Water-based zinc-iodine battery electrolyte containing phenolic additive as well as preparation method and application of water-based zinc-iodine battery electrolyte

Abstract

The invention relates to an aqueous zinc-iodine battery electrolyte containing a phenolic additive, and a preparation method and application thereof, and belongs to the technical field of aqueous zinc-iodine batteries. The invention aims to solve the technical problems of serious multi-iodide shuttling and negative electrode by-products of the existing aqueous zinc-iodine battery. The preparation method of the aqueous zinc-iodine battery electrolyte containing the phenolic additive comprises the following steps: dissolving zinc salt and the phenolic additive in deionized water, and fully stirring and mixing to obtain the aqueous zinc-iodine battery electrolyte containing the phenolic additive. The phenolic additive used in the application can accelerate conversion from I3-to I-, accelerate iodine conversion reaction kinetics and reduce generation of polyiodide, so that shuttling of the polyiodide is effectively inhibited, a phenolic additive monomer is adsorbed on the surface of a zinc negative electrode, contact between Zn < 2 + > and water molecules is reduced, and generation of zinc negative electrode by-products is inhibited; the zinc-iodine battery also has the advantages of being easy to manufacture and low in cost.

Description

Technical Field

[0001] The present application relates to the technical field of aqueous zinc-iodine batteries, and in particular to an aqueous zinc-iodine battery electrolyte containing a phenolic additive, and a preparation method and application thereof. Background Art

[0002] Lithium-ion batteries have been widely used in electric vehicles and portable electronics due to their high energy density. However, high cost, safety issues, and limited resource availability require the exploration of alternative battery chemistries. Among them, zinc-iodine batteries have become a promising candidate due to their high safety, low cost, and environmental friendliness. Zinc-iodine batteries with iodine as the positive electrode material have the advantages of relatively abundant iodine in seawater, 211 mAh g -1 The advantages of zinc-iodine batteries include high capacity and a suitable voltage platform of 1.3V. These characteristics make zinc-iodine batteries particularly attractive for grid energy storage systems. However, despite the bright prospects, the actual commercialization of zinc-iodine batteries is still severely hindered by several basic challenges, mainly the shuttle effect of polyiodide intermediates and the generation of zinc anode byproducts. Polyiodides are easily formed during the conversion of iodine in the positive electrode and iodine anions. Polyiodides can freely shuttle to the negative electrode and react with the negative electrode (Zn+I x - →Zn 2+ +xI - ), resulting in negative electrode corrosion and the production of a large amount of by-product basic zinc sulfate (Zn2SO4(OH)5·5H2O).

[0003] Therefore, addressing the problem of polyiodide shuttling and the instability of the zinc anode interface has become a research focus to improve the performance of zinc-iodine batteries. Several strategies have been proposed to address these issues. For example, carbonaceous host materials have been used to adsorb iodide, thereby suppressing the shuttling effect. However, the physical adsorption between these carbon materials and iodide is usually too weak to prevent the shuttling effect over extended cycling periods. Other approaches, including the use of highly concentrated or gel electrolytes to reduce the dissolution of polyiodides, have been explored. Although these electrolytes can alleviate the shuttling effect to some extent, their high viscosity hinders the Zn 2+ The diffusion of ions slows down the reaction kinetics, thus limiting their overall effectiveness. In addition, constructing protective layers (such as zeolite layers or zinc silicate layers) on the surface of zinc anodes has shown promise in reducing parasitic reactions and promoting uniform zinc deposition. However, these artificial interfacial layers usually require complex manufacturing processes, and it remains challenging to achieve reliable and uniform coatings on a large scale. Among these strategies, electrolyte additive engineering is considered to be a simple, effective and low-cost strategy that is promising in optimizing the Zn nucleation / deposition process and improving anode side reactions. Summary of the invention

[0004] In view of this, the present application provides an aqueous zinc-iodine battery electrolyte containing a phenolic additive, a preparation method and an application thereof. By adding a phenolic additive to the electrolyte, the shuttling of polyiodides and the large generation of negative electrode by-products can be effectively inhibited, so that the aqueous zinc-iodine battery can obtain high stability, high rate performance and long cycle life, and can effectively overcome the defects of serious polyiodide shuttling and negative electrode by-products existing in the existing aqueous zinc-iodine batteries.

[0005] In a first aspect of the present application, an aqueous zinc-iodine battery electrolyte containing a phenolic additive is provided, which includes a phenolic additive, deionized water and a zinc salt.

[0006] Preferably, the phenolic additive is selected from at least one of phenol, resorcinol, hydroquinone, and phloroglucinol.

[0007] Preferably, the weight percentage of the phenolic additive in the aqueous zinc-iodine battery electrolyte is 0.05 - 0.5 wt.%. Preferably, the weight percentage of the phenolic additive in the aqueous zinc-iodine battery electrolyte is 0.1 wt.%.

[0008] Preferably, the zinc salt is selected from at least one of zinc trifluoromethanesulfonate, zinc sulfate, and zinc chloride. Preferably, the zinc salt is zinc sulfate.

[0009] Preferably, the concentration of the zinc salt is 1 - 3 mol / L. Preferably, the concentration of the zinc salt is 2 mol / L.

[0010] The theoretical support of the technical solution of the present application: The phenolic additive is uniformly dispersed in the electrolyte. The electrostatic potential of the hydroxyl group on the benzene ring is negative, which is easy to give electrons and has strong oxidation ability, and can accelerate the conversion of I3 - →I - , reduce the concentration of polyiodides in the electrolyte, and block the shuttling behavior of anionic iodine species (I - / I3 - / I5 - ). The polar hydroxyl group on the benzene ring can also generate ion-dipole interaction with the adjacent H + ions. This interaction can effectively anchor polyiodides by the phenolic additive monomer and effectively adsorb polyiodides. During the battery cycle, the polyiodides generated at the positive electrode cannot shuttle to the negative electrode. The phenolic additive monomer preferentially adsorbs on the surface of the zinc negative electrode to form a solid electrolyte interface (SEI), reducing the contact between Zn 2+ in the solution and the interfacial H2O molecules, and inhibiting the generation of related by-products at the zinc negative electrode interface. The zinc-iodine battery prepared with the electrolyte containing the phenolic additive has ultra-high cycle stability and long cycle life, enabling the zinc-iodine battery to better meet commercial requirements.

[0011] The second aspect of the present application also provides a method for preparing the above-mentioned aqueous zinc-iodine battery electrolyte containing phenolic additives, comprising the following steps:

[0012] The zinc salt and the phenolic additive are dissolved in deionized water, and the mixture is fully stirred to obtain an aqueous zinc-iodine battery electrolyte containing the phenolic additive.

[0013] Preferably, the stirring time is 30 min.

[0014] Specifically, the method comprises the following specific preparation steps:

[0015] (1) Under normal pressure, prepare a 2 mol / L zinc sulfate solution for standby use;

[0016] (2) Weigh a certain amount of the 2 mol / L zinc sulfate solution in (1) into a beaker, then add 0.1 wt.% of a phenolic agent, add a stirring magnet and stir thoroughly for 30 min to form a uniform solution, i.e., an aqueous zinc-iodine battery electrolyte containing a phenolic additive.

[0017] The third aspect of the present application also provides a zinc-iodine battery, comprising a positive electrode plate, a negative electrode plate, a separator arranged between the positive electrode plate and the negative electrode plate, and an electrolyte, wherein the electrolyte is the above-mentioned aqueous zinc-iodine battery electrolyte containing phenolic additives.

[0018] Preferably, the negative electrode plate is a metal zinc plate; and

[0019] The preparation process of the positive electrode plate is as follows: (1) uniformly mixing iodine element and ultra-high capacity conductive carbon UAC in a mass ratio of 1:1, calcining at 120°C for 6 hours to form a carbon-supported iodine material AC / I2; (2) uniformly mixing the carbon-supported iodine material, conductive agent Ketjen black, and polytetrafluoroethylene PTFE in a mass ratio of 7:2:1, adding a small amount of water, mixing to form a uniform black paste slurry, coating the slurry on a stainless steel mesh, and naturally drying in air to obtain a positive electrode plate.

[0020] Preferably, the diaphragm is made of glass fiber.

[0021] Compared with the prior art, this application has the following beneficial effects:

[0022] The phenolic additives used in this application can accelerate I3 - →I - The transformation accelerates the iodine conversion reaction kinetics and reduces the generation of polyiodides, thereby achieving very effective inhibition of the shuttling of polyiodides. The phenolic additive monomer is adsorbed on the surface of the zinc negative electrode, reducing the Zn 2+ The contact with water molecules inhibits the generation of zinc negative electrode byproducts. On the other hand, the zinc-iodine battery of the present application also has the advantages of easy manufacturing and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] To more clearly illustrate the technical solutions in the present application or the prior art, the following will briefly introduce the drawings required for the description of the present application or the prior art. Obviously, the drawings in the following description are some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0024] Figure 1 Cycling performance graph of a zinc-iodine battery assembled with an electrolyte prepared using a phenol additive at a current density of 1 A / g;

[0025] Figure 2 Cycling performance graph of a zinc-iodine battery assembled with an electrolyte prepared using a resorcinol additive at a current density of 1 A / g;

[0026] Figure 3 Cycling performance graph of a zinc-iodine battery assembled with an electrolyte prepared using a hydroquinone additive at a current density of 1 A / g;

[0027] Figure 4 Cycling performance graph of a zinc-iodine battery assembled with an electrolyte prepared using a phloroglucinol additive at a current density of 1 A / g. Detailed implementation manners

[0028] To make the objectives, technical solutions, and advantages of the present application clearer, the following will clearly and completely describe the technical solutions in the present application in conjunction with the drawings in the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art without creative efforts based on the embodiments in the present application fall within the scope of protection of the present application.

[0029] The experimental methods used in the embodiments of the present application are all conventional methods unless otherwise specified.

[0030] In the following embodiments, unless otherwise specified, all raw materials can be obtained through commercial purchase or conventional methods.

[0031] Example 1

[0032] First, zinc sulfate was dissolved in deionized water to prepare a 2 M zinc sulfate electrolyte. 5 mL of the 2 M zinc sulfate electrolyte (the mass of 1 mL of zinc sulfate is approximately equal to 1.3 g) and 6.5 mg of phenol additive were placed in a beaker, and a magnetic stirrer was added and stirred thoroughly for 30 min to obtain an electrolyte containing the additive. The electrolyte was labeled as 2 M ZnSO4 + 0.1 wt.% PhOH.

[0033] Then, iodine and UAC are mixed evenly in a mass ratio of 1:1 and calcined at 120 °C for 6 h to obtain AC / I2. Then, AC / I2, conductive agent Ketjenblack, and PTFE are evenly mixed in a mass ratio of 7:2:1, a small amount of water is added and stirred into a slurry, which is evenly spread on a circular steel mesh with a diameter of 12 mm and naturally dried in the air to prepare the positive electrode sheet.

[0034] Finally, a 12-mm circular zinc sheet is used as the negative electrode, a separator made of glass fiber, 2M ZnSO4 + 0.1 wt.% PhOH is used as the electrolyte, and the electrode sheet carrying 10% PTFE binder is used as the positive electrode to assemble a button zinc-iodine battery. As Figure 1 shown, the prepared battery has a high reversible capacity of 125.5 mAh / g and a high capacity retention rate of 79.3% after 800 cycles at a current density of 1 A / g.

[0035] Example 2

[0036] First, zinc sulfate is dissolved in deionized water to prepare a 2M zinc sulfate electrolyte. Take 5 mL of 2M zinc sulfate electrolyte (the mass of 1 mL of zinc sulfate is approximately equal to 1.3 g) and 6.5 mg of resorcinol additive in a beaker, add a magnetic stirrer and stir well for 30 min to obtain an electrolyte containing the additive, and mark the electrolyte as 2M ZnSO4 + 0.1 wt.% RSC.

[0037] Then, iodine and UAC are mixed evenly in a mass ratio of 1:1 and calcined at 120 °C for 6 h to obtain AC / I2. Then, AC / I2, conductive agent Ketjenblack, and PTFE are evenly mixed in a mass ratio of 7:2:1, a small amount of water is added and stirred into a slurry, which is evenly spread on a circular steel mesh with a diameter of 12 mm and naturally dried in the air to prepare the positive electrode sheet.

[0038] Finally, a 12-mm circular zinc sheet is used as the negative electrode, a separator made of glass fiber, 2M ZnSO4 + 0.1 wt.% RSC is used as the electrolyte, and the electrode sheet carrying 10% PTFE binder is used as the positive electrode to assemble a button zinc-iodine battery. As Figure 2 shown, the prepared battery has a high reversible capacity of 141.1 mAh / g and a high capacity retention rate of 89.2% after 800 cycles at a current density of 1 A / g.

[0039] Example 3

[0040] First, zinc sulfate was dissolved in deionized water to prepare a 2M zinc sulfate electrolyte solution. 5 mL of the 2M zinc sulfate electrolyte solution (the mass of 1 mL of zinc sulfate is approximately equal to 1.3 g) and 6.5 mg of hydroquinone additive were placed in a beaker, and a magnetic stir bar was added and stirred thoroughly for 30 min to obtain an electrolyte solution containing the additive. The electrolyte solution was labeled as 2M ZnSO4 + 0.1 wt.% HQ.

[0041] Then, iodine and UAC were mixed evenly in a mass ratio of 1:1 and calcined at 120 °C for 6 h to obtain AC / I2. Then, AC / I2, conductive agent Ketjenblack, and PTFE were evenly mixed in a mass ratio of 7:2:1, a small amount of water was added and stirred into a slurry, and the slurry was evenly spread on a circular steel mesh with a diameter of 12 mm and naturally dried in air to prepare the positive electrode plate.

[0042] Finally, a 12-mm round zinc sheet was used as the negative electrode, a separator made of glass fiber, 2M ZnSO4 + 0.1 wt.% HQ was used as the electrolyte, and the electrode plate carrying 10% PTFE binder was used as the positive electrode to assemble a button zinc-iodine battery. As Figure 3 shown, the prepared battery had a high reversible capacity of 139.1 mAh / g and a high capacity retention rate of 84.7% after 800 cycles at a current density of 1 A / g.

[0043] Example 4

[0044] First, zinc sulfate was dissolved in deionized water to prepare a 2M zinc sulfate electrolyte solution. 5 mL of the 2M zinc sulfate electrolyte solution (the mass of 1 mL of zinc sulfate is approximately equal to 1.3 g) and 6.5 mg of phloroglucinol additive were placed in a beaker, and a magnetic stir bar was added and stirred thoroughly for 30 min to obtain an electrolyte solution containing the additive. The electrolyte solution was labeled as 2M ZnSO4 + 0.1 wt.% PG.

[0045] Then, iodine and UAC were mixed evenly in a mass ratio of 1:1 and calcined at 120 °C for 6 h to obtain AC / I2. Then, AC / I2, conductive agent Ketjenblack, and PTFE were evenly mixed in a mass ratio of 7:2:1, a small amount of water was added and stirred into a slurry, and the slurry was evenly spread on a circular steel mesh with a diameter of 12 mm and naturally dried in air to prepare the positive electrode plate.

[0046] Finally, a 12-mm round zinc sheet was used as the negative electrode, a separator made of glass fiber, 2M ZnSO4 + 0.1 wt.% PG was used as the electrolyte, and the electrode plate carrying 10% PTFE binder was used as the positive electrode to assemble a button zinc-iodine battery. As Figure 4 shown, the prepared battery was damaged and short-circuited after 450 cycles at a current density of 1 A / g, and had a high reversible capacity of 148.2 mAh / g and a high capacity retention rate of 87.1%.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than limiting them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. An aqueous zinc-iodine battery electrolyte containing phenolic additives, characterized in that, It includes phenolic additives, deionized water and zinc salts.

2. The aqueous zinc-iodine battery electrolyte containing a phenolic additive according to claim 1, wherein The phenolic additives are selected from at least one of phenol, resorcinol, hydroquinone, and phloroglucinol.

3. The aqueous zinc-iodine battery electrolyte containing phenolic additives according to claim 1, characterized in that, The weight percentage of the phenolic additives in the aqueous zinc-iodine battery electrolyte is 0.05 - 0.5 wt.%.

4. The aqueous zinc-iodine battery electrolyte containing a phenolic additive according to claim 1, wherein, The zinc salts are selected from at least one of zinc trifluoromethanesulfonate, zinc sulfate, and zinc chloride.

5. The aqueous zinc-iodine battery electrolyte containing phenolic additives according to claim 1, wherein The concentration of the zinc salts is 1 - 3 mol / L.

6. A method for preparing an aqueous zinc-iodine battery electrolyte containing a phenolic additive according to any one of claims 1 to 5, characterized in that, It includes the following steps: Dissolve the zinc salts and phenolic additives in deionized water, and stir and mix well to obtain an aqueous zinc-iodine battery electrolyte containing phenolic additives.

7. The preparation method of the aqueous zinc-iodine battery electrolyte containing phenolic additives according to claim 6, characterized in that, The stirring time is 30 min.

8. A zinc-iodine battery, comprising a positive electrode plate, a negative electrode plate, a separator disposed between the positive electrode plate and the negative electrode plate, and an electrolyte, characterized in that, The electrolyte is the aqueous zinc-iodine battery electrolyte containing phenolic additives according to any one of claims 1 - 5.

9. The zinc-iodine battery according to claim 8, characterized in that, The negative electrode plate is a metal zinc sheet; and The preparation process of the positive electrode plate is as follows: (1) Mix iodine and ultra-high-capacity conductive carbon UAC evenly according to a mass ratio of 1:1, and calcine at 120 °C for 6 h to form a carbon-supported iodine material AC / I2; (2) Mix the carbon-supported iodine material, conductive agent Ketjenblack, and polytetrafluoroethylene PTFE evenly according to a mass ratio of 7:2:1, add a small amount of water, and mix to form a uniform black paste-like slurry. Coat the slurry on a stainless steel mesh and dry it naturally in the air to obtain the positive electrode plate.

10. The zinc-iodine battery according to claim 8, characterized in that, The separator is made of glass fiber.

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