Halogen ion-based electrolyte for realizing secondary zinc-copper battery

Abstract

The invention relates to the technical field of aqueous secondary batteries, in particular to a halide ion-based electrolyte for realizing a secondary zinc-copper battery, and the halide ion-based electrolyte comprises deionized water and a zinc salt containing halide anions; and the concentration of the zinc salt containing halogen anions in the halogen ion-based electrolyte is 3 mol.L <-1 > to 15 mol.L <-1 >. The halide ion-based electrolyte can simplify the structure of the battery, so that the positive electrode and the negative electrode are soaked in the electrolyte with uniform components, a salt bridge does not need to be added, and a large battery can be assembled in the form of a soft package battery; secondly, the existence of halogen ions can change the reaction mechanism of the zinc-copper battery, so that the original two-phase conversion reaction between metal copper and copper ions dissolved in electrolyte is changed into solid-phase conversion reaction between solid copper and copper halide, the copper ions are prevented from being released into the electrolyte, and the service life of the zinc-copper battery is prolonged. Therefore, loss of copper ions for storing electric energy and corrosion of the zinc negative electrode caused by side reaction with the zinc negative electrode are avoided, and a primary zinc-copper battery is transformed into a secondary zinc-copper battery with high reversibility.

Description

Technical Field

[0001] The present invention relates to the technical field of aqueous secondary batteries, and in particular to a halogen ion-based electrolyte for realizing a secondary zinc-copper battery. Background Art

[0002] The zinc-copper battery is a battery system with a long history. It has been invented for nearly 200 years since 1836. It consists of a copper metal positive electrode, a zinc metal negative electrode and an aqueous electrolyte. It has the advantages of low cost, environmental friendliness and high safety. However, traditional zinc-copper batteries still have the following disadvantages:

[0003] On the one hand, the structure of zinc-copper batteries is relatively complex. They are composed of two electrolytes, copper sulfate solution and zinc sulfate solution. The metal copper and metal zinc are immersed in their respective sulfate solutions and connected by salt bridges, which makes it difficult to make large batteries that can be used in practice. On the other hand, zinc-copper batteries are primary batteries and cannot perform reversible charge and discharge operations. If the discharged zinc-copper battery is charged, the copper ions in the copper sulfate solution will enter the zinc sulfate solution and react with zinc, causing severe corrosion of the zinc negative electrode and failure of the entire battery.

[0004] Therefore, the prior art still needs to be improved and developed. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, an object of the present invention is to provide a halogen ion-based electrolyte for realizing a secondary zinc-copper battery, aiming to solve the problem that the existing electrolyte cannot meet the needs of large-scale aqueous secondary batteries and cannot perform reversible charge and discharge.

[0006] The technical solution of the present invention is as follows:

[0007] A halogen ion-based electrolyte for realizing a secondary zinc-copper battery, comprising deionized water and a zinc salt containing a halogen anion; the concentration of the zinc salt containing a halogen anion in the halogen ion-based electrolyte is 3 mol·L -1 -15mol·L -1 .

[0008] The halogen ion-based electrolyte for realizing a secondary zinc-copper battery, wherein the concentration of the zinc salt containing halogen anions in the halogen ion-based electrolyte is 5 mol·L -1 -10mol·L -1 .

[0009] The halogen ion-based electrolyte for realizing a secondary zinc-copper battery, wherein the concentration of the zinc salt containing halogen anions in the halogen ion-based electrolyte is 10 mol·L -1 .

[0010] The halogen ion-based electrolyte for realizing a secondary zinc-copper battery, wherein the zinc salt containing halogen anions includes one or more of zinc chloride, zinc bromide, and zinc iodide.

[0011] The halogen ion-based electrolyte for realizing a secondary zinc-copper battery comprises a positive electrode sheet and a negative electrode sheet immersed in the halogen ion-based electrolyte, and a separator arranged between the positive electrode sheet and the negative electrode sheet.

[0012] The halogen ion-based electrolyte for realizing a secondary zinc-copper battery, wherein the diaphragm is selected from one of a glass fiber membrane plus a porous polytetrafluoroethylene membrane and a hydrophilically modified polypropylene membrane.

[0013] Beneficial effect: The present invention provides a halogen ion-based electrolyte for realizing a secondary zinc-copper battery, wherein the halogen ion-based electrolyte comprises deionized water and a zinc salt containing a halogen anion; the concentration of the zinc salt containing a halogen anion in the halogen ion-based electrolyte is 3 mol·L -1 -15mol·L -1 . The halogen ion-based electrolyte provided by the present invention can firstly simplify the battery structure, so that the positive and negative electrodes are immersed in the electrolyte with uniform composition, and no salt bridge is required, and the battery can be assembled into a large battery in the form of a soft-pack battery; secondly, the presence of halogen ions can change the reaction mechanism of the zinc-copper battery, so that the original two-phase conversion reaction between metallic copper and copper ions dissolved in the electrolyte is changed to a solid-phase conversion reaction between copper and copper halide, which are both solids, to avoid the copper ions being released into the electrolyte, thereby avoiding the side reaction with the zinc negative electrode causing the loss of copper ions that store electrical energy and the corrosion of the zinc negative electrode, thereby transforming the primary zinc-copper battery into a secondary zinc-copper battery with high reversibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a charge and discharge curve diagram of the aqueous zinc-copper battery in Example 1 of the present invention;

[0015] Figure 2 The graph is a curve showing the change of the Coulombic efficiency of the aqueous zinc-copper battery as a function of the number of cycles in Example 1 of the present invention;

[0016] Figure 3 : is a typical charge and discharge curve diagram of the aqueous zinc-copper battery in Example 2 of the present invention;

[0017] Figure 4 : is a typical charge and discharge curve diagram of the aqueous zinc-copper battery in Example 3 of the present invention;

[0018] Figure 5 This is a typical charge and discharge curve of the aqueous zinc-copper battery in Example 4 of the present invention. DETAILED DESCRIPTION

[0019] The present invention provides a halogen ion-based electrolyte for realizing a secondary zinc-copper battery. In order to make the purpose, technical solution and effect of the present invention clearer and more specific, the present invention is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0020] It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as generally understood by those skilled in the art in the art to which the present invention belongs. It should also be understood that terms such as those defined in general dictionaries should be understood to have meanings consistent with the meanings in the context of the prior art, and will not be interpreted with idealized or overly formal meanings unless specifically defined as herein.

[0021] The fundamental reason why zinc-copper batteries cannot use a single-component electrolyte and cannot be reversibly charged and discharged is that the oxidizing copper ions cannot coexist with the reducing zinc metal, and a spontaneous redox reaction (Cu 2+ +Zn→Zn 2 +Cu), resulting in the loss of active copper ions and corrosion of the zinc negative electrode.

[0022] Based on this, the present invention provides a halogen ion-based electrolyte for realizing a secondary zinc-copper battery, comprising deionized water and a zinc salt containing a halogen anion; the concentration of the zinc salt containing a halogen anion in the halogen ion-based electrolyte is 3 mol·L -1 -15mol·L -1 .

[0023] In this embodiment, the halogen ion-based electrolyte is used to change the reaction mechanism of the zinc-copper battery, and the halogen ion-based electrolyte can simplify the battery structure, so that the positive and negative electrodes are immersed in the electrolyte with uniform composition, and no salt bridge is required, and the battery can be assembled into a large battery in the form of a soft-pack battery; secondly, the presence of halogen ions can change the reaction mechanism of the zinc-copper battery, so that the original two-phase conversion reaction between metallic copper and copper ions dissolved in the electrolyte is changed to a solid-phase conversion reaction between copper and copper halide, which are both solids, to avoid the copper ions being released into the electrolyte, thereby avoiding the side reaction with the zinc negative electrode causing the loss of copper ions that store electrical energy and the corrosion of the zinc negative electrode, thereby transforming the primary zinc-copper battery into a secondary zinc-copper battery with high reversibility.

[0024] Specifically, the halogen ion-based electrolyte is used as the electrolyte of the secondary zinc-copper battery. The halogen anions in the halogen ion-based electrolyte react with the copper positive electrode during charging to form copper halide (CuCl2, CuBr2, CuI2), thereby solidifying the active copper ions, avoiding the generation of active copper ions and side reactions with the zinc negative electrode, causing the loss of active substances and damage to the zinc negative electrode; and the above-mentioned halide has good electrochemical reversibility, can be reduced during the discharge process, converted into metallic copper on the surface of the copper positive electrode and release halogen ions back to the electrolyte, so that the zinc-copper battery using the halogen ion-based electrolyte can perform reversible charge and discharge operations, and realize a charge and discharge reaction with high reversibility. The preparation process of this electrolyte is relatively simple, easy to operate, and efficient, and the cost of zinc salt is relatively low, which meets the industrial production and commercial application requirements of aqueous zinc-copper batteries. At the same time, the electrochemical performance of the assembled aqueous zinc-copper battery is relatively excellent.

[0025] In some embodiments, the halogen ion-based electrolyte is composed of deionized water and a zinc salt containing a halogen anion, and the two components are stirred evenly at room temperature so that the zinc salt is completely dissolved and the entire solution is clear and transparent, thereby achieving the preparation of the electrolyte. The preparation process of this electrolyte is relatively simple, easy to operate, and highly efficient, and the cost of the zinc salt is relatively low, meeting the requirements of industrial production and commercial application of aqueous zinc-copper batteries.

[0026] In some embodiments, the concentration of the zinc salt containing halogen anions in the halogen ion-based electrolyte is 5 mol·L -1 -10mol·L -1 Within this concentration range, zinc-copper batteries can ensure excellent rate performance and high reversibility.

[0027] In some embodiments, the concentration of the zinc salt containing halogen anions in the halogen ion-based electrolyte is 10 mol·L -1 The halogen ion-based electrolyte with this concentration as the electrolyte of the zinc-copper battery can optimize the rate performance of the zinc-copper battery and has high reversibility.

[0028] In some embodiments, the zinc salt containing halogen anions includes one or more of zinc chloride, zinc bromide, and zinc iodide. These zinc salts have a large solubility in water and are inexpensive, and are suitable for use as electrolyte salts. The zinc ions in the zinc salt participate in the zinc deposition / dissolution reaction on the negative electrode side, while the halogen ions participate in the reaction between the positive electrode copper and the copper halide.

[0029] In some embodiments, the secondary zinc-copper battery comprises a positive electrode sheet and a negative electrode sheet immersed in the halogen ion-based electrolyte, and a separator disposed between the positive electrode sheet and the negative electrode sheet.

[0030] In this embodiment, a copper sheet is used as the positive electrode, a zinc sheet is used as the electrode, and the aqueous zinc-copper battery is assembled with the halogen ion-based electrolyte, and the positive and negative electrodes are immersed in the electrolyte with uniform composition, and no salt bridge is required, and the battery can be assembled into a large battery in the form of a soft-pack battery. In addition, the halogen anions in the halogen ion-based electrolyte react with the copper positive electrode during charging to generate copper halide (CuCl2, CuBr2, CuI2), thereby solidifying the active copper ions, avoiding the generation of active copper ions and side reactions with the zinc negative electrode, causing the loss of active substances and damage to the zinc negative electrode; and the above-mentioned halide has good electrochemical reversibility, can be reduced during the discharge process, converted into metallic copper on the surface of the copper positive electrode and release halogen ions back to the electrolyte, so that the zinc-copper battery using the halogen ion-based electrolyte can perform reversible charge and discharge operations, and realize a charge and discharge reaction with high reversibility.

[0031] In some embodiments, the diaphragm is selected from a glass fiber membrane plus a porous polytetrafluoroethylene membrane and a hydrophilically modified polypropylene membrane.

[0032] Specifically, compared with the previous zinc-copper battery, the electrolyte provided by the present invention can effectively simplify the battery structure, so that it can be combined with the process means of producing large batteries, providing the possibility of manufacturing commercial zinc-copper batteries. The addition of halogen ions changes the original reaction between copper and copper ions into a reaction between copper and copper halide, achieving effective protection of copper ions that are prone to side reactions with zinc, and turning the original primary battery that can only discharge into a secondary battery that can be reversibly charged and discharged. This method is simple, easy to prepare, low-cost, and suitable for large-scale production. At the same time, the assembled aqueous zinc-copper secondary battery has excellent electrochemical properties.

[0033] In this embodiment, by rationally modifying the zinc-copper battery, the introduction of halogen ions is used to achieve the solidification and protection of the originally highly active copper ions, thereby avoiding the shuttling of copper ions to the zinc negative electrode side and the side reactions between copper ions and the zinc negative electrode.

[0034] The following examples are further given to illustrate the present invention in detail. It should also be understood that the following examples are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above content of the present invention belong to the scope of protection of the present invention.

[0035] Example 1

[0036] At room temperature, prepare 10 mol·L -1 The aqueous zinc-copper battery was assembled using zinc chloride solution as the electrolyte. -2 The current density and 0.1 mAh cm -2The charge-discharge curves and the Coulomb efficiency curves with the number of cycles under the area specific capacity are shown in Figure 2. Figure 1 and Figure 2 As shown, it exhibits small polarization and excellent long-cycle performance, with a reversible cycle of more than 800 cycles at a high Coulomb efficiency of 99%.

[0037] Example 2

[0038] At room temperature, prepare 10 mol·L -1 The aqueous zinc-copper battery was assembled using zinc chloride solution as the electrolyte. -2 The current density and 0.1 mAh cm -2 The charge and discharge test was carried out under the area specific capacity. The typical charge and discharge curve is as follows Figure 3 As shown, it exhibits small polarization and excellent long-cycle performance, with a reversible cycle of more than 1000 cycles at a high Coulombic efficiency of 98%.

[0039] Example 3

[0040] At room temperature, prepare 9 mol·L -1 Zinc chloride + 1 mol·L -1 Aqueous zinc-copper battery was assembled using a double salt solution of zinc bromide as the electrolyte. -2 The current density and 0.1 mAh cm -2 The charge and discharge test was carried out under the area specific capacity. The typical charge and discharge curve is as follows Figure 4 As shown, it exhibits small polarization and excellent long-cycle performance, with a reversible cycle of more than 800 cycles at a high Coulombic efficiency of 98%.

[0041] Example 4

[0042] At room temperature, prepare 7 mol·L -1 Zinc chloride + 3 mol·L -1 Aqueous zinc-copper battery was assembled using a double salt solution of zinc bromide as the electrolyte. -2 The current density and 0.1 mAh cm -2 The charge and discharge test was carried out under the area specific capacity. The typical charge and discharge curve is as follows Figure 5 As shown, it exhibits small polarization and excellent long-cycle performance, with a reversible cycle of more than 1500 cycles at a high Coulomb efficiency of 99%.

[0043] In summary, the present invention provides a halogen ion-based electrolyte for realizing a secondary zinc-copper battery, wherein the halogen ion-based electrolyte comprises deionized water and a zinc salt containing a halogen anion; the concentration of the zinc salt containing a halogen anion in the halogen ion-based electrolyte is 3 mol·L -1 -15mol·L-1 . The halogen ion-based electrolyte provided by the present invention can firstly simplify the battery structure, so that the positive and negative electrodes are immersed in the electrolyte with uniform composition, and no salt bridge is required, and the battery can be assembled into a large battery in the form of a soft-pack battery; secondly, the presence of halogen ions can change the reaction mechanism of the zinc-copper battery, so that the original two-phase conversion reaction between metallic copper and copper ions dissolved in the electrolyte is changed to a solid-phase conversion reaction between copper and copper halide, which are both solids, to avoid the copper ions being released into the electrolyte, thereby avoiding the side reaction with the zinc negative electrode causing the loss of copper ions that store electrical energy and the corrosion of the zinc negative electrode, thereby transforming the primary zinc-copper battery into a secondary zinc-copper battery with high reversibility.

[0044] It should be understood that the application of the present invention is not limited to the above examples. For ordinary technicians in this field, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A halogen ion-based electrolyte for realizing a secondary zinc-copper battery, characterized in that: The invention comprises deionized water and a zinc salt containing a halogen anion; the concentration of the zinc salt containing a halogen anion in the halogen ion-based electrolyte is 3 mol·L -1 -15mol·L -1 .

2. The halogen ion-based electrolyte for realizing a secondary zinc-copper battery according to claim 1, characterized in that: The concentration of the zinc salt containing halogen anions in the halogen ion-based electrolyte is 5 mol·L -1 -10mol·L -1 .

3. The halogen ion-based electrolyte for realizing a secondary zinc-copper battery according to claim 1, characterized in that: The concentration of the zinc salt containing halogen anions in the halogen ion-based electrolyte is 10 mol·L -1 .

4. The halogen ion-based electrolyte for realizing a secondary zinc-copper battery according to claim 1, characterized in that: The zinc salt containing halogen anions includes one or more of zinc chloride, zinc bromide and zinc iodide.

5. The halogen ion-based electrolyte for realizing a secondary zinc-copper battery according to claim 1, characterized in that: The secondary zinc-copper battery comprises a positive electrode sheet and a negative electrode sheet immersed in the halogen ion-based electrolyte, and a separator arranged between the positive electrode sheet and the negative electrode sheet.

6. The halogen ion-based electrolyte for realizing a secondary zinc-copper battery according to claim 5, characterized in that: The diaphragm is selected from one of a glass fiber membrane plus a porous polytetrafluoroethylene membrane and a hydrophilic modified polypropylene membrane.

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