Self-deoxygenating electrolyte additive, electrolyte and zinc metal battery for zinc metal battery

Abstract

The application provides a self-deoxidizing electrolyte additive of a zinc metal battery, wherein the redox potential of the self-deoxidizing electrolyte additive is between the redox potential of zinc metal and the redox potential of oxygen, and the concentration in the electrolyte is 0.1 mM-10 mM; the electrolyte comprises water. The application also provides an electrolyte of a zinc metal battery and a zinc metal battery. The application provides a self-deoxidizing electrolyte additive of a zinc metal battery, which can effectively alleviate the corrosion problem caused by dissolved oxygen, improve the cycle stability of a zinc metal negative electrode, and the self-deoxidizing electrolyte additive can be immediately assembled and take effect in the zinc metal battery, so that the zinc metal battery can be simply assembled in air.

Description

Technical Field

[0001] This invention relates to the field of energy storage technology, and in particular to a self-deoxygenating electrolyte additive for zinc metal batteries, an electrolyte, and a zinc metal battery. Background Technology

[0002] Zinc metal batteries contain water in their electrolyte and zinc as the negative electrode, allowing for direct assembly in air. This offers advantages such as ease of assembly, environmental friendliness, and low cost. However, during this simple assembly process, oxygen dissolves into the electrolyte and saturates it. Because oxygen has strong oxidizing properties, it reacts directly with the zinc in the electrolyte, accelerating corrosion and causing the accumulation of numerous porous, insulating byproducts. This reduces the stability of the zinc negative electrode and affects the battery's cycle life.

[0003] To reduce corrosion caused by dissolved oxygen and improve the cycle stability of zinc metal batteries, electrolyte deoxygenation is essential. Currently, technologies for removing dissolved oxygen from electrolytes can be mainly divided into two types: physical methods and chemical methods. Physical deoxygenation includes methods such as passing inert gas into the electrolyte, boiling, and ultrasonication; chemical deoxygenation mainly involves adding reducing substances to the electrolyte as deoxygenating agents.

[0004] The main principle of physical deoxygenation lies in reducing the solubility of oxygen in the electrolyte. Introducing an inert gas into the electrolyte utilizes Henry's Law to lower the partial pressure of oxygen above the electrolyte surface, thus reducing its solubility and achieving deoxygenation. Boiling utilizes the relationship between oxygen solubility and temperature; as temperature increases, the solubility of oxygen in the electrolyte decreases, thereby removing dissolved oxygen. Some researchers have also adjusted the electrolyte to a high concentration, reducing the free water content to decrease dissolved oxygen solubility and diffusion coefficient. Ultrasonic deoxygenation is mainly based on the principle of acoustic cavitation, which reduces local pressure in the liquid, forming bubbles or cavities around tiny gas nuclei. These bubbles undergo strong growth and closure movements in response to changes in sound pressure until they finally collapse, allowing gas to escape and achieving deoxygenation.

[0005] Chemical deoxygenation is primarily achieved through the reduction reaction of dissolved oxygen. Currently, conventional chemical deoxygenation technology involves adding reducing agents to the electrolyte, which reduce dissolved oxygen at room temperature, thereby lowering the dissolved oxygen content of the electrolyte. It should be noted that such deoxygenating agents must ensure that the reaction products do not adversely affect the electrochemical performance of the battery.

[0006] The physical deoxygenation methods described above typically suffer from drawbacks such as being time-consuming, energy-intensive, costly, complex to operate, and incomplete in deoxygenation, making them unsuitable for commercial applications. While chemical deoxygenation overcomes some of the shortcomings of physical deoxygenation, the dosage of different chemical deoxygenating agents in different electrolytes needs to be determined through experimentation. Furthermore, all the methods described above are one-time deoxygenation technologies; the deoxygenated electrolyte must be sealed and stored in air to prevent the re-dissolution of atmospheric oxygen. During the assembly of zinc metal batteries in air, atmospheric oxygen remains highly soluble in the electrolyte, causing corrosion of the zinc metal negative electrode. However, a major advantage of zinc metal batteries is their ease of assembly in air, making it impossible to avoid the re-dissolution of atmospheric oxygen in the electrolyte during this process. Unless the storage of the electrolyte and the assembly of the battery are entirely transferred to a glove box or an inert atmosphere, the dissolved oxygen problem will always exist, hindering the commercial application of zinc metal batteries.

[0007] Therefore, there is an urgent need to propose a simple deoxygenation method that can effectively eliminate or mitigate a series of corrosion hazards caused by dissolved oxygen while retaining the advantages of easy assembly of zinc metal in air, thereby improving the stability of zinc metal in electrolyte and battery life. Summary of the Invention

[0008] The technical problem solved by this invention is to provide a self-oxygenating electrolyte additive for zinc metal batteries. The self-oxygenating electrolyte additive for zinc metal batteries provided in this application can effectively alleviate the corrosion problem caused by dissolved oxygen, effectively improve the stability of the zinc negative electrode in the electrolyte, and improve the cycle life of zinc metal batteries.

[0009] In view of this, this application provides a self-removing electrolyte additive for zinc metal batteries, wherein the redox potential of the self-removing electrolyte additive is located between the redox potential of zinc metal and the redox potential of oxygen, and the concentration in the electrolyte is 0.1 mM to 10 mM; the electrolyte includes water.

[0010] Preferably, the concentration of the self-deoxygenating electrolyte additive in the electrolyte is 1 mM to 3 mM.

[0011] Preferably, the self-deoxygenating electrolyte additive is selected from quinones, anthraquinones, phenazines, and I3. - / I - Br3 - / Br - and Fe 3+ / Fe 2+ One or more of them.

[0012] Preferably, the self-deoxygenating electrolyte additive is selected from one or more of anthraquinone-2-sulfonate sodium salt, 1,2-naphthoquinone-4-sulfonate sodium salt, 7,8-dihydroxyphenazine-2-sulfonic acid, anthraquinone, and phenothiazine.

[0013] This application also provides an electrolyte for a zinc metal battery, comprising an initial electrolyte and a self-deoxygenating electrolyte additive, wherein the initial electrolyte comprises water, and the self-deoxygenating electrolyte additive is the self-deoxygenating electrolyte additive for the zinc metal battery.

[0014] Preferably, the electrolyte is prepared by:

[0015] The self-deoxygenating electrolyte additive is added to the initial electrolyte.

[0016] Preferably, the concentration of the self-deoxygenating electrolyte additive in the electrolyte is 1-3 mM.

[0017] Preferably, the self-deoxygenating electrolyte additive is selected from quinones, anthraquinones, phenazines, and I3. - / I - Br3 - / Br - and Fe 3+ / Fe 2+ One or more of them.

[0018] Preferably, the self-deoxygenating electrolyte additive is selected from one or more of anthraquinone-2-sulfonate sodium salt, 1,2-naphthoquinone-4-sulfonate sodium salt, 7,8-dihydroxyphenazine-2-sulfonic acid, anthraquinone, and phenothiazine.

[0019] This application also provides a zinc metal battery, including a positive electrode, a negative electrode, and an electrolyte, characterized in that the electrolyte is the electrolyte described above.

[0020] This application provides a self-removing oxygen electrolyte additive for zinc metal batteries, which has the following characteristics: the redox potential of the self-removing oxygen electrolyte additive is located between the redox potential of zinc metal and the redox potential of oxygen, and its concentration in the electrolyte is 0.1 mM to 10 mM; the self-removing oxygen electrolyte additive in this application initiates the oxygen removal reaction with the help of zinc metal. After the additive comes into contact with zinc metal in the electrolyte, it is transformed into a reduced state and diffuses into the electrolyte liquid phase, and the oxygen removal reaction begins immediately; dissolved oxygen diffuses slowly in the electrolyte, so it has been reacted by the reduced oxygen remover before reaching the zinc metal interface, thereby transferring the site of the dissolved oxygen reduction reaction from the negative electrode-electrolyte interface to the electrolyte liquid phase, and the OH- obtained from the reduction of dissolved oxygen... - The byproduct precipitation threshold is not reached after dilution by the electrolyte phase, thus effectively mitigating a series of corrosion hazards caused by dissolved oxygen, effectively improving the stability of the zinc anode in the electrolyte, and improving the cycle life of the zinc metal battery.

[0021] Furthermore, since the self-oxygen-removing electrolyte additive of this application is in an oxidized state, the electrolyte after adding the additive can be left open in the air without the disadvantages of being oxidized and degraded by oxygen in the air. Moreover, the assembly of zinc metal batteries can also be carried out in the air. The oxygen removal of the additive has the advantages of immediate assembly and immediate effect, which maximizes the storage of electrolyte in the air and the advantages of easy assembly of zinc metal batteries in the air, while reducing the corrosion hazards of dissolved oxygen, providing a reference for the subsequent commercial application of zinc metal batteries. Attached Figure Description

[0022] Figure 1 A schematic diagram illustrating the principle of adding self-deoxygenating electrolyte additives to blank electrolyte and the electrolyte of the present invention;

[0023] Figure 2 SEM images of the zinc metal surface morphology for the blank aqueous electrolyte and the electrolyte provided in Example 1;

[0024] Figure 3 Cyclic stability curves for the blank aqueous electrolyte and the electrolyte provided in Example 1. Detailed Implementation

[0025] To further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the scope of the claims of the present invention.

[0026] Abandoning the complex and incomplete traditional one-time deoxygenation technology of existing technologies, this application provides a chemical self-deoxygenating electrolyte additive, which can effectively alleviate corrosion problems caused by dissolved oxygen, improve the cycle stability of zinc metal anodes, and is immediately effective upon assembly in zinc metal batteries, allowing for easy assembly of zinc metal batteries in air. Specifically, this invention discloses a self-deoxygenating electrolyte additive for zinc metal batteries, wherein the redox potential of the self-deoxygenating electrolyte additive is located between the redox potential of zinc metal and the redox potential of oxygen, and its concentration in the electrolyte is 0.1 mM to 10 mM; the electrolyte includes water.

[0027] The self-deoxygenating electrolyte additive for zinc metal batteries provided in this application has the following characteristics: 1) the oxidation-reduction potential is located between the oxidation-reduction potential of zinc metal and the oxidation-reduction potential of oxygen; 2) it has good solubility in the electrolyte and the addition concentration is 0.1mM to 10mM.

[0028] The self-deoxygenating electrolyte additive described in this application must simultaneously meet the above conditions to achieve the following effects: The deoxygenation reaction is initiated by zinc metal. Upon contact with zinc metal in the electrolyte, the additive transforms into a reduced state and diffuses into the electrolyte liquid phase, thus initiating the deoxygenation reaction. Dissolved oxygen diffuses slowly in the electrolyte, so it is reduced by the reduced oxygen scavenger before reaching the zinc metal interface. This shifts the site of dissolved oxygen reduction from the negative electrode-electrolyte interface to the electrolyte liquid phase, while the OH- obtained from the reduction of dissolved oxygen... - By diluting the liquid phase through electrolysis to prevent the byproduct precipitation threshold from being reached, a series of corrosion hazards caused by dissolved oxygen can be effectively mitigated.

[0029] The mechanism diagram of the self-oxygen-removing electrolyte additive in the electrolyte is as follows: Figure 1 As shown (taking the ZnSO4 electrolyte system as an example), specifically: in the blank electrolyte, dissolved oxygen undergoes a reduction reaction at the negative electrode-electrolyte interface, while the generated OH... - After accumulating at the interface, with Zn 2+ and SO4 2- The formation of basic zinc sulfate byproducts affects the stability of the zinc anode, exacerbating dendrite growth and battery performance degradation. In contrast, within the assembled sealed battery system, the functional self-oxygenating electrolyte additive reacts with metallic zinc to transform it into a reduced state. This reduced state then reacts with dissolved oxygen in the electrolyte, shifting the oxygen reduction reaction from the anode-electrolyte interface to the electrolyte phase. This effectively avoids the pH increase and the formation and accumulation of basic zinc sulfate byproducts caused by dissolved oxygen reduction at the anode-electrolyte interface. Furthermore, the OH- ions obtained from the reduction of dissolved oxygen... - After dilution in the electrolyte phase, the pH will not reach the critical pH for basic zinc sulfate precipitation. Therefore, it can effectively alleviate a series of corrosion hazards caused by dissolved oxygen, such as the accumulation of byproducts, and effectively improve the stability of the zinc anode in the electrolyte, thereby increasing the cycle life of the zinc metal battery. It should be noted that after this reduced-state additive reduces dissolved oxygen, it will return to the oxidized state. Therefore, the oxygen removal effect of this additive is reversible, and a very small amount can remove a large amount of oxygen present in the electrolyte.

[0030] Furthermore, the concentration of the self-deoxygenating electrolyte additive described in this application in the electrolyte is 1 to 3 mM.

[0031] The self-removing oxygen electrolyte additives described in this application include, but are not limited to, quinones, anthraquinones, phenazines, and I3. - / I - Br3 - / Br - and Fe 3+ / Fe 2+More specifically, the self-deoxygenating electrolyte additive is selected from one or more of anthraquinone-2-sulfonate sodium salt, 1,2-naphthoquinone-4-sulfonate sodium salt, 7,8-dihydroxyphenazine-2-sulfonic acid, anthraquinone, and phenothiazine.

[0032] This application also provides an electrolyte for a zinc metal battery, comprising an initial electrolyte and a self-deoxygenating electrolyte additive, wherein the initial electrolyte comprises water, and the self-deoxygenating electrolyte additive is the self-deoxygenating electrolyte additive for the zinc metal battery described in the above-mentioned scheme.

[0033] In this application, the method for preparing the electrolyte is as follows:

[0034] The self-deoxygenating electrolyte additive is added to the initial electrolyte and dispersed evenly.

[0035] Since the self-oxygen-removing electrolyte additive is in an oxidized state, it will not directly react with dissolved oxygen in the electrolyte. Instead, it first reacts with metallic zinc to transform into a reduced state before reducing the dissolved oxygen. Therefore, the electrolyte with the self-oxygen-removing electrolyte additive can be left open in the air without sealing, and it does not suffer from the disadvantages of being oxidized and degraded by oxygen in the air. Furthermore, the assembly of zinc metal batteries can also be carried out in the air.

[0036] In this application, the initial electrolyte is an electrolyte well known to those skilled in the art, and its solvent is water or a hydrated organic solvent. That is, the initial electrolyte can be an aqueous electrolyte or a hydrated organic electrolyte. For example, the initial electrolyte is a ZnSO4 aqueous electrolyte or a Zn(BF4)2 hydrated organic electrolyte.

[0037] As described above, the self-deoxygenating electrolyte additives include, but are not limited to, quinones, anthraquinones, phenazines, and I3. - / I - Br3 - / Br - and Fe 3+ / Fe 2+ More specifically, the self-deoxygenating electrolyte additive is selected from one or more of anthraquinone-2-sulfonate sodium salt, 1,2-naphthoquinone-4-sulfonate sodium salt, 7,8-dihydroxyphenazine-2-sulfonic acid, anthraquinone, and phenothiazine.

[0038] This application also provides a zinc metal battery, including a positive electrode, a negative electrode, and an electrolyte, wherein the electrolyte is the electrolyte described in the above-mentioned scheme.

[0039] In the zinc metal battery described in this application, the positive electrode and the negative electrode are well known to those skilled in the art, and this application does not impose any special limitations on them.

[0040] To further understand the present invention, the following detailed description of the self-oxygenating electrolyte additive for zinc metal batteries and the zinc metal battery provided by the present invention is provided in conjunction with embodiments. The scope of protection of the present invention is not limited by the following embodiments.

[0041] Example 1

[0042] The use of anthraquinone-2-sulfonate sodium salt (AQS) as a functional self-deoxygenating electrolyte additive was validated.

[0043] AQS was added to a 1M ZnSO4 aqueous electrolyte and the concentration was adjusted to 1mM. The AQS was dispersed and dissolved by ultrasound for several seconds until the electrolyte was clear and transparent. A 1M ZnSO4 aqueous electrolyte without additives was used as a control. The ability of AQS to mitigate dissolved oxygen corrosion was determined by scanning the surface morphology of zinc foil after soaking in different electrolytes for 3 days. Symmetrical cells were assembled in air for cycle stability testing.

[0044] Zinc foil was immersed for three days in both 1M aqueous ZnSO4 electrolyte and ZnSO4 electrolyte with added AQS. Scanning images were taken to observe the surface morphology of the zinc metal, and the corrosion status was determined by the accumulation of byproducts. Figure 2 As shown in the left figure, a large number of loose lamellae accumulated on the surface of the zinc foil in the 1MZnSO4 aqueous electrolyte, which are corrosion byproducts, proving that the zinc metal corrosion is severe in the electrolyte without additives; in contrast, as Figure 2 As shown in the right figure, under the action of AQS, the accumulation of by-products on the zinc foil surface is significantly reduced, and the zinc foil is flat overall, proving that AQS can effectively reduce the accumulation of by-products on the zinc anode surface.

[0045] Using glass fiber filter paper (GF / A) as the separator, the cycle stability of CR2032 coin cells was tested by directly assembling them in air.

[0046] like Figure 3 As shown, at 2mA cm -2 Current density and 2mAh cm -2 Under the given areal capacity conditions, the unadded symmetric cell experienced a short circuit in about 150 hours due to corrosion caused by dissolved oxygen and dendrite growth. In contrast, the symmetric cell with AQS additive achieved a stable cycle time of nearly 1000 hours, demonstrating that this oxygen scavenger effectively alleviated zinc metal corrosion caused by dissolved oxygen and significantly improved the cycle stability of zinc metal in the electrolyte.

[0047] Example 2

[0048] Add 1 mM sodium 1,2-naphthoquinone-4-sulfonate to a 1 M ZnSO4 aqueous electrolyte and disperse evenly. The resulting electrolyte can be left exposed to air for subsequent battery assembly and electrochemical performance testing.

[0049] Example 3

[0050] Add 3 mM 7,8-dihydroxyphenazine-2-sulfonic acid to a 1M ZnSO4 aqueous electrolyte and disperse evenly. The resulting electrolyte can be left exposed to air for subsequent battery assembly and electrochemical performance testing.

[0051] Example 4

[0052] Add 1 mM anthraquinone to 4 mZn(BF4)2 hydrated organic electrolyte (ethylene glycol and water are solvents) and disperse evenly. The resulting electrolyte can be used for subsequent battery assembly and electrochemical performance testing after being left open to the air.

[0053] Example 5

[0054] Add 1 mM phenothiazine to 4 m Zn(BF4)2 hydrated organic electrolyte (ethylene glycol and water are solvents) and disperse evenly. The resulting electrolyte can be used for subsequent battery assembly and electrochemical performance testing after being left open to the air.

[0055] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0056] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A self-oxygen-removing electrolyte additive for zinc metal batteries, characterized in that, The self-deoxygenating electrolyte additive is in an oxidized state, and its redox potential is located between the zinc metal redox potential and the oxygen redox potential, and its concentration in the electrolyte is 0.1 mM to 10 mM; the electrolyte includes water.

2. The self-deoxygenating electrolyte additive according to claim 1, characterized in that, The concentration of the self-deoxygenating electrolyte additive in the electrolyte is 1mM~3mM.

3. The self-deoxygenating electrolyte additive according to claim 1, characterized in that, The self-removing oxygen electrolyte additive is selected from quinones, anthraquinones, phenazines, and I3. - / I - Br3 - / Br - and Fe 3+ / Fe 2+ One or more of them.

4. The self-deoxygenating electrolyte additive according to claim 1, characterized in that, The self-deoxygenating electrolyte additive is selected from one or more of anthraquinone-2-sulfonate sodium salt, 1,2-naphthoquinone-4-sulfonate sodium salt, 7,8-dihydroxyphenazine-2-sulfonic acid, anthraquinone, and phenothiazine.

5. An electrolyte for a zinc metal battery, comprising an initial electrolyte and a self-deoxygenating electrolyte additive, wherein the initial electrolyte comprises water, and the self-deoxygenating electrolyte additive is the self-deoxygenating electrolyte additive for a zinc metal battery according to any one of claims 1 to 4.

6. The electrolyte according to claim 5, characterized in that, The electrolyte is prepared by: The self-deoxygenating electrolyte additive is added to the initial electrolyte.

7. The electrolyte according to claim 5, characterized in that, The concentration of the self-deoxygenating electrolyte additive in the electrolyte is 1~3mM.

8. The electrolyte according to claim 5, characterized in that, The self-removing oxygen electrolyte additive is selected from quinones, anthraquinones, phenazines, and I3. - / I - Br3 - / Br - and Fe 3+ / Fe 2+ One or more of them.

9. The electrolyte according to claim 5, characterized in that, The self-deoxygenating electrolyte additive is selected from one or more of anthraquinone-2-sulfonate sodium salt, 1,2-naphthoquinone-4-sulfonate sodium salt, 7,8-dihydroxyphenazine-2-sulfonic acid, anthraquinone, and phenothiazine.

10. A zinc metal battery, comprising a positive electrode, a negative electrode, and an electrolyte, characterized in that, The electrolyte is the electrolyte according to any one of claims 5 to 9.

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