Mononuclear magnesium cationization salt, its preparation method and application

Abstract

The invention discloses a mononuclear magnesium cationization salt, its preparation method and application. The chemical formula of the mononuclear magnesium cationization salt is MgR n MX 4‑m Y m , where R is a non-aqueous solvent molecule, M includes Al 3+ and / or B 3+ , X and Y include halide ions or halide-like ions, n is selected from any integer from 0 to 6, and m is selected from any integer from 0 to 4. The mononuclear magnesium cationization salt provided by the invention has simple structure, excellent electrochemical properties, and its preparation method is a low-cost one-step synthesis process, the raw materials are easy to obtain, the preparation process is simple, and it is easy to produce on a large scale. When applied to the electrolyte of rechargeable magnesium batteries, the formed electrolyte has high ionic conductivity, high magnesium reversible deposition-dissolution efficiency, excellent cycle performance and high anodic oxidation decomposition potential. When applied to magnesium batteries, its initial discharge capacity can reach more than 700mAh / g, and it can be cycled for more than 20 cycles.

Description

technical field [0001] The invention specifically relates to a mononuclear magnesium cationization salt, its preparation method and application, and belongs to the field of electrochemical energy. Background technique [0002] Facing the requirements of efficient, clean, economical and safe energy systems in the new stage of the 21st century, the development of new green, high-performance, large-scale energy storage technologies and the efficient use of new energy have become a global concern and an inevitable trend of development. Lithium-ion battery energy storage system, as an effective energy storage method, has attracted the attention and attention of energy departments and energy companies in various countries, and occupies a core position in the field of energy storage industry today. However, the global lithium resource reserves are limited and the spatial distribution is uneven (mainly in South America), which not only results in high cost of raw materials for lithi...

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Problems solved by technology

[0005] Extensive experiments have demonstrated that, compared with the simple lithium-ion salt (LiClO) commonly used in commercial lithium-ion batteries, 4 , LiPF 6 , Li(CF 3 SO 3 ) 2 etc.) differently, in simple mononuclear magnesium cationization salts (such as MgCl 2 , Mg(ClO 4 ) 2 , Mg(CF 3 SO 3 ) 2 etc.) in the aprotic polar solvent electrolyte is easy to form a dense passivation film that does not conduct magnesium ions, so that magnesium ions cannot be reversibly deposited and dissolved (Journal of Electroanalytical Chemistry, 1999, 466 (2): 203-217 ), so cannot be used in rechargeable magnesium batteries

Although studies have found that magnesium can be reversibly deposited and dissolved in ether solutions of Grignard reagents, common Grignard reagents cannot be directly used as electrolytes for rechargeable magnesium batteries due to their narrow electrochemical window and high activity.

Subsequently, ether solutions of organoboron-magnesium salts and organoaluminum-magnesium salts were also found to achieve reversible magnesium deposition and dissolution, making rechargeable magnesium batteries a big step towards practical use, but the cation part of such electrolyte salts is usually dinuclear magnesium Cations are relatively large in size, which is not conducive to ion conduction; and the anion part contains organic groups, which has poor electrochemical stability; in addition, their preparation process is relatively complicated and the cost is relatively high

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