Layer-structured Ruddlesden–Popper(RP)perovskites(RPPs)with decent stability have captured the imagination of the photovoltaic research community and bring hope for boosting the development of perovskite solar cell(P...Layer-structured Ruddlesden–Popper(RP)perovskites(RPPs)with decent stability have captured the imagination of the photovoltaic research community and bring hope for boosting the development of perovskite solar cell(PSC)technology.However,two-dimensional(2D)or quasi-2D RP PSCs are encountered with some challenges of the large exciton binding energy,blocked charge transport and poor film quality,which restrict their photovoltaic performance.Fortunately,these issues can be readily resolved by rationally designing spacer cations of RPPs.This review mainly focuses on how to design the molecular structures of organic spacers and aims to endow RPPs with outstanding photovoltaic applications.We firstly elucidated the important roles of organic spacers in impacting crystallization kinetics,charge transporting ability and stability of RPPs.Then we brought three aspects to attention for designing organic spacers.Finally,we presented the specific molecular structure design strategies for organic spacers of RPPs aiming to improve photovoltaic performance of RP PSCs.These proposed strategies in this review will provide new avenues to develop novel organic spacers for RPPs and advance the development of RPP photovoltaic technology for future applications.展开更多
Traditional electrode manufacturing for lithium-ion batteries is well established,reliable,and has already reached high processing speeds and improvements in production costs.For modern electric vehicles,however,the n...Traditional electrode manufacturing for lithium-ion batteries is well established,reliable,and has already reached high processing speeds and improvements in production costs.For modern electric vehicles,however,the need for batteries with high gravimetric and volumetric energy densities at cell level is increasing;and new production concepts are required for this purpose.During the last decade,laser processing of battery materials emerged as a promising processing tool for either improving manufacturing flexibility and product reliability or enhancing battery performances.Laser cutting and welding already reached a high level of maturity and it is obvious that in the near future they will become frequently implemented in battery production lines.This review focuses on laser texturing of electrode materials due to its high potential for significantly enhancing battery performances beyond state-of-the-art.Technical approaches and processing strategies for new electrode architectures and concepts will be presented and discussed with regard to energy and power density requirements.The boost of electrochemical performances due to laser texturing of energy storage materials is currently proven at the laboratory scale.However,promising developments in high-power,ultrafast laser technology may push laser structuring of batteries to the next technical readiness level soon.For demonstration in pilot lines adapted to future cell production,process upscaling regarding footprint area and processing speed are the main issues as well as the economic aspects with regards to CapEx amortization and the benefits resulting from the next generation battery.This review begins with an introduction of the three-dimensional battery and thick film concept,made possible by laser texturing.Laser processing of electrode components,namely current collectors,anodes,and cathodes will be presented.Different types of electrode architectures,such as holes,grids,and lines,were generated;their impact on battery performances are illustrated.The usage of high-energy materials,which are on the threshold of commercialization,is highlighted.Battery performance increase is triggered by controlling lithium-ion diffusion kinetics in liquid electrolyte filled porous electrodes.This review concludes with a discussion of various laser parameter tasks for process upscaling in a new type of extreme manufacturing.展开更多
There is an increasing demand for rechargeable batteries in high-performance energy storage systems.The current dominating Li-ion batteries are limited by price,resource availability,as well as their theoretical capac...There is an increasing demand for rechargeable batteries in high-performance energy storage systems.The current dominating Li-ion batteries are limited by price,resource availability,as well as their theoretical capacities.So that the community has started to explore alternative battery chemistries.As a promising multivalent battery type,rechargeable magnesium batteries(RMBs)have attracted increasing attention because of high safety,high volumetric energy density,and low cost thanks to abundant resource of Mg.However,the development of high-performance anodes is still hampered by formation of passivating layers on the Mg surface.Additionally,dendrites can also grow under certain conditions with pure Mg anodes,which requires further studies for reliable operation window and substitutes.Therefore,this review specifically aims to provide an overview on the often overlooked yet very important anode materials of RMBs,with the hope to inspire more attention and research efforts for the achievement of over-all better performance of future RMBs.c 2020 Published by Elsevier B.V.on behalf of Chongqing University.展开更多
Herein, the electrochemical performance and the mechanism of potassium insertion/deinsertion in orthorhombic V_(2)O_(5) nanoparticles are studied. The V2O5 electrode displays an initial potassiation/depotassiation cap...Herein, the electrochemical performance and the mechanism of potassium insertion/deinsertion in orthorhombic V_(2)O_(5) nanoparticles are studied. The V2O5 electrode displays an initial potassiation/depotassiation capacity of 200 mAh g^(−1)/217 mAh g^(−1) in the voltage range 1.5–4.0 V vs. K^(+)/K at C/12 rate, suggesting fast kinetics for potassium insertion/deinsertion. However, the capacity quickly fades during cycling, reaching 54 mAh g^(−1) at the 31st cycle. Afterwards, the capacity slowly increases up to 80 mAh g^(−1) at the 200th cycle. The storage mechanism upon K ions insertion into V2O5 is elucidated. In operando synchrotron diffraction reveals that V_(2)O_(5) first undergoes a solid solution to form K_(0.6)V_(2)O_(5) phase and then, upon further K ions insertion, it reveals coexistence of a solid solution and a two-phase reaction. During K ions deinsertion, the coexistence of solid solution and the two-phase reaction is identified together with an irreversible process. In operando XAS confirms the reduction/oxidation of vanadium during the K insertion/extraction with some irreversible contributions. This is consistent with the results obtained from synchrotron diffraction, ex situ Raman, X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). Moreover, ex situ XPS confirms the “cathode electrolyte interphase” (CEI) formation on the electrode and the decomposition of CEI film during cycling.展开更多
Density functional methods have been used for the calculation of electronic structures, electronic transitions, vertical electron affinities and intermolecular reorganization energies for tri-aryl substituted dibenzot...Density functional methods have been used for the calculation of electronic structures, electronic transitions, vertical electron affinities and intermolecular reorganization energies for tri-aryl substituted dibenzothiophenes. These model compounds were then compared to the predicted values for dibenzo[b,d]thiophen-2-yltriphenylsilane (DBTSI 2) and to dibenzo[b,d]thiophene-2,8-diylbis(diphenylphosphine oxide) (PO15), known electron transport molecules. The results indicate that these model compounds can be used in a blue OLED system.展开更多
Objective.Laser-treated surfaces for ventricular assist devices.Impact Statement.This work has scientific impact since it proposes a biofunctional surface created with laser processing in bioinert titanium.Introductio...Objective.Laser-treated surfaces for ventricular assist devices.Impact Statement.This work has scientific impact since it proposes a biofunctional surface created with laser processing in bioinert titanium.Introduction.Cardiovascular diseases are the world’s leading cause of death.An especially debilitating heart disease is congestive heart failure.Among the possible therapies,heart transplantation and mechanical circulatory assistance are the main treatments for its severe form at a more advanced stage.The development of biomaterials for ventricular assist devices is still being carried out.Although polished titanium is currently employed in several devices,its performance could be improved by enhancing the bioactivity of its surface.Methods.Aiming to improve the titanium without using coatings that can be detached,this work presents the formation of laser-induced periodic surface structures with a topology suitable for cell adhesion and neointimal tissue formation.The surface was modified by femtosecond laser ablation and cell adhesion was evaluated in vitro by using fibroblast cells.Results.The results indicate the formation of the desired topology,since the cells showed the appropriate adhesion compared to the control group.Scanning electron microscopy showed several positive characteristics in the cells shape and their surface distribution.The in vitro results obtained with different topologies point that the proposed LIPSS would provide enhanced cell adhesion and proliferation.Conclusion.The laser processes studied can create new interactions in biomaterials already known and improve the performance of biomaterials for use in ventricular assist devices.展开更多
Lithium metal(LM)is a promising anode for next-generation batteries due to its high theoretical capacity and low electrode potential.Nonetheless,side reactions,volume change,and unwanted lithium dendrite growth seriou...Lithium metal(LM)is a promising anode for next-generation batteries due to its high theoretical capacity and low electrode potential.Nonetheless,side reactions,volume change,and unwanted lithium dendrite growth seriously limit the practical application of LM.Herein,with the aid of a hard template approach,a novel lithiophilic CoF_(2)-carbon hollow sphere(CoF_(2)@C-HS)composite material is successfully prepared via a facile in-situ fluorination and etching strategy.The lithiophilic CoF_(2) acts as nucleation sites to reduce nucleation overpotential as well as induces the spatial Li deposition and the formation of LiFrich solid electrolyte interphase(SEI),and the hollow carbon matrix can enhance the electrical conductivity and offer free space for LM deposition.Theoretical simulations reveal that the synergistic effect of lithiophilic CoF_(2) and hollow carbon matrix homogenizes the electric field distribution and Li~+flux.Benefiting from these advantages,the CoF_(2)@C-HS-modified copper substrate electrode delivers an enhanced Coulombic efficiency(CE)of 93.7%for 280 cycles at 1 mA cm^(-2)and 1 mA h cm^(-2).The symmetrical cell using CoF_(2)@C-HS can stably cycle more than 1800 h with a low voltage hysteresis of 11 mV at a current density of 0.5 MA cm^(-2)and an areal capacity of 0.5 mA h cm^(-2).Moreover,the Li@CoF_(2)@C-HS composite anode enables more than 300 stable cycles at 1 C with a capacity retention of 95%in LiFePO_(4)-based full cell and 110 stable cycles at 1 C in LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM811)-based highvoltage full cell.This work might shed a new light on designing lithiophilic hosts to spatially confine LM deposition,realizing dendrite-free LM anodes and the practical applications of LM batteries.展开更多
In order to achieve combined mechanical and electrical properties,multi-walled carbon nanotubes(MWCNTs)reinforced Cu/Ti_(3)SiC_(2)/C nanocomposites were further processed by high-pressure torsion(HPT).The maximum micr...In order to achieve combined mechanical and electrical properties,multi-walled carbon nanotubes(MWCNTs)reinforced Cu/Ti_(3)SiC_(2)/C nanocomposites were further processed by high-pressure torsion(HPT).The maximum microhardness values of central and edge from the composites with 1 wt.%MWCNTs reached HV 130.0 and HV 363.5,which were 43.9%and 39.5%higher than those of the original samples,respectively.With the same content of MWCNTs,its electrical conductivity achieved 3.42×10^(7) S/m,which was increased by 78.1%compared with that of original samples.The synergistic improvement of mechanical and electrical properties is attributed to the obtained microstructure with increased homogenization and refinement,as well as improved interfacial bonding and reduced porosity.The strengthening mechanisms include dispersion and refinement strengthening for mechanical properties,as well as reduced electron scattering for electrical properties.展开更多
In order to obtain Mg alloys with fine microstructures and high mechanical performances,a novel friction-based processing method,name as“constrained friction processing(CFP)”,was investigated.Via CFP,defect-free Mg-...In order to obtain Mg alloys with fine microstructures and high mechanical performances,a novel friction-based processing method,name as“constrained friction processing(CFP)”,was investigated.Via CFP,defect-free Mg-Zn-Ca rods with greatly refined grains and high mechanical properties were produced.Compared to the previous as-cast microstructure,the grain size was reduced from more than 1 mm to around 4μm within 3 s by a single process cycle.The compressive yield strength was increased by 350%while the ultimate compressive strength by 53%.According to the established material flow behaviors by“tracer material”,the plastic material was transported by shear deformation.From the base material to the rod,the material experienced three stages,i.e.deformation by the tool,upward flow with additional tilt,followed by upward transportation.The microstructural evolution was revealed by“stop-action”technique.The microstructural development at regions adjacent to the rod is mainly controlled by twinning,dynamic recrystallization(DRX)as well as particle stimulated nucleation,while that within the rod is related to DRX combined with grain growth.展开更多
The aim of this work is to investigate microstructure,corrosion resistance characteristics and nanohardness of the oxide layer on AZ91 Mg alloy by applying different voltage with KMnO4 contained solution.There are lot...The aim of this work is to investigate microstructure,corrosion resistance characteristics and nanohardness of the oxide layer on AZ91 Mg alloy by applying different voltage with KMnO4 contained solution.There are lots of closed pores that are filled with another oxide compound compared with the typical surface morphology with pore coated until 350 V of coating voltage.The thickness of oxide layer increases with increasing coating voltage.The oxide layer formed on AZ91 Mg alloy in electrolyte with potassium permanganate consists of MgO and Mn2O3.Corrosion potential of the oxide layer on AZ91 Mg alloy obtained at different plasma electrolytic oxidation(PEO) reaction stages increases with increasing coating voltage.The corrosion resistance of AZ91 Mg alloy depends on the existence of the manganese oxide in the oxide layer.The inner barrier layer composed of the MgO and Mn2O3 may serve as diffusion barrier to enhance the corrosion resistance and may partially explain the excellent anti-corrosion performance in corrosion test.Nanohardness values increase with increasing coating voltage.The increase in the nanohardness may be due to the effect of manganese oxide in the oxide layer on AZ91 Mg alloy coated from electrolyte containing KMnO4.展开更多
Recently, a semi-solid metal processing has been acknowledged as a cost-effective technique to be able to manufacture high quality product for the transportation industry. In this study a hypo-eutectic Al alloy was fa...Recently, a semi-solid metal processing has been acknowledged as a cost-effective technique to be able to manufacture high quality product for the transportation industry. In this study a hypo-eutectic Al alloy was fabricated by means of an electromagnetic stirrer in continuous casting process and the microstructural change during solidification due to a fluid flow by electromagnetic stirring was examined. Due to the forced fluid flow during solidification a dendritic phase of primary α phase of Al alloy was turned into a globular phase, which can make the Al alloy get a thixotropic behavior in the semi-solid region. In order to establish the quantitative relationship between microstructure and the process parameters, the morphology shape, a silicon distribution and a size of primary α phase were observed according to casting speed in continuous casting machine. The primary α phase was turned into the degenerate dendrites approaching a spherical configuration with increasing casting speed. The fine-grained and equiaxed microstructure appeared at higher casting speed. A segregation behavior of Si element was declined with increasing casting speed and a very uniform distribution of Si element was observed on the billet at a casting speed of 600 mm·min-1. A thickness of the solidifying shell of the billet was shortened with increasing the casting speed.展开更多
This paper discusses the analysis and design of a very thin slotless permanent magnet （PM） brushless motor whose stator laminations are manufactured from a single strip of steel that is edge wound into a spiral （li...This paper discusses the analysis and design of a very thin slotless permanent magnet （PM） brushless motor whose stator laminations are manufactured from a single strip of steel that is edge wound into a spiral （like a ＂Slinky＂） and then fitted over the windings that are preformed on the outside surface of a non-conducting former. Analytical and finite element analysis （FEA） are used to determine the con- strained optimum dimensions of a motor used to drive a rim driven thruster in which the motor rotor is fit- ted onto the rim of the propeller and the stator is encapsulated in the thin Kort nozzle of the thruster. The paper describes the fabrication of a demonstrator motor and presents experimental results to validate the theoretical calculations. Experimental motor performance results are also reported and compared with those of a slotted motor that fits within the same active radial dimensions as the slotless motor. The slotless motor, which has longer active length and endwindings, and thicker magnets than the slotted motor, was found to be less efficient and more expensive （prototype cost） than the slotted machine.展开更多
Precise control over the charge carrier dynamics throughout the device can result in outstanding performance of perovskite solar cells(PSCs).Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)(PEDOT:PSS)is the mo...Precise control over the charge carrier dynamics throughout the device can result in outstanding performance of perovskite solar cells(PSCs).Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)(PEDOT:PSS)is the most actively studied hole transport material in p-i-n structured PSCs.However,charge transport in the PEDOT:PSS is limited and inefficient because of its low conductivity with the presence of the weak ionic conductor PSS.In addition,morphology of the underlying PEDOT:PSS layer in PSCs plays a crucial role in determining the optoelectronic quality of the active perovskite absorber layer.This work is focused on realization of a non-wetting conductive surface of hole transport layer suitable for the growth of larger perovskite crystalline domains.This is accomplished by employing a facile solventengineered(ethylene glycol and methanol)approach resulting in removal of the predominant PSS in PEDOT:PSS.The consequence of acquiring larger perovskite crystalline domains was observed in the charge carrier dynamics studies,with the achievement of higher charge carrier lifetime,lower charge transport time and lower transfer impedance in the solvent-engineered PEDOT:PSS-based PSCs.Use of this solventengineered treatment for the fabrication of MAPbI3 PSCs greatly increased the device stability witnessing a power conversion efficiency of 18.18%,which corresponds to^37%improvement compared to the untreated PEDOT:PSS based devices.展开更多
With the recent development of high entropy materials, an alternative approach to develop advanced functional materials with distinctive properties that show improved values compared to conventional materials has been...With the recent development of high entropy materials, an alternative approach to develop advanced functional materials with distinctive properties that show improved values compared to conventional materials has been provided. The high entropy concept was later successfully transferred to metal fluorides and high entropy fluorides(HEFs) were successfully synthesized. Owing to their high theoretical specific capacities in energy storage applications, HEFs were utilized as cathode materials for lithiumion batteries(LIBs) and their underlying storage mechanisms were investigated. Instead of a step-bystep reduction of each individual metal cation, the HEFs seem to exhibit a single-step reduction process,indicating a solid solution compound instead of merely a mixture of different metal fluorides. It was also observed that the electrochemical behavior of the HEFs depends on each individual incorporated element. Therefore, by altering the elemental composition, new materials that exhibit improved electrochemical properties can be designed. Remarkably, HEFs with seven incorporated metal elements exhibited a better cycling stability as well as a lower hysteresis compared to binary metal fluorides.These findings offer new guidelines for material design and tailoring towards high performance LIBs.展开更多
Direct Laser Interference Patterning(DLIP)is used to texture current collector foils in a roll-to-roll process using a high-power picosecond pulsed laser system operating at either fundamental wavelength of 1064 nm or...Direct Laser Interference Patterning(DLIP)is used to texture current collector foils in a roll-to-roll process using a high-power picosecond pulsed laser system operating at either fundamental wavelength of 1064 nm or 2nd harmonic of 532 nm.The raw beam having a diameter of 3 mm@1/e^(2) is shaped into an elongated top-hat intensity profile using a diffractive so-called FBS■-L element and cylindrical telescopes.The shaped beam is split into its diffraction orders,where the two first orders are parallelized and guided into a galvanometer scanner.The deflected beams inside the scan head are recombined with an F-theta objective on the working position generating the interference pattern.The DLIP spot has a line-like interference pattern with about 15μm spatial period.Laser fluences of up to 8 J cm^(-2) were achieved using a maximum pulse energy of 0.6 mJ.Furthermore,an in-house built roll-to-roll machine was developed.Using this setup,aluminum and copper foil of 20μm and 9μm thickness,respectively,could be processed.Subsequently to current collector structuring coating of composite electrode material took place.In case of lithium nickel manganese cobalt oxide(NMC 622)cathode deposited onto textured aluminum current collector,an increased specific discharge capacity could be achieved at a C-rate of 1℃.For the silicon/graphite anode material deposited onto textured copper current collector,an improved rate capability at all C-rates between C/10 and 5℃ was achieved.The rate capability was increased up to 100%compared to reference material.At C-rates between C/2 and 2℃,the specific discharge capacity was increased to 200 mAh g^(-1),while the reference electrodes with untextured current collector foils provided a specific discharge capacity of 100 m Ah g^(-1),showing the potential of the DLIP technology for cost-effective production of battery cells with increased cycle lifetime.展开更多
Polyoxometalates have been explored as multi-electron active species in both aqueous and non-aqueous redox flow batteries. Although non-aqueous systems in principle offer a wider voltage window for redox flow battery ...Polyoxometalates have been explored as multi-electron active species in both aqueous and non-aqueous redox flow batteries. Although non-aqueous systems in principle offer a wider voltage window for redox flow battery operation, realization of this potential requires a judicious choice of solvent as well as polyoxometalate properties. We demonstrate here the superior performance of N,N-dimethylformamide(DMF)compared to acetonitrile as a solvent for redox flow batteries based on Li3PMo12O40. This compound displays two 1-electron transfers in acetonitrile but can access an extra quasi-reversible 2-electron redox process in DMF. A cell containing 10 mM solution of Li3PMo12O40 in DMF produced a cell voltage of 0.7 V with 2-electron transfers(State of Charge = 60%) and showed a good cyclability. As a means to boost energy density, operation of the redox flow battery at a higher concentration of 0.1 M Li3PMo12O40 produced cells with cell voltage of 0.6 V in acetonitrile and a cell voltage of 1.0 V in DMF;both showed excellent coulombic efficiencies of more than 90% over the course of 30 cycles. Energy density was also increased by employing an asymmetric cell with different polyoxometalates on each side to extend cell voltage.Li6P2W18O62 exhibited 3 quasi-reversible 2-electron transfers in the potential range between-2.05 V and-0.5 V vs. Ag/Ag+. 10 mM Li6P2W18O62/Li3PMo12O40 in DMF produced a cell with cell voltage of 1.3 V involving 4-electron transfers(State of Charge = 50%) with coulombic efficiency of nearly 100% and energy efficiency of nearly 70% throughout the test with more than 20 cycles. These promising results demonstrate proof-of-concept approaches to improving the performance of polyoxometalates in non-aqueous redox flow batteries.展开更多
Tin(Sn)holds great promise as an anode material for next-generation lithium(Li)ion batteries but suffers from massive volume change and poor cycling performance.To clarify the dynamic chemical and microstructural evol...Tin(Sn)holds great promise as an anode material for next-generation lithium(Li)ion batteries but suffers from massive volume change and poor cycling performance.To clarify the dynamic chemical and microstructural evolution of Sn anode during lithiation and delithiation,synchrotron X-ray energydispersive diffraction and X-ray tomography are simultaneously employed during Li/Sn cell operation.The intermediate Li-Sn alloy phases during de/lithiation are identified,and their dynamic phase transformation is unraveled which is further correlated with the volume variation of the Sn at particle-and electrode-level.Moreover,we find that the Sn particle expansion/shrinkage induced particle displacement is anisotropic:the displacement perpendicular to the electrode surface(z-axis)is more pronounced compared to the directions(x-and y-axis)along the electrode surface.This anisotropic particle displacement leads to an anisotropic volume variation at the electrode level and eventually generates a net electrode expansion towards the separator after cycling,which could be one of the root causes of mechanical detachment and delamination of electrodes during long-term operation.The unraveled chemical evolution of Li-Sn and deep insights into the microstructural evolution of Sn anode provided here could guide future design and engineering of Sn and other alloy anodes for high energy density Li-and Na-ion batteries.展开更多
基金funding from National Science Foundation of China(52202337 and 22178015)the Young Taishan Scholars Program of Shandong Province(tsqn202211082)+1 种基金Natural Science Foundation of Shandong Province(ZR2023MB051)Independent Innovation Research Project of China University of Petroleum(East China)(22CX06023A).
文摘Layer-structured Ruddlesden–Popper(RP)perovskites(RPPs)with decent stability have captured the imagination of the photovoltaic research community and bring hope for boosting the development of perovskite solar cell(PSC)technology.However,two-dimensional(2D)or quasi-2D RP PSCs are encountered with some challenges of the large exciton binding energy,blocked charge transport and poor film quality,which restrict their photovoltaic performance.Fortunately,these issues can be readily resolved by rationally designing spacer cations of RPPs.This review mainly focuses on how to design the molecular structures of organic spacers and aims to endow RPPs with outstanding photovoltaic applications.We firstly elucidated the important roles of organic spacers in impacting crystallization kinetics,charge transporting ability and stability of RPPs.Then we brought three aspects to attention for designing organic spacers.Finally,we presented the specific molecular structure design strategies for organic spacers of RPPs aiming to improve photovoltaic performance of RP PSCs.These proposed strategies in this review will provide new avenues to develop novel organic spacers for RPPs and advance the development of RPP photovoltaic technology for future applications.
基金The research to anode material development received funding from the German Research Foundation(DFG,project No.392322200)the development of cathode materials and upscaling strategies was funded by the Federal Ministry of Education and Research(Project NextGen-3DBat,03XP0198F).
文摘Traditional electrode manufacturing for lithium-ion batteries is well established,reliable,and has already reached high processing speeds and improvements in production costs.For modern electric vehicles,however,the need for batteries with high gravimetric and volumetric energy densities at cell level is increasing;and new production concepts are required for this purpose.During the last decade,laser processing of battery materials emerged as a promising processing tool for either improving manufacturing flexibility and product reliability or enhancing battery performances.Laser cutting and welding already reached a high level of maturity and it is obvious that in the near future they will become frequently implemented in battery production lines.This review focuses on laser texturing of electrode materials due to its high potential for significantly enhancing battery performances beyond state-of-the-art.Technical approaches and processing strategies for new electrode architectures and concepts will be presented and discussed with regard to energy and power density requirements.The boost of electrochemical performances due to laser texturing of energy storage materials is currently proven at the laboratory scale.However,promising developments in high-power,ultrafast laser technology may push laser structuring of batteries to the next technical readiness level soon.For demonstration in pilot lines adapted to future cell production,process upscaling regarding footprint area and processing speed are the main issues as well as the economic aspects with regards to CapEx amortization and the benefits resulting from the next generation battery.This review begins with an introduction of the three-dimensional battery and thick film concept,made possible by laser texturing.Laser processing of electrode components,namely current collectors,anodes,and cathodes will be presented.Different types of electrode architectures,such as holes,grids,and lines,were generated;their impact on battery performances are illustrated.The usage of high-energy materials,which are on the threshold of commercialization,is highlighted.Battery performance increase is triggered by controlling lithium-ion diffusion kinetics in liquid electrolyte filled porous electrodes.This review concludes with a discussion of various laser parameter tasks for process upscaling in a new type of extreme manufacturing.
基金the German Research Foundation DFG project(LI 2839/1-1)National Natural Science Foundation of China(51971044)MF acknowledges funding from EU research and innovation framework programme via ttE-MAGIC,project(ID:824066)。
文摘There is an increasing demand for rechargeable batteries in high-performance energy storage systems.The current dominating Li-ion batteries are limited by price,resource availability,as well as their theoretical capacities.So that the community has started to explore alternative battery chemistries.As a promising multivalent battery type,rechargeable magnesium batteries(RMBs)have attracted increasing attention because of high safety,high volumetric energy density,and low cost thanks to abundant resource of Mg.However,the development of high-performance anodes is still hampered by formation of passivating layers on the Mg surface.Additionally,dendrites can also grow under certain conditions with pure Mg anodes,which requires further studies for reliable operation window and substitutes.Therefore,this review specifically aims to provide an overview on the often overlooked yet very important anode materials of RMBs,with the hope to inspire more attention and research efforts for the achievement of over-all better performance of future RMBs.c 2020 Published by Elsevier B.V.on behalf of Chongqing University.
基金This work contributes to the research performed at CELEST(Center for Electrochemical Energy Storage Ulm-Karlsruhe)and was funded by the German Research Foundation(DFG)under Project ID 390874152(POLiS Cluster of Excellence)Our research work has gained benefit from beamtime allocation(2017092405-qfu)at BL04-MSPD at ALBA Synchrotron,Barcelona,Spain and(I-20170977)at PETRA-III beamline P65 at DESY,Hamburg,Germany.The in operando XAS work was performed by using the Biologic potentiostat of PETRA-Ⅲ beamline P02.1.We thank Dr.Francois Fauth from Experiments Division at ALBA for his technical help during synchrotron diffraction measurement.We appreciate Dr.Anna-Lena Hansen(IAM-ESS)for the helpful discussion regarding to the crystal sturcture of V_(2)O_(5).Dr.Kristina Pfeifer(IAM-ESS),Dr.Noha Sabi(IAM-ESS),and Dr.Thomas Bergfeldt(IAM-AWP)are gratefully acknowledged for SEM/EDX,FTIR,and ICP-OES measurements,respectively.The TEM characterization was carried out at the Karlsruhe Nano Micro Facility(KNMF),a Helmholtz research infrastructure operated at the KIT.
文摘Herein, the electrochemical performance and the mechanism of potassium insertion/deinsertion in orthorhombic V_(2)O_(5) nanoparticles are studied. The V2O5 electrode displays an initial potassiation/depotassiation capacity of 200 mAh g^(−1)/217 mAh g^(−1) in the voltage range 1.5–4.0 V vs. K^(+)/K at C/12 rate, suggesting fast kinetics for potassium insertion/deinsertion. However, the capacity quickly fades during cycling, reaching 54 mAh g^(−1) at the 31st cycle. Afterwards, the capacity slowly increases up to 80 mAh g^(−1) at the 200th cycle. The storage mechanism upon K ions insertion into V2O5 is elucidated. In operando synchrotron diffraction reveals that V_(2)O_(5) first undergoes a solid solution to form K_(0.6)V_(2)O_(5) phase and then, upon further K ions insertion, it reveals coexistence of a solid solution and a two-phase reaction. During K ions deinsertion, the coexistence of solid solution and the two-phase reaction is identified together with an irreversible process. In operando XAS confirms the reduction/oxidation of vanadium during the K insertion/extraction with some irreversible contributions. This is consistent with the results obtained from synchrotron diffraction, ex situ Raman, X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). Moreover, ex situ XPS confirms the “cathode electrolyte interphase” (CEI) formation on the electrode and the decomposition of CEI film during cycling.
文摘Density functional methods have been used for the calculation of electronic structures, electronic transitions, vertical electron affinities and intermolecular reorganization energies for tri-aryl substituted dibenzothiophenes. These model compounds were then compared to the predicted values for dibenzo[b,d]thiophen-2-yltriphenylsilane (DBTSI 2) and to dibenzo[b,d]thiophene-2,8-diylbis(diphenylphosphine oxide) (PO15), known electron transport molecules. The results indicate that these model compounds can be used in a blue OLED system.
文摘Objective.Laser-treated surfaces for ventricular assist devices.Impact Statement.This work has scientific impact since it proposes a biofunctional surface created with laser processing in bioinert titanium.Introduction.Cardiovascular diseases are the world’s leading cause of death.An especially debilitating heart disease is congestive heart failure.Among the possible therapies,heart transplantation and mechanical circulatory assistance are the main treatments for its severe form at a more advanced stage.The development of biomaterials for ventricular assist devices is still being carried out.Although polished titanium is currently employed in several devices,its performance could be improved by enhancing the bioactivity of its surface.Methods.Aiming to improve the titanium without using coatings that can be detached,this work presents the formation of laser-induced periodic surface structures with a topology suitable for cell adhesion and neointimal tissue formation.The surface was modified by femtosecond laser ablation and cell adhesion was evaluated in vitro by using fibroblast cells.Results.The results indicate the formation of the desired topology,since the cells showed the appropriate adhesion compared to the control group.Scanning electron microscopy showed several positive characteristics in the cells shape and their surface distribution.The in vitro results obtained with different topologies point that the proposed LIPSS would provide enhanced cell adhesion and proliferation.Conclusion.The laser processes studied can create new interactions in biomaterials already known and improve the performance of biomaterials for use in ventricular assist devices.
基金supported by the Natural Science Foundation of China (52277218)the Hubei Provincial Natural Science Foundation of China (2024AFA094)+1 种基金the Excellent Discipline Cultivation Project by JHUN (2023XKZ009)supported by the U.S.Department of Energy,Office of Science,Office of Basic Energy Sciences,Materials Sciences and Engineering Division under contract number DE-AC05-00OR22725。
文摘Lithium metal(LM)is a promising anode for next-generation batteries due to its high theoretical capacity and low electrode potential.Nonetheless,side reactions,volume change,and unwanted lithium dendrite growth seriously limit the practical application of LM.Herein,with the aid of a hard template approach,a novel lithiophilic CoF_(2)-carbon hollow sphere(CoF_(2)@C-HS)composite material is successfully prepared via a facile in-situ fluorination and etching strategy.The lithiophilic CoF_(2) acts as nucleation sites to reduce nucleation overpotential as well as induces the spatial Li deposition and the formation of LiFrich solid electrolyte interphase(SEI),and the hollow carbon matrix can enhance the electrical conductivity and offer free space for LM deposition.Theoretical simulations reveal that the synergistic effect of lithiophilic CoF_(2) and hollow carbon matrix homogenizes the electric field distribution and Li~+flux.Benefiting from these advantages,the CoF_(2)@C-HS-modified copper substrate electrode delivers an enhanced Coulombic efficiency(CE)of 93.7%for 280 cycles at 1 mA cm^(-2)and 1 mA h cm^(-2).The symmetrical cell using CoF_(2)@C-HS can stably cycle more than 1800 h with a low voltage hysteresis of 11 mV at a current density of 0.5 MA cm^(-2)and an areal capacity of 0.5 mA h cm^(-2).Moreover,the Li@CoF_(2)@C-HS composite anode enables more than 300 stable cycles at 1 C with a capacity retention of 95%in LiFePO_(4)-based full cell and 110 stable cycles at 1 C in LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM811)-based highvoltage full cell.This work might shed a new light on designing lithiophilic hosts to spatially confine LM deposition,realizing dendrite-free LM anodes and the practical applications of LM batteries.
基金supported by Key Laboratory of Infrared Imaging Materials and Detectors,Shanghai Institute of Technical Physics,Chinese Academy of Sciences(No.IIMDKFJJ-21-10)China Postdoctoral Science Foundation(No.2018T110993).
文摘In order to achieve combined mechanical and electrical properties,multi-walled carbon nanotubes(MWCNTs)reinforced Cu/Ti_(3)SiC_(2)/C nanocomposites were further processed by high-pressure torsion(HPT).The maximum microhardness values of central and edge from the composites with 1 wt.%MWCNTs reached HV 130.0 and HV 363.5,which were 43.9%and 39.5%higher than those of the original samples,respectively.With the same content of MWCNTs,its electrical conductivity achieved 3.42×10^(7) S/m,which was increased by 78.1%compared with that of original samples.The synergistic improvement of mechanical and electrical properties is attributed to the obtained microstructure with increased homogenization and refinement,as well as improved interfacial bonding and reduced porosity.The strengthening mechanisms include dispersion and refinement strengthening for mechanical properties,as well as reduced electron scattering for electrical properties.
基金the China Scholarship Council for the award of fellowship and funding(No.202006230137)。
文摘In order to obtain Mg alloys with fine microstructures and high mechanical performances,a novel friction-based processing method,name as“constrained friction processing(CFP)”,was investigated.Via CFP,defect-free Mg-Zn-Ca rods with greatly refined grains and high mechanical properties were produced.Compared to the previous as-cast microstructure,the grain size was reduced from more than 1 mm to around 4μm within 3 s by a single process cycle.The compressive yield strength was increased by 350%while the ultimate compressive strength by 53%.According to the established material flow behaviors by“tracer material”,the plastic material was transported by shear deformation.From the base material to the rod,the material experienced three stages,i.e.deformation by the tool,upward flow with additional tilt,followed by upward transportation.The microstructural evolution was revealed by“stop-action”technique.The microstructural development at regions adjacent to the rod is mainly controlled by twinning,dynamic recrystallization(DRX)as well as particle stimulated nucleation,while that within the rod is related to DRX combined with grain growth.
基金the financial supports from the Natural Science Foundation of Hunan Province, China (Nos. 2020JJ4114, 2016JJ3151)the National Natural Science Foundation of China (No. 51601229)+2 种基金the Young Elite Scientist Sponsorship Program by CAST, China (No. 2015QNRC001)the Hunan Province Innovation Platform and Talent Plan Project, China (No. 2015RS4001)the Open-end Fund for the Valuable and Precision Instruments of Central South University, China (No. CSUZC201815)。
基金financially supported by the Natural Science Foundation of Hunan Province,China(Nos.2020JJ4114,2016JJ3151)the National Natural Science Foundation of China(No.51601229)+2 种基金the Young Elite Scientist Sponsorship Program by CAST,China(No.2015QNRC001)the Hunan Province Innovation Platform and Talent Plan,China(No.2015RS4001)the Open-End Fund for the Valuable and Precision Instruments of Central South University,China(No.CSUZC201815)。
基金supported by a grant from the Center of Advanced Materials Processing(CAMP) of the 21st Centry Froniter R&D Program Funded by the Ministry of Knowledge Economy(MKE),Koreasupported by the Korea Science and Engineering Foundation (No.2009-0079807)
文摘The aim of this work is to investigate microstructure,corrosion resistance characteristics and nanohardness of the oxide layer on AZ91 Mg alloy by applying different voltage with KMnO4 contained solution.There are lots of closed pores that are filled with another oxide compound compared with the typical surface morphology with pore coated until 350 V of coating voltage.The thickness of oxide layer increases with increasing coating voltage.The oxide layer formed on AZ91 Mg alloy in electrolyte with potassium permanganate consists of MgO and Mn2O3.Corrosion potential of the oxide layer on AZ91 Mg alloy obtained at different plasma electrolytic oxidation(PEO) reaction stages increases with increasing coating voltage.The corrosion resistance of AZ91 Mg alloy depends on the existence of the manganese oxide in the oxide layer.The inner barrier layer composed of the MgO and Mn2O3 may serve as diffusion barrier to enhance the corrosion resistance and may partially explain the excellent anti-corrosion performance in corrosion test.Nanohardness values increase with increasing coating voltage.The increase in the nanohardness may be due to the effect of manganese oxide in the oxide layer on AZ91 Mg alloy coated from electrolyte containing KMnO4.
基金This work was financiallysupported bythe KISTProgram(No.2E19470)and by the Components&Materials Technology Development Program of Ministry of Commerce,Industry and Energy of Korea.
文摘Recently, a semi-solid metal processing has been acknowledged as a cost-effective technique to be able to manufacture high quality product for the transportation industry. In this study a hypo-eutectic Al alloy was fabricated by means of an electromagnetic stirrer in continuous casting process and the microstructural change during solidification due to a fluid flow by electromagnetic stirring was examined. Due to the forced fluid flow during solidification a dendritic phase of primary α phase of Al alloy was turned into a globular phase, which can make the Al alloy get a thixotropic behavior in the semi-solid region. In order to establish the quantitative relationship between microstructure and the process parameters, the morphology shape, a silicon distribution and a size of primary α phase were observed according to casting speed in continuous casting machine. The primary α phase was turned into the degenerate dendrites approaching a spherical configuration with increasing casting speed. The fine-grained and equiaxed microstructure appeared at higher casting speed. A segregation behavior of Si element was declined with increasing casting speed and a very uniform distribution of Si element was observed on the billet at a casting speed of 600 mm·min-1. A thickness of the solidifying shell of the billet was shortened with increasing the casting speed.
文摘This paper discusses the analysis and design of a very thin slotless permanent magnet （PM） brushless motor whose stator laminations are manufactured from a single strip of steel that is edge wound into a spiral （like a ＂Slinky＂） and then fitted over the windings that are preformed on the outside surface of a non-conducting former. Analytical and finite element analysis （FEA） are used to determine the con- strained optimum dimensions of a motor used to drive a rim driven thruster in which the motor rotor is fit- ted onto the rim of the propeller and the stator is encapsulated in the thin Kort nozzle of the thruster. The paper describes the fabrication of a demonstrator motor and presents experimental results to validate the theoretical calculations. Experimental motor performance results are also reported and compared with those of a slotted motor that fits within the same active radial dimensions as the slotless motor. The slotless motor, which has longer active length and endwindings, and thicker magnets than the slotted motor, was found to be less efficient and more expensive （prototype cost） than the slotted machine.
基金supported by NSF MRI (1428992)NASA EPSCoR (NNX15AM83A)+3 种基金U.S.–Egypt Science and Technology (S&T) Joint FundSDBoR R&D ProgramEDA University Center Program (ED18DEN3030025)supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC0206CH11357.
文摘Precise control over the charge carrier dynamics throughout the device can result in outstanding performance of perovskite solar cells(PSCs).Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)(PEDOT:PSS)is the most actively studied hole transport material in p-i-n structured PSCs.However,charge transport in the PEDOT:PSS is limited and inefficient because of its low conductivity with the presence of the weak ionic conductor PSS.In addition,morphology of the underlying PEDOT:PSS layer in PSCs plays a crucial role in determining the optoelectronic quality of the active perovskite absorber layer.This work is focused on realization of a non-wetting conductive surface of hole transport layer suitable for the growth of larger perovskite crystalline domains.This is accomplished by employing a facile solventengineered(ethylene glycol and methanol)approach resulting in removal of the predominant PSS in PEDOT:PSS.The consequence of acquiring larger perovskite crystalline domains was observed in the charge carrier dynamics studies,with the achievement of higher charge carrier lifetime,lower charge transport time and lower transfer impedance in the solvent-engineered PEDOT:PSS-based PSCs.Use of this solventengineered treatment for the fabrication of MAPbI3 PSCs greatly increased the device stability witnessing a power conversion efficiency of 18.18%,which corresponds to^37%improvement compared to the untreated PEDOT:PSS based devices.
基金the financial support received from the China Scholarship Council(CSC)MERAGEM graduate school and the Ministry of Science,Research and Arts of the State of Baden-Wu rttemberg for funding research+4 种基金the support of the German Research Foundation(DFG)project(SE 1407/4-2)the support of the En ABLES,a project funded by the European Union’s Horizon 2020 research and innovation program under grant agreement(730957)the support of Epi Store project under grant agreement(101017709)the Centre for Electrochemical Energy Storage Ulm-Karlsruhe(CELEST)the support from the Karlsruhe Nano Micro Facility(KNMF)。
文摘With the recent development of high entropy materials, an alternative approach to develop advanced functional materials with distinctive properties that show improved values compared to conventional materials has been provided. The high entropy concept was later successfully transferred to metal fluorides and high entropy fluorides(HEFs) were successfully synthesized. Owing to their high theoretical specific capacities in energy storage applications, HEFs were utilized as cathode materials for lithiumion batteries(LIBs) and their underlying storage mechanisms were investigated. Instead of a step-bystep reduction of each individual metal cation, the HEFs seem to exhibit a single-step reduction process,indicating a solid solution compound instead of merely a mixture of different metal fluorides. It was also observed that the electrochemical behavior of the HEFs depends on each individual incorporated element. Therefore, by altering the elemental composition, new materials that exhibit improved electrochemical properties can be designed. Remarkably, HEFs with seven incorporated metal elements exhibited a better cycling stability as well as a lower hysteresis compared to binary metal fluorides.These findings offer new guidelines for material design and tailoring towards high performance LIBs.
基金funded by the German Federal Ministry of Education and Research(BMBF),project NextGen-3DBat,Grant Number 03XP0198Fby the Fraunhofer Cluster of Excellence Advanced Photon Sources(CAPS)。
文摘Direct Laser Interference Patterning(DLIP)is used to texture current collector foils in a roll-to-roll process using a high-power picosecond pulsed laser system operating at either fundamental wavelength of 1064 nm or 2nd harmonic of 532 nm.The raw beam having a diameter of 3 mm@1/e^(2) is shaped into an elongated top-hat intensity profile using a diffractive so-called FBS■-L element and cylindrical telescopes.The shaped beam is split into its diffraction orders,where the two first orders are parallelized and guided into a galvanometer scanner.The deflected beams inside the scan head are recombined with an F-theta objective on the working position generating the interference pattern.The DLIP spot has a line-like interference pattern with about 15μm spatial period.Laser fluences of up to 8 J cm^(-2) were achieved using a maximum pulse energy of 0.6 mJ.Furthermore,an in-house built roll-to-roll machine was developed.Using this setup,aluminum and copper foil of 20μm and 9μm thickness,respectively,could be processed.Subsequently to current collector structuring coating of composite electrode material took place.In case of lithium nickel manganese cobalt oxide(NMC 622)cathode deposited onto textured aluminum current collector,an increased specific discharge capacity could be achieved at a C-rate of 1℃.For the silicon/graphite anode material deposited onto textured copper current collector,an improved rate capability at all C-rates between C/10 and 5℃ was achieved.The rate capability was increased up to 100%compared to reference material.At C-rates between C/2 and 2℃,the specific discharge capacity was increased to 200 mAh g^(-1),while the reference electrodes with untextured current collector foils provided a specific discharge capacity of 100 m Ah g^(-1),showing the potential of the DLIP technology for cost-effective production of battery cells with increased cycle lifetime.
文摘Polyoxometalates have been explored as multi-electron active species in both aqueous and non-aqueous redox flow batteries. Although non-aqueous systems in principle offer a wider voltage window for redox flow battery operation, realization of this potential requires a judicious choice of solvent as well as polyoxometalate properties. We demonstrate here the superior performance of N,N-dimethylformamide(DMF)compared to acetonitrile as a solvent for redox flow batteries based on Li3PMo12O40. This compound displays two 1-electron transfers in acetonitrile but can access an extra quasi-reversible 2-electron redox process in DMF. A cell containing 10 mM solution of Li3PMo12O40 in DMF produced a cell voltage of 0.7 V with 2-electron transfers(State of Charge = 60%) and showed a good cyclability. As a means to boost energy density, operation of the redox flow battery at a higher concentration of 0.1 M Li3PMo12O40 produced cells with cell voltage of 0.6 V in acetonitrile and a cell voltage of 1.0 V in DMF;both showed excellent coulombic efficiencies of more than 90% over the course of 30 cycles. Energy density was also increased by employing an asymmetric cell with different polyoxometalates on each side to extend cell voltage.Li6P2W18O62 exhibited 3 quasi-reversible 2-electron transfers in the potential range between-2.05 V and-0.5 V vs. Ag/Ag+. 10 mM Li6P2W18O62/Li3PMo12O40 in DMF produced a cell with cell voltage of 1.3 V involving 4-electron transfers(State of Charge = 50%) with coulombic efficiency of nearly 100% and energy efficiency of nearly 70% throughout the test with more than 20 cycles. These promising results demonstrate proof-of-concept approaches to improving the performance of polyoxometalates in non-aqueous redox flow batteries.
基金sponsored by the Helmholtz Association,the China Scholarship Council(CSC)partially funded by the German Research Foundation,DFG(Project No.MA 5039/4-1)。
文摘Tin(Sn)holds great promise as an anode material for next-generation lithium(Li)ion batteries but suffers from massive volume change and poor cycling performance.To clarify the dynamic chemical and microstructural evolution of Sn anode during lithiation and delithiation,synchrotron X-ray energydispersive diffraction and X-ray tomography are simultaneously employed during Li/Sn cell operation.The intermediate Li-Sn alloy phases during de/lithiation are identified,and their dynamic phase transformation is unraveled which is further correlated with the volume variation of the Sn at particle-and electrode-level.Moreover,we find that the Sn particle expansion/shrinkage induced particle displacement is anisotropic:the displacement perpendicular to the electrode surface(z-axis)is more pronounced compared to the directions(x-and y-axis)along the electrode surface.This anisotropic particle displacement leads to an anisotropic volume variation at the electrode level and eventually generates a net electrode expansion towards the separator after cycling,which could be one of the root causes of mechanical detachment and delamination of electrodes during long-term operation.The unraveled chemical evolution of Li-Sn and deep insights into the microstructural evolution of Sn anode provided here could guide future design and engineering of Sn and other alloy anodes for high energy density Li-and Na-ion batteries.
