Hybrid Mg/Li-ions batteries ( MLIBs ), combining the fast kinetics of Li and the advantages of magnesium ion batteries (MIBs), are considered as one of the most promising electrochemical energy storage devices. However, the electrochemical performances of batteries are generally restricted with the diffusion kinetics of highly-polarized divalent Mg ions in the cathode materials. Herein, rutile-type molybdenum dioxide (R-MoO 2 ) was prepared by the hydrothermal method and subsequent heat treatment and used as the cathode materials in MIBs and MLIBs. The initial discharge capacities of R-MoO 2 cathode in MIBs and MLIBs are 49.5 and 253.2 mAh·g -1 at the current density of 50 mA·g -1 , respectively. The specific capacities are 17.0 and 111.2 mAh·g -1 after 100 cycles. The R-MoO 2 cathode possesses good Coulombic efficiency and rate capability in MLIBs. Compared with MIBs, the electrochemical performances of MLIBs were greatly enhanced. The energy storage mechanisms were investigated by the experiments results and density functional theory (DFT) calculations. Moreover, the discharge-charge mechanisms were also explored by ex-situ characterizations. The diffusion/migration of Mg 2+ and Mg storage abilities are obviously improved by introducing the Li + , promoting the electrochemical performances. The energy storage mechanisms are Mg 2+ intercalation in MIBs and Mg 2+ /Li + co-intercalation in MLIBs. This work further explores the energy storage mechanism of MLIBs and provides theoretical basis for the follow-up design of high-performance cathode materials.
Building formwork is a kind of temporary supporting structure consumable material used in the construction field. In recent years, building formwork has gradually developed to become lighter, more environmentally friendly, and have higher performance. This sets higher requirements for the materials used to make building formwork. There is an urgent need to find a lighter and more durable material for building formwork. Magnesium alloys possess the advantages of low density, high alkali resistance, and high strength. As a building formwork material, it can reduce the weight of formwork and improve its durability. Therefore, a magnesium alloy is considered a material with high potential for building formwork. Currently, magnesium alloy building formwork has attracted the attention of many companies and research and development institutions, with preliminary research applications and good feedback on usage effects. It is highly possible to obtain the opportunity to put it into market application. However, to be applied on a large scale, there are still some important problems that need to be solved. These problems fall into three main areas, including the relatively low processing efficiency of magnesium alloy materials, the unstable price of magnesium alloys, and the fact that the formwork is easily corroded during storage. Firstly, at present, the main processing methods for magnesium alloy building formwork are casting and extrusion, and the production efficiency of both methods needs to be improved. Secondly, high-performance magnesium alloy materials are usually more expensive, which is not conducive to the large-scale application of the formwork. The price of magnesium alloys has fluctuated greatly in recent years, which increases the difficulty of promoting magnesium alloy building formwork. Thirdly, in the atmosphere, the oxide film on the surface of the magnesium alloy cannot play an effective role in corrosion resistance. So, surface treatment is necessary for magnesium alloy building formwork. Among the various surface treatment methods for magnesium alloys, the chemical conversion method has the advantages of being easy to operate, cost-effective, and having good corrosion resistance. It may be a very suitable protective method for large-scale applications of magnesium alloy building formwork and possesses excellent potential for application. The future of magnesium alloy building formwork will focus on new low-cost materials, high-efficiency processing technology, and low-cost green anti-corrosion technology. With in-depth research and the maturation of technology, magnesium alloy formwork is expected to play a more important role in the construction industry.
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