Inorganic materials can solve transportable and on-site hydrolytic hydrogen generation issues.CaH_(2)/(Al/Si)composites are preferable due to their notable chemical properties.However,these composites require pretreat...Inorganic materials can solve transportable and on-site hydrolytic hydrogen generation issues.CaH_(2)/(Al/Si)composites are preferable due to their notable chemical properties.However,these composites require pretreatments,an inert environment,and long hours of physical ball milling for high homogeneity and synergistic effects.CaH_(2)also inhibits the hydrolysis reaction by forming its products on the Al/Si surface,which hinders the direct utilization of composites.This work represents the first investigation of NaH-CaH_(2)(Al/Si)fuel composites,which greatly overcome these limitations and can be directly used for on-site hydrogen generation and proton exchange membrane(PEM)fuel cells.The NaH-CaH_(2)(Al/Si)fuel composites were prepared by using a straightforward mixing method with variable composition ratios,showing high H_(2)yield and fuel cell(FC)performance.NaH addition provides the bridge effect,which opens up a new way to enable efficient hydrolysis and greatly enhances the hydrolysis activity of CaH_(2)/(Al/Si)composites.The novel fuel composites(NaH-CaH_(2)/Al)have extraordinary FC performance and a 0.42 W/cm2 peak power density greater than commercial hydrogen generators.It provides high H_(2)yield 84.4%for NaH-CaH_(2)/Al and 82%for NaH-CaH_(2)/Si compared to NaOH-CaH_(2)(Al/Si),NaCl-CaH_(2)(Al/Si),and KCl-CaH_(2)(Al/Si)composites.The NaH bridge effect hinders the direct water contact and stops the formation of Ca(OH)2 around Al/Si,which provides adequate pathways for the CaH_(2)(Al/Si)hydrolysis.The impressive capabilities of novel fuel composites are anticipated to offer practical uses in fuel cells,automobile applications,and portable/on-board H_(2)generation.展开更多
Silicon(Si)is a promising high-capacity anode in lithium-ion batteries but suffers from chronic chemical degradation and capacity fading during calendar aging,greatly hindering its automobile applications.Electrolyte ...Silicon(Si)is a promising high-capacity anode in lithium-ion batteries but suffers from chronic chemical degradation and capacity fading during calendar aging,greatly hindering its automobile applications.Electrolyte engineering currently relies on conventional evaluation criteria of reducing coulombic consumption,which implicitly presume its equivalence to irreversible capacity loss and complicates battery development.We introduce the detrimental ratioρto quantify the fraction of parasitic species that permanently degrades active material.This metric is independent and crucially complements total coulombic consumption for accurate performance evaluation.We systematically investigate multiple electrolyte formulations using high-precision leakage current measurements,open-circuit-voltage experiments,and post-mortem characterizations.Although some electrolytes exhibit similarly low coulombic consumption,they diverge significantly in capacity retention andρ.Especially,dimethyl-carbonate-based localized-high concentration electrolyte can synergically achieve low coulombic consumption and detrimental ratioρduring calendar aging,owing to its chemically inert and structurally resilient solidelectrolyte interface with minimal isolated Si material.By contrast,increasing fluoroethylene carbonate(FEC)additive content suppresses electrolyte breakdown but suffers aggravated chemical degradation of more LixSi isolation for irreversible capacity loss with a risingρ.This study critically reveals that the chemistry-characteristic detrimental ratioρestablishes physically informed performance evaluation to pave the way for accelerating battery development.展开更多
The impact of Mn addition on the microstructure,mechanical properties and corrosion behavior of T6-treated Al−Si−Mg−xMn(x=0.2−1.0 wt.%)alloys in a 3.5 wt.%NaCl solution was investigated.The results showed that adding ...The impact of Mn addition on the microstructure,mechanical properties and corrosion behavior of T6-treated Al−Si−Mg−xMn(x=0.2−1.0 wt.%)alloys in a 3.5 wt.%NaCl solution was investigated.The results showed that adding 0.2 wt.%Mn to T6-treated Al−Si−Mg alloys enhanced the corrosion resistance by promoting the formation ofα-AlFeMnSi phase,characterized by smaller absolute Volta potential values compared to eutectic Si,β-AlFeSi andπ-AlFeMgSi phases.However,the addition of 0.5 wt.%Mn and 1.0 wt.%Mn to the T6-treated Al−Si−Mg alloys increased the size of theα-AlFeMnSi phase.This decreased the properties of T6-treated Al−Si−Mg alloys.Therefore,the optimum Mn content was 0.2 wt.%,providing a novel approach for synergistically enhancing mechanical properties and corrosion resistance of Al−Si−Mg alloys.展开更多
In this paper,a comprehensive evaluation on the silicon/silicon carbide(Si/SiC)hybrid switch is performed through experimental tests in terms of both electrical performance and robustness under extreme stresses.Based ...In this paper,a comprehensive evaluation on the silicon/silicon carbide(Si/SiC)hybrid switch is performed through experimental tests in terms of both electrical performance and robustness under extreme stresses.Based on the optional turn-on and turn-off delay times under the efficiency control mode obtained from the double-pulse test(DPT),both nondestructive and destructive single-pulse avalanche tests are conducted on the Si/SiC hybrid switch as well as on the two discrete device branches inside the hybrid switch.In addition,the avalanche voltage,critical avalanche energy,and peak avalanche current,which intrinsically characterize the unclamped-inductive-switching(UIS)avalanche characteristics,are carefully examined.In this way,the physical factors dominating the UIS characteristics of the hybrid switch,thus limiting its single-pulse avalanche withstand capability,are specifically and comprehensively identified;the underlying physical mechanisms are analyzed and revealed in depth,and how the gate control sequence affects the UIS characteristics of the hybrid switch is extensively investigated.We additionally carry out short-circuit(SC)tests under the fault-under-load(FUL)condition and perform a parallel in-depth analysis to experimentally determine which branch dominates the SC withstand capability of the hybrid switch.Our experimental study indicates that,for both SC robustness and single-pulse avalanche capability,the limiting factor is a single device branch among the two parallel discrete devices,and the UIS behavior is sensitive to the variation of the gate turn-off delay time Toff_delay.The study conducted in this paper not only provides deep academic insights into the electrical performance and reliability of the Si/SiC hybrid switch,but also offers fundamental theoretical principles and technical evidence to support its more efficient and long-term reliable applications of the hybrid switch in the industrial fields.展开更多
为研究真空等离子喷涂Si/Yb_(2)Si_(2)O_(7)/Yb_(2)SiO_(5)环境障涂层试样在涂层受压、涂层受拉时的室温弯曲强度及失效原因,采用超景深三维显微镜、SEM(Scanning Electron Microscope)等方法对喷涂后的试样进行了表征,并测量了涂层孔隙...为研究真空等离子喷涂Si/Yb_(2)Si_(2)O_(7)/Yb_(2)SiO_(5)环境障涂层试样在涂层受压、涂层受拉时的室温弯曲强度及失效原因,采用超景深三维显微镜、SEM(Scanning Electron Microscope)等方法对喷涂后的试样进行了表征,并测量了涂层孔隙率;采用拉伸法测试了涂层的结合强度,并采用三点弯曲试验测试了裸材、涂层受压和涂层受拉时的室温弯曲强度。结果表明:Si/Yb_(2)Si_(2)O_(7)/Yb_(2)SiO_(5)涂层与SiC_(f)/SiC复合材料的结合强度为10.13 MPa,拉伸断裂主要在复材表层发生。计算涂层厚度时,涂层受压样的弯曲强度(503.21 MPa)与裸材(506.79 MPa)基本一致;不计算涂层厚度时,涂层受拉样的弯曲强度(499.77 MPa)与裸材一致;EBC涂层整体具有一定的压缩强度,其整体抗拉强度比复材自身抗拉强度小很多。压涂层时,在载荷增加至接近最大载荷时,复材层间发生破坏,并逐步失效,随后涂层发生飞崩,载荷迅速下降,试验停止;拉涂层时,在载荷很小时(约64 N)涂层就被拉开,随着载荷增加,直至接近最大载荷时,层间发生破坏并逐步失效。弯曲试验时复材的主要失效模式是SiC纤维断裂、复材的SiC基体开裂和复材层间撕裂,复材受拉面产生复材厚度方向的纵向裂纹;复材表层沉积的SiC膜层失效模式主要是开裂和剥落;EBC涂层在受压时的主要失效模式是整体飞崩和开裂,在受拉时,涂层在最大应力处断裂为2部分。本研究对含EBC涂层的SiC_(f)/SiC复材的最大弯曲载荷设计具有参考意义.展开更多
We report the discovery of bulk superconductivity in a new quinary intermetallic compound Th_(2)Mo_(2)Ru_(2)Si_(4)C,crystallized in a collapsed 22241-type structure.This structure is characterized by the intergrowth o...We report the discovery of bulk superconductivity in a new quinary intermetallic compound Th_(2)Mo_(2)Ru_(2)Si_(4)C,crystallized in a collapsed 22241-type structure.This structure is characterized by the intergrowth of ThMo_(2)Si_(2)C and ThRu_(2)Si_(2) units interconnected by equivalent Si-Si bonds that enhance inter-sublattice coupling.The refined lattice parameters are a=4.2212(1)Å and c=20.3899(7)Å.Electrical resistivity and magnetic susceptibility measurements of both polycrystalline and single-crystal samples consistently demonstrate bulk superconductivity with a transition temperature T_(c)∼6.0 K significantly higher than those of the constituent compound ThMo_(2)Si_(2)C and its related analogs.Under magnetic fields,the superconducting state exhibits a nearly isotropic behavior,which is attributed to strong covalent interlayer coupling.First-principles calculations reveal a substantial contribution from the Mo-d orbitals near the Fermi level,which exhibit several band-crossing points.The enhancement in T_(c) can be attributed to the synergistic combination of the valence electron concentration and the inter-sublattice self-doping effect between the[Ru_(2)Si_(2)]and[Mo_(2)Si_(2)C]layers.展开更多
基金financial support granted by the National Natural Science Foundation of China (No. 22402225)the Gusu Innovation and Entrepreneurship Leading Talent Plan(No. ZXL2023193)+2 种基金the Sinano Talents Plan (No. 2022000175)the Guangdong Basic and Applied Basic Research Foundation (No.2023A1515111133)the ANSO Scholarship for Young Talents
文摘Inorganic materials can solve transportable and on-site hydrolytic hydrogen generation issues.CaH_(2)/(Al/Si)composites are preferable due to their notable chemical properties.However,these composites require pretreatments,an inert environment,and long hours of physical ball milling for high homogeneity and synergistic effects.CaH_(2)also inhibits the hydrolysis reaction by forming its products on the Al/Si surface,which hinders the direct utilization of composites.This work represents the first investigation of NaH-CaH_(2)(Al/Si)fuel composites,which greatly overcome these limitations and can be directly used for on-site hydrogen generation and proton exchange membrane(PEM)fuel cells.The NaH-CaH_(2)(Al/Si)fuel composites were prepared by using a straightforward mixing method with variable composition ratios,showing high H_(2)yield and fuel cell(FC)performance.NaH addition provides the bridge effect,which opens up a new way to enable efficient hydrolysis and greatly enhances the hydrolysis activity of CaH_(2)/(Al/Si)composites.The novel fuel composites(NaH-CaH_(2)/Al)have extraordinary FC performance and a 0.42 W/cm2 peak power density greater than commercial hydrogen generators.It provides high H_(2)yield 84.4%for NaH-CaH_(2)/Al and 82%for NaH-CaH_(2)/Si compared to NaOH-CaH_(2)(Al/Si),NaCl-CaH_(2)(Al/Si),and KCl-CaH_(2)(Al/Si)composites.The NaH bridge effect hinders the direct water contact and stops the formation of Ca(OH)2 around Al/Si,which provides adequate pathways for the CaH_(2)(Al/Si)hydrolysis.The impressive capabilities of novel fuel composites are anticipated to offer practical uses in fuel cells,automobile applications,and portable/on-board H_(2)generation.
基金supported by the U.S.Department of Energy(DOE),Office of Energy Efficiency and Renewable Energy(EERE),Vehicle Technologies Office(VTO)under the Silicon Consortium Seedling project received by Z.H.Coperated for the DOE Office of Science by UChicago Argonne,LLC,under Contract DE-AC02-06CH11357+2 种基金Pacific Northwest National Laboratory(PNNL)was supported by the U.S.DOE,Office of Advanced Research Projects Agency-Energy(ARPA-E)under the EVs4ALL Program with the contract number DE-AC05-76RL01830operated by Battelle for the DOE under Contract DE-AC0576RL01830performed at the Oak Ridge National Laboratory(GMV)and supported by U.S.DOE’s VTO under the Silicon Consortium Program received by G.M.V.and directed by Carine Steinway,Nicolas Eidson Thomas,Thomas Do。
文摘Silicon(Si)is a promising high-capacity anode in lithium-ion batteries but suffers from chronic chemical degradation and capacity fading during calendar aging,greatly hindering its automobile applications.Electrolyte engineering currently relies on conventional evaluation criteria of reducing coulombic consumption,which implicitly presume its equivalence to irreversible capacity loss and complicates battery development.We introduce the detrimental ratioρto quantify the fraction of parasitic species that permanently degrades active material.This metric is independent and crucially complements total coulombic consumption for accurate performance evaluation.We systematically investigate multiple electrolyte formulations using high-precision leakage current measurements,open-circuit-voltage experiments,and post-mortem characterizations.Although some electrolytes exhibit similarly low coulombic consumption,they diverge significantly in capacity retention andρ.Especially,dimethyl-carbonate-based localized-high concentration electrolyte can synergically achieve low coulombic consumption and detrimental ratioρduring calendar aging,owing to its chemically inert and structurally resilient solidelectrolyte interface with minimal isolated Si material.By contrast,increasing fluoroethylene carbonate(FEC)additive content suppresses electrolyte breakdown but suffers aggravated chemical degradation of more LixSi isolation for irreversible capacity loss with a risingρ.This study critically reveals that the chemistry-characteristic detrimental ratioρestablishes physically informed performance evaluation to pave the way for accelerating battery development.
基金supported by the National Key Research and Development Program of China(No.2022YFB3404202)the National Natural Science Foundation of China(No.52271103)the Jilin Scientific and Technological Development Program,China(Nos.20220301026GX,20210301041GX)。
文摘The impact of Mn addition on the microstructure,mechanical properties and corrosion behavior of T6-treated Al−Si−Mg−xMn(x=0.2−1.0 wt.%)alloys in a 3.5 wt.%NaCl solution was investigated.The results showed that adding 0.2 wt.%Mn to T6-treated Al−Si−Mg alloys enhanced the corrosion resistance by promoting the formation ofα-AlFeMnSi phase,characterized by smaller absolute Volta potential values compared to eutectic Si,β-AlFeSi andπ-AlFeMgSi phases.However,the addition of 0.5 wt.%Mn and 1.0 wt.%Mn to the T6-treated Al−Si−Mg alloys increased the size of theα-AlFeMnSi phase.This decreased the properties of T6-treated Al−Si−Mg alloys.Therefore,the optimum Mn content was 0.2 wt.%,providing a novel approach for synergistically enhancing mechanical properties and corrosion resistance of Al−Si−Mg alloys.
基金supported in part by the Anhui Provincial Natural Science Foundation Youth Project(Category C)under Grant No.2508085QE184the Opening Project of Key Laboratory of Power Electronics and Motion Control of Anhui Higher Education Institutions under Grant No.PEMC24004+1 种基金the Anhui University of Technology Young Teachers Research Fund under Grant No.QZ202412the Scientific Research Startup Fund for Introduced Talents of Anhui University of Technology under Grant No.QD202340.
文摘In this paper,a comprehensive evaluation on the silicon/silicon carbide(Si/SiC)hybrid switch is performed through experimental tests in terms of both electrical performance and robustness under extreme stresses.Based on the optional turn-on and turn-off delay times under the efficiency control mode obtained from the double-pulse test(DPT),both nondestructive and destructive single-pulse avalanche tests are conducted on the Si/SiC hybrid switch as well as on the two discrete device branches inside the hybrid switch.In addition,the avalanche voltage,critical avalanche energy,and peak avalanche current,which intrinsically characterize the unclamped-inductive-switching(UIS)avalanche characteristics,are carefully examined.In this way,the physical factors dominating the UIS characteristics of the hybrid switch,thus limiting its single-pulse avalanche withstand capability,are specifically and comprehensively identified;the underlying physical mechanisms are analyzed and revealed in depth,and how the gate control sequence affects the UIS characteristics of the hybrid switch is extensively investigated.We additionally carry out short-circuit(SC)tests under the fault-under-load(FUL)condition and perform a parallel in-depth analysis to experimentally determine which branch dominates the SC withstand capability of the hybrid switch.Our experimental study indicates that,for both SC robustness and single-pulse avalanche capability,the limiting factor is a single device branch among the two parallel discrete devices,and the UIS behavior is sensitive to the variation of the gate turn-off delay time Toff_delay.The study conducted in this paper not only provides deep academic insights into the electrical performance and reliability of the Si/SiC hybrid switch,but also offers fundamental theoretical principles and technical evidence to support its more efficient and long-term reliable applications of the hybrid switch in the industrial fields.
基金supported by the National Key Research and Development Program of China (Grant Nos.2022YFA1403202 and 2023YFA1406101)the CAS Superconducting Research Project (Grant No.SCZX-0101)。
文摘We report the discovery of bulk superconductivity in a new quinary intermetallic compound Th_(2)Mo_(2)Ru_(2)Si_(4)C,crystallized in a collapsed 22241-type structure.This structure is characterized by the intergrowth of ThMo_(2)Si_(2)C and ThRu_(2)Si_(2) units interconnected by equivalent Si-Si bonds that enhance inter-sublattice coupling.The refined lattice parameters are a=4.2212(1)Å and c=20.3899(7)Å.Electrical resistivity and magnetic susceptibility measurements of both polycrystalline and single-crystal samples consistently demonstrate bulk superconductivity with a transition temperature T_(c)∼6.0 K significantly higher than those of the constituent compound ThMo_(2)Si_(2)C and its related analogs.Under magnetic fields,the superconducting state exhibits a nearly isotropic behavior,which is attributed to strong covalent interlayer coupling.First-principles calculations reveal a substantial contribution from the Mo-d orbitals near the Fermi level,which exhibit several band-crossing points.The enhancement in T_(c) can be attributed to the synergistic combination of the valence electron concentration and the inter-sublattice self-doping effect between the[Ru_(2)Si_(2)]and[Mo_(2)Si_(2)C]layers.
