Zwitterionic ionic liquid electrolyte for magnesium batteries

Abstract

The application discloses a kind of zwitterionic liquid electrolyte for magnesium battery, including magnesium borohydride and zwitterionic liquid, magnesium borohydride is added to zwitterionic liquid, stirring dispersion, aging 0.1-1h, and the electrolyte with concentration of 0.1-1M is prepared.The application uses the above-mentioned zwitterionic liquid electrolyte for magnesium battery, with good reversibility and stability, and has broad application prospect in magnesium-based battery.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrolyte, in particular to a zwitterionic liquid electrolyte for magnesium battery. BACKGROUND

[0002] The continuous progress of energy technology, especially the use of electrical energy, greatly facilitates human life and effectively promotes the rapid development of society. As a clean energy efficient energy storage device, lithium ion battery has attracted widespread attention. Small mobile electronic devices such as smart phones, notebook computers, and even electric vehicles are powered by lithium ion batteries. However, the high reactivity of metal lithium in the currently used liquid lithium ion battery, the tendency to form dendrites in the dissolution and redeposition cycle limits its applicability. In addition, the limited reserves of lithium require people to find another metal ion battery to replace lithium ion battery.

[0003] Magnesium is located in the diagonal position of lithium in the periodic table. According to the diagonal rule, the two have many similarities in chemical properties. However, magnesium is much more abundant than lithium, and the price of magnesium is much lower than that of lithium (1 / 24 of lithium); magnesium and almost all compounds of magnesium are non-toxic or low-toxic, environmentally friendly; magnesium is less active than lithium, easy to operate, safe to process and handle, and has good safety performance; it has high capacity and low redox potential, and can be used to manufacture high-voltage batteries. The use of magnesium metal as an anode has not found the problem of dendritic crystal formation. In the cathode, vanadium-based, sulfur-based or molybdenum-based electrodes previously studied for lithium-based batteries can be used. All of these electrodes are cobalt-free, thereby avoiding social and economic problems related to the use of cobalt.

[0004] Magnesium battery has a large theoretical capacity and is a promising energy storage device. However, there are limited number of suitable electrolytes in the prior art, and there are many deficiencies. For example, patent CN 106663833 A discloses an electrolyte and an electrochemical device, which uses sulfone or sulfone derivatives as electrolyte to perform reversible electrochemical deposition / dissolution reaction with magnesium electrode. Patent CN 104428940 A discloses an electrolyte and an electrochemical device, which uses ether or ether derivatives as electrolyte to perform reversible electrochemical deposition / dissolution reaction with magnesium electrode. The ether, sulfone and other systems have the problems of easy volatility, flammability, toxicity and instability. SUMMARY

[0005] The purpose of the present application is to provide a zwitterionic liquid electrolyte for magnesium battery, which has good reversibility and stability, and has a broad application prospect in magnesium-based batteries.

[0006] To achieve the above object, the application provides a zwitterionic liquid electrolyte for a magnesium battery, which comprises magnesium borohydride and a zwitterionic liquid, the magnesium borohydride is added into the zwitterionic liquid, stirred and dispersed, and aged for 0.1-1h to obtain the electrolyte with a concentration of 0.5M.

[0007] Preferably, the magnesium borohydride is added in an amount of 0.1-1mol / L.

[0008] Preferably, the zwitterionic liquid is 1-butyl-3-methylimidazolium-2-ethylborane.

[0009] Preferably, the zwitterionic liquid is a pure substance in a dry atmosphere.

[0010] A magnesium battery prepared by the zwitterionic liquid electrolyte for a magnesium battery, which comprises the electrolyte, a Mg cathode and an anode, the anode is selected from one of vanadium-based electrodes, sulfur-based electrodes and molybdenum-based electrodes.

[0011] Preferably, the battery reaction is carried out in a closed oxygen-free environment.

[0012] The application has the following beneficial effects:

[0013] (1) The magnesium borohydride reacts with the residual water in the zwitterionic liquid during the electrolyte preparation process, so that a truly anhydrous electrolyte is obtained;

[0014] (2) The zwitterionic liquid is very stable, has a high flowability range and low viscosity;

[0015] (3) The electrolyte based on the magnesium borohydride and the zwitterionic liquid 1-butyl-3-methylimidazolium-2-ethylborane avoids the problems of volatility, flammability, toxicity and instability of ether, sulfone and other systems;

[0016] (4) The electrolyte system has good reversibility and stability, and has a broad application prospect in magnesium-based batteries.

[0017] The technical solution of the application is described in further detail below by means of the drawings and examples. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is the cyclic voltammogram of the electrolyte [BBH3MIm+Mg(BH4)2] battery system prepared in Example 1;

[0019] Figure 2 is the cyclic voltammogram efficiency diagram of the electrolyte [BMMImTFSI+Mg(BH4)2] prepared in Example 2;

[0020] Figure 3Cyclic voltammogram of the battery system of the electrolyte [BMMImTFSI+Mg(BH4)2] prepared in Comparative Example 1. DETAILED DESCRIPTION

[0021] The application is further described in connection with the following examples, in which the various chemicals and reagents used are commercially available unless otherwise stated.

[0022] Example 1

[0023] In a glove box, 27 g of magnesium borohydride was dissolved in 1000 mL of ionic liquid 1-butyl-3-methylimidazolium-2-ethylborane to prepare an electrolyte [BBH3MIm+Mg(BH4)2] with a concentration of 0.5 M, and then a Mg electrode and a stainless steel electrode were inserted to prepare a Mg battery system.

[0024] Cyclic voltammetry test was performed, and the electrolyte [BBH3MIm+Mg(BH4)2] could reversibly deposit magnesium, and the efficiency of 100 cycles was about 96%, and the cycle shape did not change.

[0025] Example 2

[0026] In a glove box, 5.4 g of magnesium borohydride was dissolved in 1000 mL of ionic liquid 1-butyl-3-methylimidazolium-2-ethylborane to prepare an electrolyte [BBH3MIm+Mg(BH4)2] with a concentration of 0.1 M, and then a Mg electrode and a stainless steel electrode were inserted to prepare a Mg battery system.

[0027] Cyclic voltammetry test was performed, and the electrolyte [BBH3MIm+Mg(BH4)2] could reversibly deposit magnesium, and the efficiency of 400 cycles was about 96%, and the cycle shape did not change.

[0028] Example 3

[0029] In a glove box, 54 g of magnesium borohydride was dissolved in 1000 mL of ionic liquid 1-butyl-3-methylimidazolium-2-ethylborane to prepare an electrolyte [BBH3MIm+Mg(BH4)2] with a concentration of 1 M, and then a Mg electrode and a stainless steel electrode were inserted to prepare a Mg battery system.

[0030] Cyclic voltammetry test was performed, and the electrolyte [BBH3MIm+Mg(BH4)2] could reversibly deposit magnesium, and the efficiency of 100 cycles was about 96%, and the cycle shape did not change.

[0031] Comparative Example 1

[0032] In a glove box, 27 g of magnesium borohydride was dissolved in 1000 mL of ionic liquid 1-butyl-3-methylimidazolium-bistrifluoromethylsulfonylimide to prepare 0.5 M electrolyte system [BMMImTFSI+Mg(BH4)2], and then inserted into Mg electrode and stainless steel electrode to prepare Mg battery system.

[0033] Cyclic voltammetry test was performed, and the electrolyte [BMMImTFSI+Mg(BH4)2] could not perform reversible magnesium electrodeposition, indicating that TFSI - The anion is unstable, indicating the unique interaction of ionic liquid 1-butyl-3-methylimidazolium-2-ethylborane and magnesium borohydride.

[0034] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application, not to limit it. Although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present application can still be modified or replaced by equivalents, and these modifications or equivalent replacements should not make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present application.

Claims

1. An ionic liquid electrolyte for a magnesium battery, characterized in that: The electrolyte with the concentration of 0.1-1M of borohydride magnesium is prepared by adding borohydride magnesium into a zwitterionic liquid, stirring and dispersing, and aging for 0.1-1h; The zwitterionic liquid is 1-butyl-3-methylimidazolium-2-ethylborane.

2. A magnesium battery prepared from the zwitterionic ionic liquid electrolyte of claim 1 for a magnesium battery, characterized by: The electrolyte, a Mg cathode and an anode are included, and the anode is selected from one of a vanadium-based electrode, a sulfur-based electrode and a molybdenum-based electrode.

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