Rechargeable alkaline zinc-air batteries promise high energy density and safety but suffer from the sluggish 4 electron (e)/oxygen (O) chemistry that requires participation of water and from the electrochemical irreversibility originating from parasitic reactions caused by caustic electrolytes and atmospheric carbon dioxide. Here, we report a zinc-O/zinc peroxide (ZnO) chemistry that proceeds through a 2e/O process in nonalkaline aqueous electrolytes, which enables highly reversible redox reactions in zinc-air batteries. This ZnO chemistry was made possible by a water-poor and zinc ion (Zn)-rich inner Helmholtz layer on the air cathode caused by the hydrophobic trifluoromethanesulfonate anions. The nonalkaline zinc-air battery thus constructed not only tolerates stable operations in ambient air but also exhibits substantially better reversibility than its alkaline counterpart.Copyright © 2021, American Association for the Advancement of Science.

设计和制备Mg-8Zn-4Al-0.5Cu-0.5Mn-xLi (x = 0，3，5，7)(%，质量分数)系列高比模量的镁合金，研究了它的组织和性能。Li含量为3.14%和5.37%的两种镁合金，其基体为单相α-Mg，在晶界析出骨骼状Mg₃₂(Al, Zn)₄₉相，在晶粒内有颗粒状Mg₅Al₂Zn₂相和Al₂Mn相；Li含量为7.57%的合金，其基体主要为双相组织α-Mg + β-Li。添加Li元素后在晶界附近生成的共晶组织由α-Mg相和层片状AlLi相组成，并随着Li含量的提高层片状AlLi相的含量随之提高。随着Li含量的提高，合金的屈服强度呈逐渐提高的趋势，而抗拉强度基本上不变，合金的弹性模量呈现先提高后降低的趋势。铸态合金ZA84-5Li的弹性模量可达51.89 GPa，比纯Mg的弹性模量高7 GPa，但是其力学性能基本不变，屈服强度为141 MPa，抗拉强度为189 MPa，密度为1.71 g/cm³。

The microstructure and mechanical properties of extruded Mg-alloy of Mg-1Al-0.4Ca-0.5Mn-0.2Zn (mass fraction, %) were systematically investigated. As indicated by the results, the incomplete dynamic recrystallization occurred for the alloys extruded at 260℃ (denoted as AXMZ1000-260) and 290°C (AXMZ1000-290) with recrystallized grain sizes of 0.75 μm and 1.2 μm, respectively. The two alloys have high-density G.P. regions and spherical nano-phases, which can effectively inhibit the dislocation motion and provide abundant nucleation sites for dynamic recrystallization. Moreover, the nano-phases precipitated along grain boundaries can restrain the migration of grain boundary and restrict the growth of DRXed grains, which results in the ultrafine grains with a size of 0.75 μm in AXMZ1000-260 alloy. The strength of the alloy decreases with the increase of extrusion temperature, and the change of elongation is not obvious. The yield strength and elongation of alloys extruded at 260℃ and 290℃ are approximately 322 MPa and 343 MPa, as well as 13.4% and 13%, respectively. The dynamic precipitation and recovery process are promoted by the increasing extrusion temperature, and a high-density G.P. zones and spherical nano-phases are accumulated in the alloy. At the same time, many dislocations are transformed into LAGBs by dynamic recovery, and the unDRXed areas are subdivided into dense lamellar subgrains. The nano-phases and LAGBs can effectively hinder the newly generated dislocation motion, which is the major reason that the alloy extruded at 290℃ still have a high yield strength and the change of ductility is not obvious. Furthermore, TEM observations show that the pinning effect of G.P. zones can impede the dynamic recovery to certain extent, resulting in a high number of residual dislocations in the alloy, which is conducive to the improvement of the yield strength.

China has the most abundant magnesium resources in the world. Magnesium and its alloys have the advantages of low density, high specific strength, good damping property, and exceptional electromagnetic-shielding and energy-storage characteristics. They are one of the most promising lightweight materials. The enhanced applications of magnesium alloys can save energy and reduce emissions and are significant to the new Chinese energy strategy. However, magnesium alloys have a hexagonal close-packed structure and exhibit relatively low ductility. A bottleneck in expanding the application of magnesium alloys is improving the ductility of magnesium alloys. For more than ten years, efforts have been made to improve the ductility and plastic deformation ability. Progress has been made in plastic-processing technologies of magnesium alloys. The novel alloy design theory “solid solution strengthening and ductilizing” and advanced preparation technologies such as “melt self-purification through varying temperature” have been established. Series of new magnesium alloys with good ductility and corresponding alloy grades have been developed, where the impurity content of iron can be reduced to below 10 × 10-6; the elongation was more than 60% for ultrahigh plasticity magnesium alloys and is above 10% for the ultrahigh-strength magnesium alloys (UTS > 550 MPa). New plastic-processing technologies, such as asymmetric extrusion, asymmetric rolling, asymmetric modification, cyclical multipass upsetting and squeezing, expansion control large ratio forging, and extrusion and forging composite forming, have been developed. These newly developed magnesium alloys and processing technologies weaken the basal texture in wrought magnesium alloys, improving the formability of sheets, tubes, profiles, and forgings and their product quality and reducing their product cost. These technologies have been successfully applied in the processing of magnesium sheets, pipe profiles, and forgings.

我国是世界上镁资源最为丰富的国家，镁及镁合金具有质轻、比强度高、阻尼减振、电磁屏蔽性能优良、储能特性好等优点，是最有潜力的轻量化材料之一，其推广应用对节能减排和能源转型战略具有重要意义。但镁合金具有密排六方晶体结构，塑性变形能力较差。如何改善镁合金的塑性变形能力是扩大镁合金应用的瓶颈问题之一。本文综述了10多年来，世界各国在改善镁合金塑性、提升镁合金塑性变形能力等方面所做的大量工作，及在镁合金塑性加工技术等方面取得的重要进展。发展了“固溶强化增塑”新型镁合金设计理论和“熔体变温自纯化”等关键制备技术，形成了一批高塑性变形镁合金材料和牌号，其中杂质Fe含量可降到10 × 10^-6以下，超高塑性镁合金延伸率可达到60%以上，超高强度(抗拉强度大于550 MPa)镁合金延伸率可以达到10%以上；开发了非对称挤压、非对称轧制、非对称改性、往复循环多道次镦挤开坯技术、扩收控制大比率锻造技术、挤锻复合成形技术等一批镁合金新型塑性加工技术。这些合金和技术使变形镁合金基面织构显著弱化，明显提高了变形镁合金板材、管型材和锻件的塑性成形能力和制品质量，产品成本大幅度降低，在板材、管型材和锻件制备加工中实现了成功应用。

Li-air(O2) and Li-S batteries have gained much attention recently and most relevant research has aimed to improve the electrochemical performance of air(O2) or sulfur cathode materials. However, many technical problems associated with the Li metal anode have yet to be overcome. This review mainly focuses on the electrochemical behaviors and technical issues related to metallic Li anode materials as well as other metallic anode materials such as alkali (Na) and alkaline earth (Mg) metals, including Zn and Al when these metal anodes were employed for various types of secondary batteries.

AZ61 and AZ61-0.5La (wt.%) alloys are prepared by the conventional casting method and then, AZ61 and AZ61-0.5La alloy sheets are obtained with multi-pass hot rolling. Microstructures and electrochemical properties of four alloys are investigated, and discharge properties are tested by an assembled Mg-air battery using alloy anode sheets with a dimension of 70x100x2.5mm. Results show that Al11La3 phases are formed in as-cast AZ61-0.5La alloy and promote the grain refinement and the formation of uniform microstructure in as-rolled AZ61-0.5La alloy. As-rolled AZ61-0.5La alloy exhibits a weak self-corrosion tendency but a strong discharge activity. After discharge test for 5h, the Mg-air battery based on the as-rolled AZ61-0.5La sheet can provide the maximum power output of 1.625W, and as-rolled AZ61-0.5La anode can supply the maximum energy density of 1417mWhg(-1). In addition, the relationship between microstructures and discharge properties is sufficiently described and discussed in this paper.

In the present study, to understand the mechanism of Mn on inhibiting Fe-caused Mg corrosion, the corrosion behaviour of commercial pure Mg and Mg-6Mn alloy in 0.6 M NaCl solution is investigated. It is found that in Mg-6Mn alloy, Fe impurity is incorporated into Mn to form Mn (Fe) phase with Fe as solid solute. The initial galvanic corrosion cannot be reduced through converting Fe-rich phase to Mn (Fe) phase, since Mn (Fe) phase also has relatively strong cathodic activity and has much larger volume fraction than Fe-rich phase. However, the cathodic activation behaviour of pure Mg is inhibited. The cathodic activity even decreases for Mg-Mn alloy with increased exposure time, due to the reduced cathodic HER at the Mn (Fe) particles. Mn can be oxidized at the OCP of Mg-6Mn alloy, resulting in relatively dense Mn-rich corrosion film on particle surface, which separates the particle from the electrolyte and, consequently, inhibits HER. (C) 2020 Chongqing University. Publishing services provided by Elsevier B.V. on behalf of KeAi Communications Co. Ltd.

Al-Mg-Ga-In-Sn alloys with different Mg-contents were prepared and then subjected to solution and aging treatment. The microstructure and corrosion morphology after immersion in water of alloys was characterized by means of XRD and SEM with EDX. The Volta potential differences (ΔVPD) of interfacial phases with respect to Al matrix were measured using AFM/SKPFM. The Al-water reactivity of alloys in waters at different temperature were measured by using drainage method. The heat treatment influences the phase type, morphology of interfacial phases, and the content of Mg and Ga inside Al grains. As the Mg content is below 4% the heat-treated alloys contain interfacial phases of Mg2Sn, MgGa, MgGa2 andMgIn. Mg5Ga2 and Mg2Ga phases occurs as the Mg content of alloy is c.a. 5%. MgGa phase precipitates within Al grains of the aged alloys. The heat-treated alloys exhibit higher the Volta potential differences (ΔVPD) of interfacial phases with respect to Al in comparison with the cast ones. The generation rate and yield amount of hydrogen correlate with Mg contents of the heat-treated alloys. The reasons that the heat treatment affects the microstructures of alloys and the Volta potential differences (ΔVPD) of interfacial phases with respect to Al were analyzed, and the effect of heat treatment on the Al-water reactivity of alloys was also discussed.

制备不同镁含量的Al-Mg-Ga-In-Sn合金并对其进行固溶和时效热处理，用XRD和SEM分析和观察了显微结构和腐蚀表面，用AFM/SKPFM测量了合金不同晶界相与铝晶粒间的电势差，用排水法测量了在不同水温下合金的铝水反应。结果表明，热处理改变了合金低熔点界面相的种类、形态以及合金晶粒内Mg和Ga含量。热处理态Mg含量低于4%的合金，其中有Mg₂Sn、MgGa、MgGa₂、MgIn界面相；在Mg含量为5%的热处理态合金中出现了Mg₅Ga₂、Mg₂Ga相。在时效态合金晶粒内有MgGa相析出。与相同成分的铸态合金相比，时效态合金中各晶界相与铝基体间的电位差较大。热处理态合金的产氢速率和产氢率，与合金的Mg含量有关。分析了热处理使合金显微结构和晶界相与铝基体间电位差变化的原因，并讨论了热处理对合金铝水反应的影响。

A ternary alloy with composition of Mg-13Gd-1Zn (%, mass fraction) was prepared by conventional smelting and casting technique. The microstructure and mechanical properties of the as-cast, as-annealed, as-extruded and as-aged (T5) alloy were investigated. The results show that the microstructure of the as-cast alloy consists of α-Mg matrix, (Mg, Zn)3Gd eutectic and a 14H long period staking ordered (14H-LPSO) phase. The significant increase of 14H-LPSO phase after annealing and ageing (T5) treatment in the alloy microstructure indicates that the precipitation of the 14H-LPSO phase occurs in a wide temperature range (200~510oC). The β' and β1 precipitates have also been observed in the alloy after ageing (T5) treatment. Under the combined action of precipitation strengthening and LPSO strengthening, the tensile strength, yield strength and elongation of the alloy are 397 MPa, 197 MPa and 2.56%, respectively. The creep properties of the Mg-13Gd-1Zn alloy are higher than those of the WE54 alloy in the two experimental conditions of 200oC/80 MPa and 200oC/120 MPa.