The flexible materials exhibit more favorable properties than most rigid substrates in flexibility,weight saving,mechanical reliability,and excellent environmental toughness.Particularly,flexible graphene film with un...The flexible materials exhibit more favorable properties than most rigid substrates in flexibility,weight saving,mechanical reliability,and excellent environmental toughness.Particularly,flexible graphene film with unique mechanical properties was extensively explored in high frequency devices.Herein,we report the characteristics of structure and magnetic properties at high frequency of Co2FeAl thin film with different thicknesses grown on flexible graphene substrate at room temperature.The exciting finding for the columnar structure of Co2FeAl thin film lays the foundation for excellent high frequency property of Co2FeAl/flexible graphene structure.In-plane magnetic anisotropy field varying with increasing thickness of Co2FeAl thin film can be obtained by measurement of ferromagnetic resonance,which can be ascribed to the enhancement of crystallinity and the increase of grain size.Meanwhile,the resonance frequency which can be achieved by the measurement of vector network analyzer with the microstrip method increases with increasing thickness of Co2FeAl thin film.Moreover,in our case with graphene film,the resonance magnetic field is quite stable though folded for twenty cycles,which demonstrates that good flexibility of graphene film and the stability of high frequency magnetic property of Co2FeAl thin film grown on flexible graphene substrate.These results are promising for the design of microwave devices and wireless communication equipment.展开更多
Self-standing carbon-based substrates with satisfied structural stability and property adjustability have promising applications in flexible lithium(Li)metal batteries(FLMBs).Current strategies for modifying carbon ma...Self-standing carbon-based substrates with satisfied structural stability and property adjustability have promising applications in flexible lithium(Li)metal batteries(FLMBs).Current strategies for modifying carbon materials are normally carried out on powder carbon,and very few of them are suitable for self-standing carbon substrates.Herein,a pore-forming strategy based on the redox chemistry of metallic oxide nanodots is developed to prepare two porous carbon substrates for anode and cathode.Starting with cotton cloth,the resulting hollow carbon fibers substrate with nanopores effectively prevents from Li dendrites formation and large volume change in lithium metal anode(LMA).Simulations indicate that the porous structure leads to homogeneous ion flux,Li-ion concentration,and electric field during Li deposition.Li symmetrical cell based on this substrate remains stable for 8300 h with an ultralow voltage hysteresis of 9 mV.Via a similar route,porous carbon cloth substrate is obtained for subsequently seeding V_(2)O_(5)nanowires to prepare the cathode.The assembled FLMBs pouch cell delivers a capacity of 8.2 mAh with a high capacity retention of~100%even under dramatic deformation.The demonstrated strategy has far-reaching potential in preparing free-standing porous carbon-based materials for flexible energy storage devices.展开更多
We study the adsorption of zigzag graphene nanoribbons （GNRs） on Si（001） substrates using the first-principles density functional theory, exploring the effects of the interface interaction on the structurM and ele...We study the adsorption of zigzag graphene nanoribbons （GNRs） on Si（001） substrates using the first-principles density functional theory, exploring the effects of the interface interaction on the structurM and electronic prop- erties of both GNRs and the substrate. By comparing the adsorption structures predicted by the local density approximation, the generalized gradient approximation, and the DFT-D2 approach, we confirm that both edge and inner C atoms of GNRs can form covalent bonds with the substrate. The GNR/substrate interaction destroys the antiferromagnetic coupling of the edge states in GNB.s. The charge transfer from the substrate to GNRs exhibits a complicated pattern and is mainly localized near the C-Si bonds. We also observe a strong perturbation of the surface states and a surface reconstruction transition induced by the GNR adsorption.展开更多
Aluminium doped ZnO thin films（ZnO︰Al） were deposited on transparent polymer substrates at room temperature by rf magnetron sputtering method from a ZnO target with Al2O3 of 2.0 wt%. Argon gas pressure varied from ...Aluminium doped ZnO thin films（ZnO︰Al） were deposited on transparent polymer substrates at room temperature by rf magnetron sputtering method from a ZnO target with Al2O3 of 2.0 wt%. Argon gas pressure varied from 0.5 Pa to 2.5 Pa with radio frequency power of 120 W. XRD results showed that all the ZnO︰Al films had a polycrystalline hexagonal structure and a （002） preferred orientation with the c-axis perpendicular to the substrate. The grain sizes of the films were 6.3-14.8 nm.SEM images indicated the ZnO︰Al film with low Argon gas pressure was denser and the deposition rate of the films depended strongly on the Argon gas pressure, increasing firstly and then decreasing with increasing the pressure. The highest deposition rate was 5.2 nm/min at 1 Pa. The optical transmittance of the ZnO︰Al films increased and the blue shift of the absorption edge appeared when the Argon gas pressure increased. The highest transmittance of obtained ZnO︰Al films at 2.5 Pa was about 85% in the visible region. The electrical properties of the films were worsened with the increase of the Argon gas power from 1 Pa to 2.5 Pa. The resistivity of obtained film at 1.0 Pa was 2.79×10-2 Ω·cm.展开更多
Flexible lithium-ion batteries(LIBs)are critical for the development of next-generation smart electronics.Conversion reaction-based electrodes have been considered promising to construct high energy-density flexible L...Flexible lithium-ion batteries(LIBs)are critical for the development of next-generation smart electronics.Conversion reaction-based electrodes have been considered promising to construct high energy-density flexible LIBs,which satisfy the ever-increasing demand for practical use.However,these electrodes suffer from inferior lithium-storage performance and structural instability during deformation and long-term lithiation/delithiation.These are caused by the sluggish reaction kinetics of active-materials and the superposition of responsive strains originating from the large lithiation-induced stress and applied stress.Here,we propose a stress-release strategy through elastic responses of nested wrinkle texturing of graphene,to achieve high deformability while maintaining structural integrity upon prolonged cycles within high-capacity electrodes.The wrinkles endow the electrode with a robust and flexible network for effective stress release.The resulting electrode shows large reversible stretchability,along with excellent electrochemical performance including high specific capacity,high-rate capability and long-term cycling stability.This strategy offers a new way to obtain high-performance flexible electrodes and can be extended to other energy-storage devices.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51901163 and 12104171)the Fundamental Research Funds for the Central Universities(Grant No.2021XXJS025).
文摘The flexible materials exhibit more favorable properties than most rigid substrates in flexibility,weight saving,mechanical reliability,and excellent environmental toughness.Particularly,flexible graphene film with unique mechanical properties was extensively explored in high frequency devices.Herein,we report the characteristics of structure and magnetic properties at high frequency of Co2FeAl thin film with different thicknesses grown on flexible graphene substrate at room temperature.The exciting finding for the columnar structure of Co2FeAl thin film lays the foundation for excellent high frequency property of Co2FeAl/flexible graphene structure.In-plane magnetic anisotropy field varying with increasing thickness of Co2FeAl thin film can be obtained by measurement of ferromagnetic resonance,which can be ascribed to the enhancement of crystallinity and the increase of grain size.Meanwhile,the resonance frequency which can be achieved by the measurement of vector network analyzer with the microstrip method increases with increasing thickness of Co2FeAl thin film.Moreover,in our case with graphene film,the resonance magnetic field is quite stable though folded for twenty cycles,which demonstrates that good flexibility of graphene film and the stability of high frequency magnetic property of Co2FeAl thin film grown on flexible graphene substrate.These results are promising for the design of microwave devices and wireless communication equipment.
基金supported by NSFC(22035001,21574018,51433003)the National Science and Engineering Council of Canada,and the Fundamental Research Funds for the Central Universities(2412019ZD002)。
文摘Self-standing carbon-based substrates with satisfied structural stability and property adjustability have promising applications in flexible lithium(Li)metal batteries(FLMBs).Current strategies for modifying carbon materials are normally carried out on powder carbon,and very few of them are suitable for self-standing carbon substrates.Herein,a pore-forming strategy based on the redox chemistry of metallic oxide nanodots is developed to prepare two porous carbon substrates for anode and cathode.Starting with cotton cloth,the resulting hollow carbon fibers substrate with nanopores effectively prevents from Li dendrites formation and large volume change in lithium metal anode(LMA).Simulations indicate that the porous structure leads to homogeneous ion flux,Li-ion concentration,and electric field during Li deposition.Li symmetrical cell based on this substrate remains stable for 8300 h with an ultralow voltage hysteresis of 9 mV.Via a similar route,porous carbon cloth substrate is obtained for subsequently seeding V_(2)O_(5)nanowires to prepare the cathode.The assembled FLMBs pouch cell delivers a capacity of 8.2 mAh with a high capacity retention of~100%even under dramatic deformation.The demonstrated strategy has far-reaching potential in preparing free-standing porous carbon-based materials for flexible energy storage devices.
基金Supported by the National Natural Science Foundation of China under Grant No 11204296the National Basic Research Program of China under Grant No 2013CB933304
文摘We study the adsorption of zigzag graphene nanoribbons （GNRs） on Si（001） substrates using the first-principles density functional theory, exploring the effects of the interface interaction on the structurM and electronic prop- erties of both GNRs and the substrate. By comparing the adsorption structures predicted by the local density approximation, the generalized gradient approximation, and the DFT-D2 approach, we confirm that both edge and inner C atoms of GNRs can form covalent bonds with the substrate. The GNR/substrate interaction destroys the antiferromagnetic coupling of the edge states in GNB.s. The charge transfer from the substrate to GNRs exhibits a complicated pattern and is mainly localized near the C-Si bonds. We also observe a strong perturbation of the surface states and a surface reconstruction transition induced by the GNR adsorption.
基金Funded by Key Project of Natural Science Foundation of Hubei Province(No.2008CDA025)
文摘Aluminium doped ZnO thin films（ZnO︰Al） were deposited on transparent polymer substrates at room temperature by rf magnetron sputtering method from a ZnO target with Al2O3 of 2.0 wt%. Argon gas pressure varied from 0.5 Pa to 2.5 Pa with radio frequency power of 120 W. XRD results showed that all the ZnO︰Al films had a polycrystalline hexagonal structure and a （002） preferred orientation with the c-axis perpendicular to the substrate. The grain sizes of the films were 6.3-14.8 nm.SEM images indicated the ZnO︰Al film with low Argon gas pressure was denser and the deposition rate of the films depended strongly on the Argon gas pressure, increasing firstly and then decreasing with increasing the pressure. The highest deposition rate was 5.2 nm/min at 1 Pa. The optical transmittance of the ZnO︰Al films increased and the blue shift of the absorption edge appeared when the Argon gas pressure increased. The highest transmittance of obtained ZnO︰Al films at 2.5 Pa was about 85% in the visible region. The electrical properties of the films were worsened with the increase of the Argon gas power from 1 Pa to 2.5 Pa. The resistivity of obtained film at 1.0 Pa was 2.79×10-2 Ω·cm.
基金financial support from the National Natural Science Foundation of China(Nos.52020105010,51927803,51525206)the National Key R&D Program of China(2016YFA0200102 and 2016YFB0100100)+1 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA22010602)the LiaoNing Revitalization Talents Program(No.XLYC1908015)。
文摘Flexible lithium-ion batteries(LIBs)are critical for the development of next-generation smart electronics.Conversion reaction-based electrodes have been considered promising to construct high energy-density flexible LIBs,which satisfy the ever-increasing demand for practical use.However,these electrodes suffer from inferior lithium-storage performance and structural instability during deformation and long-term lithiation/delithiation.These are caused by the sluggish reaction kinetics of active-materials and the superposition of responsive strains originating from the large lithiation-induced stress and applied stress.Here,we propose a stress-release strategy through elastic responses of nested wrinkle texturing of graphene,to achieve high deformability while maintaining structural integrity upon prolonged cycles within high-capacity electrodes.The wrinkles endow the electrode with a robust and flexible network for effective stress release.The resulting electrode shows large reversible stretchability,along with excellent electrochemical performance including high specific capacity,high-rate capability and long-term cycling stability.This strategy offers a new way to obtain high-performance flexible electrodes and can be extended to other energy-storage devices.
