The practical applications of high-capacity alloy-type anode materials in sodium-ion batteries(SIBs)are challenged by their vast volume effects and resulting unstable electrode-electrolyte interphases during discharge...The practical applications of high-capacity alloy-type anode materials in sodium-ion batteries(SIBs)are challenged by their vast volume effects and resulting unstable electrode-electrolyte interphases during discharge-charge cycling.Taking red phosphorus(P)/carbon anode material as an example,we report an on-site conversion reaction to intentionally eliminate the volume effect-dominated surface P and yield an ionically conducting layer of Na3PS4solid-state electrolyte on the composite.Such a surface reconstruction can significantly suppress the electrode swelling and simultaneously enable the activation energy of interfacial Na+transfer as low as 36.7 k J mol^(-1),resulting in excellent electrode stability and ultrafast reaction kinetics.Consequently,excellent cycling performance(510 mA h g^(-1)at 5 A g^(-1)after 1000 cycles with a tiny capacity fading rate of 0.016%per cycle)and outstanding rate capability(484 mA h g^(-1)at 10 A g^(-1)are achieved in half cells.When coupled with Na_(3)V_(2)(PO4)3cathode,the full cells exhibit 100%capacity retention over 200 cycles at 5C with an average Coulombic efficiency of 99.93%and a high energy density of 125.5 W h kg^(-1)at a power density of 8215.6 W kg^(-1)(charge or discharge within~49 s).Remarkably,the full cell can steadily operate at a high areal capacity of 1.9 mA h cm^(-2),the highest level among red P-based full SIBs ever reported.展开更多
A solution to the linear Boltzmann equation satisfies an energy bound,which reflects a natural fact:The energy of particles in a finite volume is bounded in time by the energy of particles initially occupying the volu...A solution to the linear Boltzmann equation satisfies an energy bound,which reflects a natural fact:The energy of particles in a finite volume is bounded in time by the energy of particles initially occupying the volume augmented by the energy transported into the volume by particles entering the volume over time.In this paper,we present boundary conditions(BCs)for the spherical harmonic(P_(N))approximation,which ensure that this fundamental energy bound is satisfied by the P_(N) approximation.Our BCs are compatible with the characteristic waves of P_(N) equations and determine the incoming waves uniquely.Both,energy bound and compatibility,are shown on abstract formulations of P_(N) equations and BCs to isolate the necessary structures and properties.The BCs are derived from a Marshak type formulation of BC and base on a non-classical even/odd-classification of spherical harmonic functions and a stabilization step,which is similar to the truncation of the series expansion in the P_(N) method.We show that summation by parts(SBP)finite differences on staggered grids in space and the method of simultaneous approximation terms(SAT)allows to maintain the energy bound also on the semi-discrete level.展开更多
The discrete duality finite volume method has proven to be a practical tool for discretizing partial differential equations coming from a wide variety of areas of physics on nearly arbitrary meshes.The main ingredient...The discrete duality finite volume method has proven to be a practical tool for discretizing partial differential equations coming from a wide variety of areas of physics on nearly arbitrary meshes.The main ingredients of the method are:(1)use of three meshes,(2)use of the Gauss-Green theorem for the approximation of derivatives,(3)discrete integration by parts.In this article we propose to extend this method to the coupled grey thermal-P_(N) radiative transfer equations in Cartesian and cylindrical coordinates in order to be able to deal with two-dimensional Lagrangian approximations of the interaction of matter with radiation.The stability under a Courant-Friedrichs-Lewy condition and the preservation of the diffusion asymptotic limit are proved while the experimental second-order accuracy is observed with manufactured solutions.Several numerical experiments are reported which show the good behavior of the method.展开更多
基金support from the National Natural Science Foundation of China(51976143)the Guangdong Key Areas Research and Development Program(2020B090904001 and 2019B090909003)。
文摘The practical applications of high-capacity alloy-type anode materials in sodium-ion batteries(SIBs)are challenged by their vast volume effects and resulting unstable electrode-electrolyte interphases during discharge-charge cycling.Taking red phosphorus(P)/carbon anode material as an example,we report an on-site conversion reaction to intentionally eliminate the volume effect-dominated surface P and yield an ionically conducting layer of Na3PS4solid-state electrolyte on the composite.Such a surface reconstruction can significantly suppress the electrode swelling and simultaneously enable the activation energy of interfacial Na+transfer as low as 36.7 k J mol^(-1),resulting in excellent electrode stability and ultrafast reaction kinetics.Consequently,excellent cycling performance(510 mA h g^(-1)at 5 A g^(-1)after 1000 cycles with a tiny capacity fading rate of 0.016%per cycle)and outstanding rate capability(484 mA h g^(-1)at 10 A g^(-1)are achieved in half cells.When coupled with Na_(3)V_(2)(PO4)3cathode,the full cells exhibit 100%capacity retention over 200 cycles at 5C with an average Coulombic efficiency of 99.93%and a high energy density of 125.5 W h kg^(-1)at a power density of 8215.6 W kg^(-1)(charge or discharge within~49 s).Remarkably,the full cell can steadily operate at a high areal capacity of 1.9 mA h cm^(-2),the highest level among red P-based full SIBs ever reported.
基金The authors acknowledge funding of the German Research Foundation(DFG)under grant TO 414/4-1.
文摘A solution to the linear Boltzmann equation satisfies an energy bound,which reflects a natural fact:The energy of particles in a finite volume is bounded in time by the energy of particles initially occupying the volume augmented by the energy transported into the volume by particles entering the volume over time.In this paper,we present boundary conditions(BCs)for the spherical harmonic(P_(N))approximation,which ensure that this fundamental energy bound is satisfied by the P_(N) approximation.Our BCs are compatible with the characteristic waves of P_(N) equations and determine the incoming waves uniquely.Both,energy bound and compatibility,are shown on abstract formulations of P_(N) equations and BCs to isolate the necessary structures and properties.The BCs are derived from a Marshak type formulation of BC and base on a non-classical even/odd-classification of spherical harmonic functions and a stabilization step,which is similar to the truncation of the series expansion in the P_(N) method.We show that summation by parts(SBP)finite differences on staggered grids in space and the method of simultaneous approximation terms(SAT)allows to maintain the energy bound also on the semi-discrete level.
文摘The discrete duality finite volume method has proven to be a practical tool for discretizing partial differential equations coming from a wide variety of areas of physics on nearly arbitrary meshes.The main ingredients of the method are:(1)use of three meshes,(2)use of the Gauss-Green theorem for the approximation of derivatives,(3)discrete integration by parts.In this article we propose to extend this method to the coupled grey thermal-P_(N) radiative transfer equations in Cartesian and cylindrical coordinates in order to be able to deal with two-dimensional Lagrangian approximations of the interaction of matter with radiation.The stability under a Courant-Friedrichs-Lewy condition and the preservation of the diffusion asymptotic limit are proved while the experimental second-order accuracy is observed with manufactured solutions.Several numerical experiments are reported which show the good behavior of the method.
