High-voltage lithium(Li)metal batteries(LMBs)face substantial challenges,including Li dendrite growth and instability in high-voltage cathodes such as LiNi_(0.8)Mn_(0.1)Co_(0.1)O_(2)(NCM811),which impede their practic...High-voltage lithium(Li)metal batteries(LMBs)face substantial challenges,including Li dendrite growth and instability in high-voltage cathodes such as LiNi_(0.8)Mn_(0.1)Co_(0.1)O_(2)(NCM811),which impede their practical applications and long-term stability.To address these challenges,tris(pentafluorophenyl)borane additive as an electron acceptor is introduced into an ethyl methyl carbonate/fluoroethylene carbonate-based electrolyte.This approach effectively engineers robust dual interfaces on the Li metal anode and the NCM811 cathode,thereby mitigating dendritic growth of Li and enhancing the stability of the cathode.This additive-driven strategy enables LMBs to operate at ultra-high voltages up to 4.7 V.Consequently,Li||Cu cells achieve a coulombic efficiency of 98.96%,and Li||Li symmetric cells extend their cycle life to an impressive 4000 h.Li||NCM811 full cells maintain a high capacity retention of 87.8%after 100 cycles at 4.7 V.Additionally,Li||LNMO full cells exhibit exceptional rate capability,delivering 132.2 mAh g^(-1)at 10 C and retaining 95.0%capacity after 250 cycles at 1 C and 5 V.As a result,NCM811||graphite pouch cells maintain a 93.4%capacity retention after 1100 cycles at 1 C.These findings underscore the efficacy of additive engineering in addressing Li dendrite formation and instability of cathode under high voltage,thereby paving the road for durable,high-performance LMBs.展开更多
The interaction of a planar shock with SF_(6)/Ar/He dual interfaces(SF_(6)/Ar interface is sinusoidal and Ar/He interface is unperturbed)is numerically studied with a compressible multi-component flow solver that is c...The interaction of a planar shock with SF_(6)/Ar/He dual interfaces(SF_(6)/Ar interface is sinusoidal and Ar/He interface is unperturbed)is numerically studied with a compressible multi-component flow solver that is capable of simultaneously capturing discontinuities and resolving small-scale smooth structures.Six cases with different interface distances and incident shock strengths are considered.For all cases,after the shock impact,the amplitude of the first interface reduces gradually to zero(i.e.,phase inversion)and then increases continuously in the negative direction.The rarefaction wave(RW2)reflected from the second interface promotes or suppresses the development of the first interface depending on the interface distance(D).Specifically,if D is small,RW2 arrives at the first interface at a time before phase inversion,and thus promotes the instability growth at the first interface.If D is large,RW2 encounters the first interface at a time after phase inversion,and thus suppresses the instability growth.A theoretical model for the critical distance,under which the first interface just completes phase inversion at the arrival time of RW2,is developed.With this model,one can regulate the instability growth at the first interface by giving a desired D.The development of the second interface belongs to non-standard Richtmyer-Meshkov instability,which depends heavily on the phase of the rippled transmitted shock.It is found that the model of Ishizaki(Phys.Rev.E 53,R5592,1996)fails to predict the perturbation growth of the second interface for cases where the transmitted shock is at phase 2 due to the ignorance of baroclinic vorticity.A new model considering the combined effects of baroclinic vorticity,velocity perturbation,and pressure disturbance is proposed,which gives a reasonable prediction of perturbation growth at the second interface.展开更多
Two-dimensional(2D)transition metal carbides(MXene)possess attractive conductivity and abundant surface functional groups,providing immense potential in the field of electromagnetic wave(EMW)absorption.However,high co...Two-dimensional(2D)transition metal carbides(MXene)possess attractive conductivity and abundant surface functional groups,providing immense potential in the field of electromagnetic wave(EMW)absorption.However,high conductivity and spontaneous aggregation of MXene suffer from limited EMW response.Inspired by dielectric–magnetic synergy effect,the strategy of decorating MXene with magnetic elements is expected to solve this challenge.In this work,zigzag-like Mo_(2)TiC_(2)–MXene nanofibers(Mo-based MXene(Mo–MXene)NFs)with cross-linked networks are fabricated by hydrofluoric acid(HF)etching and potassium hydroxide(KOH)shearing processes.Subsequently,Co-metal–organic framework(MOF)and derived CoNi layered double hydroxide(LDH)ultrathin nanosheets are grown inside Mo–MXene NFs,and the N-doped carbon matrix anchored by CoNi alloy nanoparticles formed by pyrolysis is firmly embedded in the Mo–MXene NFs network.Benefiting from synergistic effect of highly dispersed small CoNi alloy nanoparticles,a three-dimensional(3D)conductive network assembled by zigzag-like Mo–MXene NFs,numerous N-doped hollow carbon vesicles,and abundant dual heterogeneous interface,the designed Mo–MXene/CoNi–NC heterostructure provides robust EMW absorption ability with a reflection loss(RL)value of−68.45 dB at the thickness(d)of 4.38 mm.The robust EMW absorption performance can be attributed to excellent dielectric loss,magnetic loss,impedance matching(Z),and multiple scattering and reflection triggered by the unique 3D network structure.This work puts up great potential in developing advanced MXene-based EMW absorption devices.展开更多
Intermetallic compounds produced in laser additive manufacturing are the main factors restricting the joint performance of dissimilar metals.To solve this problem,a dual molten pool interface interlocking mechanism wa...Intermetallic compounds produced in laser additive manufacturing are the main factors restricting the joint performance of dissimilar metals.To solve this problem,a dual molten pool interface interlocking mechanism was proposed in this study.Based on a dual molten pool interface interlocking mechanism,the dissimilar metals,aluminum alloy and stainless steel,were produced as single-layer and multilayer samples,using the wire-feed laser additive manufacturing directed energy deposition technology.The preferred parameters for the dual molten pool interface interlocking mechanism process of the dissimilar metals,aluminum alloy and stainless steel,were obtained.The matching relationship between the interface connection of dissimilar metals and the process parameters was established.The results demonstrated excellent mechanical occlusion at the connection interface and no apparent intermetallic compound layer.Good feature size and high microhardness were observed under a laser power of 660 W,a wire feeding speed of 55 mm/s,and a platform moving speed of 10 mm/s.Molecular dynamics simulations demonstrated a faster rate of aluminum diffusion in the aluminum alloy substrate to stainless steel under the action of the initial contact force than without the initial contact force.Thus,the dual molten pool interface interlocking mechanism can effectively reduce the intermetallic compound layer when dissimilar metals are connected in the aerospace field.展开更多
基金financially supported by the Guangdong Major Project of Basic and Applied Basic Research(No.2023B0303000002)the Shenzhen Key Laboratory of Advanced Energy Storage(ZDSYS20220401141000001)the High level of special funds(G03034K001)。
文摘High-voltage lithium(Li)metal batteries(LMBs)face substantial challenges,including Li dendrite growth and instability in high-voltage cathodes such as LiNi_(0.8)Mn_(0.1)Co_(0.1)O_(2)(NCM811),which impede their practical applications and long-term stability.To address these challenges,tris(pentafluorophenyl)borane additive as an electron acceptor is introduced into an ethyl methyl carbonate/fluoroethylene carbonate-based electrolyte.This approach effectively engineers robust dual interfaces on the Li metal anode and the NCM811 cathode,thereby mitigating dendritic growth of Li and enhancing the stability of the cathode.This additive-driven strategy enables LMBs to operate at ultra-high voltages up to 4.7 V.Consequently,Li||Cu cells achieve a coulombic efficiency of 98.96%,and Li||Li symmetric cells extend their cycle life to an impressive 4000 h.Li||NCM811 full cells maintain a high capacity retention of 87.8%after 100 cycles at 4.7 V.Additionally,Li||LNMO full cells exhibit exceptional rate capability,delivering 132.2 mAh g^(-1)at 10 C and retaining 95.0%capacity after 250 cycles at 1 C and 5 V.As a result,NCM811||graphite pouch cells maintain a 93.4%capacity retention after 1100 cycles at 1 C.These findings underscore the efficacy of additive engineering in addressing Li dendrite formation and instability of cathode under high voltage,thereby paving the road for durable,high-performance LMBs.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.12122213,12072341,and 91952205).
文摘The interaction of a planar shock with SF_(6)/Ar/He dual interfaces(SF_(6)/Ar interface is sinusoidal and Ar/He interface is unperturbed)is numerically studied with a compressible multi-component flow solver that is capable of simultaneously capturing discontinuities and resolving small-scale smooth structures.Six cases with different interface distances and incident shock strengths are considered.For all cases,after the shock impact,the amplitude of the first interface reduces gradually to zero(i.e.,phase inversion)and then increases continuously in the negative direction.The rarefaction wave(RW2)reflected from the second interface promotes or suppresses the development of the first interface depending on the interface distance(D).Specifically,if D is small,RW2 arrives at the first interface at a time before phase inversion,and thus promotes the instability growth at the first interface.If D is large,RW2 encounters the first interface at a time after phase inversion,and thus suppresses the instability growth.A theoretical model for the critical distance,under which the first interface just completes phase inversion at the arrival time of RW2,is developed.With this model,one can regulate the instability growth at the first interface by giving a desired D.The development of the second interface belongs to non-standard Richtmyer-Meshkov instability,which depends heavily on the phase of the rippled transmitted shock.It is found that the model of Ishizaki(Phys.Rev.E 53,R5592,1996)fails to predict the perturbation growth of the second interface for cases where the transmitted shock is at phase 2 due to the ignorance of baroclinic vorticity.A new model considering the combined effects of baroclinic vorticity,velocity perturbation,and pressure disturbance is proposed,which gives a reasonable prediction of perturbation growth at the second interface.
基金This work was supported by the National Natural Science Foundation of China(No.22269010)the Jiangxi Provincial Natural Science Foundation(No.20224BAB214021)+3 种基金the Training Program for Academic and Technical Leaders of Major Disciplines in Jiangxi Province(No.20212BCJ23020)the Science and Technology Project of Jiangxi Provincial Department of Education(No.GJJ211305)the National Natural Science Foundation of China(No.U2004177)the Outstanding Youth Fund of Henan Province(No.212300410081).
文摘Two-dimensional(2D)transition metal carbides(MXene)possess attractive conductivity and abundant surface functional groups,providing immense potential in the field of electromagnetic wave(EMW)absorption.However,high conductivity and spontaneous aggregation of MXene suffer from limited EMW response.Inspired by dielectric–magnetic synergy effect,the strategy of decorating MXene with magnetic elements is expected to solve this challenge.In this work,zigzag-like Mo_(2)TiC_(2)–MXene nanofibers(Mo-based MXene(Mo–MXene)NFs)with cross-linked networks are fabricated by hydrofluoric acid(HF)etching and potassium hydroxide(KOH)shearing processes.Subsequently,Co-metal–organic framework(MOF)and derived CoNi layered double hydroxide(LDH)ultrathin nanosheets are grown inside Mo–MXene NFs,and the N-doped carbon matrix anchored by CoNi alloy nanoparticles formed by pyrolysis is firmly embedded in the Mo–MXene NFs network.Benefiting from synergistic effect of highly dispersed small CoNi alloy nanoparticles,a three-dimensional(3D)conductive network assembled by zigzag-like Mo–MXene NFs,numerous N-doped hollow carbon vesicles,and abundant dual heterogeneous interface,the designed Mo–MXene/CoNi–NC heterostructure provides robust EMW absorption ability with a reflection loss(RL)value of−68.45 dB at the thickness(d)of 4.38 mm.The robust EMW absorption performance can be attributed to excellent dielectric loss,magnetic loss,impedance matching(Z),and multiple scattering and reflection triggered by the unique 3D network structure.This work puts up great potential in developing advanced MXene-based EMW absorption devices.
基金supported by the National Natural Science Foundation of China(Grant No.51901162)the support of the National Talent Program of China。
文摘Intermetallic compounds produced in laser additive manufacturing are the main factors restricting the joint performance of dissimilar metals.To solve this problem,a dual molten pool interface interlocking mechanism was proposed in this study.Based on a dual molten pool interface interlocking mechanism,the dissimilar metals,aluminum alloy and stainless steel,were produced as single-layer and multilayer samples,using the wire-feed laser additive manufacturing directed energy deposition technology.The preferred parameters for the dual molten pool interface interlocking mechanism process of the dissimilar metals,aluminum alloy and stainless steel,were obtained.The matching relationship between the interface connection of dissimilar metals and the process parameters was established.The results demonstrated excellent mechanical occlusion at the connection interface and no apparent intermetallic compound layer.Good feature size and high microhardness were observed under a laser power of 660 W,a wire feeding speed of 55 mm/s,and a platform moving speed of 10 mm/s.Molecular dynamics simulations demonstrated a faster rate of aluminum diffusion in the aluminum alloy substrate to stainless steel under the action of the initial contact force than without the initial contact force.Thus,the dual molten pool interface interlocking mechanism can effectively reduce the intermetallic compound layer when dissimilar metals are connected in the aerospace field.
