Synergistic aqueous zinc-ion battery electrolyte and application thereof

Abstract

The application discloses a synergistic aqueous zinc ion battery electrolyte and application thereof, and relates to the technical field of batteries.The electrolyte comprises a deionized water solvent, a zinc salt electrolyte and a functional additive, wherein the functional additive is composed of an alcohol and a multidentate ligand organic chelating agent; the chelating agent has a Zn 2+ Complexation constant logK satisfies 10 <= logK <= 19, the additive alcohol forms a strong hydrogen bond interaction with water molecules in the system, destroys the hydrogen bond network of the water molecules, reduces the activity of free water, and inhibits the hydrogen evolution side reaction and the electrochemical corrosion of the zinc negative electrode; the chelating agent enters the Zn 2+ Solvation sheath, reconfigures the short-range solvation structure, and accelerates the ion migration dynamics process, and the full battery assembled by the electrolyte has excellent cycle stability, and can be applied to the fields of large-scale energy storage, low-speed electric vehicle power supply and the like.

Description

Technical Field

[0001] This invention relates to the field of battery technology, specifically to a synergistic aqueous zinc-ion battery electrolyte and its application. Background Technology

[0002] The demand for large-scale, long-duration, safe, and low-cost energy storage technologies is surging in new power systems. Aqueous zinc-ion batteries (AZIBs), using metallic zinc as the negative electrode and aqueous electrolyte as the ion conductor, possess core advantages such as high theoretical specific capacity (820mAh / g), low standard electrode potential, high ionic conductivity of aqueous electrolyte, abundant zinc sources, low cost, intrinsic safety with no risk of thermal runaway, and environmental friendliness and recyclability. They are widely recognized as one of the most promising large-scale energy storage technologies for industrialization.

[0003] Currently, lithium-ion batteries are limited in their application in long-term, large-scale scenarios such as grid energy storage and industrial / commercial backup power supplies due to lithium scarcity, high cost, and significant thermal safety hazards. Lead-acid batteries, on the other hand, are gradually being replaced due to lead pollution, short cycle life (500-1000 cycles), and low energy density. Aqueous zinc-ion batteries can effectively overcome these technological shortcomings and are suitable for niche scenarios such as low-speed electric vehicles, IoT backup power supplies, and low-temperature special power supplies, showing broad prospects for industrialization.

[0004] The commercialization of aqueous zinc-ion batteries is primarily constrained by two intertwined technical challenges: instability at the zinc anode interface and defects in the electrolyte system. Specifically, in conventional pure aqueous zinc salt electrolytes, the zinc metal anode surface exhibits high chemical activity, readily reacting with free water molecules to undergo hydrogen evolution side reactions, interfacial chemical corrosion, and disordered growth of the passivation layer. This continuously consumes the electrolyte and active zinc anode material, leading to irreversible capacity decay. Furthermore, the irregular growth of zinc ions during deposition on the anode surface easily forms needle-like and dendritic zinc dendrites. The continuous growth of these dendrites can pierce the separator, causing micro-short circuits, increased self-discharge, and a precipitous drop in cycle life.

[0005] To address the aforementioned technical challenges, mainstream industry technologies include positive electrode modification, zinc negative electrode coating, separator functionalization, and electrolyte additives. Among these, electrolyte additives have become the easiest technology to industrialize due to their ability to perform modifications to existing electrode and battery assembly processes without altering existing methods, their intuitive modification effects, and their low cost. Currently, electrolyte additives for aqueous zinc-ion batteries are mainly classified into three categories: inorganic additives, polymeric additives, and small-molecule organic additives. Inorganic additives regulate zinc deposition through ion doping, but their modification mechanism is singular and they are prone to introducing impurities. Polymeric additives suppress dendrite formation by forming physical barriers, but their high viscosity and low ionic conductivity easily clog the separator. Small-molecule organic additives, with their advantages of small molecular weight, amphiphilicity, and easy water miscibility, can simultaneously achieve interfacial adsorption, solvation regulation, and binding of free water, making them a current research hotspot.

[0006] To address these issues, we provide a synergistic aqueous zinc-ion battery electrolyte and its application. Summary of the Invention

[0007] To solve the above-mentioned technical problems, the present invention is achieved through the following technical solution: A synergistic aqueous zinc-ion battery electrolyte, characterized by comprising the following components: solvent, zinc salt electrolyte, lithium salt electrolyte, functional additive A, and functional additive B; wherein the solvent is deionized water; functional additive A is an organic alcohol additive; and functional additive B is a chelating agent selected from multidentate ligand organic chelating agents, wherein the multidentate ligand organic chelating agent contains Zn 2+ The complexation constant logK is 10≤logK≤19, and the molar concentration of the chelating agent in the electrolyte is 0.001-0.1mol / L.

[0008] Further, the chelating agent is any one or more of disodium ethylenediaminetetraacetate, pentasodium diethylenetriaminepentaacetate, disodium iminodiacetate, and sodium hydroxyethylethylenediaminetriacetate; wherein the concentration of disodium ethylenediaminetetraacetate is 0.005-0.05 mol / L; the concentration of pentasodium diethylenetriaminepentaacetate is 0.002-0.02 mol / L; the concentration of disodium iminodiacetate is 0.03-0.12 mol / L; and the concentration of sodium hydroxyethylethylenediaminetriacetate is 0.003-0.04 mol / L.

[0009] Furthermore, the zinc salt electrolyte is any one or more of zinc sulfate, zinc trifluoromethanesulfonate, zinc chloride, zinc nitrate, and zinc acetate, and the molar concentration of the zinc salt electrolyte in the electrolyte is 0.5-3 mol / L.

[0010] Furthermore, the lithium salt electrolyte is any one or more of lithium sulfate, lithium trifluoromethanesulfonate, lithium chloride, lithium nitrate, and lithium acetate, and the molar concentration of the lithium salt electrolyte in the electrolyte is 0.5-3 mol / L.

[0011] Furthermore, the volume ratio of the functional additive A to deionized water is (1-3):10, and the molar ratio of zinc salt electrolyte to lithium salt electrolyte is 1:(0.5-2).

[0012] The present invention also provides an aqueous zinc-ion battery comprising the above-mentioned electrolyte, wherein the aqueous zinc-ion battery comprises the electrolyte, a positive electrode, a negative electrode, and a separator, wherein the zinc negative electrode is any one of pure zinc foil, zinc alloy foil, zinc-plated current collector, and three-dimensional porous zinc; the active material of the positive electrode is any one of lithium manganese oxide, manganese dioxide, Prussian blue and its derivatives, vanadium pentoxide, vanadate, and organic quinones; and the separator is a glass fiber separator.

[0013] Furthermore, the thickness of the pure zinc foil is 0.1 mm.

[0014] Furthermore, the active material, conductive agent, and binder are present, wherein the mass ratio of the active material, conductive agent, and binder is 8:1:1.

[0015] Furthermore, the battery can be any one of the following: button cell, pouch cell, cylindrical cell, or prismatic cell.

[0016] The present invention has the following beneficial effects: 1. This invention regulates the surface energy of the negative electrode and the deposition behavior of zinc ions through organic alcohol molecules, inducing the uniform two-dimensional deposition of zinc ions and inhibiting zinc dendrite growth at its source. Simultaneously, methanol forms strong hydrogen bonds with water molecules in the system, disrupting the original hydrogen bond network of pure water molecules, reducing the activity of free water in the electrolyte, and weakening the redox reaction activity between water molecules and the zinc negative electrode, effectively inhibiting hydrogen evolution side reactions and electrochemical corrosion of the zinc negative electrode.

[0017] 2. This invention constructs a tiered synergistic protection mechanism using alcohols and chelating agents to achieve multi-dimensional protection of the zinc anode. At the bulk level, organic alcohols interact strongly with water molecules through hydroxyl groups, disrupting the hydrogen bond network of water and significantly reducing free water activity, thereby inhibiting hydrogen evolution side reactions and electrochemical corrosion of the zinc anode. The chelating agent, on the other hand, enters the primary solvation sheath of zinc ions in the short term, reconstructing the solvation structure, reducing the number of coordinated water molecules, lowering the desolvation energy barrier, and accelerating ion migration kinetics. Simultaneously, at the zinc anode interface, it preferentially adsorbs polar functional groups, regulating zinc ion deposition behavior, homogenizing ion flux, inducing uniform and dense deposition, and inhibiting dendrite growth at its source. The tiered cooperation of organic alcohols and chelating agents at the bulk, short-term, and interfacial levels forms a synergistic protection mechanism of organic alcohols providing bulk open-circuit protection, chelating agents reconstructing in the short term, and interfacial regulation. Even if any layer fails, the remaining layers can still provide protection, resulting in system performance significantly higher than any single additive system.

[0018] 3. The chelating agent of this invention uses a medium chelating strength. By controlling the zinc ion complexation constant of the chelating agent between 10 and 19, it is ensured that the chelating agent can effectively reconstruct the solvation structure without excessively binding zinc ions and hindering the deposition reaction due to excessive chelation, thus balancing interface protection and deposition kinetics. Specifically, when the complexation constant is below 10, the binding force between the chelating agent and zinc ions is too weak, making it difficult for the multidentate ligand to stably enter the solvation sheath, failing to effectively reconstruct the coordination environment of zinc ions, and limiting the solvation structure regulation effect. When the complexation constant is above 20, the binding force of the chelating agent on zinc ions is too strong, significantly increasing the desolvation energy barrier, making it difficult for zinc ions to be released from the solvation structure to participate in the deposition reaction, resulting in sluggish deposition kinetics and intensified electrochemical polarization. This invention limits the complexation constant to a medium strength range, ensuring both effective regulation of the solvation structure by the chelating agent and smooth desolvation and deposition of zinc ions at the electrode interface, thereby achieving a balance between suppressing dendrites and maintaining charge-discharge performance. This invention achieves simultaneous suppression of zinc dendrite formation, hydrogen evolution, and corrosion side reactions through the synergistic effect of the above-mentioned multiple mechanisms, resulting in a zinc symmetric battery cycle life of over 4000 hours and excellent full-cell cycle stability. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below.

[0020] Figure 1 This is a battery cycle performance diagram of the Zn / / LiMn2O4 full cell in Example 1 of the present invention; Figure 2 This is a battery cycle performance diagram of the Zn / / MnO2 full cell in Example 2 of the present invention; Figure 3 This is a battery cycle performance diagram of the Zn / / Na2MnFe(CN)6 full cell in Example 3 of the present invention; Figure 4 This is a battery cycle performance diagram of the Zn / / V2O5 full cell in Example 4 of the present invention; Figure 5 This is a battery cycle performance diagram of the Zn / / LiMn2O4 full cell in Example 5 of the present invention; Figure 6 This is a battery cycle performance diagram of the control battery in Comparative Example 1 of the present invention. Detailed Implementation

[0021] The technical solutions of the present invention will be described below with reference to the accompanying drawings. The described embodiments are only some embodiments of the present invention, and not all embodiments.

[0022] Example 1 refer to Figure 1350 mg of commercial lithium manganese oxide powder, 100 mg of conductive carbon black and 50 mg of polyvinylidene fluoride were ground and mixed in a mortar, and then 2.0 g of N-methylpyrrolidone was added as a solvent. The mixture was stirred for 12 hours to obtain a uniform slurry. The slurry was then uniformly coated onto a stainless steel current collector and dried under vacuum at 60 °C for 12 hours to obtain a lithium manganese oxide electrode sheet.

[0023] Zinc sulfate heptahydrate and lithium sulfate monohydrate were added sequentially to deionized water and stirred for 30 minutes until completely dissolved. Anhydrous methanol with a purity of 99.9% was added and stirred for another 30 minutes. Disodium ethylenediaminetetraacetate was then added to the above solution and stirred for 30 minutes until completely dissolved. The pH of the electrolyte was adjusted to 4.0 to obtain a synergistic aqueous zinc-ion battery electrolyte, wherein the volume ratio of methanol to deionized water was 1:10, the concentration of zinc sulfate was 2 mol / L, the concentration of lithium sulfate was 1 mol / L, and the concentration of disodium ethylenediaminetetraacetate was 0.01 mol / L.

[0024] A 10mm diameter circular electrode of lithium manganese oxide was punched as the positive electrode, a 15mm diameter pure zinc foil was used as the negative electrode, and a 16mm diameter glass fiber was used as the separator. 150μL of synergistic aqueous zinc-ion battery electrolyte was added to assemble a Zn / / LiMn2O4 full cell.

[0025] After 100 cycles at 25°C and 0.5C, the battery retained 93.8% of its capacity.

[0026] Example 2 refer to Figure 2 350 mg of commercial manganese dioxide powder, 100 mg of conductive carbon black and 50 mg of polyvinylidene fluoride were ground and mixed in a mortar, and then 2.0 g of N-methylpyrrolidone was added as a solvent. The mixture was stirred continuously for 12 hours to obtain a uniform slurry. The slurry was coated onto a stainless steel current collector and dried under vacuum at 60 °C for 12 hours to obtain a manganese dioxide electrode sheet.

[0027] Zinc sulfate heptahydrate and lithium sulfate monohydrate were added sequentially to deionized water and stirred for 30 minutes until completely dissolved. Glycerol was added and stirring was continued for 30 minutes. Disodium ethylenediaminetetraacetate was then added to the above solution and stirred for 30 minutes until completely dissolved. The pH of the electrolyte was adjusted to 4.0 to obtain a synergistic aqueous zinc-ion battery electrolyte, wherein the volume ratio of glycerol to deionized water was 1:10, the concentration of zinc sulfate was 2 mol / L, the concentration of lithium sulfate was 1 mol / L, and the concentration of disodium ethylenediaminetetraacetate was 0.02 mol / L.

[0028] A 10mm diameter circular electrode was punched from a manganese dioxide electrode sheet to serve as the positive electrode, a 15mm diameter zinc-nickel alloy foil was used as the negative electrode, and a 16mm diameter glass fiber was used as the separator. 150μL of synergistic aqueous zinc-ion battery electrolyte was added to assemble a Zn / / MnO2 full cell.

[0029] After cycling at 25°C and 0.5C, the battery retains 97.3% of its capacity after 100 cycles and 97.3% after 120 cycles.

[0030] Example 3 refer to Figure 3 350 mg of Prussian blue derivative Na2MnFe(CN)6 powder, 100 mg of conductive carbon black and 50 mg of polyvinylidene fluoride were ground and mixed in a mortar, and then 2.0 g of N-methylpyrrolidone was added as a solvent. The mixture was stirred continuously for 12 hours to obtain a uniform slurry. The slurry was coated onto a stainless steel current collector and dried under vacuum at 60 °C for 12 hours to obtain a Prussian blue derivative electrode sheet.

[0031] Weigh zinc chloride and lithium chloride, add them to deionized water, and stir for 30 minutes until dissolved. Cool to room temperature, add ethylene glycol, and stir for 30 minutes. Then add disodium ethylenediaminetetraacetate to the above solution and stir for 30 minutes until completely dissolved. Adjust the pH of the electrolyte to 4.0 to obtain a synergistic aqueous zinc-ion battery electrolyte, wherein the volume ratio of ethylene glycol to deionized water is 1:10, the concentration of zinc chloride is 1.5 mol / L, the concentration of lithium chloride is 0.8 mol / L, and the concentration of disodium ethylenediaminetetraacetate is 0.05 mol / L.

[0032] A 10mm diameter circular electrode was punched from a Prussian blue derivative electrode sheet to serve as the positive electrode, a 15mm diameter three-dimensional porous zinc electrode was used as the negative electrode, and a 16mm diameter glass fiber was used as the separator. 150μL of electrolyte was added to assemble a Zn / / Na2MnFe(CN)6 full cell.

[0033] After 150 cycles at 25°C and 0.5C, the battery retained 94.5% of its capacity.

[0034] Example 4 refer to Figure 4 350 mg of vanadium pentoxide powder, 100 mg of conductive carbon black and 50 mg of polyvinylidene fluoride were ground and mixed in a mortar, and then 2.0 g of N-methylpyrrolidone was added as a solvent. The mixture was stirred continuously for 12 hours to obtain a uniform slurry. The slurry was coated onto a stainless steel current collector and dried under vacuum at 60 °C for 12 hours to obtain a vanadium pentoxide electrode sheet.

[0035] Zinc sulfate heptahydrate and lithium sulfate monohydrate were added sequentially to deionized water and stirred for 30 minutes until completely dissolved. Anhydrous methanol with a purity of 99.9% was added and stirred for another 30 minutes. Then, pentasodium diethylenetriaminepentaacetate was added to the above solution and stirred for 30 minutes until completely dissolved. The pH of the electrolyte was adjusted to 4.0 to obtain a synergistic aqueous zinc-ion battery electrolyte, wherein the volume ratio of methanol to deionized water was 1:10, the concentration of zinc sulfate was 2 mol / L, the concentration of lithium sulfate was 1 mol / L, and the concentration of pentasodium diethylenetriaminepentaacetate was 0.01 mol / L.

[0036] A vanadium pentoxide electrode sheet was punched into a 10 mm diameter circular electrode as the positive electrode, a 15 mm diameter zinc-copper current collector was used as the negative electrode, and a 16 mm diameter glass fiber was used as the separator. 150 μL of synergistic aqueous zinc-ion battery electrolyte was added to assemble a Zn / / V2O5 full cell.

[0037] After 190 cycles at 25°C and 0.5C, the battery retained 88.9% of its capacity.

[0038] Example 5 refer to Figure 5 350 mg of commercial lithium manganese oxide powder, 100 mg of conductive carbon black and 50 mg of polyvinylidene fluoride were ground and mixed in a mortar, and then 2.0 g of N-methylpyrrolidone was added as a solvent. The mixture was stirred for 12 hours to obtain a uniform slurry. The slurry was then uniformly coated onto a stainless steel current collector and dried under vacuum at 60 °C for 12 hours to obtain a lithium manganese oxide electrode sheet.

[0039] Zinc sulfate heptahydrate and lithium sulfate monohydrate were added sequentially to deionized water and stirred for 30 minutes until completely dissolved. Anhydrous methanol with a purity of 99.9% was added and stirred for another 30 minutes. Then, pentasodium diethylenetriaminepentaacetate was added to the above solution and stirred for 30 minutes until completely dissolved. The pH of the electrolyte was adjusted to 4.0 to obtain a synergistic aqueous zinc-ion battery electrolyte, wherein the volume ratio of methanol to deionized water was 1:5, the concentration of zinc sulfate was 2 mol / L, the concentration of lithium sulfate was 1 mol / L, and the concentration of pentasodium diethylenetriaminepentaacetate was 0.02 mol / L.

[0040] A 10mm diameter circular electrode of lithium manganese oxide was punched as the positive electrode, a 15mm diameter pure zinc foil was used as the negative electrode, and a 16mm diameter glass fiber was used as the separator. 150μL of synergistic aqueous zinc-ion battery electrolyte was added to assemble a Zn / / LiMn2O4 full cell.

[0041] After 220 cycles at 25°C and 0.5C, the battery retained 98.7% of its capacity.

[0042] Comparative Example 1 refer to Figure 5The electrolyte was replaced with a control electrolyte, and the rest was the same as in Example 1. The control electrolyte was prepared as follows: 32.29 g of zinc sulfate heptahydrate and 21.98 g of lithium sulfate monohydrate were weighed and added to 100 g of deionized water, and stirred for 30 minutes until completely dissolved; without adding anhydrous methanol, stirring was continued for 30 minutes to obtain an aqueous zinc-ion battery control electrolyte without methanol additive.

[0043] Under the same test conditions, the control battery exhibited extensive dendrite growth on the zinc anode surface, severe hydrogen evolution corrosion, and a capacity retention rate of only 15% after just 120 cycles. The battery was also prone to short-circuit failure and could not meet the requirements of practical applications.

[0044] The preferred embodiments of the present invention disclosed above are only for the purpose of illustrating the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation described herein. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can better understand and utilize the present invention.

Claims

1. A synergistic aqueous zinc-ion battery electrolyte, characterized in that: The product comprises the following components: solvent, zinc salt electrolyte, lithium salt electrolyte, functional additive A, and functional additive B; the solvent is deionized water; functional additive A is an organic alcohol additive, such as methanol, ethylene glycol, glycerol, etc.; and functional additive B is a chelating agent selected from multidentate ligand organic chelating agents, specifically the Zn group of the multidentate ligand organic chelating agent. 2+ The complexation constant logK is 10≤logK≤19, and the molar concentration of the chelating agent in the electrolyte is 0.001-0.1mol / L.

2. The synergistic aqueous zinc-ion battery electrolyte according to claim 1, characterized in that: The chelating agent is any one or more of disodium ethylenediaminetetraacetate, pentasodium diethylenetriaminepentaacetate, disodium iminodiacetate, and sodium hydroxyethylethylenediaminetriacetate; wherein the concentration of disodium ethylenediaminetetraacetate is 0.005-0.05 mol / L; the concentration of pentasodium diethylenetriaminepentaacetate is 0.002-0.02 mol / L; the concentration of disodium iminodiacetate is 0.03-0.12 mol / L; and the concentration of sodium hydroxyethylethylenediaminetriacetate is 0.003-0.04 mol / L.

3. The synergistic aqueous zinc-ion battery electrolyte according to claim 1, characterized in that: The zinc salt electrolyte is any one or more of zinc sulfate, zinc trifluoromethanesulfonate, zinc chloride, zinc nitrate, and zinc acetate, and the molar concentration of the zinc salt electrolyte in the electrolyte is 0.5-3 mol / L.

4. The synergistic aqueous zinc-ion battery electrolyte according to claim 1, characterized in that: The lithium salt electrolyte is any one or more of lithium sulfate, lithium trifluoromethanesulfonate, lithium chloride, lithium nitrate, and lithium acetate, and the molar concentration of the lithium salt electrolyte in the electrolyte is 0.5-3 mol / L.

5. The synergistic aqueous zinc-ion battery electrolyte according to claim 1 is characterized in that: The volume ratio of the functional additive A to deionized water is (1-3):10, and the molar ratio of zinc salt electrolyte to lithium salt electrolyte is 1:(0.5-2).

6. The application of the electrolyte according to any one of claims 1-5 in an aqueous zinc-ion battery, characterized in that: The aqueous zinc-ion battery includes an electrolyte, a positive electrode, a negative electrode, and a separator. The zinc negative electrode is any one of pure zinc foil, zinc alloy foil, zinc-plated current collector, and three-dimensional porous zinc. The active material of the positive electrode is any one of lithium manganese oxide, manganese dioxide, Prussian blue and its derivatives, vanadium pentoxide, vanadate, and organic quinones. The separator is a glass fiber separator.

7. The aqueous zinc-ion battery according to claim 6, characterized in that: The thickness of the pure zinc foil is 0.1 mm.

8. The aqueous zinc-ion battery according to claim 6, characterized in that: The positive electrode is composed of an active material, a conductive agent, and a binder, wherein the mass ratio of the active material, the conductive agent, and the binder is 8:1:

1.

9. The aqueous zinc-ion battery according to claim 6, characterized in that: The battery can be any one of the following: button cell, pouch cell, cylindrical cell, or prismatic cell.

10. A synergistic aqueous zinc-ion battery electrolyte according to any one of claims 1-9, characterized in that: The aqueous zinc-ion battery is used in large-scale energy storage, low-speed electric vehicle power supply, Internet of Things backup power supply, and low-temperature special power supply.

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