Multi-element high-concentration high-conductivity mixed aqueous electrolyte as well as preparation method and application thereof

Abstract

The invention relates to a multi-element high-concentration high-conductivity mixed aqueous electrolyte and a preparation method and application thereof, through cooperation of multi-element high-concentration components and use of various high-concentration salt components, the multi-element high-concentration components have a dissolvability promoting effect, the conductivity and the battery performance are improved, and the electrolyte has the advantages of high conductivity, high conductivity and high conductivity. The problem that the conductivity is obviously reduced due to ion crowding caused by a single high-concentration component is greatly avoided, the energy efficiency and the resource utilization rate of the battery are improved, and the rapid charging and discharging capability of the battery is favorably improved; meanwhile, the dependence on a single type of high-solubility and expensive high-concentration salt is reduced through a multi-element high-concentration component, so that the method also has relatively good economical efficiency; during preparation, only water is used as a solvent, an organic solvent is not needed as an auxiliary solvent, and the prepared electrolyte still has good stability.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrolytes, and in particular relates to a multi-element high-concentration and high-conductivity mixed aqueous electrolyte and a preparation method and application thereof. Background Art

[0002] Aqueous batteries, as an important electrochemical energy storage device, have occupied a large application market. They are currently mainly used in electric bicycles, electric vehicles, energy storage systems, uninterruptible power supplies (UPS) and other fields. Aqueous batteries have attracted widespread attention due to their high safety and environmental friendliness. With the rapid development of new energy and electronic products, the demand for electrolytes is increasing. At present, existing aqueous electrolytes have problems such as low conductivity, insufficient stability and strong corrosiveness. The existing electrolytes are not stable enough, which easily leads to performance degradation of electrochemical devices during long-term use; at the same time, the corrosion of electrolytes to electrode materials is also a problem that needs to be solved urgently, which limits its application in high-performance electrochemical devices.

[0003] There are many studies on aqueous electrolytes, but most of them are single high-concentration salt electrolytes and "salt-in-water" electrolytes. Such electrolytes usually face the problems of high viscosity and low conductivity, which limits the rapid charging and discharging capabilities of the battery. In addition, the utilization rate of high-concentration single ions in the electrolyte is low, which not only reduces the energy efficiency of the battery, but also leads to a waste of resources. At the same time, the function of the electrolyte is relatively single and lacks versatility, which limits its applicability in diverse electrochemical systems.

[0004] Therefore, developing a multi-component, high-concentration, and high-conductivity mixed electrolyte has great theoretical and practical significance for improving the chemical properties and cycle life of aqueous batteries and promoting the widespread application of aqueous batteries. Summary of the invention

[0005] The purpose of the present invention is to overcome the deficiencies in the prior art and to provide a multi-element, high-concentration, high-conductivity mixed aqueous electrolyte and a preparation method and application thereof.

[0006] The multi-element high-concentration high-conductivity mixed aqueous electrolyte comprises: water, ion reactant A, ion auxiliary agent B and molecular permeation agent C, wherein the ion reactant A comprises an active cationic reactant A1 and an active dual ion reactant A2, and the ion auxiliary agent B comprises a conductive agent B1 and a stabilizer B2;

[0007] At least one of the ion reactant A, high concentration ion auxiliary agent B and molecular permeation agent C has a molar concentration greater than or equal to 5 mol / kg, the total molar concentration of the electrolyte is greater than or equal to 24 mol / kg, and the water content is 25-50 wt.%.

[0008] Preferably, in the active cationic reactant A1, the active cation includes at least one of zinc, lithium, sodium and potassium, and the anion includes at least one of acetate, sulfate, sulfonic acid, fluoride ion of sulfonic acid, sulfonimide and fluoride ion of sulfonimide.

[0009] Preferably, in the active dual ion reactant A2, the active cation includes at least one of zinc, lithium, sodium and potassium, and the active anion includes at least one of reactive halide ion, ferrocyanide ion and ferrocyanide ion.

[0010] Preferably, the conductive promoter B1 is at least one of magnesium sulfate, aluminum sulfate, magnesium sulfonate and aluminum sulfonate.

[0011] Preferably, the stabilizer B2 is at least one of ammonium acetate, ammonium sulfate, ammonium sulfonate, diamine maleate and multi-stage ammonium salt derivatives.

[0012] Preferably, the molecular permeabilizer C comprises at least one of urea, acetamide, sorbitol, mannitol, sucrose, glucose and fructose.

[0013] The method for preparing the multi-element high-concentration and high-conductivity mixed aqueous electrolyte comprises the following steps:

[0014] Step 1, adding ion reagent A into deionized water, stirring to obtain a mixed solution 1;

[0015] Step 2, adding ion auxiliary agent B to the mixed solution 1, stirring to obtain the mixed solution 2;

[0016] Step 3, adding molecular permeabilizer C to the mixed solution 2, stirring to obtain a clarified electrolyte;

[0017] Step 4: Adjust the pH value of the clarified electrolyte to 6.5-12.5 to obtain a mixed aqueous electrolyte.

[0018] This multi-element, high-concentration, and high-conductivity mixed aqueous electrolyte is used in zinc ion batteries, lithium ion batteries, sodium ion batteries, or potassium ion batteries.

[0019] The beneficial effects of the present invention are:

[0020] 1) The present invention uses a variety of high-concentration salt components through the combination of multiple high-concentration components, so that the solubility between them is promoted, the conductivity and battery performance are improved, and the problem of ion crowding caused by a single high-concentration component and a significant reduction in conductivity is greatly avoided, thereby improving the energy efficiency and resource utilization of the battery, and is conducive to improving the rapid charge and discharge capability of the battery; at the same time, the multiple high-concentration components reduce the dependence on a single type of highly soluble and expensive high-concentration salt, so it also has good economic efficiency.

[0021] 4) The electrolyte proposed in the present invention uses only water as a solvent during preparation, and does not require an organic solvent as an auxiliary solvent. The prepared electrolyte still has good stability and maintains its intrinsic safety properties, which is beneficial to extending the cycle life of electrochemical equipment and reducing safety hazards.

[0022] 3) The multi-element high-concentration and high-conductivity mixed aqueous electrolyte proposed in the present invention is multifunctional and suitable for a variety of electrochemical systems, thus broadening its application in the field of electrochemistry. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The electrolyte conductivity bar graphs of the embodiments and comparative examples;

[0024] Figure 2 The battery cycle curves of Example 1, Comparative Example 1 and Comparative Example 3 are shown;

[0025] Figure 3 The battery cycle curves of Example 2, Comparative Example 2 and Comparative Example 3 are shown. DETAILED DESCRIPTION

[0026] 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.

[0027] Embodiment 1

[0028] As an embodiment, a multi-component high-concentration and high-conductivity mixed aqueous electrolyte comprises three major components, namely, an ion reactant A, an ion auxiliary agent B, and a molecular permeant C.

[0029] Wherein the ion reactant A includes two types, namely active cationic reactant A1 and active diionic reactant A2. The ion auxiliary agent B includes two types, namely conductive promoter B1 and stabilizer B2. The above-mentioned ion reactant A, ion auxiliary agent B and molecular permeation agent C contain at least one component with a molar concentration of not less than 5 mol / kg, and the total molar concentration of the electrolyte is not less than 24 mol / kg. Preferably, the electrolyte contains 25-50 wt.% of water as a single solvent, which is significantly different from the current typical "water in salt" and "eutectic" electrolytes, and is substantially different from electrolytes based on high-concentration organic solvents.

[0030] The conductive promoter B1 is a high-concentration salt that assists strong ionization, the stabilizer B2 is a high-concentration salt with acid-base buffering effect, and the molecular permeation agent C is a sugar (alcohol) and amide in an organic compound that can evenly disperse water and various solute components. The reasonable selection of the types and concentrations of the above high-concentration components can reduce the dependence on a single type of highly soluble and expensive organic high-concentration salt, thereby improving the economy of the electrolyte.

[0031] In this embodiment: the active cationic reactant A1 is zinc acetate and the active diionic reactant A2 is sodium bromide; the conductive promoter B1 is magnesium sulfate, the stabilizer B2 is ammonium acetate, and the molecular permeation agent C is glucose.

[0032] The preparation method of this multi-element high-concentration and high-conductivity mixed aqueous electrolyte comprises the following steps:

[0033] Step 1: Add 500 g of deionized water according to a predetermined ratio, weigh 550 g of zinc acetate and 308 g of sodium bromide, and stir for 20 minutes to obtain a uniform mixed solution 1.

[0034] Step 2: Add 300 g of magnesium sulfate and 192 g of ammonium acetate to the mixed solution 1, and stir for 20 min to obtain a uniform mixed solution 2.

[0035] Step 3: Add 720 g of glucose to the mixed solution 2 and stir for 30 min to obtain a clear electrolyte.

[0036] Step 4: Use acetic acid or sodium hydroxide to fine-tune the pH value of the electrolyte to 7.5 to obtain the multi-element high-concentration and high-conductivity mixed aqueous electrolyte.

[0037] Then the Zn / / MnO2 batteries were assembled and electrochemical tests were performed.

[0038] Embodiment 2

[0039] As another embodiment, this embodiment 2 proposes another multi-element high-concentration and high-conductivity mixed aqueous electrolyte on the basis of embodiment 1:

[0040] The active cationic reactant A1 is lithium sulfate, and the active diionic reactant A2 is zinc bromide.

[0041] The conductive agent B1 is magnesium sulfonate, the stabilizer B2 is ammonium sulfonate, and the molecular permeation agent C is acetamide.

[0042] The preparation method of this multi-element high-concentration and high-conductivity mixed aqueous electrolyte comprises the following steps:

[0043] Step 1: Add 500 g of deionized water according to a predetermined ratio, weigh 330 g of lithium sulfate and 675 g of zinc bromide, and stir for 20 minutes to obtain a uniform mixed solution 1.

[0044] Step 2: Add 588 g of magnesium sulfonate and 285 g of ammonium sulfonate to the mixed solution 1, stir for 20 min, and obtain a uniform mixed solution 2.

[0045] Step 3: Add 354 g of acetamide to the mixed solution 2 and stir for 30 min to obtain a clear electrolyte.

[0046] Step 4: Use sulfonic acid or lithium hydroxide to fine-tune the pH value of the electrolyte to 8.5 to obtain the multi-element high-concentration and high-conductivity mixed aqueous electrolyte.

[0047] Then the Zn / / MnO2 batteries were assembled and electrochemical tests were performed.

[0048] 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.

[0049] Comparative Example 1

[0050] As a comparative example, in this comparative example 1, based on Example 1, the components and amounts of ion reactant A, ion auxiliary agent B and molecular permeation agent C remain unchanged, while the amount of water is increased, specifically, increased to 2500g, which is equivalent to diluting the electrolyte in Example 1 by 5 times, and the rest of the preparation methods remain unchanged.

[0051] 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.

[0052] Comparative Example 2

[0053] As a comparative example, based on Example 2, this comparative example 2 also dilutes the electrolyte in Example 2 by 5 times, that is, the components and amounts of ion reactant A, ion auxiliary agent B and molecular permeation agent C remain unchanged, while the amount of water is increased to 2500g, and the rest of the preparation method remains unchanged.

[0054] Comparative Example 3

[0055] As another comparative example, in this comparative example 3, 161 g of zinc sulfate was weighed and added into 500 g of deionized water, and stirred for 30 min to obtain a clear electrolyte.

[0056] The electrolytes obtained in Example 1, Example 2, and Comparative Examples 1 to 3 were assembled into Zn / / MnO2 batteries, and the batteries were subjected to electrochemical tests. The conductivity and battery cycle curves obtained are shown in FIG. Figures 1 to 3 As shown:

[0057] The conductivity of Example 1 to Comparative Example 3 is as follows Figure 1As shown in the electrolyte conductivity bar graph of Example 2 and Comparative Examples 2 and 3, it can be seen that the conductivity of the multi-element high-concentration and high-conductivity mixed aqueous electrolyte obtained by the components and preparation method proposed in the present invention is not less than 75% of the conductivity of its five-fold diluted solution, and is significantly higher than the conductivity of the "water in salt" and "eutectic" electrolytes. The conductivity of its five-fold diluted solution is equivalent to that of a conventional zinc sulfate electrolyte. On the basis of having a higher conductivity, it reduces the dependence on a single type of high-concentration salt with a higher cost, that is, zinc sulfate in Comparative Example 3, thereby improving the economy of the electrolyte.

[0058] like Figure 2 As shown, the battery prepared by the electrolyte obtained in Example 1 has a weaker trend of changing with the number of cycles, and still maintains about 95% after 181 cycles. The battery capacity retention rate of Comparative Example 1 obtained after five-fold dilution still reaches 80% after 181 cycles, while Comparative Example 3 uses only a single and expensive zinc sulfate to prepare the electrolyte, and the battery capacity retention rate drops to about 60% after the same number of cycles. It can be seen that the electrolyte battery capacity retention rate proposed in the present invention is significantly higher. Therefore, the electrolyte preparation method proposed in the present invention has better economic benefits and better stability, maintains intrinsic safety properties, is conducive to extending the cycle life of electrochemical equipment, and reduces safety hazards.

[0059] like Figure 3 As shown in the figure, it can be seen from the battery cycle curves of the electrolyte tests of Example 2, Comparative Example 2 and Comparative Example 3 that the battery using a multi-element high-concentration and high-conductivity mixed aqueous electrolyte of Example 2 also exhibits excellent long-cycle stability, and the capacity retention rate after 181 cycles is maintained at about 95%, while the corresponding cycle capacity retention rates of the batteries of Comparative Example 2 and Comparative Example 3 decline to about 80% and 60%, respectively, which is consistent with the Figure 2 This is consistent with the demonstrated rules, which further verifies that the electrolyte proposed in the present invention has a very obvious effect on improving the long-cycle stability of aqueous batteries.

[0060] 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 multi-element high-concentration and high-conductivity mixed aqueous electrolyte, characterized in that: include: Water, ion reagent A, ion auxiliary agent B and molecular permeation agent C, ion reagent A includes active cationic reagent A1 and active diionic reagent A2, ion auxiliary agent B includes conductive agent B1 and stabilizer B2; At least one of the ion reactant A, high concentration ion auxiliary agent B and molecular permeation agent C has a molar concentration greater than or equal to 5 mol / kg, the total molar concentration of the electrolyte is greater than or equal to 24 mol / kg, and the water content is 25-50 wt.%.

2. The multi-element high-concentration and high-conductivity mixed aqueous electrolyte according to claim 1, characterized in that: In the active cationic reactant A1, the active cation includes at least one of zinc, lithium, sodium and potassium, and the anion includes at least one of acetate, sulfate, sulfonic acid, fluoride ion of sulfonic acid, sulfonimide and fluoride ion of sulfonimide.

3. The multi-element high-concentration and high-conductivity mixed aqueous electrolyte according to claim 1, characterized in that: In the active dual ion reactant A2, the active cation includes at least one of zinc, lithium, sodium and potassium, and the active anion includes at least one of reactive halide ion, ferrocyanide ion and ferrocyanide ion.

4. The multi-element high-concentration and high-conductivity mixed aqueous electrolyte according to claim 1, characterized in that: The conductive promoter B1 is at least one of magnesium sulfate, aluminum sulfate, magnesium sulfonate and aluminum sulfonate.

5. The multi-element high-concentration and high-conductivity mixed aqueous electrolyte according to claim 1, characterized in that: The stabilizer B2 is at least one of ammonium acetate, ammonium sulfate, ammonium sulfonate, maleic acid diamine and multi-stage ammonium salt derivatives.

6. The multi-element high-concentration and high-conductivity mixed aqueous electrolyte according to claim 1, characterized in that: The molecular permeabilizing agent C includes at least one of urea, acetamide, sorbitol, mannitol, sucrose, glucose and fructose.

7. The method for preparing a multi-element high-concentration and high-conductivity mixed aqueous electrolyte according to any one of claims 1 to 6, characterized in that: The following steps are involved: Step 1, adding ion reagent A into deionized water, stirring to obtain a mixed solution 1; Step 2, adding ion auxiliary agent B to the mixed solution 1, stirring to obtain the mixed solution 2; Step 3, adding molecular permeabilizer C to the mixed solution 2, stirring to obtain a clarified electrolyte; Step 4: Adjust the pH value of the clarified electrolyte to 6.5-12.5 to obtain a mixed aqueous electrolyte.

8. The use of the multi-component high-concentration and high-conductivity mixed aqueous electrolyte according to any one of claims 1 to 6, characterized in that: Used in zinc ion batteries, lithium ion batteries, sodium ion batteries or potassium ion batteries.

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