Magnesium battery electrolyte and application thereof

Abstract

The invention belongs to the technical field of electrolyte, and discloses magnesium battery electrolyte added with indium chloride and application of the magnesium battery electrolyte, the magnesium battery electrolyte is composed of one or more of a Grignard reagent system, an MACC system, an Mg-TFSI system, an Mg-B system and Mg-HMDS and indium chloride, the indium chloride is an additive which can be dissolved in the magnesium electrolyte without the assistance of a large amount of aluminum trichloride, and through the synergistic effect of electrolyte components and the indium chloride, the cycle life of the magnesium battery is prolonged, and the specific discharge capacity of the magnesium battery is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of electrolytes, and in particular to a magnesium battery electrolyte and a preparation and application thereof. Background Art

[0002] Adding salts containing metal cations to the electrolyte is an important method to improve battery performance. The metal lithium negative electrode in the lithium battery is relatively active and easily reacts with the electrolyte. The addition of metal cation salts can form a solid electrolyte interface (SEI) film, thereby protecting the lithium negative electrode. Chinese patent CN 202310361619.4 "An electrolyte additive, electrolyte and lithium-air battery or lithium-lithium symmetric battery", CN 202011525861.3 "An electrolyte and metal battery for metal batteries", Korean patent KR 20230082383A "Electrolyte for lithium secondary batteries and lithium secondary batteries containing the electrolyte", assemble metal batteries by adding additives to the electrolyte, form an SEI film on the surface of the negative electrode, protect the negative electrode, reduce the diffusion barrier, promote the rapid migration of target ions, inhibit dendrite growth, and improve the cycle stability of the negative electrode.

[0003] The zinc negative electrode in the zinc battery is prone to dendrite formation. By adding salts containing metal cations, zinc ions can be induced to deposit uniformly, thereby preventing the formation of dendrites. Chinese patents CN 202211563056.9 "An aqueous electrolyte and zinc ion battery for inhibiting zinc dendrites" and CN 202211568700.1 "An aqueous zinc ion battery electrolyte, a method for inhibiting zinc dendrites, and a battery" add cation-containing additives to the electrolyte to induce uniform deposition / dissolution of zinc ions and inhibit the growth of dendrites, thereby improving electrochemical performance.

[0004] The problems faced by magnesium batteries are different from those of lithium / zinc batteries. Magnesium is not easy to produce dendrites, but it is easy to react with air or moisture to form a passivation film. Unlike the passivation film of lithium, this passivation film on the surface of magnesium is more difficult to conduct magnesium ions, which reduces the activity of magnesium. Therefore, the magnesium negative electrode faces the problem of how to remove the passivation film rather than forming a passivation film. The passivation film on the surface of magnesium is generally removed by grinding. Chinese patent CN 201580064216.7 prepares a magnesium-containing electrolyte with a high oxidation decomposition potential. The passivation film on the surface of magnesium is removed by grinding, and the charge and discharge voltage platform is improved after assembling into a battery. The grinding method often reduces the surface smoothness of magnesium. Since it is difficult to completely isolate moisture and oxygen during the grinding process, it is also difficult to completely eliminate the influence of the passivation film.

[0005] In this regard, Chinese patent CN 115347230A "A non-nucleophilic electrolyte for magnesium secondary batteries that generates magnesium salts in situ, and its preparation method and application" has developed an electrolyte composed of aluminum chloride, metal chloride and organic solvent, wherein the metal chloride is a metal element with a standard electrode potential higher than that of magnesium, including one of gallium, chromium, titanium, cerium, tin, bismuth, zinc, germanium, copper, iron, manganese, silver, etc.

[0006] In metal compounds, the magnitude of the interaction between anions and cations is related to their charge quantity and radius. The smaller the ionic radius, the higher the charge density, the stronger the interaction with the lone pair of electrons of oxygen in the water molecule, and the more water molecules the cations bind. This results in most metal chlorides (such as gallium, titanium, zinc, germanium, copper, iron, manganese, etc.) actually being dissolved in organic solvents in the form of bound water. For the above-mentioned metal chlorides that do not contain crystal water at all, it is often necessary to add a large amount of cosolvents such as aluminum chloride to the organic electrolyte to dissolve it. If no cosolvent is added, the dissolution of these metal chlorides such as gallium, titanium, zinc, germanium, copper, iron, and manganese in the magnesium electrolyte is very difficult, and the expected effect of the metal chloride cannot be achieved. The amount of cosolvent used is often large, generally accounting for 1 / 3 of the total amount, and it does not work on the effective ingredients, so it will reduce efficiency and increase costs. Therefore, it is an important problem to find an additive that can dissolve and efficiently activate the magnesium passivation film to reduce or even avoid the use of cosolvents. Summary of the invention

[0007] In view of the problems in the background technology, the present invention proposes an additive that does not contain crystal water and can be dissolved in a magnesium electrolyte without a large amount of aluminum chloride dissolution aid, namely, indium chloride. The radius of indium ions is larger than the radius of most metal cations (gallium, titanium, zinc, germanium, copper, iron, manganese, etc.), and exists in the form of pure substances at room temperature. A small amount of indium chloride additive is added to the magnesium battery electrolyte to obtain a high-performance magnesium battery electrolyte. During the charge and discharge process of the magnesium battery, the indium ions in the electrolyte are deposited on the surface of the magnesium anode. Due to the potential difference between the indium and magnesium electrodes, microgalvanic corrosion is formed, thereby corroding the passivation film on the magnesium surface, accelerating the conduction of magnesium ions, and improving the activity of the magnesium negative electrode, thereby improving the electrochemical performance of the magnesium battery.

[0008] The present invention provides the following technical solutions:

[0009] A magnesium battery electrolyte, comprising a matrix electrolyte and indium chloride dissolved in an organic solvent;

[0010] The matrix electrolyte component is a composite of one or more of a Grignard reagent system electrolyte, an APC electrolyte, a MACC system electrolyte, a Mg-TFSI system electrolyte, a Mg-B system electrolyte, and a Mg-HMDS-based electrolyte;

[0011] The organic solvent is preferably an ether organic solvent, more preferably one of DME, THF, and TEGDME;

[0012] The indium chloride is one or a composite of InCl3 and InCl2;

[0013] The amount of the indium-containing substance added is 0.01-5wt.% of the matrix electrolyte.

[0014] The magnesium battery is a composite of one or more of a magnesium ion battery, a magnesium oxygen battery, and a magnesium sulfur battery.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] The present invention proposes to use indium ions as additives, avoids the use of a large amount of co-solvents, can remove the magnesium metal passivation film, accelerate the dissociation and transmission of magnesium ions, and thus improve the coulombic efficiency and life of the magnesium battery. The additive of the present invention is added in a small amount, so that the battery still has a long cycle life under high current density charging and discharging, and has a high charge and discharge specific capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The first cycle charge and discharge curves of the magnesium battery assembled with the electrolyte prepared in Example 1 and Comparative Example 1 at 0.05C;

[0018] Figure 2 Comparison of electrochemical performance of magnesium batteries assembled with electrolytes prepared in Example 1, Example 2 and Example 3;

[0019] Figure 3 0.1mAcm -2 Under the current density, after standing for 9 hours in the blank APC electrolyte and the APC electrolyte with InCl3 added, the EDS results of the deposited products on the surface of the Mg anode show that the content of Mg element is greatly increased and the content of O element is reduced. DETAILED DESCRIPTION

[0020] The present invention is further described below in conjunction with specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0021] Example 1

[0022] Preparation of magnesium-sulfur batteries

[0023] In a circulating purification glove box with a water content and an oxygen content both lower than 0.1 ppm, 0.004 g of InCl3 was weighed, and then APC electrolyte was added to make the total mass 1 g. The solution was stirred magnetically until a transparent solution was obtained. After standing, a magnesium battery electrolyte APC-InCl3 (indium ion content of 0.4 wt.%) containing an indium ion additive was obtained.

[0024] A magnesium-sulfur battery was assembled with magnesium metal as the negative electrode, sulfur-carbon composite material as the positive electrode, PP / PE composite porous membrane as the separator, and the obtained electrolyte. The first cycle specific capacity of the sulfur-carbon positive electrode was 1352 mA hg at a rate of 0.05C. -1 , the capacity retention rate after 100 cycles is 70%.

[0025] Comparative Example 1

[0026] Preparation of magnesium-sulfur batteries

[0027] The preparation method of the electrolyte was the same as that of Example 1, except that InCl3 was not added. The battery was assembled in the same way, and the initial capacity was 736 mAh g -1 After 100 cycles, the capacity is 457 mAh g -1 , the capacity retention rate is 62%.

[0028] Figure 1 The first cycle charge and discharge curves at 0.05C for the magnesium batteries assembled with the electrolytes prepared in Example 1 and Comparative Example 1 (blank control group); it can be seen that the capacity of the APC electrolyte magnesium battery with an indium ion content of 0.4wt.% is greatly improved at a relatively high charge and discharge rate, and the discharge voltage platform is close to 1.2V.

[0029] Comparative Example 2

[0030] Preparation of magnesium-sulfur batteries

[0031] The preparation method of the electrolyte is the same as that of Example 1, except that InCl3 is replaced by BiCl3, and the addition amount is 0.4wt.%. The battery is assembled in the same way. The first cycle specific capacity of the sulfur-carbon positive electrode at a rate of 0.05C is 766mAh g -1 , the capacity retention rate after 100 cycles is 58%.

[0032] Comparative Example 3

[0033] Preparation of magnesium-sulfur batteries

[0034] The preparation method of the electrolyte is the same as that of Example 1, except that InCl3 is replaced by CeCl3, and the addition amount is 0.4wt.%. The battery is assembled in the same way. The first cycle specific capacity of the sulfur-carbon positive electrode is 792mAh g at a rate of 0.05C. -1 , the capacity retention rate after 100 cycles is 62%.

[0035] Comparative Example 4

[0036] The preparation method of the electrolyte is the same as that of Example 1, except that InCl3 is replaced by CrCl3, and the added amount is 0.4wt.%. During the preparation process, it is found that the substance is almost insoluble in the APC electrolyte.

[0037] Example 2

[0038] Preparation of magnesium-sulfur batteries

[0039] The preparation method of the electrolyte is the same as that of Example 1. A mixture of InCl3 and InCl2 (1:1 mass ratio) is used as an additive with a total amount of 0.4 wt.%. The battery is assembled in the same way. The first cycle specific capacity of the sulfur-carbon positive electrode is 932 mAh g at a rate of 0.05 C. -1 , the capacity retention rate after 100 cycles is 68%.

[0040] Example 3

[0041] Preparation of magnesium-sulfur batteries

[0042] The preparation method of the electrolyte is the same as that of Example 1, except that InCl3 is replaced by InCl2, and the amount of InCl2 added is 0.4wt.%. The battery is assembled in the same way, and the first cycle specific capacity of the sulfur-carbon positive electrode is 809mAh g at a rate of 0.05C. -1 , the capacity retention rate after 100 cycles is 69%.

[0043] Figure 2 The electrochemical performance of magnesium batteries assembled with the electrolytes prepared in Example 1, Example 2 and Example 3 is compared. It can be seen that the addition of indium ions significantly improves the charge and discharge capacity of magnesium-sulfur batteries, and the battery assembled with the electrolyte containing trivalent indium ions has the best performance. The first cycle specific capacity of the sulfur-carbon positive electrode is 1352 mAh g at a rate of 0.05C. -1 .

[0044] Example 4

[0045] Preparation of magnesium oxygen battery

[0046] The electrolyte preparation method is the same as that in Example 1, with metallic magnesium as the negative electrode, magnesium peroxide as the positive electrode, and the PP / PE composite porous membrane as the separator. The magnesium oxygen battery is prepared by the conventional method, and the obtained battery has a first discharge time of 3000 min at a rate of 0.05C, which is more than 3 times higher than the battery cycle performance without indium chloride added to the electrolyte.

[0047] Example 5

[0048] Preparation of magnesium ion batteries

[0049] The preparation method of the electrolyte is the same as that of Example 1, except that InCl3 is replaced by InCl2, and the addition amount is 0.4wt.%. MgFeSiO4 is used as the positive electrode, magnesium metal is used as the negative electrode, and the PP / PE composite porous membrane is used as the separator. A battery is assembled with the above electrolyte, and the specific capacity of the positive electrode of the obtained battery can reach 302mAh g -1 Compared with the sample without InCl2, the overpotential is 55mV lower and the capacity retention rate after 100 cycles is about 68%, which is more than 2 times higher.

[0050] Example 6

[0051] Preparation of magnesium-sulfur batteries

[0052] The magnesium battery electrolyte is obtained by using a Mg-TFSI system electrolyte as an initial electrolyte and adding a trace amount of indium to the electrolyte. The specific preparation process is as follows:

[0053] In a circulating purification glove box with a water content and an oxygen content of less than 0.1ppm, 0.004g InCl3 powder was weighed and added to a sample bottle, and Mg-TFSI electrolyte was added to the sample bottle to make a total mass of 1g to obtain an electrolyte with an indium ion concentration of 0.4wt.%. Magnetic stirring was performed until a transparent solution was obtained, and the obtained solution was allowed to stand, which was a magnesium battery electrolyte Mg(TFSI)2-InCl3 (indium ion content of 0.4wt.%) containing an indium ion additive.

[0054] The magnesium battery assembled with the obtained electrolyte has a first cycle specific capacity of 724 mAh g at a rate of 0.05C. -1 The specific capacity and capacity retention rate after 100 cycles are improved compared with the initial Mg(TFSI)2 electrolyte without indium ion additive.

[0055] Example 7

[0056] Preparation of magnesium-sulfur batteries

[0057] MgCl2, Mg[B(hfip)4]2, and Mg(HMDS)2 were mixed and dissolved in DME in a mass ratio of 1:1:1 to obtain a magnesium battery electrolyte. 0.004 g of InCl3 powder was weighed and added to a sample bottle, and then the above electrolyte was added to make the total mass 1 g. The solution was stirred magnetically until a transparent solution was obtained. After standing, a magnesium battery electrolyte containing an indium ion additive (the indium ion content was 0.4 wt.%) was obtained. The remaining operations were the same as in Example 1 to prepare a magnesium-sulfur battery. The magnesium-sulfur battery assembled with the obtained electrolyte had a first-cycle specific capacity of 833 mAh g at a rate of 0.05C. -1 The discharge specific capacity of the battery is increased by 30% compared with the electrolyte without indium ion additives, and the capacity retention rate after 100 cycles is about 66%, which is increased by more than 1.5 times.

[0058] The above-described embodiments are only preferred embodiments for fully illustrating the present invention, and the protection scope of the present invention is not limited thereto. Equivalent substitutions or changes made by those skilled in the art based on the present invention are within the protection scope of the present invention, and the protection scope of the present invention shall be subject to the claims.

Claims

1. A magnesium battery electrolyte, characterized in that: The magnesium battery electrolyte consists of a magnesium matrix electrolyte and indium chloride dissolved in an organic solvent.

2. The magnesium battery electrolyte according to claim 1, characterized in that: The magnesium matrix electrolyte is a composite of one or more of a Grignard reagent system electrolyte, an APC electrolyte, a MACC system electrolyte, a Mg-TFSI system electrolyte, a Mg-B system electrolyte, and a Mg-HMDS electrolyte.

3. The magnesium battery electrolyte according to claim 1, characterized in that: The organic solvent is one of ether solvents, DME, THF, and TEGDME.

4. The magnesium battery electrolyte according to claim 1, characterized in that: The indium chloride is one of InCl3 and InCl2 or a composite of both.

5. The magnesium battery electrolyte according to claim 1, characterized in that: The amount of indium chloride added is 0.01-5 wt.% of the electrolyte.

6. Use of the electrolyte according to any one of claims 1 to 5 in a magnesium battery, characterized in that: The magnesium battery is a combination of one or more of a magnesium ion battery, a magnesium oxygen battery, and a magnesium sulfur battery.

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