Application of an additive in aqueous zinc ion battery electrolyte and preparation method thereof

Abstract

The invention relates to the technical field of battery electrolytes, and specifically discloses a functional electrolyte additive for aqueous zinc ion batteries and a preparation method of the battery thereof. The structural formula of the additive is as follows: The additive can adjust the deposition and stripping process of the zinc negative electrode during charging and discharging of the aqueous zinc ion battery, inhibit the irregular growth of zinc negative electrode dendrites and adverse side reactions such as hydrogen evolution corrosion, and significantly improve the stability and cycle life of the zinc ion battery.

Description

Technical Field

[0001] The invention relates to the technical field of battery electrolytes, and in particular to a functional electrolyte additive for an aqueous zinc ion battery and a preparation method of a battery thereof. Background Art

[0002] In recent years, with the promotion of the concept of green and sustainable development, the development and utilization of clean energy (such as solar energy, tidal energy, wind energy, etc.) has attracted widespread attention and developed rapidly under the background of the times. However, with the further development of science and technology, the storage problem of new energy has greatly limited the large-scale application of such energy, and the research and development and application of energy storage technology are particularly important. At present, lead-acid batteries and organic lithium-ion batteries are still the mainstream energy storage technologies on the market. However, lead-acid batteries not only have low energy density but also contain a large amount of toxic lead metal, while organic lithium-ion batteries have safety issues such as resource scarcity, high production cost, and flammability and explosion. These negative effects greatly limit the development prospects of the above two types of batteries in the field of large-scale energy storage. In contrast, aqueous energy storage batteries mainly rely on aqueous solutions as electrolytes. Compared with organic system batteries, they have unique advantages such as large resource reserves, low production costs, and safety and non-toxicity, which can meet the application conditions of large-scale energy storage. Among various types of aqueous energy storage batteries, aqueous zinc-ion batteries (AZIBs) have a higher theoretical specific capacity (820mAhg -1 ), low redox potential (0.76Vvs standard hydrogen electrode) and abundant resource reserves, it is considered by many scholars to be one of the most promising aqueous energy storage materials. In addition, aqueous zinc-ion batteries also have advantages such as green and non-toxic side effects, low production cost, low safety risk, and environmental friendliness.

[0003] However, the negative electrode material of aqueous zinc-ion batteries, zinc metal, is easily unstable during the electroplating and stripping process of long-term charge and discharge. Usually, the cycle stability of AZIBs is reduced due to negative electrode dendrite growth, passivation, and side reactions such as hydrogen evolution reaction (HER), which further leads to a decrease in the cycle stability and cycle life of the zinc negative electrode in the aqueous electrolyte medium, which greatly hinders the large-scale practical application of AZBs. Therefore, how to solve the above problems has become an important research direction for researchers in the field of aqueous zinc-ion batteries. Summary of the invention

[0004] In view of the above problems, the present invention provides a functional electrolyte additive for aqueous zinc ion batteries and a preparation method of the battery thereof, wherein the additive can adjust the deposition and stripping process of the zinc negative electrode during charging and discharging of the aqueous zinc ion battery, inhibit the irregular growth of zinc negative electrode dendrites and adverse side reactions such as hydrogen evolution corrosion, and significantly improve the stability and cycle life of the zinc ion battery. Specifically, the technical solution of the present invention is as follows.

[0005] First, the present invention provides an aqueous zinc ion battery functional electrolyte additive, the structural formula of which is shown in formula (1):

[0006] Formula (1).

[0007] Wherein: the n is 1, 2, 3, 4, or 5.

[0008] When n=1, it is coumarin 12-crown-4 (denoted as C12C4), when n=2, it is coumarin 15-crown-5 (denoted as C15C5), when n=3, it is coumarin 18-crown-6 (denoted as C18C6), when n=4, it is coumarin 21-crown-7 (denoted as C21C7), when n=5, it is coumarin 24-crown-8 (denoted as C24C8), and so on.

[0009] Furthermore, the concentration of the additive in the electrolyte is 0.1-1000 mmol / kg.

[0010] Furthermore, the molar concentration of the electrolyte in the electrolyte is 0.1-30 mol / kg.

[0011] Furthermore, the electrolyte in the electrolyte includes ZnSO 4 、Zn(OTF) 2 、ZnCl 2 、Zn(NO 3 ) 2 、Zn(ClO 4 ) 2 At least one of the above.

[0012] Secondly, the present invention provides a method for preparing an aqueous zinc ion battery, comprising the following steps:

[0013] (1) Mix the positive electrode material, acetylene black, graphite and binder evenly, then apply the obtained slurry evenly on the current collector. After completion, dry it to obtain the positive electrode sheet for use.

[0014] (2) Assemble the negative electrode shell, the zinc sheet negative electrode, the separator, the electrolyte, wherein the electrolyte includes the aqueous zinc ion battery functional electrolyte of the present invention, the positive electrode sheet, the gasket, the spring, and the positive electrode shell in this order to obtain the product.

[0015] Furthermore, in step (1), the binder includes at least one of polytetrafluoroethylene, polyvinylidene fluoride, etc.

[0016] Furthermore, in step (1), the mass ratio of the positive electrode material, acetylene black, graphite, and binder is 70-95: 0-10: 0-10: 5-10. Optionally, the positive electrode material includes at least one of activated carbon, manganese dioxide, vanadium pentoxide, and the like.

[0017] Furthermore, in step (1), the slurry is applied to a thickness of 5 to 50 μm.

[0018] Furthermore, in step (1), the drying temperature is 45-85°C and the drying time is 3-20 h.

[0019] Furthermore, in step (2), the thickness of the zinc sheet negative electrode is 10-500 μm.

[0020] Furthermore, in step (2), the material of the diaphragm includes at least one of glass fiber, polypropylene, non-woven fabric, etc.

[0021] Compared with the prior art, the present invention has the following beneficial technical effects: the present invention adds the above-mentioned additives to the aqueous zinc ion battery functional electrolyte, which contains rich ether oxygen groups and can form hydrogen bonds with water, break the original water molecule network structure, and insert Zn 2+ The solvation sheath affects the Zn 2+ Solvation equilibrium inhibits side reactions such as hydrogen evolution corrosion, and this additive has a positive effect on Zn 2+ It has a specific affinity, and its good zinc affinity can induce uniform zinc ion deposition, avoid the irregular generation of dendrites, and extend the cycle life of zinc ion batteries. In addition, this additive also has the advantages of low addition amount, low production cost, and green and non-toxic to the natural environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] 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. The embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein:

[0023] Figure 1 This is a cycle life test graph of the Zn||Zn symmetric battery prepared in Example 1 below.

[0024] Figure 2 This is a cycle life test graph of the Zn||Zn symmetric battery prepared in the following Example 2.

[0025] Figure 3 The following is a corrosion potential test graph of the Zn||Zn symmetric battery prepared in Example 2 and Comparative Example 1.

[0026] Figure 4 This is a cycle life test graph of the Zn||Zn symmetric battery prepared in the following Example 3.

[0027] Figure 5 The following is a cycle life test diagram of the zinc ion battery prepared in Example 4.

[0028] Figure 6 The following are test graphs of hydrogen evolution current and hydrogen evolution potential of the Zn||SS battery prepared in Example 5 and Comparative Example 3.

[0029] Figure 7 This is a cycle life test chart of the Zn||Zn symmetric battery prepared in the following comparative example 1.

[0030] Figure 8 This is a cycle life test diagram of the zinc ion battery prepared in the following comparative example 2. DETAILED DESCRIPTION

[0031] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. The experimental methods in the following examples without specifying specific conditions are usually carried out under conventional conditions or under conditions recommended by the manufacturer.

[0032] Unless otherwise defined, all professional and scientific terms used herein have the same meanings as those familiar to those skilled in the art. The reagents or raw materials used in the present invention can be purchased through conventional channels. If not otherwise specified, the reagents or raw materials used in the present invention are used in a conventional manner in the art or in accordance with the product instructions. In addition, any method and material similar to or equivalent to the described content can be applied to the method of the present invention. Now, the present invention is further described in conjunction with the accompanying drawings and specific embodiments of the present invention, and the preferred implementation methods and materials described in the present invention are only for demonstration purposes.

[0033] Embodiment 1:

[0034] A method for preparing an aqueous zinc ion battery comprises the following steps:

[0035] (1) Add 2 mol of zinc sulfate (ZnSO 4 ) and 1 mmol of C15C5 additive, ultrasonically treat for 10 min to obtain a zinc sulfate electrolyte with a C15C5 concentration of 1 mmol / kg, which is set aside.

[0036] (2) A zinc sheet with a thickness of 20 μm is used as the positive electrode and the negative electrode respectively, a glass fiber is used as a separator, and the electrolyte prepared in this embodiment is added to assemble a Zn||Zn symmetrical battery. The assembly process includes the following steps: assembling the negative electrode shell, the zinc sheet negative electrode, the separator, the electrolyte, the zinc sheet positive electrode, the gasket, the spring, and the positive electrode shell in order.

[0037] The Zn||Zn symmetric battery in this embodiment has a current density of 0.25 mA•cm -2 、Discharge capacity is 0.05mAh•cm -2 Performance test under the conditions of Figure 1 As shown, the results showed that a short circuit occurred after 2400 hours of cycling.

[0038] Embodiment 2:

[0039] A method for preparing an aqueous zinc ion battery comprises the following steps:

[0040] (1) Add 2 mol of zinc trifluoromethanesulfonate (Zn(OTF)) to 1 kg of water. 2 ) and 1000mmol of C18C6 additive, ultrasonically treat for 10min to obtain a zinc trifluoromethanesulfonate electrolyte with a C18C6 concentration of 1000mmol / kg, and set aside.

[0041] (2) A zinc sheet with a thickness of 50 μm was used as the positive electrode and the negative electrode respectively, and a glass fiber was used as a separator. The electrolyte prepared in this example was added to assemble a Zn||Zn symmetrical battery (the assembly method was the same as that in Example 1).

[0042] The Zn||Zn symmetric battery in this embodiment has a current density of 0.25 mA•cm -2 、Discharge capacity is 0.05mAh•cm -2 Performance test under the conditions of Figure 2 As shown in the results, short circuit occurred after 2610h of cycling. In addition, the corrosion potential of the battery was tested using the Chenhua electrochemical workstation Tafel technology. The test results are shown in Figure 3 It can be clearly observed that the presence of functional additives greatly reduces the obvious corrosion current on the zinc metal surface, indicating that the presence of functional additives reduces the corrosion reaction tendency of the zinc metal electrode.

[0043] Comparative Example 1:

[0044] A method for preparing an aqueous zinc ion battery comprises the following steps:

[0045] (1) With a concentration of 2 mol / kg zinc trifluoromethanesulfonate (Zn(OTF) 2) solution is used as electrolyte for future use.

[0046] (2) A zinc sheet with a thickness of 50 μm was used as the positive electrode and the negative electrode respectively, and a glass fiber was used as a separator. The electrolyte prepared in this comparative example was added to assemble a Zn||Zn symmetrical battery (the assembly method was the same as that in Example 1).

[0047] This example is a comparative example of the above-mentioned Example 2. The Zn||Zn symmetrical battery of this comparative example has a current density of 0.25 mA•cm -2 、Discharge capacity is 0.05mAh•cm -2 Performance test under the conditions of Figure 7 As shown in the results, short circuit occurred after 100 hours of cycling. In addition, the corrosion potential of the battery was tested using the Chenhua electrochemical workstation Tafel technology. The test results are shown in Figure 3 It can be observed that the battery system without adding C18C6 to the electrolyte exhibits a higher corrosion current, which indicates that the zinc metal negative electrode is more susceptible to corrosion passivation in the comparative electrolyte.

[0048] Embodiment 3:

[0049] A method for preparing an aqueous zinc ion battery comprises the following steps:

[0050] (1) Add 2 mol of zinc trifluoromethanesulfonate (Zn(OTF)) to 1 kg of water. 2 ) and 10 mmol of C21C7 additive, and ultrasonically treat for 10 min to obtain a zinc trifluoromethanesulfonate electrolyte with a C21C7 concentration of 10 mmol / kg for standby use.

[0051] (2) A zinc sheet with a thickness of 200 μm was used as the positive electrode and the negative electrode respectively, a non-woven fabric was used as the separator, and the electrolyte prepared in this example was added to assemble a Zn||Zn symmetrical battery (the assembly method was the same as that in Example 1).

[0052] The Zn||Zn symmetric battery in this embodiment has a current density of 0.25 mA•cm -2 、Discharge capacity is 0.05mAh•cm -2 Performance test under the conditions of Figure 4 As shown, the results showed that a short circuit occurred after 1881 hours of cycling.

[0053] Embodiment 4:

[0054] A method for preparing an aqueous zinc ion battery comprises the following steps:

[0055] (1) Add 2 mol of zinc chloride (ZnCl) to 1 kg of water. 2) and 0.5 mmol of C18C6 additive, and ultrasonically treat for 10 min to obtain a zinc chloride electrolyte with a C18C6 concentration of 0.5 mmol / kg for use.

[0056] (2) A zinc sheet with a thickness of 300 μm was used as the negative electrode, activated carbon (YP80F) was used as the positive electrode, glass fiber was used as the separator, and the electrolyte prepared in this example was added to assemble an aqueous zinc ion battery.

[0057] The aqueous zinc ion battery of this embodiment has a current density of 0.5A•g -1 Performance test under the conditions of Figure 5 As shown, the results showed that a short circuit occurred after 1160 cycles.

[0058] Comparative Example 2:

[0059] A method for preparing an aqueous zinc ion battery comprises the following steps:

[0060] (1) With a concentration of 2 mol / kg zinc chloride (ZnCl 2 ) solution is used as electrolyte for future use.

[0061] (2) A zinc sheet with a thickness of 300 μm was used as the negative electrode, activated carbon (YP80F) was used as the positive electrode, glass fiber was used as the separator, and the electrolyte prepared in this example was added to assemble an aqueous zinc ion battery.

[0062] This embodiment is a comparative example of the above embodiment 4. The aqueous zinc ion battery of this embodiment has a current density of 0.5A•g -1 Performance test under the conditions of Figure 8 As shown, the results showed that a short circuit occurred after 400 cycles.

[0063] Embodiment 5:

[0064] A method for preparing an aqueous zinc ion battery comprises the following steps:

[0065] (1) Add 2 mol of zinc trifluoromethanesulfonate (Zn(OTF)) to 1 kg of water. 2 ) and 20 mmol of C24C8 additive, ultrasonically treat for 10 min to obtain a zinc trifluoromethanesulfonate electrolyte with a C24C8 concentration of 20 mmol / kg for standby use.

[0066] (2) A zinc sheet with a thickness of 100 μm is used as the negative electrode, a stainless steel mesh is used as the positive electrode, and a polypropylene is used as a separator, and the electrolyte prepared in this embodiment is added to assemble a Zn||SS battery. The assembly process includes the following steps: assembling the negative electrode shell, the zinc sheet negative electrode, the separator, the electrolyte, the stainless steel sheet positive electrode, the gasket, the spring, and the positive electrode shell in order to obtain.

[0067] The Zn||SS battery of this embodiment was subjected to LSV test using Chenhua electrochemical workstation to detect its hydrogen evolution potential. The battery performance test of this embodiment is as follows: Figure 6 The results show that the C24C8 additive in the electrolyte makes the battery system have a lower hydrogen evolution current and a higher hydrogen evolution potential, which fully proves that the introduction of functional additives has a significant help in inhibiting the hydrogen evolution reaction of the battery system.

[0068] Comparative Example 3:

[0069] A method for preparing an aqueous zinc ion battery comprises the following steps:

[0070] (1) With a concentration of 2 mol / kg zinc trifluoromethanesulfonate (Zn(OTF) 2 ) solution is used as electrolyte for future use.

[0071] (2) A zinc sheet with a thickness of 100 μm was used as the negative electrode, a stainless steel mesh was used as the positive electrode, and polypropylene was used as the separator. The electrolyte prepared in this example was added to assemble a Zn||SS battery (the same as the above-mentioned Example 5).

[0072] This embodiment is a comparative example of the above embodiment 5. The Zn||SS battery of this embodiment is subjected to LSV test using a Chenhua electrochemical workstation to detect its hydrogen evolution potential. The battery performance test of this embodiment is as follows: Figure 6 The results show that the hydrogen evolution reaction is more likely to occur and more violent in the comparative electrolyte, which indicates that the battery system without additives in the electrolyte has a relatively higher hydrogen evolution current and a lower hydrogen evolution potential.

[0073] Embodiment 6:

[0074] A method for preparing an aqueous zinc ion battery comprises the following steps:

[0075] (1) Add 0.1 mol of zinc nitrate (Zn(NO 3 ) 2 ) and 0.1 mmol of C12C4 additive, and ultrasonically treat for 10 min to obtain a zinc nitrate electrolyte with a C12C4 concentration of 0.1 mmol / kg for use.

[0076] (2) A zinc sheet with a thickness of 500 μm was used as the positive electrode and the negative electrode respectively, and a glass fiber was used as a separator. The electrolyte prepared in this embodiment was added to assemble a Zn||Zn symmetrical battery (the same as the above embodiment 1).

[0077] For the Zn||Zn symmetrical battery of this embodiment, the current density is 0.25 mA•cm -2 、Discharge capacity is 0.05mAh•cm -2 The cycle performance under the conditions of was tested, and the results showed that a short circuit occurred after 2032h of cycling.

[0078] Embodiment 7:

[0079] A method for preparing an aqueous zinc ion battery comprises the following steps:

[0080] (1) Add 30 mol of zinc chlorate (ZnCl 2 ) and 200 mmol of C12C4, C15C5, C18C6, C21C7 and C24C8 additives respectively, and ultrasonically treat for 10 min to obtain a zinc chlorate electrolyte with the above five additives concentration of 200 mmol / kg respectively, for standby use.

[0081] (2) A zinc sheet with a thickness of 100 μm was used as the positive electrode and the negative electrode respectively, and a glass fiber was used as a separator. The electrolyte prepared in this embodiment was added to assemble a Zn||Zn symmetrical battery (the same as the above embodiment 1).

[0082] For the Zn||Zn symmetrical battery of this embodiment, the current density is 0.25 mA•cm -2 、Discharge capacity is 0.05mAh•cm -2 The cycle performance under the conditions of was tested, and the results showed that a short circuit occurred after 2527h of cycling.

[0083] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An application of an additive in an aqueous zinc ion battery electrolyte, characterized in that: Its structural formula is shown in formula (1): Formula (1); Wherein: the n is 1, 2, 3, 4, 5.

2. The use according to claim 1, characterized in that: The concentration of the additive in the electrolyte is 0.1-1000 mmol / kg.

3. The use according to claim 1, characterized in that: The molar concentration of the electrolyte in the electrolyte is 0.1-30 mol / kg.

4. The use according to any one of claims 1 to 3, characterized in that: The electrolyte in the electrolyte solution includes at least one of ZnSO4, Zn(OTF)2, ZnCl2, Zn(NO3)2, and Zn(ClO4)2.

5. A method for preparing an aqueous zinc ion battery, characterized in that: The steps include: (1) The positive electrode material, acetylene black, graphite and binder are mixed evenly, and then the obtained slurry is evenly applied on the current collector. After completion, it is dried to obtain the positive electrode sheet for standby use; (2) Assemble a negative electrode shell, a zinc sheet negative electrode, a separator, an electrolyte, wherein the electrolyte comprises the aqueous zinc ion battery electrolyte additive according to any one of claims 1 to 4, the above-mentioned positive electrode sheet, a gasket, a spring, and a positive electrode shell in this order to obtain a product.

6. The method for preparing an aqueous zinc ion battery according to claim 5, wherein: In step (1), the binder includes at least one of polytetrafluoroethylene and polyvinylidene fluoride.

7. The method for preparing an aqueous zinc ion battery according to claim 5, wherein: In step (1), the mass ratio of the positive electrode material, acetylene black, graphite and binder is 70-95:0-10:0-10:5-10.

8. The method for preparing an aqueous zinc ion battery according to claim 5, wherein: In step (1), the positive electrode material includes at least one of activated carbon, manganese dioxide, and vanadium pentoxide.

9. The method for preparing an aqueous zinc ion battery according to claim 5, wherein: In step (1), the slurry is applied with a thickness of 5 to 50 μm.

10. The method for preparing an aqueous zinc ion battery according to claim 5, wherein: In step (1), the drying temperature is 45-85°C and the drying time is 3-20 hours.

11. The method for preparing an aqueous zinc ion battery according to any one of claims 5 to 10, characterized in that: In step (2), the thickness of the zinc sheet negative electrode is 10-500 μm.

12. The method for preparing an aqueous zinc ion battery according to any one of claims 5 to 10, characterized in that: In step (2), the material of the diaphragm includes at least one of glass fiber, polypropylene, and non-woven fabric.

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