Method for recycling decommissioned alkaline zinc-manganese battery negative electrode material from eutectic ionic liquid and application of decommissioned alkaline zinc-manganese battery negative electrode material

Abstract

The invention discloses a method for recycling a decommissioned alkaline zinc-manganese battery negative electrode material from eutectic ionic liquid and application of the decommissioned alkaline zinc-manganese battery negative electrode material, and belongs to the field of comprehensive utilization of solid waste resources and application of secondary batteries. According to the method, the decommissioned alkaline zinc-manganese battery is disassembled, a negative electrode material in the decommissioned alkaline zinc-manganese battery is sorted out, after pretreatment, the decommissioned alkaline zinc-manganese battery is leached through eutectic ionic liquid, and the eutectic ionic liquid is choline chloride-urea eutectic ionic liquid or choline chloride-oxalic acid eutectic ionic liquid. According to the invention, a novel recovery thought is provided for the recovery of the retired alkaline zinc-manganese battery, green and efficient comprehensive resource utilization is realized, and meanwhile, the ternary eutectic electrolyte provided by the invention can be used as the electrolyte of the zinc ion battery, so that the common problems of zinc dendrite growth and the like of the zinc ion battery can be effectively solved.

Description

Technical Field

[0001] The invention belongs to the technical field of comprehensive utilization of solid waste resources and application of secondary batteries, and in particular relates to a method for recycling negative electrode materials of retired alkaline zinc-manganese batteries using low-eutectic ionic liquids and an application thereof. Background Art

[0002] With the excessive consumption of mineral resources and the increasing attention to environmental protection, exploring safe, economical and sustainable energy storage technologies has become a global trend. At present, lithium-ion batteries, as a high-efficiency energy device, are widely used in electric vehicles, portable electronic devices and other fields, but there are problems such as high cost, toxic electrolyte, flammability and volatility. The emerging rechargeable aqueous zinc-ion batteries (AZBs) are expected to solve these problems because of their high specific capacity (820mAh / g) and volume capacity (5855mAh / cm 3 ) and low electrochemical reduction potential (-0.76V vs. SHE), which are superior to lithium-ion batteries in terms of safety, cost-effectiveness and environmental protection.

[0003] On the other hand, the continuous development of society has also led to an increase in the amount of electronic waste year by year. For example, in daily life, the annual production of the most common alkaline zinc-manganese dry batteries is about 30 billion, which are often discarded after they run out of power. Due to the lack of an effective and systematic recycling system, serious resource waste and environmental pollution have been caused. Summary of the invention

[0004] In order to solve the above technical problems, the present invention proposes a method for recycling the negative electrode material of retired alkaline zinc-manganese batteries using low-eutectic ionic liquid and its application. The present invention can efficiently and greenly recycle retired alkaline zinc-manganese batteries, while meeting the requirements of stable discharge of zinc ion batteries and reducing dendrite growth.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] One of the technical solutions of the present invention:

[0007] The present invention provides a method for recycling the negative electrode material of retired alkaline zinc-manganese batteries by using a low-melting ionic liquid, comprising the following steps: disassembling the retired alkaline zinc-manganese batteries, sorting out the negative electrode materials therein, and leaching them by using a low-melting ionic liquid after pretreatment;

[0008] The eutectic ionic liquid is a choline chloride-urea eutectic ionic liquid (abbreviated as ChCl-Ur) or a choline chloride-oxalic acid eutectic ionic liquid (abbreviated as ChCl-Ox).

[0009] In the method of recycling the negative electrode material of retired alkaline zinc-manganese batteries with low eutectic ionic liquid of the present invention, the leaching liquid obtained after leaching with low eutectic ionic liquid is the recycled negative electrode material of retired alkaline zinc-manganese batteries. The present invention discloses a simple way to recycle and reuse retired alkaline zinc-manganese batteries, which can not only alleviate the shortage of zinc resources, but also effectively reduce the production cost of AZBs and solve the problem of various side reactions during use. During the discharge process of alkaline zinc-manganese batteries, the negative electrode reaction is Zn+2OH - →2e - +Zn(OH)2·ZnO+H2O. As the power is exhausted, the negative electrode material made of zinc powder is converted into zinc oxide. When ChCl-Ur is used as a leaching agent for recovery, the oxygen atoms on the surface of zinc oxide can form multiple hydrogen bonds with choline cations, and the zinc atoms can form chemical bonds with urea molecules and chloride ions. Finally, zinc oxide can be [ZnOCl(NH2CONH2)2] - The complex is dissolved in ChCl-Ur; when ChCl-Ox is used as a leaching agent, zinc oxide can form a zinc complex ZnC2O4 with oxalic acid, and then further dissolve into zinc ions in an acidic environment, thereby achieving the purpose of leaching.

[0010] Exemplarily, the disassembly is manual disassembly or mechanical disassembly.

[0011] The pretreatment is as follows: washing the sorted negative electrode materials with water until they are neutral, drying, crushing and screening.

[0012] Furthermore, the pretreatment is: washing the selected negative electrode material with ultrapure water until the washing liquid is neutral, drying the washed negative electrode material in a vacuum drying oven, removing the water, fully crushing it with a pulverizer, and sieving it with a screen. The pretreatment can remove a small amount of unreacted single substance Zn in the negative electrode material of retired alkaline zinc-manganese batteries, so that the negative electrode material is all ZnO.

[0013] Exemplarily, the temperature of the vacuum drying oven is set to 80° C., the relative vacuum degree is set to −0.05 MPa, and the drying time is 24 h; the screen used is 60 mesh (ie, pore size 0.25 mm).

[0014] When leaching is performed using a low eutectic ionic liquid, the solid-liquid ratio is 80 g / L to 100 g / L, the leaching temperature is 25 to 100° C., and the leaching time is 2 to 30 hours.

[0015] The preparation method of ChCl-Ur is as follows: choline chloride (ChCl) and urea (Urea) are placed in a vacuum drying oven respectively, and after drying, they are sealed for standby use; the dried ChCl and Urea are weighed according to a molar ratio of 1:2, placed in a conical flask, mixed evenly, and heated and stirred in an oil bath until the mixed white solid powder becomes a colorless transparent solution, thereby obtaining ChCl-Ur.

[0016] The preparation method of ChCl-Ox is as follows: ChCl and oxalic acid are placed in a vacuum drying oven respectively, and after drying, they are sealed for standby use; the dried ChCl and ChCl-Ox are weighed according to a molar ratio of 1:1, placed in a conical flask, mixed evenly, and heated and stirred in an oil bath until the mixed white solid powder becomes a colorless transparent solution, thereby obtaining ChCl-Ox.

[0017] The second technical solution of the present invention:

[0018] The present invention also provides an application of the retired alkaline zinc-manganese battery negative electrode material recovered according to the above method in preparing a zinc ion battery electrolyte.

[0019] Retired alkaline zinc-manganese batteries contain abundant zinc and manganese resources. After full discharge, the main component of the negative electrode material of alkaline zinc-manganese batteries is ZnO. After leaching it with a low-eutectic ionic liquid, the ternary eutectic electrolyte composed of water, ethanol, betaine and ethylene glycol has the characteristics of high ion conductivity and stable hydrogen bond network. This ternary eutectic electrolyte can be directly used as a new electrolyte for AZBs, effectively reducing free water activity, inhibiting cathode dissolution and zinc dendrite growth. This new electrolyte system can circumvent the problems of complex production process, high energy consumption, uncontrollable dendrite growth and severe hydrogen evolution of zinc salts used in traditional AZBs (such as ZnCl2, ZnSO4, Zn(Ac)2, etc.). Specifically, when the ternary eutectic electrolyte is used as a new electrolyte for AZBs, the solvent molecules (such as hydrogen bond donors or coordination groups, etc.) interact with zinc ions through electrostatic effects, hydrogen bonds or coordination effects, forming a "shell" structure. This solvent shell structure can improve the solubility and stability of zinc ions, reduce the unevenness of zinc ion dissolution and precipitation, and effectively promote the diffusion and reaction of zinc ions; on the other hand, the ternary eutectic electrolyte enhances the in-situ formation of a stable solid electrolyte interface (SEI) film during zinc deposition. The SEI film is composed of trace zinc carbonate and a large amount of chloride ions, etc., which can form a protective layer on the electrode surface, reduce the dissolution and uneven deposition of zinc ions, and thus achieve long-term stable circulation. In addition, when using traditional zinc sulfate aqueous solution as an electrolyte, a byproduct, basic zinc sulfate, will be generated on the surface of the zinc sheet. This is an electrochemically inert product with very low solubility. It is loosely accumulated on the surface of the metal zinc negative electrode, which will increase the electrochemical impedance, hinder the transmission of zinc ions, and affect the normal operation of the battery. In the ternary eutectic electrolyte, which itself has a lower viscosity, the binding force between water molecules and other solvent molecules is inhibited, thereby reducing the activity of water molecules, which is beneficial to inhibiting the occurrence of side reactions.

[0020] The third technical solution of the present invention:

[0021] The invention provides a zinc ion battery electrolyte, which contains the retired alkaline zinc-manganese battery negative electrode material recovered by the method.

[0022] The fourth technical solution of the present invention:

[0023] The invention provides a method for preparing the zinc ion battery electrolyte, comprising the following steps: adding one of water, ethanol, betaine and ethylene glycol to the recovered retired alkaline zinc-manganese battery negative electrode material, stirring evenly, and obtaining the zinc ion battery electrolyte.

[0024] When one of water, ethanol, betaine and ethylene glycol is added to the recycled retired alkaline zinc-manganese battery negative electrode material, the amount of water added is 0-80%, the amount of ethanol added is 0-80%, and the amount of ethylene glycol added is 0-70% by volume, and the amount of water, ethanol and ethylene glycol added is not 0, that is, the volume ratio of one of water, ethanol and ethylene glycol to the recycled retired alkaline zinc-manganese battery negative electrode material is 0-80%, 0-80% or 0-70% respectively;

[0025] Calculated by mole percentage, the amount of betaine added is 0 to 80%, and the amount of betaine added is not 0, that is, the molar proportion of betaine in the leachate of recycled retired alkaline zinc-manganese battery negative electrode material is 0 to 80%.

[0026] Compared with the prior art, the present invention has the following advantages and technical effects:

[0027] (1) Compared with the traditional pyrometallurgical recycling process, the method for recycling the negative electrode material of retired alkaline zinc-manganese batteries provided by the present invention does not require high-temperature treatment, thereby reducing energy consumption and waste gas generation. At the same time, compared with the hydrometallurgical process, the process is simpler, has less impact on the environment, and has good prospects for industrial application.

[0028] (2) The method provided by the present invention has the characteristics of simple process, abundant raw materials and low cost.

[0029] (3) The retired alkaline zinc-manganese battery negative electrode material recovered by the method of the present invention (i.e., the leachate obtained by using a low eutectic ionic liquid) and one of water, ethanol, betaine and ethylene glycol can form a ternary eutectic electrolyte, which has the characteristics of high ion conductivity and stable hydrogen bond network. This ternary eutectic electrolyte can be directly used as a new electrolyte for AZBs, effectively reducing the free water activity, which can not only alleviate the shortage of zinc resources, but also effectively reduce the production cost of AZBs and solve the problem of various side reactions during use. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0031] Figure 1 A flow chart of using the method of the present invention to recycle the negative electrode material of retired alkaline zinc-manganese batteries and using it as a zinc ion battery electrolyte to prepare a new type of zinc ion battery;

[0032] Figure 2 This is a comparison chart of X-ray diffraction (XRD) analysis results of the alkaline zinc-manganese battery negative electrode material before and after pretreatment in Example 1;

[0033] Figure 3 It is a comparison diagram of Fourier transform infrared spectra of the electrolytes in Example 1, Example 2 and Example 3;

[0034] Figure 4 It is a comparison diagram of the linear sweep voltammetric curves of the electrolytes in Example 4 and Comparative Example 1;

[0035] Figure 5 It is a comparison chart of the test results of cyclic charge and discharge stability of Zn||Zn symmetrical batteries assembled in Example 1, Example 6 and Comparative Example 1;

[0036] Figure 6 It is a comparison chart of the test results of cyclic charge and discharge stability of the Zn||Zn symmetrical battery assembled in Example 2 and Comparative Example 3;

[0037] Figure 7 A comparison chart of the coulombic efficiency of the Zn||Cu symmetric battery assembled in Example 5 and Comparative Example 1 during cyclic charge and discharge;

[0038] Figure 8 This is a scanning electron microscope (SEM) analysis comparison diagram of the zinc negative electrode surface of the Zn||MnO2 full battery assembled in Example 3, Example 7 and Comparative Example 2 after the cyclic charge and discharge stability test. DETAILED DESCRIPTION

[0039] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0040] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0041] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0042] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0043] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0044] Unless otherwise specified, the normal temperature in the examples and comparative examples of the present invention is 25±2°C.

[0045] All raw materials used in the examples of the present invention are commercially available.

[0046] In an embodiment of the present invention, retired alkaline zinc-manganese batteries refer to alkaline zinc-manganese batteries that have been completely discharged, and their models include but are not limited to No. 5 and No. 7 batteries, and their brands include but are not limited to Nanfu batteries, Xiaomi batteries, Duracell batteries, etc.

[0047] In the embodiment of the present invention, the zinc ion battery electrolyte was used to assemble a Zn||Zn symmetrical battery, a Zn||Cu symmetrical battery and a Zn||MnO2 full battery and test the relevant performance. The current used for the test was 1 mA / cm 2 ~10mA / cm 2 .

[0048] It should be pointed out that the matters not described in detail in the present invention are conventional operating means in the field and are not the focus of the present invention. For example, the specific methods of manual disassembly or mechanical disassembly, the specific assembly methods of Zn||Zn symmetrical batteries, Zn||Cu symmetrical batteries and Zn||MnO2 full batteries are all completed by conventional methods.

[0049] The process flow of using the method of the present invention to recycle the negative electrode material of retired alkaline zinc-manganese battery and using it as the electrolyte of zinc ion battery to prepare a new type of zinc ion battery is shown in Figure 1 .

[0050] The technical solution of the present invention is further illustrated by the following embodiments.

[0051] Example 1

[0052] This embodiment provides a method for recycling the negative electrode material of retired alkaline zinc-manganese battery by using a eutectic ionic liquid and using the eutectic ionic liquid as a novel zinc ion battery electrolyte, comprising the following steps:

[0053] (i) Discharge a commercially available No. 5 alkaline zinc-manganese battery to below 0.9V, then mechanically disassemble it, collect the negative electrode material therein, wash the collected negative electrode material with ultrapure water several times until the washing liquid is neutral, and then dry it in a vacuum drying oven at 80°C for 20 hours (the relative vacuum degree is set to -0.05Mpa), remove moisture, fully crush it with a pulverizer, and sieve it with a 60-mesh screen to finally obtain the pretreated negative electrode material;

[0054] (ii) placing choline chloride (ChCl) and urea (Urea) in a vacuum drying oven respectively, after drying, weighing the dried ChCl and Urea in a molar ratio of 1:2, placing them in a conical flask, mixing them evenly, and heating and stirring them in an oil bath, the temperature being set to 343K, until the mixed white solid powder becomes a colorless and transparent solution, namely ChCl-Ur; weighing the above-mentioned pretreated negative electrode material and ChCl-Ur in a solid-liquid ratio of 100g / L, placing them in a conical flask and heating and stirring them in an oil bath, the leaching temperature being 90°C, the leaching time being 30h, the stirring speed being 500rpm, and finally obtaining a transparent and colorless leaching solution;

[0055] (iii) adding 20% ​​by volume of water to the above-mentioned leaching solution (i.e., the volume ratio of water to the leaching solution is 20%), and stirring at room temperature for 30 minutes to obtain a ternary eutectic electrolyte.

[0056] The above ternary eutectic electrolyte was used to assemble Zn||Zn symmetric battery, Zn||Cu symmetric battery and Zn||MnO2 full battery respectively. 2 , 1mAh / cm 2 The cycle charge and discharge stability was tested.

[0057] Example 2

[0058] This embodiment provides a method for recycling the negative electrode material of retired alkaline zinc-manganese battery with a low eutectic ionic liquid and using it as a novel zinc ion battery electrolyte. The difference from the embodiment 1 is that: in step (iii), 30% by volume of ethylene glycol is added to the leachate, and after stirring at room temperature for 30 minutes, a ternary eutectic electrolyte is obtained, and the electrolyte is used to assemble Zn||Zn symmetric battery, Zn||Cu symmetric battery and Zn||MnO2 full battery respectively. 2 , 1mAh / cm 2 The cycle charge and discharge stability was tested.

[0059] Example 3

[0060] This embodiment provides a method for recycling the negative electrode material of retired alkaline zinc-manganese battery with a low eutectic ionic liquid and using it as a novel zinc ion battery electrolyte. The only difference from the embodiment 1 is that in step (iii), 50% by volume of ethylene glycol is added to the leachate, and the ternary eutectic electrolyte is obtained after stirring at room temperature for 30 minutes. The electrolyte is used to assemble Zn||Zn symmetric battery, Zn||Cu symmetric battery and Zn||MnO2 full battery respectively. 2 , 5mAh / cm 2 The cycle charge and discharge stability was tested.

[0061] Example 4

[0062] This embodiment provides a method for recycling the negative electrode material of retired alkaline zinc-manganese battery with a low eutectic ionic liquid and using it as a novel zinc ion battery electrolyte. The difference from the embodiment 1 is that in step (iii), 20% by volume of ethanol is added to the leachate, and the ternary eutectic electrolyte is obtained after stirring at room temperature for 30 minutes. The electrolyte is used to assemble Zn||Zn symmetric battery, Zn||Cu symmetric battery and Zn||MnO2 full battery respectively. 2 , 1mAh / cm 2 The cycle charge and discharge stability was tested.

[0063] Example 5

[0064] This embodiment provides a method for recycling the negative electrode material of retired alkaline zinc-manganese battery with a low-melting ionic liquid and using it as a new type of zinc ion battery electrolyte. The only difference from Example 1 is that in step (iii), 30 mol% of betaine is added to the leachate (i.e., the molar number of betaine in the leachate accounts for 30%), and a ternary eutectic electrolyte is obtained after stirring at room temperature for 30 minutes. The electrolyte is used to assemble Zn||Zn symmetric cells, Zn||Cu symmetric cells and Zn||MnO2 full cells, respectively. At 1 mA / cm 2 , 1mAh / cm 2 The cycle charge and discharge stability was tested.

[0065] Example 6

[0066] This embodiment provides a method for recycling the negative electrode material of retired alkaline zinc-manganese battery by using a low-melting ionic liquid and using it as a novel zinc ion battery electrolyte. The difference from the embodiment 1 is that in step (ii), the dried ChCl and oxalic acid are weighed in a molar ratio of 1:1, respectively. acid), placed in a conical flask, mixed evenly and heated and stirred in an oil bath, the temperature was set to 343K, until the mixed white solid powder became a colorless and transparent solution, namely ChCl-Ox; the pretreated negative electrode material and ChCl-Ox were weighed according to a solid-liquid ratio of 100g / L, placed in a conical flask and heated and stirred in an oil bath, the leaching temperature was 90°C, the leaching time was 20h, and the stirring speed was 500rpm; in step (iii), 30% by volume of ethanol was added to the leaching solution, and after stirring at room temperature for 30min, a ternary eutectic electrolyte was obtained, and the electrolyte was respectively assembled into a Zn||Zn symmetric battery, a Zn||Cu symmetric battery and a Zn||MnO2 full battery, and the electrolyte was stirred at 1mA / cm 2 , 1mAh / cm 2 The cycle charge and discharge stability was tested.

[0067] Example 7

[0068] This embodiment provides a method for recovering the negative electrode material of retired alkaline zinc-manganese battery by using a low eutectic ionic liquid and using it as a novel zinc ion battery electrolyte. The difference from Example 6 is that in step (iii), 20% molar ratio of betaine is added to the leachate, and after stirring at room temperature for 30 minutes, a ternary eutectic electrolyte is obtained, and the electrolyte is used to assemble Zn||Zn symmetric battery, Zn||Cu symmetric battery and Zn||MnO2 full battery respectively. 2 , 5mAh / cm 2 The cycle charge and discharge stability was tested.

[0069] Comparative Example 1

[0070] This comparative example provides a method for preparing an aqueous zinc ion battery electrolyte, the specific steps of which are to dissolve zinc sulfate in deionized water to prepare a 2 mol / L zinc sulfate aqueous solution as the electrolyte. The electrolyte is used to assemble a Zn||Zn symmetric battery, a Zn||Cu symmetric battery, and a Zn||MnO2 full battery, respectively. 2 , 1mAh / cm 2 The cycle charge and discharge stability was tested.

[0071] Comparative Example 2

[0072] This comparative example provides a method for preparing an aqueous zinc ion battery electrolyte, the specific steps of which are to dissolve zinc sulfate in deionized water to prepare a 2 mol / L zinc sulfate aqueous solution as the electrolyte. The electrolyte is used to assemble a Zn||Zn symmetric battery, a Zn||Cu symmetric battery, and a Zn||MnO2 full battery at 5 mA / cm 2 , 5mAh / cm 2 The cycle charge and discharge stability was tested.

[0073] Comparative Example 3

[0074] This comparative example provides a method for recycling the negative electrode material of retired alkaline zinc-manganese battery with a low eutectic ionic liquid and using it as a novel zinc ion battery electrolyte. The difference from Example 2 is that the binary eutectic electrolyte prepared by steps 1 and 2 is used as the electrolyte. The electrolyte is used to assemble Zn||Zn symmetric battery, Zn||Cu symmetric battery and Zn||MnO2 full battery respectively. 2 , 1mAh / cm 2 The cycle charge and discharge stability was tested.

[0075] Figure 2 This is a comparison chart of the X-ray diffraction (XRD) analysis results of the alkaline zinc-manganese battery negative electrode material before and after pretreatment in Example 1. It can be seen that after full discharge, the main component of the alkaline zinc-manganese battery negative electrode material is ZnO, containing a trace amount of unreacted single substance Zn; while the negative electrode material after pretreatment is all ZnO.

[0076] Figure 3 The Fourier transform infrared spectra of the electrolytes in Example 1, Example 2 and Example 3 are compared. -1 The peak at [ZnOCl·urea] - The stretching vibration between the accumulated double bonds formed between Zn(II) and urea indicates that ZnO can be dissolved in ChCl-Ur by forming a complex. Adding water or ethylene glycol will not destroy this coordination form, and at the same time it can reduce the viscosity of the electrolyte, improve the conductivity, and facilitate the efficient migration of zinc ions in the electrolyte between the positive and negative electrodes of the battery.

[0077] Figure 4 This is a comparison diagram of the linear sweep voltammetric curves of the electrolytes in Example 4 and Comparative Example 1. It can be seen that the electrochemical window of the low-eutectic ionic liquid is significantly wider than that of the traditional zinc sulfate aqueous solution, which means that the electrolyte is less likely to decompose and can work stably at a higher voltage, which is beneficial to improving the energy density, cycle life, safety and overall performance of the zinc ion battery.

[0078] Figure 5The figure is a comparison of the test results of the cyclic charge-discharge stability of the Zn||Zn symmetric battery assembled in Example 1, Example 6 and Comparative Example 1. It can be seen that the use of a low eutectic ionic liquid as the electrolyte of the zinc ion battery, the hydrogen bond network therein can significantly reduce the volatility and corrosiveness of the electrolyte, while reducing the side reactions caused by water, such as zinc dendrite growth, zinc corrosion, etc., thereby improving the stability of the zinc ion battery.

[0079] Figure 6 The figure is a comparison of the test results of the cyclic charge-discharge stability of the Zn||Zn symmetric battery assembled in Example 2 and Comparative Example 3. Compared with the binary deep eutectic solvent, adding a certain volume of ethylene glycol can reduce the viscosity of the electrolyte, which is conducive to promoting faster diffusion of zinc ions, thereby improving the ionic conductivity of the electrolyte and the cycle life of the battery.

[0080] Figure 7 This is a comparison chart of the coulombic efficiency of the Zn||Cu symmetric battery assembled in Example 5 and Comparative Example 1 during cyclic charge and discharge. It can be seen that the battery using the low eutectic ionic liquid as the electrolyte can be stably cycled for more than 300 times, with an average coulombic efficiency of up to 99.2%, which is significantly better than using zinc sulfate aqueous solution as the electrolyte. This shows that the battery system has excellent reversibility and stability, and there is no significant electrolyte decomposition or impurity deposition.

[0081] Figure 8 The following is a comparison of the scanning electron microscope (SEM) analysis of the zinc negative electrode surface of the Zn||MnO2 full battery assembled in Example 3, Example 7 and Comparative Example 2 after cyclic charge and discharge. It can be seen that the uneven current distribution during the charge and discharge process of the traditional aqueous zinc ion battery causes zinc ions to preferentially deposit in certain areas, forming a sharp dendrite structure, which may eventually pierce the diaphragm, causing the battery to short-circuit and fail. The use of a low-eutectic ionic liquid as an electrolyte for the leachate of the retired alkaline zinc-manganese battery negative electrode material can form a protective layer on the surface of the zinc negative electrode, which can not only inhibit the direct contact between water and the zinc negative electrode, but also guide the zinc ions to preferentially grow on the (002) crystal plane to form a flat and continuous deposition layer, which helps to improve the cycle life and stability of the battery.

[0082] In summary, the present invention provides a method for recycling the negative electrode material of retired alkaline zinc-manganese batteries by using a low-eutectic ionic liquid, and using it as a new type of zinc ion battery electrolyte. The present invention uses a low-eutectic ionic liquid (ChCl-Ox, ChCl-Ur) to recycle the negative electrode material of retired alkaline zinc-manganese batteries. Compared with the traditional wet / fire recovery process, the energy consumption is reduced, the process is simple, and the impact on the environment is small. At the same time, the new zinc ion battery electrolyte prepared in this way has a low vapor pressure, good conductivity and thermal stability; and can effectively control the crystal plane structure of the zinc negative electrode, and improve the electrochemical performance and cycle stability of the battery. The present invention not only provides a new recycling idea for the recycling of retired alkaline zinc-manganese batteries, and realizes green and efficient comprehensive resource utilization, but also the ternary eutectic electrolyte provided by the present invention as an electrolyte for zinc ion batteries can effectively solve the problems of zinc dendrite growth that are common in zinc ion batteries.

[0083] The above are only preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for recovering the negative electrode material of retired alkaline zinc-manganese batteries using a eutectic ionic liquid, characterized in that: The method comprises the following steps: disassembling retired alkaline zinc-manganese batteries, sorting out the negative electrode materials therein, and leaching them using a low eutectic ionic liquid after pretreatment; The eutectic ionic liquid is a choline chloride-urea eutectic ionic liquid or a choline chloride-oxalic acid eutectic ionic liquid.

2. The method for recovering the negative electrode material of retired alkaline zinc-manganese battery by using eutectic ionic liquid according to claim 1, characterized in that: The pretreatment is as follows: washing the sorted negative electrode materials with water until they are neutral, drying, crushing and screening.

3. The method for recovering the negative electrode material of retired alkaline zinc-manganese battery by using eutectic ionic liquid according to claim 1, characterized in that: When leaching is performed using a low eutectic ionic liquid, the solid-liquid ratio is 80 g / L to 100 g / L, the leaching temperature is 25 to 100° C., and the leaching time is 2 to 30 hours.

4. Use of a retired alkaline zinc-manganese battery negative electrode material recovered by the method according to any one of claims 1 to 3 in preparing a zinc ion battery electrolyte.

5. A zinc ion battery electrolyte, characterized in that: Contains retired alkaline zinc-manganese battery negative electrode material recovered according to the method described in any one of claims 1 to 3.

6. A method for preparing a zinc ion battery electrolyte according to claim 5, characterized in that: The following steps are involved: One of water, ethanol, betaine and ethylene glycol is added to the recovered retired alkaline zinc-manganese battery negative electrode material, and the mixture is stirred evenly to obtain the zinc ion battery electrolyte.

7. The preparation method of zinc ion battery electrolyte according to claim 6, characterized in that, When one of water, ethanol, betaine and ethylene glycol is added to the recycled retired alkaline zinc-manganese battery negative electrode material, the amount of water added is 0-80%, the amount of ethanol added is 0-80%, and the amount of ethylene glycol added is 0-70% by volume, and the amount of water, ethanol and ethylene glycol added is not 0; According to molar percentage, the amount of betaine added is 0-80%, and the amount of betaine added is not 0.

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