves. This lower Mach number of shock waves differs from the corresponding ideal value by a factor, which is about the square root of shock attenuation rate.
