Combined complexing agent solution and application thereof in zinc-based battery

Abstract

The invention relates to a combined complexing agent solution and application thereof in a zinc-based battery, the strategy that a complexing agent and zinc are coordinated to generate a zinc complex is adopted, the synergistic effect of a main complexing agent and an auxiliary complexing agent is adopted, and compared with a traditional electrolyte preparation strategy, the combined complexing agent solution provided by the invention is applied to an electrolyte of the zinc-based battery, so that the service life of the zinc-based battery is prolonged, and the service life of the zinc-based battery is prolonged. The electrolyte has the advantages of high stability, good cycle reversibility, inhibition of zinc dendrite growth and the like; the zinc-based energy storage battery electrolyte has the advantages of simple preparation process, wide working pH range, wide application range and the like, can be matched with various zinc-based energy storage battery systems, is wide in universality and has a wide application prospect.

Description

Technical Field

[0001] The invention belongs to the field of energy storage batteries, and in particular relates to a combined complexing agent solution and application thereof in a zinc-based battery. Background Art

[0002] As current environmental problems and energy shortages caused by the non-renewable nature of fossil fuels become increasingly serious, efforts are being made around the world to find renewable energy as an alternative. However, due to the constraints of intermittent and volatile renewable energy, it is impossible to directly access the energy network. Therefore, long-term energy storage technology is considered to be a better solution. Currently, lithium-ion batteries are the mainstream of energy storage technology due to their high energy density, but they are not suitable for large-scale long-term energy storage due to the shortage of lithium mineral resources and their own safety hazards. Mechanical energy storage, pumped energy storage, and compressed air energy storage have high requirements for the geographical environment and are difficult to use on a large scale. Therefore, it is urgent to find a storage solution with high safety and good stability.

[0003] Aqueous zinc-based energy storage batteries are receiving more and more attention due to their excellent performance, low cost and high safety, and good theoretical prospects. However, their aqueous electrolytes also face some challenges, including severe competitive hydrogen evolution reaction (HER), corrosion and dendrite growth on the Zn anode. Therefore, it is urgent to develop a high-performance electrolyte with small hydrogen evolution side reaction and inhibiting zinc dendrite growth to provide support for the stability of zinc-based energy storage batteries in long-term cycles. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a combined complexing agent solution and its application in a zinc-based battery.

[0005] The combined complexing agent solution comprises: a main complexing agent and an auxiliary complexing agent, wherein the main complexing agent is one or more of tartaric acid, ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, citric acid, glycine and gluconic acid, and the auxiliary complexing agent is one or more of salicylic hydroxamic acid, acetohydroxamic acid, pyrophosphoric acid and tris(hydroxymethyl)aminomethane.

[0006] The method for preparing an electrolyte of a zinc-based energy storage battery using the combined complexing agent solution comprises the following steps:

[0007] Step 1: adding the main complexing agent into deionized water, stirring and dissolving, and then adding the auxiliary complexing agent, and obtaining solution A after the auxiliary complexing agent is dissolved;

[0008] Step 2: Dissolve the zinc salt in deionized water to obtain solution B.

[0009] Step 3: Then, solution B is added dropwise to solution A, and the mixture is stirred and mixed until solution B and solution A are completely mixed and the volume is fixed to obtain an electrolyte.

[0010] Preferably, the zinc salt is one or more of zinc oxide, zinc bromide, zinc acetate, zinc sulfate and zinc oxalate, and the type and concentration of the zinc salt are determined according to the positive electrode system.

[0011] Preferably, the molar ratio of the main complexing agent to the zinc salt in the combined complexing agent solution is 1:1 to 3:1, and the concentration of the auxiliary additive is 0.1 to 1 mol / L.

[0012] Preferably, in step three, potassium salt or sodium salt is added at a concentration of 1 to 3 mol / L.

[0013] Preferably, in step three, an acid or a base is added to adjust the pH of the base liquid to 4-13, wherein the acid is one or more of hydrochloric acid or sulfuric acid, and the base is one or more of sodium hydroxide and potassium hydroxide.

[0014] Preferably, in step three, solution B and solution A are mixed under ultrasound and stirring.

[0015] The beneficial effects of the present invention are:

[0016] 1) The present invention adopts a strategy of forming a zinc complex by coordination between a complexing agent and zinc, and adopts a synergistic effect of a main complexing agent and an auxiliary complexing agent. Compared with the traditional electrolyte configuration strategy, the combined complexing agent solution proposed in the present invention is applied to the electrolyte of a zinc-based battery, and has the advantages of high electrolyte stability, good cycle reversibility, and inhibition of zinc dendrite growth.

[0017] 2) The electrolyte system for zinc-based energy storage batteries involved in the present invention has the advantages of simple configuration, low cost, good cycle stability, wide working pH range, and wide application range. It can be matched with a variety of zinc-based energy storage battery systems, has wide versatility, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] FIG1 is a graph showing the cycling data of a Zn||Zn symmetric battery in Example 1 ( Figure 1a is a schematic diagram of voltage fluctuation over time. Figure 1b Schematic diagram of the change of Coulomb efficiency with the number of cycles);

[0019] Figure 2 is a graph showing the cycle data of the Zn||Zn symmetric battery in Example 2 ( Figure 2a is a schematic diagram of voltage fluctuation over time. Figure 2b Schematic diagram of the change of Coulomb efficiency with the number of cycles);

[0020] Figure 3 is a graph showing the cycle data of the Zn||Zn symmetric battery in Comparative Example 1 ( Figure 3a is a schematic diagram of voltage fluctuation over time. Figure 3b Schematic diagram of the change of Coulomb efficiency with the number of cycles);

[0021] Figure 4 is a graph showing the cycle data of the Zn||Zn symmetric battery in Comparative Example 2 ( Figure 4a is a schematic diagram of voltage fluctuation over time. Figure 4b (a) is a schematic diagram showing the variation of Coulomb efficiency with the number of cycles. DETAILED DESCRIPTION

[0022] The present invention is further described below in conjunction with embodiments. The description of the following embodiments is only used to help understand the present invention. It should be noted that for ordinary persons in the art, without departing from the principle of the present invention, the present invention can also be modified in some ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0023] Embodiment 1

[0024] As an example, in this first embodiment, the electrolyte of a zinc-based energy storage battery is prepared using this combined complexing agent solution:

[0025] The combined complexing agent consists of two parts: a main complexing agent and an auxiliary complexing agent. It will react with zinc ions in an aqueous solution to form a stable complex. The complex can be stable under alkaline conditions of pH>7.

[0026] The type and concentration of the zinc salt are used in conjunction with the positive electrode system, and a suitable zinc salt is selected to prepare the electrolyte according to different positive electrode systems.

[0027] In this example, the materials used to prepare the electrolyte are: main complexing agent ethylenediaminetetraacetic acid, auxiliary complexing agent acetohydroxamic acid, NaOH, NaCl, ZnCl2 and deionized water. Among them, the concentration of ethylenediaminetetraacetic acid is 0.3 mol / L, acetohydroxamic acid is 0.1 mol / L, NaOH is 1.2 mol / L, and the concentration of NaCl is 2 mol / L.

[0028] The specific preparation method steps of the electrolyte of the zinc-based energy storage battery are as follows:

[0029] Step 1: Weigh 4.38 g of ethylenediaminetetraacetic acid and 4 g of sodium hydroxide particles in a beaker and dissolve them in deionized water. After clarification, add 0.375 g of acetohydroxamic acid and obtain solution A after complete dissolution.

[0030] Step 2: Dissolve 2.04 g of zinc chloride in an appropriate amount of deionized water to obtain solution B.

[0031] Step 3: Stir solution A with ultrasound, then slowly add solution B into solution A. After the addition is complete, turn off the ultrasound and continue stirring for 10 minutes. Then add 5.84 g of NaCl and continue stirring. After the NaCl is completely dissolved, adjust the pH of the electrolyte to 12 with aqueous sodium hydroxide solution and dilute to volume in a 50 mL volumetric flask to obtain the target electrolyte.

[0032] The results of the electrolyte cycle in the Zn||Zn symmetric battery in this example are as follows: Figure 1a and Figure 1b As shown, it can be seen that the electrolyte system remained stable for more than 800 cycles and more than 3000 hours, showing excellent cycling performance, which indicates that the dual complexing agent structure contributes to the suppression of zinc dendrites and high reversibility.

[0033] Embodiment 2

[0034] As another embodiment, this embodiment 2 proposes, based on the embodiment 1, another electrolyte of a zinc-based energy storage battery prepared by the same method:

[0035] The materials used to prepare the electrolyte are: gluconic acid as the main complexing agent, tris(hydroxymethylaminomethane) as the auxiliary complexing agent, NaOH, NaCl, ZnBr2 and deionized water, wherein the concentration of gluconic acid is 0.9 mol / L, tris(hydroxymethylaminomethane) is 0.2 mol / L, NaOH is 0.9 mol / L, and the concentration of NaCl is 2 mol / L.

[0036] The specific preparation method steps of the electrolyte of the zinc-based energy storage battery are as follows:

[0037] Step 1: Weigh 8.82 g of gluconic acid and 1.8 g of sodium hydroxide particles in a beaker and dissolve them in deionized water. After clarification, add 1.21 g of tris(hydroxymethyl)aminomethane and obtain solution A after complete dissolution.

[0038] Step 2: Dissolve 3.37 g zinc bromide in an appropriate amount of deionized water to obtain solution B.

[0039] Step 3: Stir solution A with ultrasound, then slowly add solution B into solution A. After the addition is complete, turn off the ultrasound and continue stirring for 10 minutes. Then add 5.84 g of NaCl and continue stirring. After the NaCl is completely dissolved, adjust the pH of the electrolyte to 10 with an aqueous sodium hydroxide solution to obtain the target electrolyte.

[0040] The results of the electrolyte cycle in the Zn||Zn symmetric battery in this example are as follows: Figure 2a and Figure 2b As shown, similar to the cycle results of Example 1, the system remained stable in nearly 900 cycles and more than 3000 hours of cycles, further illustrating the improvement of the cycle stability of zinc by the combined complexing agent.

[0041] It should be noted that the parts in this embodiment that are the same or similar to those in the first embodiment can be referenced to each other and will not be described in detail in this application.

[0042] Comparative Example 1

[0043] As a comparative example, this comparative example 1 proposes an electrolyte comprising: NaOH, ZnO and deionized water, without adding a combined complexing agent solution. The concentration of sodium hydroxide is 5 mol / L, and the concentration of ZnO is 0.3 mol / L. The specific steps of its preparation are:

[0044] Dissolve 10g of sodium hydroxide in a beaker, add 1.2g of zinc oxide after it is completely dissolved, stir to dissolve, and then dilute to volume in a 50mL volumetric flask to obtain the target electrolyte.

[0045] The cycling results of the electrolyte in this comparative example in the Zn||Zn symmetric battery are as follows Figure 3a and Figure 3b As shown, the cycle results show that the symmetrical battery had a short circuit phenomenon after more than 200 cycles and 800 hours, which indicates that in a system without a chelating agent, the cycle stability of zinc is poor and it is easier to cause the growth of zinc dendrites.

[0046] Comparative Example 2

[0047] As another comparative example, this comparative example 2, based on the embodiment 2, proposes an electrolyte comprising: main complexing agent gluconic acid, NaOH, NaCl, ZnBr2 and deionized water, without adding auxiliary complexing agent. Among them, the concentration of gluconic acid is 0.9 mol / L, the concentration of NaOH is 0.9 mol / L, and the concentration of NaCl is 2 mol / L. The specific steps of its preparation are:

[0048] Step 1: Dissolve 8.82 g of gluconic acid in deionized water in a beaker to obtain solution A after it is completely dissolved.

[0049] Step 2: Dissolve 3.37 g zinc bromide in an appropriate amount of deionized water to obtain solution B.

[0050] Step 3: Stir solution A with ultrasound, then slowly add solution B into solution A. After the addition is complete, turn off the ultrasound and continue stirring for 10 minutes. Then add 5.84 g of NaCl and continue stirring. After the NaCl is completely dissolved, adjust the pH of the electrolyte to 12 with an aqueous sodium hydroxide solution to obtain the target electrolyte.

[0051] The results of the electrolyte cycle in the Zn||Zn symmetric battery in this example are as follows: Figure 4a and Figure 4bAs shown, the system can remain stable in a cycle of nearly 400 cycles and 1600 hours, but short circuit occurs in a longer cycle, and its stability is much lower than that of the electrolyte in Example 2. This is because under the condition of only the main complexing agent, there is a lack of synergistic effect of the auxiliary complexing agent. Although the stability is higher than that of the electrolyte without adding a complexing agent at all, compared with the scheme of using the main complexing agent and the auxiliary complexing agent in Example 1 and Example 2, the stability of zinc in long-term cycles is still insufficient, which is caused by the reduced reversibility of the complexation of zinc with the main complexing agent.

[0052] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

Claims

1. A combined complexing agent solution, characterized in that: include: The main complexing agent and the auxiliary complexing agent are selected from one or more of tartaric acid, ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, citric acid, glycine and gluconic acid, and the auxiliary complexing agent is selected from one or more of salicylic acid, acetohydroxamic acid, pyrophosphoric acid and tris(hydroxymethyl)aminomethane.

2. A method for preparing an electrolyte for a zinc-based energy storage battery using the combined complexing agent solution according to claim 1, characterized in that: The following steps are involved: Step 1: adding the main complexing agent into deionized water, stirring and dissolving, and then adding the auxiliary complexing agent, and obtaining solution A after the auxiliary complexing agent is dissolved; Step 2: Dissolve the zinc salt in deionized water to obtain solution B. Step 3: Then, solution B is added dropwise to solution A, and the mixture is stirred and mixed until solution B and solution A are completely mixed and the volume is fixed to obtain an electrolyte.

3. The method for preparing an electrolyte for a zinc-based energy storage battery according to claim 2, characterized in that: The zinc salt is one or more of zinc oxide, zinc bromide, zinc acetate, zinc sulfate and zinc oxalate, and the type and concentration of the zinc salt are determined according to the positive electrode system.

4. The method for preparing an electrolyte for a zinc-based energy storage battery according to claim 2, characterized in that: The molar ratio of the main complexing agent to the zinc salt in the combined complexing agent solution is 1:1 to 3:1, and the concentration of the auxiliary additive is 0.1 to 1 mol / L.

5. The method for preparing an electrolyte for a zinc-based energy storage battery according to claim 2, characterized in that: In step 3, potassium salt or sodium salt is added at a concentration of 1 to 3 mol / L.

6. The method for preparing an electrolyte for a zinc-based energy storage battery according to claim 2, characterized in that: In step three, an acid or a base is added to adjust the pH of the base solution to 4-13, wherein the acid is one or more of hydrochloric acid or sulfuric acid, and the base is one or more of sodium hydroxide and potassium hydroxide.

7. The method for preparing an electrolyte for a zinc-based energy storage battery according to claim 2, characterized in that: In step 3, solution B and solution A are mixed under ultrasound and stirring.

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