Armoring lithium metal anode with soft–rigid gradient interphase toward high-capacity and long-life all-solid-state battery

Solid polymer electrolytes(SPEs)are highly promising for realizing high-capacity,low-cost,and safe Li metal batteries.However,the Li dendritic growth and side reactions between Li and SPEs also plague these systems.Herein,a fluorinated lithium salt coating(FC)with organic-inorganic gradient and soft–rigid feature is introduced on Li surface as an artificial protective layer by the in-situ reaction between Li metal and fluorinated carboxylic acid.The FC layer can improve the interface stability and wettability between Li and SPEs,assist the transport of Li ions,and guide Li nucleation,contributing to a dendrite-free Li deposition and long-lifespan Li metal batteries.The symmetric cell with FC-Li anodes exhibits a high areal capacity of 1 mAh cm^(-2)at 0.5 mA cm^(-2),and an ultra-long lifespan of 2000 h at a current density of 0.1 mA cm^(-2).Moreover,the full cell paired with the LiFePO4 cathode exhibits improved cycling stability,remaining 83.7%capacity after 500 cycles at 1 C.When matching with the S cathode,the FC layer can prevent the shuttle effect,contributing to stable and high-capacity Li–S battery.This work provided a promising way for the construction of stable all-solid-state lithium metal batteries with prolonged lifespan.

Lithiophilic seeds and rigid arrays synergistic induced dendrite-free and stable Li anode towards long-life lithium-oxygen batteries

High energy density lithium-oxygen battery(LOB) is currently regraded as a promising candidate for next-generation power system.However,the dendrite and instability issues of Li metal anode lead to its poor cyclic stability and low energy density.In this work,lithiophilic Al_(2) O_(3) seeds induced rigid carbon nanotube arrays(CNTA)/three-dimensional graphene(3 DG) is developed as a host material for Li anode,namely Al_(2) O_(3)-CNTA/3 DG.It is demonstrated that the lithiophilic feature of Al_(2) O_(3) seeds and the enhanced rigidity of arrays can synergistically induce the uniform Li flux,inhibit the collapse of arrays,and stabilize electrolyte/electrode interfaces.As a result,the Al_(2) O_(3)-CNTA/3 DG-Li anode delivers a high Coulombic efficiency above 97% after 140 cycles(8 mAh cm^(-2) at 4 mA cm^(-2)).With this anode and the breathable CNTA/3 DG cathode,the full LOB exhibits a significantly increased life-span up to 160 cycles(500 mAh g^(-1) at 100 mA g^(-1)),which is almost 3 times longer than that with pure Li foil as the anodes.This work demonstrates a new approach to highly reversibly long-cycling performance of LOBs towards practical application.

Simultaneously optimizing pore morphology and enhancing mechanical properties of Al-Si alloy composite foams by graphene nanosheets

The integrity and regularity of pore morphology play an important role in determining the mechanical properties of the metallic foam materials.The conventional methods on refining pore morphology are mainly focused on the optimization of fabrication techniques,however,they are usually inconvenient and complicated.Recently,incorporating nano reinforcement is considered to be a suitable way to fabricate metallic composite foams accompanied by optimized pore morphology and enhanced mechanical properties.In this work,through a facile and rapid powder metallurgy foaming method,the aluminum-silicon(Al-Si)alloy composite foams reinforced by graphene nanosheets(GNSs)are successfully fabricated.The microstructure analyses reveal that,for the Al-Si alloy foams incorporating the GNSs(GNSs/Al-Si composite foams),the pore size is transformed to be smaller,the pore size distributions become more homogeneous and the pore shape is also refined to a regular and roundish state.Meanwhile,the shape of Si precipitates is found transforming from an irregular long strip(length of~20μm,width of~5μm)to a fine particle state(diameter of~5μm).Moreover,the compressive testing results show that,the 0.4wt%GNSs/Al-Si composite foams own the optimal compression stress of 11.7±0.5 MPa,plateau stress of 10.0±1.0 MPa and energy absorption capacity of 6.8±0.7 MJ/m^(3),which have improvement of 58.1%,53.8%and 51.1%in comparison with the Al-Si alloy foams counterpart,respectively.The present findings may pave a new way for developing new generation of metallic composite foams that with stable microstructure and excellent mechanical performance.

Cu nanoparticle-decorated two-dimensional carbon nanosheets with superior photothermal conversion efficiency of 65 % for highly efficient disinfection under near-infrared light

Low photothermal conversion efficiency restricts the antibacterial application of photothermal materials.In this work,two-dimensional carbon nanosheets(2D C)were prepared and decorated with Cu nanoparticles(2D C/Cu)by using a simple soluble salt template method combined with ultrasonic exfoliation.The photothermal conversion efficiency of 2 D C/Cu system can be optimized by changing the content of Cu nanoparticles,where the 2D C/Cu2 showed the best photothermal conversion efficiency(á)of 65.05%under 808 nm near-infrared light irradiation.In addition,the photothermal performance can affect the release behavior of Cu ions.This superior photothermal property combined with released Cu ions can endow this 2D hybrid material with highly efficient antibacterial efficacy of 99.97%±0.01%,99.96%±0.01%,99.97%±0.01%against Escherichia coli,Staphylococcus aureus,and methicillin-resistant Staphylococcus aureus,respectively,because of the synergetic effect of photothermy and ion release.In addition,this 2D hybrid system exhibited good cytocompatibility.Hence,this study provides a novel strategy to enhance the photothermal performance of 2D materials and thus will be beneficial for development of antibiotics-free antibacterial materials with safe and highly efficient bactericidal activity.

Si-Assisted Solidification Path and Microstructure Control of 7075 Aluminum Alloy with Improved Mechanical Properties by Selective Laser Melting

The construction and application of traditional high-strength 7075 aluminum alloy(Al7075) through selective laser melting(SLM) are currently restricted by the serious hot cracking phenomenon. To address this critical issue, in this study, Si is employed to assist the SLM printing of high-strength Al7075. The laser energy density during SLM is optimized, and the eff ects of Si element on solidification path, relative density, microstructure and mechanical properties of Al7075 alloy are studied systematically. With the modified solidification path, laser energy density, and the dense microstructure with refined grain size and semi-continuous precipitates network at grain boundaries, which consists of fine Si, β-MgSi, Q-phase and θ-AlCu, the hot cracking phenomenon and mechanical properties are eff ectively improved. As a result, the tensile strength of the SLM-processed Si-modified Al7075 can reach 486 ± 3 MPa, with a high relative density of ~ 99.4%, a yield strength of 291 ± 8 MPa, fracture elongation of(6.4 ± 0.4)% and hardness of 162 ± 2(HV) at the laser energy density of 112.5 J/mm~3. The main strengthening mechanism with Si modification is demonstrated to be the synergetic enhancement of grain refinement, solution strengthening, load transfer, and dislocation strengthening. This work will inspire more new design of high-strength alloys through SLM.

Toughening Effects through Optimizing Cell Structure and Deformation Behaviors of Al–Mg Foams

As widely used protective materials,the application of Al foams is still limited by their low intrinsic mechanical properties caused by the brittleness of struts.The introduction of Mg is recently demonstrated effective to improve the mechanical performance of Al foams;however,the mechanism of Mg modification is still not clear.In this work,Al-Mg foams are developed through a powder metallurgy process with excellent compression performance and high energy absorption capacity.The effects of Mg modification on the cell structure,toughness,and deformation behavior are investigated systematically.As a result,the small cell size of~1.8 mm and the high sphericity of 0.92 are achieved with 5% of Mg addition,delivering high compression stress of 8.5±0.43 MPa and energy absorption capacity of 6.9±0.36 MJ/m^(3),simultaneously.The synergistic mechanism for the improved mechanical performance is also demonstrated to be the combination of stress transfer and plastic deformation behavior of cells.The results provide a new strategy to develop high-performance foam materials by improving toughness and further promote the practical application.

Manipulating mechanical properties of graphene/Al composites by an in-situ synthesized hybrid reinforcement strategy

The structural deterioration caused by the relatively weak out-of-plane bending stiffness and the chemically-active edge area of graphene limits its outperformance in strengthening for Al matrix composites(AMCs).Introducing one-dimensional(1D)carbon nanotubes(CNTs)to graphene/metal system is one of the promised strategies to complement the weakness of 2D graphene and make full use of the outstanding intrinsic properties of the both reinforcements.To date,such synergistic strengthening and toughening mechanisms are largely unknown.In this study,AMCs reinforced by a novel hybrid reinforcement,i.e.,graphene nanosheets decorated with Cu nanoparticles and CNTs(Cu@GNS-CNTs),are fabricated by an in-situ synthesis method.The combined contrast experiments validated that the organically integrated reinforcing structure promotes the intrinsic load bearing capacity of GNS and the strain hardening capability of the Al matrix simultaneously.As a result,the composites achieved excellent tensile strength and uniform elongation with almost no loss.The strengthening mechanism originated primarily from the hybrid reinforcement exhibits superior load-transfer,fracture inhibition and dislocation storage capability by controlling the interface reaction to construct an effective interface structure without damaging the reinforcement.Our work identifies a promising structural modification strategy for 2D materials and provides mechanistic insights into the synergistic strengthening effect of graphene/CNTs hybrid reinforcement.