Sodium(Na)metal stands out as a highly promising anode material for highenergy-density Na batteries owing to its abundant resources and exceptional theoretical capacity at low redox potential.Nevertheless,the uncontro...Sodium(Na)metal stands out as a highly promising anode material for highenergy-density Na batteries owing to its abundant resources and exceptional theoretical capacity at low redox potential.Nevertheless,the uncontrolled growth of Na dendrites and the accompanying volumetric changes during the plating/stripping process lead to safety concerns and poor electrochemical performances.This study introduces nitrogen and oxygen co-doped carbon nanofiber networks wrapped carbon felt(NO-CNCF),serving as Na deposition skeletons to facilitate a highly reversible Na metal anode.The NO-CNCF framework with uniformly distributed“sodiophilic”functional groups,nanonetwork protuberances,and cross-linked network scaffold structure can avoid charge accumulation and facilitate the dendrite-free Na deposition.Benefiting from these features,the NO-CNCF@Na symmetrical cells demonstrate notable enhancements in cycling stability,achieving 4000 h cycles at 1mA cm^(−2) for 1 mAh cm^(−2) and 2400 h cycles at 2mA cm^(−2) for 2 mAh cm^(−2) with voltage overpotential of approximately 6 and 10 mV,respectively.Furthermore,the NVP//NO-CNCF@Na full cells achieve stable cycling performance and favorable rate capability.This investigation offers novel insights into fabricating a“sodiophilic”matrix with a multistage structure toward high-performance Na metal batteries.展开更多
A second-order moment two-phase turbulence model for simulating dense gas-particle flows （USM-Θ model）, combining the unified second-order moment twophase turbulence model for dilute gas-particle flows with the kin...A second-order moment two-phase turbulence model for simulating dense gas-particle flows （USM-Θ model）, combining the unified second-order moment twophase turbulence model for dilute gas-particle flows with the kinetic theory of particle collision, is proposed. The interaction between gas and particle turbulence is simulated using the transport equation of two-phase velocity correlation with a two-time-scale dissipation closure. The proposed model is applied to simulate dense gas-particle flows in a horizontal channel and a downer. Simulation results and their comparison with experimental results show that the model accounting for both anisotropic particle turbulence and particle-particle collision is obviously better than models accounting for only particle turbulence or only particle-particle collision. The USM-Θ model is also better than the k-ε-kp-Θ model and the k-ε-kp-εp-Θ model in that the first model can simulate the redistribution of anisotropic particle Reynolds stress components due to inter-particle collision, whereas the second and third models cannot.展开更多
The two-fluid model is widely adopted in simulations of dense gas-particle flows in engineering facili- ties. Present two-phase turbulence models for two-fluid modeling are isotropic. However, turbulence in actual gas...The two-fluid model is widely adopted in simulations of dense gas-particle flows in engineering facili- ties. Present two-phase turbulence models for two-fluid modeling are isotropic. However, turbulence in actual gas-particle flows is not isotropic. Moreover, in these models the two-phase velocity correlation is closed using dimensional analysis, leading to discrepancies between the numerical results, theoretical analysis and experiments. To rectify this problem, some two-phase turbulence models were proposed by the authors and are applied to simulate dense gas-particle flows in downers, risers, and horizontal channels; Experimental results validate the simulation results. Among these models the USM-O and the two-scale USM models are shown to give a better account of both anisotropic particle turbulence and particle-particle collision using the transport equation model for the two-phase velocity correlation.展开更多
基金Talent Project of University and Research Institute of Jinan,Grant/Award Number:2020GXRC044Talent research project of Qilu University of Technology(Shandong Academy of Sciences),Grant/Award Number:2023RCKY161+3 种基金Shandong Provincial Key Laboratory of Biomass Gasification Technology,Qilu University of Technology(Shandong Academy of Sciences),Grant/Award Number:BG-KFX-01Science and Technology Project of Shandong Province,Grant/Award Number:WST2020010Natural Science Foundation of Shandong Province,Grant/Award Number:ZR2021QB138Science,Education and Industry Integration of Basic Research Projects of Qilu University of Technology(Shandong Academy of Sciences),Grant/Award Number:2023PX007。
文摘Sodium(Na)metal stands out as a highly promising anode material for highenergy-density Na batteries owing to its abundant resources and exceptional theoretical capacity at low redox potential.Nevertheless,the uncontrolled growth of Na dendrites and the accompanying volumetric changes during the plating/stripping process lead to safety concerns and poor electrochemical performances.This study introduces nitrogen and oxygen co-doped carbon nanofiber networks wrapped carbon felt(NO-CNCF),serving as Na deposition skeletons to facilitate a highly reversible Na metal anode.The NO-CNCF framework with uniformly distributed“sodiophilic”functional groups,nanonetwork protuberances,and cross-linked network scaffold structure can avoid charge accumulation and facilitate the dendrite-free Na deposition.Benefiting from these features,the NO-CNCF@Na symmetrical cells demonstrate notable enhancements in cycling stability,achieving 4000 h cycles at 1mA cm^(−2) for 1 mAh cm^(−2) and 2400 h cycles at 2mA cm^(−2) for 2 mAh cm^(−2) with voltage overpotential of approximately 6 and 10 mV,respectively.Furthermore,the NVP//NO-CNCF@Na full cells achieve stable cycling performance and favorable rate capability.This investigation offers novel insights into fabricating a“sodiophilic”matrix with a multistage structure toward high-performance Na metal batteries.
基金the Special Funds for Major State Basic Research of China(G-1999-0222-08)the National Natural Science Foundation of China(50376004)Ph.D.Program Foundation,Ministry of Education of China(20030007028)
文摘A second-order moment two-phase turbulence model for simulating dense gas-particle flows （USM-Θ model）, combining the unified second-order moment twophase turbulence model for dilute gas-particle flows with the kinetic theory of particle collision, is proposed. The interaction between gas and particle turbulence is simulated using the transport equation of two-phase velocity correlation with a two-time-scale dissipation closure. The proposed model is applied to simulate dense gas-particle flows in a horizontal channel and a downer. Simulation results and their comparison with experimental results show that the model accounting for both anisotropic particle turbulence and particle-particle collision is obviously better than models accounting for only particle turbulence or only particle-particle collision. The USM-Θ model is also better than the k-ε-kp-Θ model and the k-ε-kp-εp-Θ model in that the first model can simulate the redistribution of anisotropic particle Reynolds stress components due to inter-particle collision, whereas the second and third models cannot.
基金supported by the Special Funds for Major State Basic Research,PRC under the Grant G-1999-0222-08the Projects of National Natural Science Foundation of China under the Grants 50606026 and 50736006completed during a visit by one of the coauthors(LXZ) to VTT Technical Research Center of Finland,financially supported by this center
文摘The two-fluid model is widely adopted in simulations of dense gas-particle flows in engineering facili- ties. Present two-phase turbulence models for two-fluid modeling are isotropic. However, turbulence in actual gas-particle flows is not isotropic. Moreover, in these models the two-phase velocity correlation is closed using dimensional analysis, leading to discrepancies between the numerical results, theoretical analysis and experiments. To rectify this problem, some two-phase turbulence models were proposed by the authors and are applied to simulate dense gas-particle flows in downers, risers, and horizontal channels; Experimental results validate the simulation results. Among these models the USM-O and the two-scale USM models are shown to give a better account of both anisotropic particle turbulence and particle-particle collision using the transport equation model for the two-phase velocity correlation.
