Bilayer separator enabling dendrite-free zinc anode with ultralong lifespan >5000 h

Aqueous zinc(Zn)batteries with Zn metal anodes are promising clean energy storage devices with intrinsic safety and low cost.However,Zn dendrite growth severely restricts the use of Zn anodes.To effectively suppress Zn dendrite growth,we propose a bilayer separator consisting of commercial butter paper and glassfiber membrane.The dense cellulose-based butter paper(BP)with low zincophilicity and high mechanical properties prevents the pore-filling behavior of deposited Zn and related separator piercing,effectively suppressing the Zn dendrite growth.As a result,the bilayer separators endow the ZnjjZn symmetrical batteries with a superlong cycling life of Zn anodes(over 5000 h)at 0.5 mA cm^(-2) and the full batteries enhanced capacity retention,demonstrating the advancement of the bilayer separator to afford excellent cyclability of aqueous metal batteries.

二次电池研究进展

能源的存储和利用是当今科学和技术发展中的重大课题之一,尤其是作为高效的电能/化学能转化装置的二次电池相关技术一直是科学家研究的热点领域。在此背景下,本文较为系统地介绍目前二次电池的重要研究进展,将从二次电池的发展历史引入,再到其相关的基础理论知识的介绍。随后较为详细地讨论当前不同体系的二次电池及相关应的关键材料的研究进展,涉及到锂离子电池、钠离子电池、钾离子电池、镁离子电池、锌离子电池、钙离子电池、铝离子电池、氟离子电池、氯离子电池、双离子电池、锂-硫(硒)电池、钠-硫(硒)电池、钾-硫(硒)电池、多价金属-硫基电池、锂-氧电池、钠-氧电池、钾-氧电池、多价金属-氧气电池、锂-溴(碘)电池、水系金属离子电池、光辅助电池、柔性电池、有机电池、金属-二氧化碳电池等。此外,也介绍了电池研究中常见的电极反应过程表征技术,包括冷冻电镜、透射电镜、同步辐射、原位谱学表征、磁性表征等。本文将有助于研究人员对二次电池进行全面系统的了解与把握,并为之后二次电池的研究提供很好的指导作用。

Effect of internal defects on tensile strength in SLM additively-manufactured aluminum alloys by simulation

This research investigates the effect of internal defects on the tensile strength of Selective Laser Melting(SLM)additively-manufactured aluminum alloy(AlSi10Mg)test parts used for civil aircraft light weight design.A Finite Element Analysis(FEA)model containing internal defects was established by combining test data and the stress concentration factor comparison method.The effect of variation in the number,location and shape of defects on the finite element results was analyzed.Its results show that it is reasonable to use spherical defect modeling.The finite element modeling and analysis methods are also applied to the study of the effect of internal defects on tensile strength in additive manufacturing of other metallic materials.According to the FEA results of single defects at different scales,the formula for calculating the weakening degree of tensile strength applicable to the defective area of less than 15%was established.The result of the procedure is reliable and conservative.This research results can guide the selection of process parameters for the additive manufacturing of aluminum alloys.Further,the research results can promote the application of metal additive manufacturing in designing light-weight civil aircraft structures.

Interfacial high-concentration electrolyte for stable lithium metal anode:Theory,design,and demonstration

Lithium metal anodes hold great potential for high-energy-density secondary batteries.However,the uncontrollable lithium dendrite growth causes poor cycling efficiency and severe safety concerns,hindering lithium metal anode from practical application.Electrolyte components play important roles in suppressing lithium dendrite growth and improving the electrochemical performance of long-life lithium metal anode,and it is still challenging to effectively compromise the advantages of the conventional electrolyte(1 mol·L^(−1)salts)and high-concentration electrolyte(>3 mol·L^(−1)salts)for the optimizing electrochemical performance.Herein,we propose and design an interfacial high-concentration electrolyte induced by the nitrogen-and oxygen-doped carbon nanosheets(NO-CNS)for stable Li metal anodes.The NO-CNS with abundant surface negative charges not only creates an interfacial high-concentration of lithium ions near the electrode surface to promote chargetransfer kinetics but also enables a high ionic conductivity in the bulk electrolyte to improve ionic mass-transfer.Benefitting from the interfacial high-concentration electrolyte,the NO-CNS@Ni foam host presents outstanding electrochemical cycling performances over 600 cycles at 1 mA·cm^(−2) and an improved cycling lifespan of 1,500 h for symmetric cells.

A carbon-based 3D current collector with surface protection for Li metal anode

Lithium metal is considered the ideal anode material for Li-ion-based batteries because it exhibits the highest specific capacity and lowest redox potential for this type of cells. However, growth of Li dendrites, unstable solid electrolyte interphases, low Coulombic efficiencies, and safety hazards have significantly hindered the practical application of metallic Li anodes. Herein, we propose a three-dimensional （3D） carbon nanotube sponge （CNTS） as a Li deposition host. The high specific surface area of the CNTS enables homogenous charge distribution for Li nucleation and minimizes the effective current density to overcome dendrite growth. An additional conformal A1203 layer on the CNTS coated by atomic layer deposition （ALD） robustly protects the Li metal electrode/electrolyte interface due to the good chemical stability and high mechanical strength of the layer. The Li@ALD-CNTS electrode exhibits stable voltage profiles with a small overpotential ranging from 16 to 30 mV over 100 h of cycling at 1.0 mA·cm^-2. Moreover, the electrodes display a dendrite-free morphology after cycling and a Coulombic efficiency of 92.4% over 80 cycles at 1.0 mA·cm^-2 in an organic carbonate electrolyte, thus demonstrating electrochemical stability superior to that of planar current collectors. Our results provide an important strategy for the rational design of current collectors to obtain stable Li metal anodes.

Development of Neutralizing Antibodies against Zika Virus Based on Its Envelope Protein Structure

As we know more about Zika virus(ZIKV), as well as its linkage to birth defects(microcephaly) and autoimmune neurological syndromes, we realize the importance of developing an efficient vaccine against it. Zika virus disease has affected many countries and is becoming a major public health concern. To deal with the infection of ZIKV, plenty of experiments have been done on selection of neutralizing antibodies that can target the envelope(E) protein on the surface of the virion. However, the existence of antibody-dependent enhancement(ADE) effect might limit the use of them as therapeutic candidates. In this review, we classify the neutralizing antibodies against ZIKV based on the epitopes and summarize the resolved structural information on antibody/antigen complex from X-ray crystallography and cryo-electron microscopy(cryo-EM), which might be useful for further development of potent neutralizing antibodies and vaccines toward clinical use.

Garnet/polymer hybrid ion-conducting protective layer for stable lithium metal anode

Rechargeable Li metal batteries using Li metal anodes have attracted worldwide interest because of their high energy density. The critical barriers limiting their commercial application include uncontrolled dendritic Li growth and the unstable Li-electrolyte interface. Considerable efforts have been directed towards solving these problems, e.g., modifying the electrolyte, creating artificial interfacial layers for the Li metal, and constructing three-dimensional structures for the Li metal. However, stabilizing the Li metal interface remains challenging because of the highly reactive nature of the Li metal. In this study, we utilize a Li-ion conducting hybrid film comprising a garnet-type ion conductor and a poly（ethylene oxide）-based polymer electrolyte as a protective layer to stabilize the Li-electrolyte interface and mitigate the growth of Li dendrites. The hybrid ion-conducting layer can block Li dendrites from proliferating and accommodate Li volume expansion because of its robust mechanical properties. Moreover, the ion-conducting layer allows Li deposition only underneath it, rather than on the surface, functioning as a permanent protective layer to ensure the stability of the Li metal over a long cycling life. The dendrite-inhibiting effect of the ion-conducting protective layer is visually evidenced by in situ microscopy using planar batteries. The protective Li metal anode exhibits excellent cycling stability and low voltage hysteresis （-15 mV at 0.2 mA-cm-2） for a cycle life as long as 1,000 h. It also shows a high Coulombic efficiency （-99.5%） in a full cell against a LiFePO4 cathode, exhibiting promise for application in Li metal batteries. Our results imply that the ion-conducting protective layer markedly improves the metal anode, yielding safe, long-life, and high-energy-density batteries.

Uncovering the critical impact of the solid electrolyte interphase structure on the interfacial stability

Solid electrolyte interphase(SEI)plays a critical role in determining the interfacial stability,which in turn impacts the plating/stripping process of the lithium metal anode.Substantial research has been focused on the composition of SEI and its contribution to the interfacial stability.Herein,we illustrate the significance of SEI structure,in a comprehensive comparison of a diluted electrolyte(1 M LiTFSI-PC)and a super-concentrated electrolyte(8 M LiTFSI-PC).Illustrated by in situ optical and atomic force microscope observation,homogeneous plating on lithium anode is achieved in the concentrated electrolyte.However,x-ray photoelectron spectroscopy and molecular dynamics simulations reveal that,contrary to the general understanding,the components of SEI is nearly identical for lithium anode cycled in both two electrolytes.Detailed characterizations demonstrate the structure of SEI is quite different.In concentrated electrolyte,a compact structure of SEI layer can be obtained,mainly due to the reduced solubility and outstanding formation kinetics of the interfacial layer.This work provided a new understanding to the excellent performance of super-concentrated electrolyte in lithium metal battery.

Strong and Superhydrophobic Wood with Aligned Cellulose Nanofibers as a Waterproof Structural Material

Lightweight structural materials are important for the energy efficiency of applications,particularly those in the building sector.Here,inspired by nature,we developed a strong,superhydrophobic,yet lightweight material by simple in situ growth of nano-SiO2 and subsequent densification of the wood substrate.In situ generation of SiO2 nanoparticles both inside the wood channels and on the wood surfaces gives the material superhydrophobicity,with static and dynamic contact angles of 159.4°and 3°,respectively.Densification of the wood to remove most of the spaces among the lumen and cell walls results in a laminated,dense structure,with aligned cellulose nanofibers,which in turn contributes to a high mechanical strength up to 384.2 MPa(7-times higher than natural wood).Such treatment enables the strong and superhydrophobic wood(SH-Wood)to be stable and have excellent water,acid,and alkaline resistance.The high mechanical strength of SH-Wood combined with its excellent structural stability in harsh environments,as well its low density,positions the strong and superhydrophobic wood as a promising candidate for strong,lightweight,and durable structural materials that could potentially replace steel.