Electrolyte for aqueous zinc ion battery and zinc ion battery

Abstract

The invention relates to an electrolyte for an aqueous zinc ion battery and the zinc ion battery. The electrolyte consists of soluble zinc salt, an electrolyte additive and solvent water, and the electrolyte additive is a thiazole derivative containing functional groups such as sulfydryl, amino, sulfonic acid group and formic acid group. According to the electrolyte provided by the invention, the electrolyte additive can regulate and control the coordination environment through coordination with zinc ions so as to realize uniform deposition of zinc, meanwhile, the electrolyte additive can also be grafted to the surface of zinc through functional groups such as sulfydryl, amino, sulfonic acid group and formic acid group so as to form a layer of stable protective film, and the protective film has good zinc affinity; direct contact between an electrolyte and the zinc negative electrode can be effectively blocked, chemical corrosion and hydrogen evolution reaction of the zinc negative electrode can be reduced, interface ion transmission can be regulated and controlled, zinc dendrite growth is effectively inhibited, the cycling stability of the zinc negative electrode is improved, the cycle life of the battery is prolonged, the rate performance of the battery is improved, and the method is easy and convenient to prepare, low in cost, high in safety and suitable for industrial production. The large-scale production is easy to realize.

Description

Technical Field

[0001] The invention relates to the technical field of aqueous zinc ion batteries, and in particular to an electrolyte for aqueous zinc ion batteries and a zinc ion battery. Background Art

[0002] In recent years, electrical equipment and electric vehicles have developed rapidly, and lithium-ion batteries have dominated the market due to their advantages such as high gravimetric energy density and long cycle life. However, the shortage of metallic lithium resources, poor safety of flammable organic electrolytes, and high costs have restricted their further development. Aqueous zinc-ion batteries (AZIBs) have good safety, simple and easy process operation, low redox potential (-0.76 V vs SHE), high theoretical capacity, and high volumetric energy density (5851 mA hcm -3 ) Zinc has advantages such as abundant zinc resources and has good application prospects in energy storage systems. However, zinc-ion battery negative electrodes have problems such as dendrite growth, hydrogen evolution corrosion, and by-product generation during repeated deposition / stripping processes, resulting in low cycle life and reduced battery performance. Therefore, inhibiting dendrite growth and building a stable electrochemical interface have become urgent issues to be solved in the practical application of metal zinc negative electrodes.

[0003] The electrolyte is an important component of aqueous zinc-ion batteries. At present, the main electrolytes of aqueous zinc-ion batteries are ZnSO4, Zn(NO3)2, Zn(ClO4)2, Zn(CF3SO3)2, ZnCl2, Zn(CH3COO)2, etc. ZnSO4 is low in cost, but the negative electrode is prone to dendrites, and the positive electrode will generate byproducts such as Zn4(OH)6SO4·nH2O. The nitrate in Zn(NO3)2 is highly oxidizing and will reduce the performance of the zinc negative electrode. The chlorate in Zn(ClO4)2 is relatively weak in oxidizing, but it will produce zinc oxide with zinc, making the overpotential higher. Zn(CF3SO3)2 is expensive and has a high cost. The poorly stable anions in ZnCl2 and Zn(CH3COO)2 will lead to poor electrochemical performance.

[0004] The use of electrolyte additives can effectively improve the electrochemical performance of the battery and is simple and easy to operate. Electrolyte additives include inorganic ions, organic small molecules, polymers, ionic liquid additives and other types. In the positive electrode, electrolyte additives can reduce the dissolution of positive electrode materials, increase the working platform voltage, increase specific capacity, etc., and promote the stability of material structure; in the negative electrode, electrolyte additives can effectively inhibit the growth of zinc dendrites, reduce side reactions, and inhibit the generation of by-products through electrostatic shielding strategies and surface structure regulation.

[0005] Therefore, finding effective methods to improve zinc deposition, inhibit the corrosion and passivation of zinc sheets by the electrolyte, and improve the cycle life and coulombic efficiency of aqueous zinc-ion batteries in order to further promote the large-scale application of aqueous zinc-ion batteries remains the focus of current research. Summary of the invention

[0006] Based on this, the present invention provides an electrolyte for an aqueous zinc ion battery, which effectively improves the electrochemical performance of the aqueous zinc ion battery by modifying the zinc negative electrode through an electrolyte additive, thereby effectively inhibiting the growth of zinc dendrites, extending the battery life, and achieving the purpose of improving battery performance.

[0007] To achieve the above object, the present invention provides an electrolyte for an aqueous zinc ion battery, wherein the electrolyte consists of a soluble zinc salt, an electrolyte additive and deionized water, wherein the concentration of the soluble zinc salt is 1-3 mol / L, and the concentration of the electrolyte additive is 0.0001-0.2 mol L -1 ; The electrolyte additive is a thiazole derivative, and the functional group it contains is at least one of a thiol group, an amino group, a sulfonic acid group, a carboxylic acid group, and a phosphate group.

[0008] As a further preferred technical solution of the present invention, the soluble zinc salt is one or more of zinc sulfate, zinc nitrate, zinc acetate, zinc chloride, zinc perchlorate, zinc tetrafluoroborate, and zinc trifluoromethanesulfonate.

[0009] As a further preferred technical solution of the present invention, the thiazole derivative is mercaptothiazole, aminothiazole, sulfonic acid thiazole, thiazolecarboxylic acid, thiazole phosphate or thiothiazole acetate.

[0010] As a further preferred technical solution of the present invention, the concentration of the thiazole derivative in the electrolyte is 0.001 to 0.005 mol L -1 .

[0011] According to another aspect of the present invention, the present invention also provides a zinc ion battery, which adopts the above-mentioned electrolyte and is assembled in the order of a negative electrode shell, a spring sheet, a gasket, a zinc sheet, a diaphragm, an electrolyte, a zinc sheet, and a positive electrode shell.

[0012] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0013] 1) The electrolyte for aqueous zinc ion batteries provided by the present invention, wherein the electrolyte additive is a thiazole derivative. Thiazole is a sulfur-containing five-membered heterocyclic compound, which is easily soluble in water and can be complexed with zinc ions to form a complex, regulate the coordination environment of zinc ions, and facilitate the uniform deposition of zinc. Thiazole derivatives containing functional groups such as thiol, amino, sulfonic acid, and carboxylic acid groups can also be grafted onto the surface of metallic zinc through these functional groups to form a stable protective film. On the one hand, the protective film has good zinc affinity, effectively blocks direct contact between the electrolyte and the zinc negative electrode, and reduces chemical corrosion and hydrogen evolution reaction of the zinc negative electrode. On the other hand, it can also coordinate with zinc ions to regulate interfacial ion transmission, thereby effectively inhibiting zinc dendrite growth, improving the cycle stability of the zinc negative electrode, and thus improving the cycle life and rate performance of the battery.

[0014] 3) The electrolyte for aqueous zinc ion battery provided by the present invention has a small amount of electrolyte additive (preferably 0.001 to 0.005 mol L -1 ), which has a significant effect on improving the cycle life and rate performance of aqueous zinc-ion batteries, is economical and affordable, and is not prone to producing by-products.

[0015] 2) The electrolyte for aqueous zinc ion batteries provided by the present invention has a simple preparation method, and the zinc salts, electrolyte additives, etc. used can be purchased commercially, with low preparation cost, high safety, and easy large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0017] Figure 1 The Zn / / Zn symmetric cell assembled using blank zinc sulfate electrolyte and electrolyte containing mercaptothiazole additive in Comparative Example 1 and Example 1, respectively, at 1 mA cm -2 The current density of 1 mAh cm -2 Constant current charge and discharge test curves under dissolution / deposition amount;

[0018] Figure 2 The scanning electron microscope (SEM) images of the zinc sheets after being immersed in (a) a blank electrolyte and (b) an electrolyte containing an aminothiazole additive for 24 hours in Comparative Example 1 and Example 2, respectively;

[0019] Figure 3 The Zn / / Zn symmetric cells assembled using blank electrolyte and electrolyte containing aminothiazole additive in Comparative Example 1 and Example 2 were tested at 4 mA cm -2 The current density is 4 mAh cm -2 Constant current charge and discharge test curve under dissolution / deposition amount.

[0020] Figure 4 The Zn / / Zn symmetric cells assembled using blank electrolyte and electrolyte containing aminothiazole additive in Comparative Example 1 and Example 2 were tested at 8 mA cm -2 The current density is 8 mAh cm -2 Constant current charge and discharge test curve under dissolution / deposition amount.

[0021] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings in conjunction with the embodiments. DETAILED DESCRIPTION

[0022] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the present invention, and is not used to limit the present invention.

[0023] Unless otherwise defined, the technical terms used in the following examples have the same meanings as those generally understood by those skilled in the art to which the present invention belongs. The test reagents used in the following examples, unless otherwise specified, are all conventional biochemical reagents; the experimental methods, unless otherwise specified, are all conventional methods.

[0024] The electrolyte for aqueous zinc ion battery provided by the present invention is actually an electrolyte for zinc negative electrode modification, which is composed of a soluble zinc salt, an electrolyte additive and solvent water. The electrolyte additive in the present invention is a thiazole derivative containing at least one functional group of a mercapto group, an amino group, a sulfonic acid group, a carboxylic acid group, and a phosphate group, and is preferably mercaptothiazole, aminothiazole, sulfonic acid thiazole, thiazole carboxylic acid, thiazole phosphate or thiothiazole acetate.

[0025] Soluble zinc salt in the present invention and solvent water form zinc salt electrolyte, it is the conventional technology of prior art, wherein soluble zinc salt is conventional selection, soluble zinc salt includes and is not limited to one or more in zinc sulfate, zinc nitrate, zinc acetate, zinc chloride, zinc perchlorate, zinc tetrafluoroborate, zinc trifluoromethanesulfonate.The soluble zinc salt of following each embodiment all chooses zinc sulfate, and the effect of remaining soluble zinc salt is similar to zinc sulfate, and detailed illustration is not done here.In addition, solvent water can be deionized water or ultrapure water etc., and following each embodiment solvent for use is deionized water.

[0026] Comparative Example 1:

[0027] Configuration of blank electrolyte and assembly of zinc ion battery based on it:

[0028] As a control experimental group of Example 1, a 2 mol / L zinc sulfate aqueous solution (without adding electrolyte additives) was used to assemble an aqueous zinc ion battery in the order of negative electrode shell, spring sheet, gasket, zinc sheet, diaphragm, electrolyte, zinc sheet, and positive electrode shell.

[0029] Embodiment 1:

[0030] Configuration of electrolyte for aqueous zinc ion battery and assembly of zinc ion battery based thereon:

[0031] Add 2-mercaptothiazole to a 2 mol / L aqueous zinc sulfate solution at a concentration of 0.005 mol L -1 , stirring evenly and ultrasonicating for 30 minutes to obtain the target electrolyte (BBA+2M ZnSO4). The aqueous zinc ion battery was assembled in the order of negative electrode shell, spring piece, gasket, zinc sheet, diaphragm, electrolyte, zinc sheet and positive electrode shell.

[0032] Figure 1 The zinc-zinc symmetric battery assembled using the electrolytes of Example 1 and Comparative Example 1 at 1 mA cm -2 、1mAh cm -2 From the constant current charge and discharge test under the conditions of , it can be seen that the battery cycle life of the battery using only zinc sulfate electrolyte is only 93h. The addition of 2-mercaptothiazole additive increases the battery cycle life to 3293h. It is obvious that the 2-mercaptothiazole electrolyte additive can effectively improve the battery cycle performance.

[0033] After soaking the zinc sheet in the electrolyte (BBA+2M ZnSO4) of Example 1 for 24 hours, the surface of the zinc sheet was scanned by electron microscope. It can be seen that the surface of the zinc sheet is smooth without obvious protrusions, indicating that the surface modification effect of mercaptothiazole on the zinc negative electrode can effectively block the direct contact between the electrolyte and the zinc sheet.

[0034] Embodiment 2:

[0035] Configuration of electrolyte for aqueous zinc-ion battery, and assembly of zinc-ion battery based thereon:

[0036] Add 4-aminothiazole to a 2 mol / L zinc sulfate aqueous solution at a concentration of 0.005 mol L -1 , stirring evenly and ultrasonicating for 30 minutes to obtain the target electrolyte (DPA+2M ZnSO4). The aqueous zinc ion battery was assembled in the order of negative electrode shell, spring sheet, gasket, zinc sheet, diaphragm, electrolyte, zinc sheet and positive electrode shell.

[0037] Figure 2 (a) and (b) are scanning electron microscope (SEM) images of zinc sheets immersed in the electrolyte of Example 2 and Comparative Example 1 for 24 hours, respectively. Figure 2 (a) shows that the surface of the zinc sheet without electrolyte additives is severely corroded, producing a large number of irregular byproducts and severe dendrite growth; Figure 2It can be seen from (b) that the surface of the zinc sheet with the addition of electrolyte additives is smooth, without obvious protrusions, and no dendrite growth is achieved. This is due to the surface modification effect of aminothiazole, which effectively blocks the direct contact between the electrolyte and the zinc sheet, inhibits the corrosion and passivation of the zinc sheet by the electrolyte, and improves its chemical stability.

[0038] The assembled Zn-Zn symmetric battery was subjected to constant current charge and discharge tests at a current density of 1 mA cm -2 , the deposition amount is 1 mAh cm -2 Under the conditions, it can circulate stably for 2700h.

[0039] Figure 3 The zinc-zinc symmetric battery assembled using the electrolytes of Example 2 and Comparative Example 1 at 4 mA cm -2 、4mAh cm -2 The constant current charge and discharge test under the conditions of , it can be seen that the battery cycle life of the blank electrolyte using only zinc sulfate is only 56h, and the battery cycle life after adding aminothiazole additive increases to 598h, and the battery cycle performance is significantly improved.

[0040] Figure 4 The zinc-zinc symmetric battery assembled using the electrolytes of Example 2 and Comparative Example 1 at 8 mA cm -2 、8mAh cm -2 From the constant current charge and discharge test under the conditions of , it can be seen that the battery cycle life of the blank electrolyte using only zinc sulfate is only 64h. After adding the aminothiazole additive, the battery cycle life increases to 339h, indicating that the aminothiazole additive can increase the battery cycle life.

[0041] Comparative Example 2:

[0042] Configuration of electrolyte for aqueous zinc ion battery and assembly of zinc ion battery based thereon:

[0043] Thiazole was added to a 2 mol / L aqueous solution of zinc sulfate at a concentration of 0.005 mol L -1 , stirring evenly and ultrasonicating for 30 minutes to obtain the target electrolyte. The aqueous zinc ion battery is assembled in the order of negative electrode shell, spring piece, gasket, zinc sheet, diaphragm, electrolyte, zinc sheet and positive electrode shell.

[0044] The assembled zinc-zinc symmetric battery was subjected to constant current charge and discharge tests. The test results of the symmetric battery showed that at a current density of 1 mA cm -2 , the deposition amount is 1 mAh cm -2 Under the conditions of , the zinc negative electrode can stably cycle for 1400h in the electrolyte containing thiazole additive.

[0045] Embodiment three:

[0046] Configuration of electrolyte for aqueous zinc ion battery and assembly of zinc ion battery based thereon:

[0047] Add thiazole sulfonate to a 2 mol / L aqueous zinc sulfate solution at a concentration of 0.005 mol L -1 , stirring evenly and ultrasonicating for 30 minutes to obtain the target electrolyte. The aqueous zinc ion battery is assembled in the order of negative electrode shell, spring piece, gasket, zinc sheet, diaphragm, electrolyte, zinc sheet and positive electrode shell.

[0048] The assembled zinc-zinc symmetric battery was subjected to constant current charge and discharge tests. The test results of the symmetric battery showed that at a current density of 1 mA cm -2 , the deposition amount is 1 mAh cm -2 Under the conditions of sulfonate thiazole, the zinc negative electrode can stably cycle for 2100 hours in the electrolyte containing sulfonate thiazole additive.

[0049] By comparison, it can be seen that the electrolyte containing thiazole derivatives with functional groups such as mercapto, amino or sulfonic acid as additives is significantly better than thiazole without functional groups in improving battery cycle performance.

[0050] Comparative Example 3:

[0051] Configuration of electrolyte for aqueous zinc ion battery and assembly of zinc ion battery based thereon:

[0052] Thiazole was added to a 2 mol / L aqueous solution of zinc sulfate at a concentration of 0.002 mol L -1 , stirring evenly and ultrasonicating for 30 minutes to obtain the target electrolyte. The aqueous zinc ion battery is assembled in the order of negative electrode shell, spring piece, gasket, zinc sheet, diaphragm, electrolyte, zinc sheet and positive electrode shell.

[0053] The assembled zinc-zinc symmetric battery was subjected to constant current charge and discharge tests. The test results of the symmetric battery showed that at a current density of 1 mA cm -2 , the deposition amount is 1 mAh cm -2 Under the conditions of , the zinc anode can stably cycle for 800 h in the electrolyte containing thiazole additive.

[0054] Embodiment 4:

[0055] Configuration of electrolyte for aqueous zinc ion battery and assembly of zinc ion battery based thereon:

[0056] Thiazolecarboxylic acid was added to a 2 mol / L aqueous solution of zinc sulfate at a concentration of 0.002 mol L -1 , stirring evenly and ultrasonicating for 30 minutes to obtain the target electrolyte. The aqueous zinc ion battery is assembled in the order of negative electrode shell, spring piece, gasket, zinc sheet, diaphragm, electrolyte, zinc sheet and positive electrode shell.

[0057] The assembled zinc-zinc symmetric battery was subjected to constant current charge and discharge tests. The test results of the symmetric battery showed that at a current density of 1 mA cm -2 , the deposition amount is 1 mAh cm -2 Under the conditions of , the zinc negative electrode can stably cycle for 2000h in the electrolyte containing thiazolecarboxylic acid additive.

[0058] Embodiment five:

[0059] Configuration of electrolyte for aqueous zinc ion battery and assembly of zinc ion battery based thereon:

[0060] Thiazole phosphate was added to a 2 mol / L aqueous solution of zinc sulfate at a concentration of 0.001 mol L -1 , stirring evenly and ultrasonicating for 30 minutes to obtain the target electrolyte. The aqueous zinc ion battery is assembled in the order of negative electrode shell, spring piece, gasket, zinc sheet, diaphragm, electrolyte, zinc sheet and positive electrode shell.

[0061] The assembled zinc-zinc symmetric battery was subjected to constant current charge and discharge tests. The test results of the symmetric battery showed that at a current density of 1 mA cm -2 , the deposition amount is 1 mAh cm -2 Under the conditions of , the zinc negative electrode can stably cycle for 1700 h in the electrolyte containing thiazole phosphate additive.

[0062] The assembled zinc-zinc symmetric battery was subjected to constant current charge and discharge tests. The test results of the symmetric battery showed that at a current density of 4 mA cm -2 , the deposition amount is 4 mAh cm -2 Under the conditions of , the zinc anode can stably cycle for 400 h in the electrolyte containing thiazole phosphate additive.

[0063] Embodiment six:

[0064] Configuration of electrolyte for aqueous zinc ion battery and assembly of zinc ion battery based thereon:

[0065] Add thiothiazole acetate to a 2 mol / L zinc sulfate aqueous solution at a concentration of 0.005 mol L -1 , stirring evenly and ultrasonicating for 30 minutes to obtain the target electrolyte. The aqueous zinc ion battery is assembled in the order of negative electrode shell, spring piece, gasket, zinc sheet, diaphragm, electrolyte, zinc sheet and positive electrode shell.

[0066] The assembled zinc-zinc symmetric battery was subjected to constant current charge and discharge tests. The test results of the symmetric battery showed that at a current density of 4 mA cm -2 , the deposition amount is 4 mAh cm -2 Under the conditions of , the zinc negative electrode can stably cycle for 400 h in the electrolyte containing thiothiazole acetate additive.

[0067] Although specific embodiments of the present invention are described above, those skilled in the art should understand that these are merely examples and that various changes or modifications may be made to the embodiments without departing from the principles and essence of the present invention. The scope of protection of the present invention is limited only by the appended claims.

Claims

1. An electrolyte for an aqueous zinc ion battery, characterized in that: The electrolyte consists of a soluble zinc salt, an electrolyte additive and deionized water; wherein the electrolyte additive is a thiazole derivative containing at least one functional group of thiol, amino, sulfonic acid, carboxylic acid and phosphate.

2. The electrolyte for aqueous zinc ion batteries according to claim 1, characterized in that The soluble zinc salt is one or more of zinc sulfate, zinc nitrate, zinc acetate, zinc chloride, zinc perchlorate, zinc tetrafluoroborate and zinc trifluoromethanesulfonate.

3. The electrolyte for aqueous zinc ion batteries according to claim 1, characterized in that The thiazole derivative is mercaptothiazole, aminothiazole, sulfonic acid thiazole, thiazolecarboxylic acid, thiazole phosphate or thiothiazole acetate.

4. The electrolyte for aqueous zinc ion batteries according to claim 1, characterized in that: The concentration of the thiazole derivative in the electrolyte is 0.0001 to 0.2 mol L -1 .

5. The electrolyte for aqueous zinc ion battery according to claim 1, characterized in that: The concentration of the thiazole derivative in the electrolyte is 0.001 to 0.005 mol L -1 .

6. The electrolyte for aqueous zinc ion batteries according to claim 1, characterized in that: The concentration of the soluble zinc salt in the electrolyte is 1-3 mol / L.

7. A zinc ion battery, characterized in that: The electrolyte for aqueous zinc ion battery according to any one of claims 1 to 6 is used.

8. The zinc ion battery according to claim 1, characterized in that The aqueous zinc ion battery is assembled in the order of a negative electrode shell, a spring sheet, a gasket, a zinc sheet, a diaphragm, an electrolyte, a zinc sheet and a positive electrode shell.

Images