The effects of solid solution on the deformation behavior of binary Mg-xZn(x=0,1,2 wt%)alloys featuring a designated texture that enables extension twinning under tension parallel to the basal pole in most grains,were...The effects of solid solution on the deformation behavior of binary Mg-xZn(x=0,1,2 wt%)alloys featuring a designated texture that enables extension twinning under tension parallel to the basal pole in most grains,were investigated using in-situ neutron diffraction and the EVPSC-TDT model.Neutron diffraction was used to quantitatively track grain-level lattice strains and diffraction intensity changes(related to mechanical twinning)in differently oriented grains of each alloy during cyclic tensile/compressive loadings.These measurements were accurately captured by the model.The stress-strain curves of Mg-1 wt%Zn and Mg-2 wt%Zn alloys show as-expected solid solution strengthening from the addition of Zn compared to pure Mg.The macroscopic yielding and hardening behaviors are explained by alternating slip and twinning modes as calculated by the model.The solid solution's influence on individual deformation modes,including basal〈a〉slip,prismatic〈a〉slip,and extension twinning,was then quantitatively assessed in terms of activity,yielding behavior,and hardening response by combining neutron diffraction results with crystal plasticity predictions.The Mg-1 wt%Zn alloy displays distinct yielding and hardening behavior due to solid solution softening of prismatic〈a〉slip.Additionally,the dependence of extension twinning,in terms of the twinning volume fraction,on Zn content exhibits opposite trends under tensile and compressive loadings.展开更多
All-solid-state batteries(ASSBs)are a promising next-generation energy storage solution due to their high energy density and enhanced safety.To achieve this,specialized electrode designs are required to efficiently en...All-solid-state batteries(ASSBs)are a promising next-generation energy storage solution due to their high energy density and enhanced safety.To achieve this,specialized electrode designs are required to efficiently enhance interparticle lithium-ion transport between solid components.In particular,for active materials with high specific capacity,such as silicon,their volume expansion and shrinkage must be carefully controlled to maintain mechanical interface stability,which is crucial for effective lithium-ion transport in ASSBs.Herein,we propose a mechanical stress-tolerant all-solid-state graphite/silicon electrode design to ensure stable lithium-ion diffusion at the interface through morphology control of active material particles.Plate-type graphite with a high surface-area-to-volume ratio is used to maximize the dispersion of silicon within the electrode.The carefully designed electrode can accommodate the volume changes of silicon,ensuring stable capacity retention over cycles.Additionally,spherical graphite is shown to contribute to improved rate performance by providing an efficient lithium-ion diffusion pathway within the electrode.Therefore,the synergistic effect of our electrode structure offers balanced electrochemical performance,providing practical insights into the mechano-electrochemical interactions essential for designing highperformance all-solid-state electrodes.展开更多
Zinc metal anodes(ZMA)have high theoretical capacities(820 mAh g−1 and 5855 mAh cm−3)and redox potential(−0.76 V vs.standard hydrogen electrode),similar to the electrochemical voltage window of the hydrogen evolution ...Zinc metal anodes(ZMA)have high theoretical capacities(820 mAh g−1 and 5855 mAh cm−3)and redox potential(−0.76 V vs.standard hydrogen electrode),similar to the electrochemical voltage window of the hydrogen evolution reaction(HER)in a mild acidic electrolyte system,facilitating aqueous zinc batteries competitive in next-generation energy storage devices.However,the HER and byproduct formation effectuated by water-splitting deteriorate the electrochemical performance of ZMA,limiting their application.In this study,a key factor in promoting the HER in carbon-based electrode materials(CEMs),which can provide a larger active surface area and guide uniform zinc metal deposition,was investigated using a series of threedimensional structured templating carbon electrodes(3D-TCEs)with different local graphitic orderings,pore structures,and surface properties.The ultramicropores of CEMs are the determining critical factors in initiating HER and clogging active surfaces by Zn(OH)2 byproduct formation,through a systematic comparative study based on the 3D-TCE series samples.When the 3D-TCEs had a proper graphitic structure with few ultramicropores,they showed highly stable cycling performances over 2000 cycles with average Coulombic efficiencies of≥99%.These results suggest that a well-designed CEM can lead to high-performance ZMA in aqueous zinc batteries.展开更多
In a Dirac semimetal, the massless Dirac fermion has zero chirality, leading to surface states connected adiabatically to a topologically trivial surface state as well as vanishing anomalous Hall effect. Recently, it ...In a Dirac semimetal, the massless Dirac fermion has zero chirality, leading to surface states connected adiabatically to a topologically trivial surface state as well as vanishing anomalous Hall effect. Recently, it is predicted that in the nonrelativistic limit of certain collinear antiferromagnets, there exists a type of chiral“Dirac-like” fermion, whose dispersion manifests four-fold degenerate crossing points formed by spin-degenerate linear bands, with topologically protected Fermi arcs. Such an unconventional chiral fermion, protected by a hidden SU(2) symmetry in the hierarchy of an enhanced crystallographic group, namely spin space group, is not experimentally verified yet. Here, by angle-resolved photoemission spectroscopy measurements, we reveal the surface origin of the electron pocket at the Fermi surface in collinear antiferromagnet CoNb3S6. Combining with neutron diffraction and first-principles calculations, we suggest a multidomain collinear antiferromagnetic configuration, rendering the the existence of the Fermi-arc surface states induced by chiral Dirac-like fermions.Our work provides spectral evidence of the chiral Dirac-like fermion caused by particular spin symmetry in CoNb_(3)S_(6), paving an avenue for exploring new emergent phenomena in antiferromagnets with unconventional quasiparticle excitations.展开更多
In exploring the frontier of high-energy-density cathode materials for lithium-ion batteries,substantial progress has been made by fine-tuning the composition of Ni-rich cathodes tailored for high-capacity operation.E...In exploring the frontier of high-energy-density cathode materials for lithium-ion batteries,substantial progress has been made by fine-tuning the composition of Ni-rich cathodes tailored for high-capacity operation.Equally promising are Li-rich cathode materials,which leverage the novel mechanism of oxygen-redox chemistry to achieve enhanced capacities.Nonetheless,the practical realization of these capacities remains elusive,falling short of the desired benchmarks.In this work,we pioneer a Mn-based,Co-free,reduced-nickel,high-capacity cathode material:Li_(0.75)[Li_(0.15)Ni_(0.15)Mn 0.7]O_(2)ionic exchanged from Na_(0.75)[Li_(0.15)Ni_(0.15)Mn 0.7]O_(2).This material is an O_(2)-type layered structure,distinguished by honeycomb ordering within the transition-metal layer,as confirmed by comprehensive neutron and X-ray studies and extensive electrostatic screening.The material's unique structural integrity facilitates the delivery of an exceptional quantity of Li^(+)ions via O^(2-)/O_(2)^(n-)redox,circumventing oxygen release and phase transition.The de/lithiation process enables the delivery of a substantial reversible capacity of~284 mAh(g-oxide)^(-1)(956 Wh(kg-oxide)^(-1)).Moreover,this structural and chemical stability contributes to an acceptable cycling stability for 500 cycles in full cells,providing improved thermal stability with lower exothermic heat generation and thus highlighting the feasibility of a Mn-based,Co-free,reduced-nickel composition.This investigation marks a pivotal advancement in layered lithium cathode materials.展开更多
Bulk metallic glass (BMG) composites with the austenite B2 phase as reinforcement macroscopically showed strain hardening behavior due to the plasticity induced by martensitic transformation during deformation. Relati...Bulk metallic glass (BMG) composites with the austenite B2 phase as reinforcement macroscopically showed strain hardening behavior due to the plasticity induced by martensitic transformation during deformation. Relationship between characteristics of the B2-CuZr reinforcing phase and uniaxial compressive properties of CuZr-based BMG composites was studied. Mechanical properties of these BMG composites were found to depend on not only the reinforced phases but also the amorphous matrix,and the yield and fracture strength can be roughly estimated by the rule of mixture principle. Distribution of the reinforced B2-CuZr phase has an important impact on the compressive plasticity even for the composites with a similar volume fraction of the crystalline phase.展开更多
Na-ion batteries （NIBs） are considered one of the most attractive alternatives for Li-ion batteries （LIBs） because of the natural abundance of Na and the similarities between the NIB technology and the well-establ...Na-ion batteries （NIBs） are considered one of the most attractive alternatives for Li-ion batteries （LIBs） because of the natural abundance of Na and the similarities between the NIB technology and the well-established LIB technology. However, the discovery of high-performance electrode materials remains a key factor in the success of NIBs. Herein, we propose a new type of cathode material for NIBs based on a nanocomposite of an alkali metal fluoride （NaF） and a transition metal fluoride （FeF2）. Although neither of these components is electrochemically active with Na, the nanoscale mixture of the two can deliver a reversible capacity of -125 mAh/g in the voltage range of 1.2--4.8 V vs. Na/Na＋ via an Fe2＋/Fe3＋ redox couple. X-ray absorption spectroscopy reveals that the reversible Na storage is aided by the F-ions due to the decomposition of NaF, which are absorbed on the surface of FeF2, promoting the redox reaction of Fe and triggering the gradual transformation of the mother structure （FeF2） into a new （FeFB-like） host structure for the Na ions. This unique Na-ion storage phenomenon, which is reported for the first time, will introduce an avenue for designing novel cathode materials for NIBs.展开更多
基金supported by the National Research Foundation grant funded by the Korean government(No,2023R1A2C2007190,RS-2024-00398068)partially funded by the Natural Science Foundation of Shandong Province,China(No.ZR2022QE206).
文摘The effects of solid solution on the deformation behavior of binary Mg-xZn(x=0,1,2 wt%)alloys featuring a designated texture that enables extension twinning under tension parallel to the basal pole in most grains,were investigated using in-situ neutron diffraction and the EVPSC-TDT model.Neutron diffraction was used to quantitatively track grain-level lattice strains and diffraction intensity changes(related to mechanical twinning)in differently oriented grains of each alloy during cyclic tensile/compressive loadings.These measurements were accurately captured by the model.The stress-strain curves of Mg-1 wt%Zn and Mg-2 wt%Zn alloys show as-expected solid solution strengthening from the addition of Zn compared to pure Mg.The macroscopic yielding and hardening behaviors are explained by alternating slip and twinning modes as calculated by the model.The solid solution's influence on individual deformation modes,including basal〈a〉slip,prismatic〈a〉slip,and extension twinning,was then quantitatively assessed in terms of activity,yielding behavior,and hardening response by combining neutron diffraction results with crystal plasticity predictions.The Mg-1 wt%Zn alloy displays distinct yielding and hardening behavior due to solid solution softening of prismatic〈a〉slip.Additionally,the dependence of extension twinning,in terms of the twinning volume fraction,on Zn content exhibits opposite trends under tensile and compressive loadings.
基金supported by the National Research Council of Science&Technology(NST)grant by the Korea government(MSIT)(No.GTL24011-000)the National Research Foundation of Korea(NRF2022M3J1A1085396)the Technology Innovation Program(RS-2024-00445442)through the Korea Planning&Evaluation Institute of Industrial Technology(KEIT)funded by the Ministry of Trade,Industry&Energy(MOTIE,Korea).
文摘All-solid-state batteries(ASSBs)are a promising next-generation energy storage solution due to their high energy density and enhanced safety.To achieve this,specialized electrode designs are required to efficiently enhance interparticle lithium-ion transport between solid components.In particular,for active materials with high specific capacity,such as silicon,their volume expansion and shrinkage must be carefully controlled to maintain mechanical interface stability,which is crucial for effective lithium-ion transport in ASSBs.Herein,we propose a mechanical stress-tolerant all-solid-state graphite/silicon electrode design to ensure stable lithium-ion diffusion at the interface through morphology control of active material particles.Plate-type graphite with a high surface-area-to-volume ratio is used to maximize the dispersion of silicon within the electrode.The carefully designed electrode can accommodate the volume changes of silicon,ensuring stable capacity retention over cycles.Additionally,spherical graphite is shown to contribute to improved rate performance by providing an efficient lithium-ion diffusion pathway within the electrode.Therefore,the synergistic effect of our electrode structure offers balanced electrochemical performance,providing practical insights into the mechano-electrochemical interactions essential for designing highperformance all-solid-state electrodes.
基金National Research Foundation of Korea,Grant/Award Numbers:NRF-2019R1A2C1084836,NRF-2021R1A4A2001403,NRF-2022R1C1C1011484。
文摘Zinc metal anodes(ZMA)have high theoretical capacities(820 mAh g−1 and 5855 mAh cm−3)and redox potential(−0.76 V vs.standard hydrogen electrode),similar to the electrochemical voltage window of the hydrogen evolution reaction(HER)in a mild acidic electrolyte system,facilitating aqueous zinc batteries competitive in next-generation energy storage devices.However,the HER and byproduct formation effectuated by water-splitting deteriorate the electrochemical performance of ZMA,limiting their application.In this study,a key factor in promoting the HER in carbon-based electrode materials(CEMs),which can provide a larger active surface area and guide uniform zinc metal deposition,was investigated using a series of threedimensional structured templating carbon electrodes(3D-TCEs)with different local graphitic orderings,pore structures,and surface properties.The ultramicropores of CEMs are the determining critical factors in initiating HER and clogging active surfaces by Zn(OH)2 byproduct formation,through a systematic comparative study based on the 3D-TCE series samples.When the 3D-TCEs had a proper graphitic structure with few ultramicropores,they showed highly stable cycling performances over 2000 cycles with average Coulombic efficiencies of≥99%.These results suggest that a well-designed CEM can lead to high-performance ZMA in aqueous zinc batteries.
基金supported by the National Key R&D Program of China (Grant Nos. 2020YFA0308900 and 2022YFA1403700)the National Natural Science Foundation of China (Grant Nos. 12074163, 12134020, 11974157, 12104255, 12004159, and 12374146)+8 种基金Guangdong Provincial Key Laboratory for Computational Science and Material Design (Grant No. 2019B030301001)the Science, Technology and Innovation Commission of Shenzhen Municipality (Grant Nos. ZDSYS20190902092905285 and KQTD20190929173815000)Guangdong Basic and Applied Basic Research Foundation (Grant Nos. 2022B1515020046, 2021B1515130007, 2022A1515011915, 2019A1515110712, and 2022B1515130005)Shenzhen Science and Technology Program (Grant Nos. RCJC20221008092722009 and RCBS20210706092218039)the Guangdong Innovative and Entrepreneurial Research Team Program (Grant No. 2019ZT08C044)the beam time awarded by Australia’s Nuclear Science and Technology Organisation (ANSTO) (Grant No. P8130)the Materials and Life Science Experimental Facility of the Japan Proton Accelerator Research Complex (J-PARC) was performed under a user program (Proposal No. 2019B0140)performed at the Hiroshima Synchrotron Radiation Center (HiSOR) of Japan (Grant Nos. 22BG023 and 22BG029)Shanghai Synchrotron Radiation Facility (SSRF) BL03U (Grant No. 2022-SSRF-PT-020848)。
文摘In a Dirac semimetal, the massless Dirac fermion has zero chirality, leading to surface states connected adiabatically to a topologically trivial surface state as well as vanishing anomalous Hall effect. Recently, it is predicted that in the nonrelativistic limit of certain collinear antiferromagnets, there exists a type of chiral“Dirac-like” fermion, whose dispersion manifests four-fold degenerate crossing points formed by spin-degenerate linear bands, with topologically protected Fermi arcs. Such an unconventional chiral fermion, protected by a hidden SU(2) symmetry in the hierarchy of an enhanced crystallographic group, namely spin space group, is not experimentally verified yet. Here, by angle-resolved photoemission spectroscopy measurements, we reveal the surface origin of the electron pocket at the Fermi surface in collinear antiferromagnet CoNb3S6. Combining with neutron diffraction and first-principles calculations, we suggest a multidomain collinear antiferromagnetic configuration, rendering the the existence of the Fermi-arc surface states induced by chiral Dirac-like fermions.Our work provides spectral evidence of the chiral Dirac-like fermion caused by particular spin symmetry in CoNb_(3)S_(6), paving an avenue for exploring new emergent phenomena in antiferromagnets with unconventional quasiparticle excitations.
基金supported by Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education,Science and Technology(NRF-2022R1F1A1063351 and RS-2024-00446825).
文摘In exploring the frontier of high-energy-density cathode materials for lithium-ion batteries,substantial progress has been made by fine-tuning the composition of Ni-rich cathodes tailored for high-capacity operation.Equally promising are Li-rich cathode materials,which leverage the novel mechanism of oxygen-redox chemistry to achieve enhanced capacities.Nonetheless,the practical realization of these capacities remains elusive,falling short of the desired benchmarks.In this work,we pioneer a Mn-based,Co-free,reduced-nickel,high-capacity cathode material:Li_(0.75)[Li_(0.15)Ni_(0.15)Mn 0.7]O_(2)ionic exchanged from Na_(0.75)[Li_(0.15)Ni_(0.15)Mn 0.7]O_(2).This material is an O_(2)-type layered structure,distinguished by honeycomb ordering within the transition-metal layer,as confirmed by comprehensive neutron and X-ray studies and extensive electrostatic screening.The material's unique structural integrity facilitates the delivery of an exceptional quantity of Li^(+)ions via O^(2-)/O_(2)^(n-)redox,circumventing oxygen release and phase transition.The de/lithiation process enables the delivery of a substantial reversible capacity of~284 mAh(g-oxide)^(-1)(956 Wh(kg-oxide)^(-1)).Moreover,this structural and chemical stability contributes to an acceptable cycling stability for 500 cycles in full cells,providing improved thermal stability with lower exothermic heat generation and thus highlighting the feasibility of a Mn-based,Co-free,reduced-nickel composition.This investigation marks a pivotal advancement in layered lithium cathode materials.
基金supported in part by the National Natural Science Foundation of China (50725104, 51010001 and 51001009)China Postdoctoral Science Foundation (20100470208) the Fundamental Research Funds for the Central Universities (FRF-BR-10-036B)
文摘Bulk metallic glass (BMG) composites with the austenite B2 phase as reinforcement macroscopically showed strain hardening behavior due to the plasticity induced by martensitic transformation during deformation. Relationship between characteristics of the B2-CuZr reinforcing phase and uniaxial compressive properties of CuZr-based BMG composites was studied. Mechanical properties of these BMG composites were found to depend on not only the reinforced phases but also the amorphous matrix,and the yield and fracture strength can be roughly estimated by the rule of mixture principle. Distribution of the reinforced B2-CuZr phase has an important impact on the compressive plasticity even for the composites with a similar volume fraction of the crystalline phase.
文摘Na-ion batteries （NIBs） are considered one of the most attractive alternatives for Li-ion batteries （LIBs） because of the natural abundance of Na and the similarities between the NIB technology and the well-established LIB technology. However, the discovery of high-performance electrode materials remains a key factor in the success of NIBs. Herein, we propose a new type of cathode material for NIBs based on a nanocomposite of an alkali metal fluoride （NaF） and a transition metal fluoride （FeF2）. Although neither of these components is electrochemically active with Na, the nanoscale mixture of the two can deliver a reversible capacity of -125 mAh/g in the voltage range of 1.2--4.8 V vs. Na/Na＋ via an Fe2＋/Fe3＋ redox couple. X-ray absorption spectroscopy reveals that the reversible Na storage is aided by the F-ions due to the decomposition of NaF, which are absorbed on the surface of FeF2, promoting the redox reaction of Fe and triggering the gradual transformation of the mother structure （FeF2） into a new （FeFB-like） host structure for the Na ions. This unique Na-ion storage phenomenon, which is reported for the first time, will introduce an avenue for designing novel cathode materials for NIBs.
