Rechargeable aluminum batteries(RABs),which use earth-abundant and high-volumetric-capacity metal anodes(8040 m Ah cm-3),have great potential as next-generation power sources because they use cheaper resources to deli...Rechargeable aluminum batteries(RABs),which use earth-abundant and high-volumetric-capacity metal anodes(8040 m Ah cm-3),have great potential as next-generation power sources because they use cheaper resources to deliver higher energies,compared to current lithium ion batteries.However,the mechanism of charge delivery in the newly developed,ionic liquid-based electrolytic system for RABs differs from that in conventional organic electrolytes.Thus,targeted research efforts are required to address the large overpotentials and cycling decay encountered in the ionic liquid-based electrolytic system.In this study,a nanoporous carbon(NPC)electrode with well-developed nanopores is used to develop a high-performance aluminum anode.The negatively charged nanopores can provide quenched dynamics of electrolyte molecules in the aluminum deposition process,resulting in an increased collision rate.The fast chemical equilibrium of anionic species induced by the facilitated anionic collisions leads to more favorable reduction reactions that form aluminum metals.The nanoconfinement effect causes separated nucleation and growth of aluminum nanoparticles in the multiple confined nanopores,leading to higher coulombic efficiencies and more stable cycling performance compared with macroporous carbon black and 2D stainless steel electrodes.展开更多
Understanding the integrated transport behavior of oil in shale nanopores is critical to efficient shale oil development. In this paper, based on the time-dependent Poiseuille flow momentum equation, we present a nove...Understanding the integrated transport behavior of oil in shale nanopores is critical to efficient shale oil development. In this paper, based on the time-dependent Poiseuille flow momentum equation, we present a novel transient model to describe oil transport in unsteady and steady states. The model incorporates the effect of the critical shift density, apparent viscosity, slip length, and alkane property, as well as pore tortuosity and surface roughness. We evaluated our model through a comparison with other models, experiments, and molecular dynamics simulations. The results show that the development rates of the volume flows of C_(6)–C_(12) alkane confined in inorganic nanopores and C_(12) alkane confined in organic nanopores were faster than that of the corresponding bulk alkane. In addition, the critical drift density positively promoted the volume flow development rate in the unsteady state and negatively inhibited the mass flow rate in the steady state. This effect was clearest in pores with a smaller radius and lower-energy wall and in alkane with shorter chain lengths. Furthermore, both the nanoconfinement effect and pore structure determined whether the volume flow enhancement rate was greater than or less than 1. The rate increased or decreased with time and was controlled mainly by the nanoconfinement effect. Moreover, as the wall energy increased, the flow inhibition effect increased;as the carbon number of alkane increased, the flow promotion effect increased. The results indicate that the proposed model can accurately describe oil transport in shale nanopores.展开更多
In molecular modeling of electrical double layers(EDLs),the constant charge method(CCM)is prized for its computational efficiency but cannot maintain electrode equipotentiality like the more resourceintensive constant...In molecular modeling of electrical double layers(EDLs),the constant charge method(CCM)is prized for its computational efficiency but cannot maintain electrode equipotentiality like the more resourceintensive constant potential method(CPM),potentially leading to inaccuracies.In certain scenarios,CCM can yield results identical to CPM.However,there are no clear guidelines to determine when CCM is sufficient and when CPM is required.Here,we conduct a series of molecular simulations across various electrodes and electrolytes to present a comprehensive comparison between CCM and CPM under different charging modes.Results reveal that CCM approximates CPM effectively in capturing equilibrium EDL and current-driven dynamics in open electrode systems featuring ionic liquids or regular concentration aqueous electrolytes,while CPM is indispensable in scenarios involving organic and highly concentrated aqueous electrolytes,nanoconfinement effects,and voltage-driven dynamics.This work helps to select appropriate methods for modeling EDL systems,prioritizing accuracy while considering computationalefficiency.展开更多
The practical deployment of metallic anodes in the energy-dense batteries is impeded by the thermodynamically unstable interphase in contact with the aprotic electrolyte,structural collapse of the substrates as well a...The practical deployment of metallic anodes in the energy-dense batteries is impeded by the thermodynamically unstable interphase in contact with the aprotic electrolyte,structural collapse of the substrates as well as their insufficient affinity toward the metallic deposits.Herein,the mechanical flexible,lightweight(1.2 mg cm^(−2))carbon nanofiber scaffold with the monodispersed,ultrafine Sn_(4)P_(3) nanoparticles encapsulation(Sn_(4)P_(3)NPs@CNF)is proposed as the deposition substrate toward the high-areal-capacity sodium loadings up to 4 mAh cm^(−2).First-principles calculations manifest that the alloy intermediates,namely the Na_(15)Sn_(4) and Na_(3)P matrix,exhibit the intimate Na affinity as the“sodiophilic”sites.Meanwhile,the porous CNF regulates the heterogeneous alloying process and confines the deposit propagation along the nanofiber orientation.With the precise control of pairing mode with the NaVPO4F cathode(8.7 mg cm^(−2)),the practical feasibility of the Sn_(4)P_(3) NPs@CNF anode(1^(*)Na excess)is demonstrated in 2 mAh single-layer pouch cell prototype,which achieves the 95.7%capacity retention for 150 cycles at various mechanical flexing states as well as balanced energy/power densities.展开更多
Confined water exhibits anomalous behavior distinct from bulk water,fundamentally influencing chemical reactions at the nanoscale.However,the scale-dependent nature of water properties remains poorly understood,partic...Confined water exhibits anomalous behavior distinct from bulk water,fundamentally influencing chemical reactions at the nanoscale.However,the scale-dependent nature of water properties remains poorly understood,particularly regarding the respective contributions of spatial confinement and surface interactions.Here,we comprehensively investigate the mechanisms and scale-dependent behavior of confined water between Al2O3 layers across a confinement range of 1 to 50 nm.Our findings reveal that surface interactions primarily induce abnormal behavior in interfacial water,characterized by ordered structure,anisotropic and highly connected hydrogen bond network,reduced dielectric profiles,and suppressed self-diffusion.In contrast,spatial confinement selectively extends certain anomalous properties from the interfacial layer to the entire confined region following theoretical predictions.Such extension results in confined water exhibiting an extremely low dielectric response,high surface potential,and unexpectedly enhanced in-plane diffusion.Notably,we identify a confinement range of 10 to 20 nm as a threshold marking the transition between confined and bulk water behavior.We also elucidate the specific effects of ionic concentration,pH levels,surface functional groups,and surface polarity on the behavior of confined water.This work highlights the critical role of spatial confinement in determining the properties of confined water,advances our understanding of confined water in metal oxide systems,and informs the rational design of nanoconfined systems for applications in mass transport and chemical reactions.展开更多
基金supported by the Basic Science Research Program through the National Research Foundation of Korea(NRF)Funded by the Ministry of Education(NRF-2019R1A2C1084836,NRF-2018M1A2A2061994,and NRF-2021R1A4A2001403)the KU-KIST School Program。
文摘Rechargeable aluminum batteries(RABs),which use earth-abundant and high-volumetric-capacity metal anodes(8040 m Ah cm-3),have great potential as next-generation power sources because they use cheaper resources to deliver higher energies,compared to current lithium ion batteries.However,the mechanism of charge delivery in the newly developed,ionic liquid-based electrolytic system for RABs differs from that in conventional organic electrolytes.Thus,targeted research efforts are required to address the large overpotentials and cycling decay encountered in the ionic liquid-based electrolytic system.In this study,a nanoporous carbon(NPC)electrode with well-developed nanopores is used to develop a high-performance aluminum anode.The negatively charged nanopores can provide quenched dynamics of electrolyte molecules in the aluminum deposition process,resulting in an increased collision rate.The fast chemical equilibrium of anionic species induced by the facilitated anionic collisions leads to more favorable reduction reactions that form aluminum metals.The nanoconfinement effect causes separated nucleation and growth of aluminum nanoparticles in the multiple confined nanopores,leading to higher coulombic efficiencies and more stable cycling performance compared with macroporous carbon black and 2D stainless steel electrodes.
基金supported by the National Natural Science Foundation for Youths of China(Grant No.12201374)the Scientific Research Foundation of Education Department of Shaanxi Province(Grant No.22JK0315)+2 种基金the Research Foundation for the Doctoral Program of Shaanxi University of Technology(Grant No.SLGRCQD2136)the Key R&D Plan,Shaanxi Province(2022GY-138)the Science and Technology Plan Project,Guizhou Province([2022]ZD005).
文摘Understanding the integrated transport behavior of oil in shale nanopores is critical to efficient shale oil development. In this paper, based on the time-dependent Poiseuille flow momentum equation, we present a novel transient model to describe oil transport in unsteady and steady states. The model incorporates the effect of the critical shift density, apparent viscosity, slip length, and alkane property, as well as pore tortuosity and surface roughness. We evaluated our model through a comparison with other models, experiments, and molecular dynamics simulations. The results show that the development rates of the volume flows of C_(6)–C_(12) alkane confined in inorganic nanopores and C_(12) alkane confined in organic nanopores were faster than that of the corresponding bulk alkane. In addition, the critical drift density positively promoted the volume flow development rate in the unsteady state and negatively inhibited the mass flow rate in the steady state. This effect was clearest in pores with a smaller radius and lower-energy wall and in alkane with shorter chain lengths. Furthermore, both the nanoconfinement effect and pore structure determined whether the volume flow enhancement rate was greater than or less than 1. The rate increased or decreased with time and was controlled mainly by the nanoconfinement effect. Moreover, as the wall energy increased, the flow inhibition effect increased;as the carbon number of alkane increased, the flow promotion effect increased. The results indicate that the proposed model can accurately describe oil transport in shale nanopores.
基金the funding support from the National Natural Science Foundation of China(T2325012 and 52161135104)the Program for HUST Academic Frontier Youth Team.
文摘In molecular modeling of electrical double layers(EDLs),the constant charge method(CCM)is prized for its computational efficiency but cannot maintain electrode equipotentiality like the more resourceintensive constant potential method(CPM),potentially leading to inaccuracies.In certain scenarios,CCM can yield results identical to CPM.However,there are no clear guidelines to determine when CCM is sufficient and when CPM is required.Here,we conduct a series of molecular simulations across various electrodes and electrolytes to present a comprehensive comparison between CCM and CPM under different charging modes.Results reveal that CCM approximates CPM effectively in capturing equilibrium EDL and current-driven dynamics in open electrode systems featuring ionic liquids or regular concentration aqueous electrolytes,while CPM is indispensable in scenarios involving organic and highly concentrated aqueous electrolytes,nanoconfinement effects,and voltage-driven dynamics.This work helps to select appropriate methods for modeling EDL systems,prioritizing accuracy while considering computationalefficiency.
基金financially supported by the National Natural Science Foundation of China(5217130394)the Natural Science Foundation of Shaanxi(2019KJXX-099,2020YZ0037,2019JLZ-09 and 2019QYPY-194)+2 种基金the Fundamental Research Funds for the Central Universities(3102019JC005)Key R&D Program of Shaanxi(No.2019ZDLGY04-05)the Development and Industrialization Fund(2020KJRC0120)。
文摘The practical deployment of metallic anodes in the energy-dense batteries is impeded by the thermodynamically unstable interphase in contact with the aprotic electrolyte,structural collapse of the substrates as well as their insufficient affinity toward the metallic deposits.Herein,the mechanical flexible,lightweight(1.2 mg cm^(−2))carbon nanofiber scaffold with the monodispersed,ultrafine Sn_(4)P_(3) nanoparticles encapsulation(Sn_(4)P_(3)NPs@CNF)is proposed as the deposition substrate toward the high-areal-capacity sodium loadings up to 4 mAh cm^(−2).First-principles calculations manifest that the alloy intermediates,namely the Na_(15)Sn_(4) and Na_(3)P matrix,exhibit the intimate Na affinity as the“sodiophilic”sites.Meanwhile,the porous CNF regulates the heterogeneous alloying process and confines the deposit propagation along the nanofiber orientation.With the precise control of pairing mode with the NaVPO4F cathode(8.7 mg cm^(−2)),the practical feasibility of the Sn_(4)P_(3) NPs@CNF anode(1^(*)Na excess)is demonstrated in 2 mAh single-layer pouch cell prototype,which achieves the 95.7%capacity retention for 150 cycles at various mechanical flexing states as well as balanced energy/power densities.
基金supported by the Shenzhen Science and Technology Program(No.WDZC20231128115832002)the National Natural Science Foundation of China(Nos.22306091 and 52460003)+1 种基金Natural Science Foundation of Jiangsu Province(No.BK20230797)the Key-Area Research and Development Program of Guangdong Province(No.2022B0111130001).
文摘Confined water exhibits anomalous behavior distinct from bulk water,fundamentally influencing chemical reactions at the nanoscale.However,the scale-dependent nature of water properties remains poorly understood,particularly regarding the respective contributions of spatial confinement and surface interactions.Here,we comprehensively investigate the mechanisms and scale-dependent behavior of confined water between Al2O3 layers across a confinement range of 1 to 50 nm.Our findings reveal that surface interactions primarily induce abnormal behavior in interfacial water,characterized by ordered structure,anisotropic and highly connected hydrogen bond network,reduced dielectric profiles,and suppressed self-diffusion.In contrast,spatial confinement selectively extends certain anomalous properties from the interfacial layer to the entire confined region following theoretical predictions.Such extension results in confined water exhibiting an extremely low dielectric response,high surface potential,and unexpectedly enhanced in-plane diffusion.Notably,we identify a confinement range of 10 to 20 nm as a threshold marking the transition between confined and bulk water behavior.We also elucidate the specific effects of ionic concentration,pH levels,surface functional groups,and surface polarity on the behavior of confined water.This work highlights the critical role of spatial confinement in determining the properties of confined water,advances our understanding of confined water in metal oxide systems,and informs the rational design of nanoconfined systems for applications in mass transport and chemical reactions.
