Aqueous zinc ion battery electrolyte and preparation method and application thereof

Abstract

The invention relates to the technical field of energy storage batteries, and particularly discloses an aqueous zinc ion battery electrolyte as well as a preparation method and application thereof. The electrolyte is composed of electrolyte zinc salt, pyridine organic metal salt and water. And after hydrolysis, metal ions in the weakly acidic pyridine organic metal salt are in a positively charged state. Therefore, in the zinc deposition process, positively charged metal ions and picolinate radicals can be adsorbed on zinc favorable nucleation sites to promote uniform deposition of zinc ions. Compared with a metal ion additive in the prior art, interface adsorption of hydrolyzed pyridine organic molecules can effectively reduce the water content of the surface of the zinc negative electrode and construct a hydrophobic interface channel, so that hydrogen evolution reaction (HER) can be effectively inhibited, and the interface corrosion phenomenon of the zinc negative electrode is further eliminated. According to the analysis, the pyridine organic metal salt additive has the advantage of synergistic effect of multiple functions at the same time, so that dendrite-free growth and corrosion inhibition of the zinc negative electrode are realized, and the cycle life of the battery is prolonged.

Description

Technical Field

[0001] The invention belongs to the technical field of energy storage batteries, and specifically relates to an aqueous zinc ion battery electrolyte and a preparation method and application thereof. Background Art

[0002] Among the new generation of energy storage systems, aqueous zinc-ion batteries have attracted widespread attention due to their low redox potential, low cost, non-toxicity, and high theoretical specific capacity (820 mAh g -1 or 5855 mAh cm -3 ). However, uncontrolled dendrite growth, hydrogen evolution reaction (HER), and interfacial corrosion lead to poor stability and reversibility of Zn anode during the electroplating / stripping process, which hinders the commercialization of Zn-ion batteries. Specifically, the inherent defects on the surface of Zn anode lead to uneven electric field distribution and uneven Zn ion flux during Zn deposition. Under the action of local electric field, Zn 2+ Ions tend to deposit unevenly, forming irregular dendrites and even causing internal short circuits. 2+ H in the solvation shell 2 O molecules exhibit high chemical reactivity and spontaneously undergo HER reactions, leading to local pH increases and the formation of byproducts. These high surface area byproducts further deteriorate the Zn 2+ The uniformity of deposition leads to the aggravation of dendrite growth and the eventual formation of dead zinc. These shortcomings jointly affect its cycle life and Coulombic efficiency.

[0003] To date, several strategies have been implemented to improve the electrochemical stability and reversibility of Zn metal electrodes by inhibiting dendrite formation and eliminating water-induced parasitic reactions, including structural design of host substrates, membrane modification, artificial protective layers, electrolyte optimization, etc. Among them, the optimization of electrolytes using functional additives is considered to be a promising method due to its simplicity and low manufacturing cost. Generally, electrolyte additives can be adsorbed on the interface or participate in the Zn 2+The solvation shell of Zn can be used to regulate the Zn deposition process, so that Zn nucleates uniformly and delays the occurrence of side reactions. For example, saccharin, zwitterionic liquids, N-methylimidazole, 1,4-dioxane, choline ions, etc., as electrolyte additives, can be preferentially adsorbed on the surface of Zn metal due to their high affinity with Zn metal, thereby forming a water-poor double layer structure, preventing side reactions caused by water and inhibiting dendrite growth. On the other hand, recent studies have shown that the preferential growth of the (002) plane can form a dense deposition layer, effectively inhibiting the growth of dendrites. In order to obtain the Zn (002) texture of the dendrite-free anode, most of these studies require surface pretreatment, such as acid etching, rolling adjustment, and high-temperature annealing, which makes the preparation process complicated. In addition, the current density and areal capacity are also unsatisfactory. The nucleation / growth mechanism of the Zn (002) crystal plane is still unclear. Therefore, it is of great significance to study the effect of electrolyte additives on the Zn negative electrode, which helps to inhibit the occurrence of HER reaction and induce the oriented growth of Zn during the long cycle of the battery. Summary of the invention

[0004] The purpose of the present invention is to provide an aqueous zinc ion battery electrolyte and a preparation method and application thereof in view of the above-mentioned deficiencies in the prior art, by providing an organic metal salt electrolyte improver, while having the advantages of multiple functional synergistic effects, to achieve the zinc negative electrode without dendrite growth and eliminate interface corrosion, thereby improving the overall cycle life of the battery.

[0005] To achieve the above object, the present invention adopts the following technical solution: The first aspect of the present invention is to provide an aqueous zinc ion electrolyte, the electrolyte is composed of an electrolyte zinc salt, a pyridine organic metal salt and water, and the chemical formula of the pyridine organic metal salt is , Where X is a metal ion, m and n represent the number of picolinate and metal ions, respectively, m is 2 or 3, and n is 1; When m is 2 and n is 1, the pyridine organic metal salt is any one of a pyridine organic zinc salt, a pyridine organic copper salt or a pyridine organic calcium salt; When m is 3 and n is 1, the pyridine organometallic salt is a pyridine organoferric salt.

[0006] Furthermore, the electrolyte zinc salt is any one of hydrated zinc sulfate, hydrated zinc chloride, and zinc trifluoromethanesulfonate.

[0007] Furthermore, the concentration of the electrolyte zinc salt is 1-2 mol / L.

[0008] Furthermore, the concentration of the pyridine organometallic salt is 0.01 mol / L to 0.3 mol / L.

[0009] Furthermore, the pH value of the electrolyte is 2.8-3.5.

[0010] The second object of the present invention is to provide the use of the above-mentioned electrolyte in the preparation of aqueous zinc ion batteries, symmetrical button cells or half cells.

[0011] Furthermore, the aqueous zinc ion battery uses zinc sheet as the negative electrode material and I / C as the positive electrode material.

[0012] Furthermore, the symmetrical button battery uses zinc sheets as positive and negative electrodes.

[0013] Furthermore, the half-cell uses a zinc sheet as a negative electrode and a copper foil as a positive electrode.

[0014] The third object of the present invention is to provide an electrolyte for protecting zinc-based current collectors, copper-based current collectors and titanium-based current collectors.

[0015] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects: (1) The present invention provides an aqueous zinc ion electrolyte, which is composed of an electrolyte zinc salt, a pyridine organic metal salt and water. Since the electrolyte is weakly acidic after hydrolysis, the metal ions in the pyridine organic metal salt will be positively charged. Therefore, during the zinc deposition process, the positively charged metal ions, pyridine carboxylate, will be adsorbed on the zinc favorable nucleation site to promote the uniform deposition of zinc ions. Compared with the metal ion additives in the prior art, the interfacial adsorption of the hydrolyzed pyridine organic molecules can effectively reduce the water content on the surface of the zinc negative electrode and construct a hydrophobic interface channel, so it can effectively inhibit the hydrogen evolution reaction (HER) and further eliminate the interfacial corrosion phenomenon of the zinc negative electrode. From the above analysis, it can be concluded that the pyridine organic metal salt additive has the advantages of multiple functional synergistic effects at the same time, so that the zinc negative electrode can achieve no dendrite growth and corrosion inhibition, thereby improving the cycle life of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is the deposition morphology of zinc in Example 1; Figure 2 This is the zinc deposition morphology of Comparative Example 1; Figure 3 This is an optical microscope image of zinc in Example 1 for in-situ observation of zinc deposition.

[0017] Figure 4 This is a microscope image of zinc deposition in Comparative Example 1; Figure 5 This is a test diagram of the cycle life of the zinc symmetric battery of Example 1 and Comparative Example 1 under the same test conditions; Figure 6 This is the zinc deposition morphology of Example 2; Figure 7This is a microscope image of zinc deposition in Example 2; Figure 8 This is the zinc deposition morphology of Example 3; Fig. 9 This is the zinc deposition morphology of Comparative Example 3; Fig.10 It is a test chart of the cycle life of zinc symmetric batteries of Example 3 and Comparative Example 3 under the same test conditions. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical scheme and advantages of the present invention clearer, the specific embodiments of the present invention are further described in detail below in conjunction with specific examples and drawings. If no specific test method, instrument or condition is specified in the examples, it is carried out according to the technology or condition described in the literature in this field or according to the product instructions. If the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be obtained commercially.

[0019] The embodiment of the present invention provides an aqueous zinc ion electrolyte, which can inhibit the growth of zinc dendrites. The electrolyte is composed of an electrolyte zinc salt, a pyridine organic metal salt and water. The chemical formula of the pyridine organic metal salt is , Where X is a metal ion, m and n represent the number of picolinate and metal ions, respectively, m is 2 or 3, and n is 1; When m is 2 and n is 1, the pyridine organic metal salt is any one of a pyridine organic zinc salt, a pyridine organic copper salt or a pyridine organic calcium salt; When m is 3 and n is 1, the pyridine organometallic salt is a pyridine organoferric salt.

[0020] The electrolyte zinc salt is any one of hydrated zinc sulfate, hydrated zinc chloride, and zinc trifluoromethanesulfonate. These electrolytes all provide zinc ions, which can provide replenishment for the ion migration of the electrolyte. It is not excluded that the pyridine organic metal salt in the present invention can also be applied to other weakly acidic electrolytes of aqueous zinc ion batteries to achieve the expected technical effect of the present invention.

[0021] Preferably, the concentration of the electrolyte zinc salt is 1-2 mol / L, the concentration of the pyridine organic metal salt is 0.01 mol / L-0.3 mol / L, and the pH value of the electrolyte is 2.0-3.5.

[0022] The assembly method of the aqueous zinc ion battery is as follows: the electrolyte, the positive electrode, the negative electrode and the separator are assembled into a sandwich structure in the order of positive electrode / separator / negative electrode, and then the electrolyte is added and packaged, wherein the electrolyte is the above-mentioned electrolyte, the commercial zinc sheet is used as the negative electrode material, the I / C is used as the positive electrode material, and the separator is a glass fiber membrane.

[0023] Symmetric button cell: The assembly order is positive electrode shell, gasket, zinc sheet, diaphragm zinc sheet, gasket, shrapnel, negative electrode shell, and each cell uses 100 μL of electrolyte containing zinc picolinate. Assemble Zn / / Zn symmetric cells for electrochemical testing. Zinc full batteries were assembled for electrochemical testing. The assembly order was positive electrode shell, gasket, zinc sheet, separator zinc sheet, gasket, shrapnel, and negative electrode shell. Each battery used 100 μL of electrolyte containing zinc picolinate.

[0024] The aqueous zinc ion battery provided by the present invention is a new type of energy storage technology that is safe and environmentally friendly and has been deeply integrated into daily life scenes. In the field of smart home, the family energy storage wall adopts a modular zinc ion battery pack, which is safe and has no risk of explosion. It can support the operation of all household appliances for 8 hours, and the charging speed is 3 times faster than that of traditional lithium batteries, and the price is reduced by 40%. In terms of wearable devices, the button-type zinc battery equipped with smart watches can achieve 0-100% charging in only 7 minutes, with a battery life of 30 days, and has passed the IP68 waterproof test and has become the first choice for swimming enthusiasts. The "Zinc Safety" series of models used in electric bicycles are equipped with detachable battery packs, which support normal use at low temperatures of -20°C, and the community smart power exchange cabinet can complete energy replenishment in 5 minutes. More strikingly, some children's toys have been fully switched to aqueous zinc batteries, completely eliminating the risk of chemical damage caused by accidentally swallowing batteries, and parents can monitor the health status of the batteries in real time through mobile phone APP. As the cost of aqueous zinc batteries continues to decline, their advantages of being non-flammable, non-leaking, environmentally friendly and non-toxic are accelerating the replacement of traditional lithium batteries.

[0025] The embodiments of the present invention have achieved some positive effects during the development or use process, and indeed have great advantages over the prior art. The following content is described in conjunction with data, charts, etc. of the test process.

[0026] Example 1 This embodiment provides an electrolyte containing a pyridine organic metal salt.

[0027] The pyridine organometallic salt used in this embodiment is specifically: , Wherein m is 2, n is 1, and X is a metal zinc ion, namely zinc picolinate.

[0028] Dissolve 0.02 mol of zinc picolinate and 0.2 mol of zinc sulfate in deionized water to prepare 100 mL of electrolyte containing 2 mol / L zinc sulfate and 0.2 mol / L zinc picolinate. Place Zn sheets, Cu sheets or Ti sheets as current collectors in the electrolyte for zinc deposition. The zinc deposition morphology is as follows: Figure 1 As shown in Figure 2, the zinc deposition is smooth and has no obvious dendrites. Then an optical microscope was used to observe the surface of the zinc deposition in situ, as shown in Figure 2. Figure 3As shown in the figure, there are no obvious bubbles during the deposition process, reflecting that the hydrogen evolution reaction is inhibited during the zinc deposition process. The configured electrolyte was tested for zinc symmetric battery, and the cycle life of the zinc symmetric battery exceeded 2100 h. Figure 5 shown.

[0029] Comparative Example 1 The method is substantially the same as in Example 1, except that zinc picolinate is not added.

[0030] Dissolve 0.2 mol of zinc sulfate in deionized water to prepare 100 mL of 2 mol / L zinc sulfate electrolyte. Place Zn sheets, Cu sheets, or Ti sheets as current collectors in the electrolyte for zinc electrodeposition. The corresponding zinc deposition morphology is as follows: Figure 2 As shown in Figure 1, it can be found that there is obvious uneven deposition and disordered dendrites appear on the surface. Then, an optical microscope was used to observe the zinc deposition surface in situ, as shown in Figure 1. Figure 4 As shown in the figure, obvious bubbles and growing zinc dendrites appeared during the deposition process. The prepared electrolyte was used for zinc symmetric battery testing, and the cycle life of the zinc symmetric battery was less than 100 h. Figure 5 shown.

[0031] By comparing the zinc deposition process morphology and battery test results of Example 1 and Comparative Example 1, it is obviously found that Example 1 adds zinc picolinate to the electrolyte, which effectively inhibits the hydrogen evolution reaction and interfacial corrosion in the zinc deposition process and achieves dendrite-free growth of the zinc negative electrode, thereby significantly improving the reversible cycle life of the battery.

[0032] Example 2 This embodiment provides an electrolyte containing a pyridine organic metal salt.

[0033] The pyridine organometallic salt used in this embodiment is specifically: , Wherein m is 1, n is 1, and X is a metal copper ion, that is, copper picolinate.

[0034] 0.005 mol of the additive copper picolinate and 0.2 mol of zinc chloride were dissolved in deionized water to prepare 100 mL of electrolyte containing 2 mol / L zinc chloride and 0.05 mol / L copper picolinate. Zn sheets, Cu sheets or Ti sheets were placed in the electrolyte as current collectors to carry out zinc electrodeposition. The zinc deposition morphology is as follows: Figure 6 As shown in the figure, the zinc deposition morphology has no obvious dendrites. Subsequently, the zinc electrodeposition process was observed in situ using an optical microscope, as shown in the figure. Figure 7 As shown, it can be clearly seen from the figure that there are no obvious bubbles during the deposition process, reflecting that the hydrogen evolution reaction during zinc deposition is significantly weakened.

[0035] Example 3 This embodiment provides an electrolyte containing a pyridine organic metal salt.

[0036] The pyridine organometallic salt used in this embodiment is specifically:

[0037] Wherein m is 3, n is 1, and X is a metal iron ion, that is, iron picolinate.

[0038] 0.02 mol of additive iron picolinate and 0.1 mol of zinc trifluoromethanesulfonate were dissolved in deionized water to prepare 100 mL of electrolyte containing 1 mol / L zinc trifluoromethanesulfonate and 0.2 mol / L iron picolinate. Zn sheets, Cu sheets or Ti sheets were placed in the electrolyte as current collectors for zinc deposition. The zinc deposition morphology was as follows: Figure 8 As shown, the zinc deposition is smooth without obvious dendrites.

[0039] The prepared electrolyte was used for zinc symmetric battery test, and the cycle life of zinc symmetric battery exceeded 600 h. Fig.10 shown.

[0040] Comparative Example 3 Dissolve 0.1 mol of zinc trifluoromethanesulfonate in deionized water to prepare 100 mL of electrolyte containing 1 mol / L zinc chloride. Place Zn sheets, Cu sheets or Ti sheets as current collectors in the electrolyte for zinc electrodeposition. Obvious disordered dendrites appear on the surface of the zinc electrode, such as Fig. 9 shown.

[0041] In the absence of conflict, the above embodiments and features in the embodiments may be combined with each other.

[0042] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An aqueous zinc ion electrolyte, characterized in that The electrolyte is composed of an electrolyte zinc salt, a pyridine organic metal salt and water, and the chemical formula of the pyridine organic metal salt is , Where X is a metal ion, m and n represent the number of picolinate and metal ions, respectively, m is 2 or 3, and n is 1; When m is 2 and n is 1, the pyridine organic metal salt is any one of a pyridine organic zinc salt, a pyridine organic copper salt or a pyridine organic calcium salt; When m is 3 and n is 1, the pyridine organometallic salt is a pyridine organoferric salt.

2. The electrolyte according to claim 1, characterized in that The electrolyte zinc salt is any one of hydrated zinc sulfate, hydrated zinc chloride and zinc trifluoromethanesulfonate.

3. The electrolyte according to claim 1, characterized in that The concentration of the electrolyte zinc salt is 1-2 mol / L.

4. The electrolytic salt according to claim 1, characterized in that The concentration of the pyridine organic metal salt is 0.01 mol / L~0.3 mol / L.

5. The electrolyte according to claim 1, characterized in that The pH value of the electrolyte is 2.8-3.

5.

6. Use of the electrolyte according to any one of claims 1 to 5 in the preparation of an aqueous zinc ion battery, a symmetrical button cell or a half cell.

7. The use according to claim 6, characterized in that The aqueous zinc ion battery uses zinc sheet as negative electrode material and I / C as positive electrode material.

8. The use according to claim 6, characterized in that The symmetrical button cell uses zinc sheets as positive and negative electrodes.

9. The use according to claim 6, characterized in that The half-cell uses a zinc sheet as a negative electrode and a copper foil as a positive electrode.

10. The electrolyte according to any one of claims 1 to 5 is used for protecting zinc-based current collectors, copper-based current collectors and titanium-based current collectors.

Images