The properties of the confined liquid are dramatically different from those of the bulk state, which were reviewed in the present work. We performed large-scale molecular dynamics simulations and full-atom nonequilibr...The properties of the confined liquid are dramatically different from those of the bulk state, which were reviewed in the present work. We performed large-scale molecular dynamics simulations and full-atom nonequilibrium molecular dynamics simulations to investigate the shear response of the confined simple liquid as well as the n-hexadecane ultrathin films. The shear viscosity of the confined simple liquid increases with the decrease of the film thickness. Apart from the well-known ordered structure, the confined n-hexaxiecane exhibited a transition from 7 layers to 6 in our simulations while undergoing an increasing shear velocity. Various slip regimes of the confined n-hexadecane were obtained. Viscosity coefficients of individual layers were examined and the results revealed that the local viscosity＇coefficient varies with the distance from the wall. The individual n-hexadecane layers showed the shear-thinning behaviors which can be correlated with the occurrence of the slip. This study aimed at elucidating the detailed shear response of the confined liquid and may be used in the design and application of microand nano-devices.展开更多
This paper proposes a novel hybrid method to simulate the dry granular flow of materials over a wide range of inertial numbers that simultaneously covers the quasi-static and dense granular flow regimes. To overcome t...This paper proposes a novel hybrid method to simulate the dry granular flow of materials over a wide range of inertial numbers that simultaneously covers the quasi-static and dense granular flow regimes. To overcome the lack of incremental objectivity whenever large deformations occur in solid-like regimes and to remove computational singularities in fluid-like regimes close to rest, the elastic–perfectly plastic theory based on the Drucker–Prager yield criterion is combined with the theory of dense granular flows. By implementing some new modifications at the boundaries and removing all ghost particles, smoothed particle hydrodynamics （SPH） is used as the framework for the method. A number of benchmark problems have been solved to show the capabilities of the new modified SPH method. Precise prediction of both location and pressure makes the modifications comparable with the previous works on SPH. Finally, the method is used to solve the classic 2D dry granular cliff collapse problem and to model dry granular material flow inside a rotary drum. The outcomes of the numerical simulation show good agreement with tabletop experiments and published results.展开更多
Solid polymer electrolytes(SPEs)have attracted extensive attention by virtue of lightweight and flexible processability for solidstate lithium metal batteries(LMBs)with high energy density and intrinsic safety.However...Solid polymer electrolytes(SPEs)have attracted extensive attention by virtue of lightweight and flexible processability for solidstate lithium metal batteries(LMBs)with high energy density and intrinsic safety.However,the SPEs suffer from the trade-off effect between ionic conductivity and mechanical strength.Herein,we report an ionic solid-like conductor with high Li+conductivity and good thermal stability as the conductive phase of polymer electrolytes for advanced LMBs.Using poly(vinylidene fluoride-co-hexafluoropropylene)(PVDF-HFP)as the polymer matrix,the ionic solid-like conductor can be regarded as a solid plasticizer due to its advantages of non-fluidity and non-leakage.It increases the amorphous region and the dissociation degree of lithium salts in SPEs,while minimizing the loss of mechanical properties.As a result,the Li+conductivity of SPEs incorporating the ionic solid-like conductor is enhanced by four orders of magnitude compared to the blank PVDF-HFPbased electrolyte.The optimized SPE membranes can be processed as thin as 50μm with a high Young's modulus of 16.8 MPa,therefore ensuring stable long-term cycling of solid-state LMBs.The Li/Li symmetric cells stably cycled for more than 750 h without short circuits,and the LiFePO_(4)/Li solid-state batteries demonstrate excellent electrochemical performance over 350cycles with a capacity retention of 82.5%.This work provides a new strategy for designing ionic solid-like conductors as solid plasticizers for high-performance polymer electrolytes.展开更多
Solid-state electrolyte(SSE)of the sodium-ion battery have attracted tremendous attention in the next generation energy storage materials on account of their wide electrochemical window and thermal stability.However,t...Solid-state electrolyte(SSE)of the sodium-ion battery have attracted tremendous attention in the next generation energy storage materials on account of their wide electrochemical window and thermal stability.However,the high interfacial impedance,low ion transference number and complex preparation process restrict the application of SSE.Herein,inspired by the excellent sieving function and high specific surface area of red blood cells,we obtained a solid-like electrolyte(SLE)based on the combination of the pancake-like metal-organic framework(MOF)with liquid electrolyte,possessing a high ionic conductivity of 6.60×10^(-4) S cm^(−1),and excellent sodium metal compatibility.In addition,we investigated the ion restriction effect of MOF’s apertures size and special functional groups,and the ion transference number increased from 0.16 to 0.33.Finally,the assembled Na_(0.44)MnO_(2)//SLE//Na full batteries showed no obvious capacity decrease after 160 cycles.This material design of SLE in our work is an important key to obtain fast ion migration SLE for high-performance sodium-ion batteries.展开更多
基金supported by the National Natural Science Foundation of China (NSFC, Nos. 60936001 and 11072244)the National Basic Research Program of China (973 Program, No. 2007CB310500)the Shanghai Supercomputer Center
文摘The properties of the confined liquid are dramatically different from those of the bulk state, which were reviewed in the present work. We performed large-scale molecular dynamics simulations and full-atom nonequilibrium molecular dynamics simulations to investigate the shear response of the confined simple liquid as well as the n-hexadecane ultrathin films. The shear viscosity of the confined simple liquid increases with the decrease of the film thickness. Apart from the well-known ordered structure, the confined n-hexaxiecane exhibited a transition from 7 layers to 6 in our simulations while undergoing an increasing shear velocity. Various slip regimes of the confined n-hexadecane were obtained. Viscosity coefficients of individual layers were examined and the results revealed that the local viscosity＇coefficient varies with the distance from the wall. The individual n-hexadecane layers showed the shear-thinning behaviors which can be correlated with the occurrence of the slip. This study aimed at elucidating the detailed shear response of the confined liquid and may be used in the design and application of microand nano-devices.
文摘This paper proposes a novel hybrid method to simulate the dry granular flow of materials over a wide range of inertial numbers that simultaneously covers the quasi-static and dense granular flow regimes. To overcome the lack of incremental objectivity whenever large deformations occur in solid-like regimes and to remove computational singularities in fluid-like regimes close to rest, the elastic–perfectly plastic theory based on the Drucker–Prager yield criterion is combined with the theory of dense granular flows. By implementing some new modifications at the boundaries and removing all ghost particles, smoothed particle hydrodynamics （SPH） is used as the framework for the method. A number of benchmark problems have been solved to show the capabilities of the new modified SPH method. Precise prediction of both location and pressure makes the modifications comparable with the previous works on SPH. Finally, the method is used to solve the classic 2D dry granular cliff collapse problem and to model dry granular material flow inside a rotary drum. The outcomes of the numerical simulation show good agreement with tabletop experiments and published results.
基金supported by the National Key Research and Development Program of China(2023YFB2503700,and 2023YFC3008804)the National Natural Science Foundation of China(22071133)+1 种基金Beijing Municipal Science&Technology Commission(Z231100006123003)the Science Foundation of China Academy of Safety Science and Technology(2023JBKY17)。
文摘Solid polymer electrolytes(SPEs)have attracted extensive attention by virtue of lightweight and flexible processability for solidstate lithium metal batteries(LMBs)with high energy density and intrinsic safety.However,the SPEs suffer from the trade-off effect between ionic conductivity and mechanical strength.Herein,we report an ionic solid-like conductor with high Li+conductivity and good thermal stability as the conductive phase of polymer electrolytes for advanced LMBs.Using poly(vinylidene fluoride-co-hexafluoropropylene)(PVDF-HFP)as the polymer matrix,the ionic solid-like conductor can be regarded as a solid plasticizer due to its advantages of non-fluidity and non-leakage.It increases the amorphous region and the dissociation degree of lithium salts in SPEs,while minimizing the loss of mechanical properties.As a result,the Li+conductivity of SPEs incorporating the ionic solid-like conductor is enhanced by four orders of magnitude compared to the blank PVDF-HFPbased electrolyte.The optimized SPE membranes can be processed as thin as 50μm with a high Young's modulus of 16.8 MPa,therefore ensuring stable long-term cycling of solid-state LMBs.The Li/Li symmetric cells stably cycled for more than 750 h without short circuits,and the LiFePO_(4)/Li solid-state batteries demonstrate excellent electrochemical performance over 350cycles with a capacity retention of 82.5%.This work provides a new strategy for designing ionic solid-like conductors as solid plasticizers for high-performance polymer electrolytes.
基金the National Natural Science Foundation of China(51802239)the National Key Research and Development Program of China(2020YFA0715000,2019YFA0704902)+3 种基金Foshan Xianhu Laboratory of the Advanced Energy Science and Technology Guangdong Laboratory(XHT2020-005,XHT2020-003)the Natural Science Foundation of Hubei Province(2019CFA001)the Fundamental Research Funds for the Central Universities(2020III011GX,2020IVB057,2019IVB054,2019III062JL)and National Innovation and Entrepreneurship Training Program for College Students(202010497080).
文摘Solid-state electrolyte(SSE)of the sodium-ion battery have attracted tremendous attention in the next generation energy storage materials on account of their wide electrochemical window and thermal stability.However,the high interfacial impedance,low ion transference number and complex preparation process restrict the application of SSE.Herein,inspired by the excellent sieving function and high specific surface area of red blood cells,we obtained a solid-like electrolyte(SLE)based on the combination of the pancake-like metal-organic framework(MOF)with liquid electrolyte,possessing a high ionic conductivity of 6.60×10^(-4) S cm^(−1),and excellent sodium metal compatibility.In addition,we investigated the ion restriction effect of MOF’s apertures size and special functional groups,and the ion transference number increased from 0.16 to 0.33.Finally,the assembled Na_(0.44)MnO_(2)//SLE//Na full batteries showed no obvious capacity decrease after 160 cycles.This material design of SLE in our work is an important key to obtain fast ion migration SLE for high-performance sodium-ion batteries.
