Electrolyte and zinc-based battery

Abstract

The application provides an electrolyte and a zinc-based battery, and relates to the technical field of batteries. The electrolyte comprises a metal salt, an additive and water; wherein the additive comprises a complex formed by metal ions and an organic ligand, and the organic ligand comprises a structure as shown in formula A: wherein R1, R2 and R3 are independently selected from any one of a hydrogen atom, a C1-C 20 substituted or unsubstituted alkyl, a C2-C 20 substituted or unsubstituted alkenyl, a C2-C 20 substituted or unsubstituted alkyl, a C1-C 20 substituted or unsubstituted carboxylate, a pyridyl group, or R1 and R2 are connected to each other to form a ring, or R1 and R3 are connected to each other to form a ring, or R2 and R3 are connected to each other to form a ring, so that the problems of uneven deposition, dendrite growth and poor cycle stability and service life of the battery caused thereby of the zinc metal negative electrode in the water-based electrolyte in the prior art can be solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, in particular to an electrolyte and a zinc-based battery. BACKGROUND

[0002] Aqueous zinc-ion batteries are widely used in large-scale energy storage fields such as grid energy storage, renewable energy integration and electric vehicles due to their high safety, low cost and abundant resources. Compared with organic electrolyte lithium-ion batteries, aqueous zinc-ion batteries use water-based electrolytes, have higher thermal stability and lower fire risk, and provide a solid foundation for high-safety energy storage systems. However, in aqueous zinc-ion batteries, the deposition and stripping process of zinc ions is often uneven, leading to the growth of zinc dendrites. Zinc dendrites not only cause internal short circuits in the battery, reducing battery safety, but also cause loss of active materials, seriously affecting the cycle stability of the battery. Zinc metal anodes in aqueous electrolytes are prone to hydrogen evolution side reactions during charging. In aqueous electrolytes, zinc metal anodes are prone to self-corrosion, especially the increase of local corrosion current, leading to uneven consumption of zinc metal, further exacerbating the formation of zinc dendrites and hydrogen evolution side reactions, seriously damaging the long-term stability and service life of the battery. SUMMARY

[0003] The main purpose of the present application is to provide an electrolyte and a zinc-based battery to solve the problems of uneven deposition of zinc metal anodes in aqueous electrolytes, dendrite growth and poor cycle stability and service life of the battery caused thereby in the prior art.

[0004] In order to achieve the above-mentioned purpose, according to one aspect of the present application, an electrolyte is provided, the electrolyte comprising a metal salt, an additive and water; wherein the additive comprises a complex of a metal ion and an organic ligand, and the organic ligand comprises a structure as shown in Formula A:

[0005]

[0006] Formula A

[0007] wherein R1, R2, R3 are independently selected from any one of a hydrogen atom, a C1-C 20 a substituted or unsubstituted alkyl group, a C2-C 20 a substituted or unsubstituted alkenyl group, a C2-C 20 a substituted or unsubstituted alkyl group interrupted by at least one -O- to form a substituent, a C1-C 20 a substituted or unsubstituted carboxylate group, a pyridyl group, or R1 and R2 are connected to each other to form a ring, or R1 and R3 are connected to each other to form a ring, or R2 and R3 are connected to each other to form a ring.

[0008] Furthermore, R1, R2, and R3 are independently selected from hydrogen atoms, C1-C atoms. 10 Substituted or unsubstituted alkyl groups, C2-C 10 Substituted or unsubstituted alkenyl groups, C2-C 10 Substituents formed by substituted or unsubstituted alkyl groups interrupted by at least one -O-, C1-C 10 The substituted or unsubstituted carboxylic acid ester group or pyridinyl group, or R1 and R2 linked together to form a ring, or R1 and R3 linked together to form a ring, or R2 and R3 linked together to form a ring.

[0009] Furthermore, when R1 and R2 are connected to form a loop, a loop is formed. or R3 is selected from methyl;

[0010] When R2 and R3 are connected to form a loop, it forms or R1 is selected from methyl;

[0011] When R1 and R3 are connected to form a loop, it forms , , , Any one of them, R2 is selected from hydrogen atoms.

[0012] Furthermore, organic ligands include , , , , , , , , , , At least one of them.

[0013] Further, the metal ion includes at least one selected from zinc ions, calcium ions, magnesium ions, and aluminum ions; preferably, the metal ion includes zinc ions; and / or,

[0014] Metal salts include the first zinc salt;

[0015] Preferably, the first zinc salt includes at least one of zinc sulfate, zinc chloride, zinc nitrate, zinc acetate, zinc acetate, and zinc trifluoroformyl sulfonate.

[0016] Furthermore, the mass content of the additive in the electrolyte is 0.1% to 5%; and / or,

[0017] The concentration of metal salt in the electrolyte is 0.1~5 mol / L.

[0018] Furthermore, the preparation method of the additive includes: mixing an organic ligand with water to obtain an organic ligand solution; adding a compound containing metal ions to the organic ligand solution, and stirring to obtain a mixture;

[0019] After the mixture is allowed to stand and separate into layers, the organic phase is collected to obtain the additive;

[0020] Preferably, the volume ratio of organic ligand to water is (1~20):(1~100).

[0021] Preferably, the molar ratio of the compound containing metal ions to the organic ligand is 1:(1~3).

[0022] Compounds containing metal ions include at least one of zinc sulfate, zinc chloride, zinc nitrate, zinc acetate, zinc acetate, zinc trifluoroformyl sulfonate, calcium chloride, calcium nitrate, calcium acetate, magnesium chloride, magnesium sulfate, and aluminum chloride.

[0023] A second aspect of the present invention provides a zinc-based battery, including a housing and an electrode assembly and an electrolyte located within the housing; the electrolyte includes the electrolyte of the first aspect.

[0024] Furthermore, the electrode assembly includes a positive electrode plate, a negative electrode plate, and a separator disposed between the positive electrode plate and the negative electrode plate. The positive electrode plate includes a positive electrode material, which includes at least one of vanadium oxide-based positive electrode materials, manganese oxide-based positive electrode materials, and Prussian blue-based positive electrode materials. Preferably, the chemical formula of the positive electrode material includes M... x V2O5·nH2O, where 0 < x < 2, 0 < n < 20, and M includes at least one of Zn, Mn, K, Ca, Na, Li, and Al.

[0025] Furthermore, the negative electrode includes zinc and / or zinc alloys, wherein the zinc alloys include at least one of zinc-copper alloys, zinc-tin alloys, zinc-aluminum alloys, and zinc-nickel alloys; and / or, the separator includes at least one of glass fiber-based separators, cellulose-based separators, polyethylene-based separators, and polypropylene separators.

[0026] By applying the technical solution of this invention, a complex formed by an organic ligand with a specific structure and metal ions is used as an additive in an aqueous electrolyte. On the one hand, this complex can form a protective layer with dynamic adsorption characteristics on the surface of the zinc metal anode, effectively regulating the electric field distribution and avoiding excessively high local current density. This ensures the normal diffusion of zinc ions and inhibits dendrite growth, preventing dendrites from penetrating the separator and avoiding the risk of internal short circuits in the battery, thereby improving the long-term cycle stability of the battery. On the other hand, this complex can promote more uniform deposition of zinc ions in metal salts on the surface of the zinc metal anode by regulating the interaction between metal ions and water molecules, thereby avoiding dendrite formation. At the same time, it reduces uneven deposition and side reactions, which helps to enhance the stability and reversibility of the zinc metal anode. In particular, it can inhibit hydrogen evolution reaction and reduce by-product deposition, which helps to improve the initial coulombic efficiency of the battery, reduce the self-corrosion of the zinc metal anode, and thus extend the battery's service life. Attached Figure Description

[0027] Figure 1 Fourier transform infrared spectra of ZnABL complexes prepared from pure water (H2O), zinc sulfate solution (ZnSO4), α-acetyl-γ-butyrolactone (ABL), and mixed solutions with zinc sulfate concentrations of 1 mol / L, 2 mol / L, 3 mol / L, and 4 mol / L, respectively.

[0028] Figure 2 The charge-discharge curves of the zinc-zinc symmetric battery containing the electrolyte in Example 1 during the charge-discharge process;

[0029] Figure 3 The in-situ Fourier transform infrared spectrum of the zinc metal electrode surface of the zinc-zinc symmetric battery containing the electrolyte in Example 1 during the charging and discharging process.

[0030] Figure 4 The coulombic efficiency diagram of the zinc-copper asymmetric battery containing the electrolyte in Example 1 during long-cycle cycling.

[0031] Figure 5 For the zinc-zinc symmetric battery containing the electrolyte of Example 1, at a current density of 1 mA / cm² 2 Time-voltage plot during a long-cycle process;

[0032] Figure 6 For the zinc-zinc symmetric battery containing the electrolyte of Example 1, at a current density of 6 mA / cm² 2 Time-voltage plot during a long-cycle process;

[0033] Figure 7 The graph shows the specific capacity change of full cells containing the electrolytes of Example 1 and Comparative Example 1 during long-cycle cycling.

[0034] Figure 8 For the zinc-zinc symmetric battery containing the electrolyte of Example 2, at a current density of 6 mA / cm² 2 Time-voltage plot during a long-cycle process;

[0035] Figure 9 For the zinc-zinc symmetric battery containing the electrolyte of Example 3, at a current density of 6 mA / cm² 2 Time-voltage plot during a long-cycle process;

[0036] Figure 10 For the zinc-zinc symmetric battery containing the electrolyte of Example 4, at a current density of 6 mA / cm² 2 Time-voltage plot during a long-cycle process;

[0037] Figure 11 For the zinc-zinc symmetric battery containing the electrolyte of Example 5, at a current density of 6 mA / cm² 2 Time-voltage plot during a long-cycle process;

[0038] Figure 12 This is a graph showing the change in specific capacity of a full cell containing the electrolyte from Example 6 during a long-cycle process. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0040] As described in the background section of this invention, existing technologies suffer from uneven deposition of zinc metal anodes in aqueous electrolytes, dendrite growth, and consequently poor battery cycle stability and lifespan. To address these issues, in a typical embodiment of this invention, an electrolyte is provided, comprising a metal salt, an additive, and water; wherein the additive comprises a complex formed by metal ions and an organic ligand, the organic ligand comprising a structure as shown in Formula A:

[0041]

[0042] Formula A

[0043] Among them, R1, R2, and R3 are independently selected from hydrogen atoms, C1-C atoms, and C2-C3 atoms. 20 Substituted or unsubstituted alkyl groups, C2-C 20 Substituted or unsubstituted alkenyl groups, C2-C 20Substituents formed by substituted or unsubstituted alkyl groups interrupted by at least one -O-, C1-C 20 The substituted or unsubstituted carboxylic acid ester group or pyridinyl group, or R1 and R2 linked together to form a ring, or R1 and R3 linked together to form a ring, or R2 and R3 linked together to form a ring.

[0044] The electrolyte of this invention is suitable for zinc-based batteries, which primarily use a zinc metal anode. During charging and discharging, the zinc metal anode releases or stores zinc ions through an electrochemical reaction, while the cathode can store and release zinc ions. In zinc-based batteries, the electrolyte acts as the medium for zinc ion transport, and its performance directly affects the overall efficiency and lifespan of the battery. When the battery is charging, zinc ions are oxidized at the cathode, transported through the electrolyte to the anode, and reduced to zinc metal at the anode. When the battery discharges, zinc metal is oxidized back to zinc ions, transported back through the electrolyte to the cathode, and reduced there.

[0045] In traditional aqueous zinc-ion batteries, zinc ion deposition during charging and discharging often exhibits high localized non-uniformity, easily leading to the formation of zinc dendrites on the zinc metal anode surface. These dendrites gradually penetrate the separator, eventually causing a short circuit and severely impacting battery safety and cycle life. In aqueous electrolytes, during the reduction of zinc ions on the zinc anode surface, water molecules surrounding the zinc ions are easily reduced to hydrogen gas, generating a hydrogen evolution reaction. Furthermore, byproducts gradually cover the zinc metal anode surface, hindering normal zinc ion deposition and increasing the battery's internal resistance. These combined effects result in a decrease in the battery's initial coulombic efficiency and accelerated zinc metal anode consumption. Due to the uneven zinc ion deposition and the continuous occurrence of the hydrogen evolution reaction, localized corrosion occurs on the zinc metal anode, leading to irreversible consumption of the active zinc. This self-corrosion not only reduces battery capacity but also damages the structural stability of the zinc metal anode, shortening the battery's lifespan.

[0046] The electrolyte of this invention comprises a metal salt, an additive, and water. The metal salt provides a charge carrier (such as Zn). 2+ Water is used to dissolve the metal salts and additives. The additives are complexes formed by metal ions and organic ligands. The organic ligands have a structure as shown in Formula A, which allows for keto-enol tautomerism. This structure enables the organic ligands to dynamically switch between keto and enol forms according to changes in the electrochemical environment (such as potential). This reversible structural change provides flexibility for the binding of the organic ligands to metal ions, allowing the complex to form a dynamically regulated protective layer on the electrode surface, which helps improve the uniformity of zinc ion deposition. The keto-enol tautomerism of the organic ligands is shown below:

[0047]

[0048] Specifically, during battery charging and discharging, the potential and zinc ion concentration of the zinc metal anode undergo dynamic changes. For example, during charging, the zinc ion concentration decreases, and the potential of the zinc metal anode increases; during discharging, the zinc ion concentration increases, and the potential of the zinc metal anode decreases. The additives in the protective layer, i.e., the complex formed by metal ions and organic ligands, are sensitive to potential changes. When the potential of the zinc metal anode increases, the organic ligand molecules in the complex can adsorb more tightly onto the surface of the zinc metal anode, forming a thicker protective layer to prevent uneven zinc ion deposition and dendrite formation caused by excessively high local potentials. Conversely, when the potential of the zinc metal anode decreases, the adsorption of organic ligand molecules can be moderately reduced as the potential decreases, maintaining a uniform ion flow distribution on the surface of the zinc metal electrode. This creates a dynamic balance between the adsorption and desorption of the protective layer and the zinc metal anode surface. Under conditions of excessively high local potential or zinc ion concentration, the protective layer can increase adsorption, reduce the active sites on the electrode surface, and guide zinc ions to deposit more uniformly. This effectively prevents uneven zinc ion deposition caused by excessively high local potential, significantly reduces dendrite formation, and avoids battery short circuits and performance degradation. When the potential and concentration return to normal levels, the protective layer can dissociate appropriately, ensuring sufficient active sites on the electrode surface for normal charge and discharge processes. Simultaneously, the protective layer is also sensitive to changes in zinc ion concentration. In areas with high zinc ion concentration, the protective layer can preferentially form or strengthen to guide uniform zinc ion deposition and avoid dendrite problems caused by excessive local deposition. This concentration responsiveness ensures the uniformity and stability of the protective layer at different electrochemical reaction stages, thereby improving the battery's cycle performance. Furthermore, the dynamic adjustment of the protective layer reduces local corrosion and side reactions, improving the stability and cycle life of the zinc metal anode, enabling the battery to operate stably for a long time.

[0049] In aqueous electrolytes, metal ions are surrounded by water molecules. Organic ligands have a higher binding affinity to metal ions than to water molecules, competitively binding to them. This competitive binding reduces the number of water molecules surrounding the metal ions, altering the solvation effect and thus contributing to the deposition kinetics of zinc ions. Simultaneously, by reducing the concentration of water molecules around the metal ions, the hydrogen evolution side reaction is effectively suppressed, helping to improve the stability of the zinc metal anode during charge and discharge processes and enhancing the cycle stability of the battery.

[0050] Therefore, the electrolyte of this invention, by introducing specific additives, can regulate the solvation environment of metal ions by modulating the interaction between metal ions and water molecules, promoting more uniform deposition of zinc ions in the metal salt on the negative electrode surface, thereby avoiding dendrite formation. Simultaneously, it reduces uneven deposition and side reactions, contributing to enhanced stability and reversibility of the zinc metal negative electrode. In particular, it can suppress hydrogen evolution reaction and reduce by-product deposition, helping to improve the initial coulombic efficiency of the battery, reduce self-corrosion of the zinc metal negative electrode, and thus extend the battery's lifespan. The protective layer formed by the additives has dynamic adsorption characteristics, adapting to changes in the electrochemical environment, effectively regulating the electric field distribution, and avoiding excessively high local current density. This protective layer establishes a dynamic barrier on the surface of the zinc metal negative electrode, ensuring normal diffusion of zinc ions while inhibiting dendrite growth paths through its structural characteristics and charge distribution, preventing dendrite penetration of the separator, avoiding the risk of internal short circuits in the battery, and thus contributing to improved long-cycle stability of the battery.

[0051] In some embodiments, R1, R2, and R3 are independently selected from hydrogen atoms, C1-C... 10 Substituted or unsubstituted alkyl groups, C2-C 10 Substituted or unsubstituted alkenyl groups, C2-C 10 Substituents formed by substituted or unsubstituted alkyl groups interrupted by at least one -O-, C1-C 10 The substituted or unsubstituted carboxylic acid ester group or pyridinyl group, or R1 and R2 linked together to form a ring, or R1 and R3 linked together to form a ring, or R2 and R3 linked together to form a ring.

[0052] In some embodiments, when R1 and R2 are connected to form a loop, a loop is formed. or R3 is selected from methyl groups; when R2 and R3 are linked together to form a ring, a ring is formed. or R1 is selected from methyl groups; when R1 and R3 are linked together to form a ring, a ring is formed. , , , Any one of them, R2 is selected from hydrogen atoms.

[0053] To further improve the overall performance of the electrolyte, in some embodiments, the organic ligand includes , , , , , , , , , , At least one of the following: α-acetyl-γ-butyrolactone, 1,3-cyclopentanedione, 4-cyclopenten-1,3-dione, 1,3-cyclohexanedione, 1,3-cycloheptanedione, 3-methyl-2,4-pentanedione, 2-methyl-1,3-cyclopentanedione, 2-ethyl-1,3-cyclopentanedione, ethyl 2,4-dicarbonylheptanoate, 1,3-di(2-pyridyl)-1,3-propanedione, and 3-acetylpyridin-2(1H)-one. These organic ligands possess unique keto-enol tautomerism and can form complexes with metal ions.

[0054] Taking α-acetyl-γ-butyrolactone (ABL) as an example, the structural formula of ABL is as follows: The keto and enol tautomerisms of ABL are shown below:

[0055]

[0056] ABL and metal ions (such as Zn) 2+ They can form stable complexes. During electrochemical reactions, the enol-structured ABL has a strong binding affinity for metal ions, effectively guiding the uniform deposition of metal ions and inhibiting dendrite formation. For example, α-acetyl-γ-butyrolactone and Zn... 2+ The reaction equation is shown below:

[0057]

[0058] In some embodiments, the metal ions include, but are not limited to, at least one of zinc ions, calcium ions, magnesium ions, and aluminum ions, with zinc ions being preferred. The combination of metal ions with organic ligands can significantly improve the electrochemical performance of the zinc metal anode, including increasing deposition uniformity, suppressing hydrogen evolution side reactions, and reducing corrosion.

[0059] In some embodiments, the metal salt includes a first zinc salt, which comprises at least one selected from zinc sulfate, zinc chloride, zinc nitrate, zinc acetate, zinc trifluoroformylsulfonate, and zinc trifluorosulfonate. These metal salts exhibit good water solubility and stability, ensuring their uniform dispersion in the electrolyte to form a stable complex. Furthermore, these metal salts are widely available and inexpensive, contributing to reduced production costs.

[0060] In some embodiments, the mass content of the additive in the electrolyte is 0.5% to 5%. Too low an additive content may fail to effectively form a protective layer, while too high a content may alter the physical and chemical properties of the electrolyte, affecting the overall performance of the battery. Controlling the mass content of the additive to 0.5% to 5% helps achieve optimal electrochemical performance and economy. The mass content of the additive in the electrolyte can be a range of 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, or any combination thereof.

[0061] In some embodiments, the concentration of the metal salt in the electrolyte is 0.1 mol / L to 5 mol / L. The concentration of the metal salt directly affects the ionic conductivity of the electrolyte and the deposition of zinc ions. A higher concentration of metal salt can provide more charge carriers, thereby improving the conductivity of the electrolyte and benefiting the charge / discharge rate and power density of the battery. Concentrations that are too high or too low can lead to dendrite formation, affecting the cycle stability and safety of the battery. Maintaining a metal salt concentration of 0.1 mol / L to 5 mol / L in the electrolyte helps ensure the ionic conductivity of the electrolyte, achieves stable zinc ion deposition, and effectively inhibits dendrite growth.

[0062] Specifically, the concentration of the metal salt in the electrolyte can be within the range of 0.1 mol / L, 0.5 mol / L, 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L, 5 mol / L, or any combination thereof.

[0063] In some embodiments, the method for preparing the additive includes: mixing an organic ligand with water to obtain an organic ligand solution; adding a compound containing metal ions to the organic ligand solution, stirring, and obtaining a mixture; allowing the mixture to stand and separate into layers, collecting the upper organic phase to obtain the additive.

[0064] Specifically, the organic ligand is mixed with water in a certain proportion to ensure that the organic ligand is fully dissolved in the water, forming an organic ligand solution. A compound containing metal ions is added to the organic ligand solution, followed by thorough stirring to ensure uniform mixing of the metal ions and organic ligand, promoting complex formation. The stirring time may be adjusted according to actual needs, for example, stirring for 20-60 minutes to ensure complete reaction. The stirred mixture needs to be allowed to stand for a period of time to allow the reaction to further complete and the solution to separate into two layers: an upper layer of organic phase rich in the complex, and a lower layer of aqueous phase and unreacted compound. The collected upper organic phase is the prepared additive, which can be used directly in the electrolyte or further processed to improve its purity or concentration.

[0065] In some embodiments, the volume ratio of organic ligand to water is (1~20):(1~100), for example, 1:100, 1:50, 1:20, 1:10, 1:5, 1:1, 2:1, 5:1, 10:1, 15:1, 20:1, or any combination thereof. Controlling the volume ratio of organic ligand to water helps ensure sufficient dissolution and activity of the organic ligand in the aqueous phase, while also guaranteeing solution stability and providing a suitable environment for subsequent complex formation.

[0066] In some embodiments, the molar ratio of the metal ion-containing compound to the organic ligand is 1:(1~3), for example, a range consisting of 1:1, 1:1.5, 1:2, 1:2.5, 1:3, or any two of these. By controlling the molar ratio of the metal ion-containing compound to the organic ligand within the above range, sufficient reaction between the metal ion and the organic ligand is ensured, waste of raw materials is avoided, and a balance between performance and production costs is achieved.

[0067] In some embodiments, the metal ion-containing compounds include at least one selected from zinc sulfate, zinc chloride, zinc nitrate, zinc acetate, zinc acetate, zinc trifluoroformylsulfonate, calcium chloride, calcium nitrate, calcium acetate, magnesium chloride, magnesium sulfate, and aluminum chloride. These metal ion-containing compounds exhibit good water solubility and stability, ensuring their uniform dispersion in the electrolyte to form a stable complex. Furthermore, these metal ion-containing compounds are widely available and inexpensive, contributing to reduced production costs.

[0068] A second aspect of the present invention provides a zinc-based battery, including a housing and an electrode assembly and an electrolyte located within the housing; the electrolyte includes the electrolyte of the first aspect.

[0069] Due to the inclusion of the aforementioned high-performance electrolyte, this zinc-based battery exhibits excellent cycle stability and a long service life.

[0070] Specifically, the casing can be made of a casing material with good sealing performance, such as stainless steel or aluminum alloy, to encapsulate the electrode components and electrolyte, ensuring that the battery interior is not affected by the external environment.

[0071] In some embodiments, the electrode assembly includes a positive electrode, a negative electrode, and a separator disposed between the positive and negative electrode. The positive electrode includes a positive electrode material, which includes at least one of vanadium oxide-based positive electrode materials, manganese oxide-based positive electrode materials, and Prussian blue-based positive electrode materials. Preferably, the chemical formula of the positive electrode material includes M... x V2O5·nH2O, where 0 < x < 2, 0 < n < 20, and M includes at least one of Zn, Mn, K, Ca, Na, Li, and Al.

[0072] In some embodiments, the negative electrode comprises zinc and / or a zinc alloy, wherein the zinc alloy comprises at least one of zinc-copper alloy, zinc-tin alloy, zinc-aluminum alloy, and zinc-nickel alloy.

[0073] The diaphragm effectively prevents short circuits between the positive and negative electrodes. In some embodiments, the diaphragm includes at least one of glass fiber-based diaphragms, cellulose-based diaphragms, polyethylene-based diaphragms, and polypropylene diaphragms.

[0074] In the preparation of zinc-based batteries, the positive and negative electrode plates are separated by a separator and placed inside the casing; then the electrolyte is filled into the casing to ensure that the positive and negative electrodes are fully wetted, and after sealing, the zinc-based battery is obtained.

[0075] The present application will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed in the present application.

[0076] Example 1

[0077] I. Preparation of Additives

[0078] α-Acetyl-γ-butyrolactone was mixed with water at a 1:1 volume ratio to obtain an organic ligand solution. Zinc sulfate solutions of 1 mol / L, 2 mol / L, 3 mol / L, and 4 mol / L were added to the organic ligand solution, and the mixtures were stirred for 30 min to obtain ZnABL complex mixtures of different concentrations. The reaction was more complete after mixing the 4 mol / L zinc sulfate solution with the organic ligand solution, resulting in a higher concentration of the ZnABL complex. The ZnABL complex used in this example is the product obtained by mixing the 4 mol / L zinc sulfate solution with the organic ligand solution.

[0079] The mixture was allowed to stand for 2 hours, and the upper organic phase was collected to obtain the ZnABL complex (purple-red). The ZnABL complex was characterized by Fourier transform infrared spectroscopy (FTIR), and the absorption peaks of the ZnABL complex (e.g., ...) were obtained. Figure 1 As shown in the figure, it is similar to α-acetyl-γ-butyrolactone.

[0080] II. Preparation of Electrolyte

[0081] The ZnABL complex was added to a 2 mol / L zinc sulfate aqueous solution to obtain the electrolyte S1 of this embodiment; wherein the mass content of the ZnABL complex was 1%.

[0082] Example 2

[0083] The difference from Example 1 is that the mass content of the ZnABL complex in the electrolyte is 0.2%.

[0084] Example 3

[0085] The difference from Example 1 is that the mass content of the ZnABL complex in the electrolyte is 2%.

[0086] Example 4

[0087] The difference from Example 1 is that the mass content of the ZnABL complex in the electrolyte is 0.1%.

[0088] Example 5

[0089] The difference from Example 1 is that the mass content of the ZnABL complex in the electrolyte is 3%.

[0090] Example 6

[0091] I. Preparation of Additives

[0092] 1,3-cyclopentanedione was mixed with water at a volume ratio of 1:1 to obtain an organic ligand solution; 4 mol / L zinc sulfate solution was added to the organic ligand solution and stirred for 30 min to obtain a metal ligand complex mixture.

[0093] The mixture was allowed to stand for 2 hours, and the upper organic phase was collected to obtain the metal ligand complex.

[0094] II. Preparation of Electrolyte

[0095] The metal ligand complex was added to a 2 mol / L zinc sulfate aqueous solution to obtain the electrolyte of this embodiment; wherein the mass content of the metal ligand complex was 1%.

[0096] Comparative Example 1

[0097] The difference from Example 1 is that the electrolyte of this comparative example does not include the ZnABL complex, resulting in electrolyte D1 of this comparative example.

[0098] Test case

[0099] I. Assembly of Zinc-Zinc Symmetric Cells

[0100] A 50μm thick zinc foil was cut into 1cm×1cm square pieces to serve as the positive and negative electrodes. A polyethylene terephthalate (PE) separator was used as the separator. Electrolytes prepared in the examples and comparative examples were injected to assemble a CR2032 type zinc-zinc symmetric battery.

[0101] The zinc-zinc symmetric cell was connected to a CHI 760E electrochemical workstation, and the cell was placed in a Fourier transform infrared spectrometer. The light source probe was aimed at the working zinc metal electrode surface, and a constant current charge-discharge test was performed at a current density of 5 mA / cm². 2 The charging / discharging capacity is 5mAh / cm³. 2The cutoff voltage is -0.5V to +0.5V. The charge / discharge curve of the battery assembled in Example 1 is shown below. Figure 2 As shown; it was observed that during the charging and discharging process, the ZnABL complex of the battery assembled in Example 1 was tightly adsorbed onto the surface of the working zinc metal electrode (e.g., Figure 3 (As shown).

[0102] The zinc-zinc symmetric battery was connected to a blue electrochemical tester for long-cycle constant current charge-discharge cycle testing at a current density of 1 mA / cm². 2 Constant current discharge to 1mAh / cm 2 The cutoff voltage is -0.5V (when the discharge capacity reaches 1mAh / cm³). 2 (And the effective cycle is defined as the cutoff voltage not exceeding -0.5V), and then the current density is 1mA / cm. 2 Constant current charging to 1mAh / cm 2 The cutoff voltage is +0.5V (when the charging capacity reaches 1mAh / cm³). 2 And the effective cycle is defined as the cutoff voltage not exceeding +0.5V). This cycle is repeated, and the zinc-zinc symmetric battery assembled in Example 1 accumulates 3850 cycles, achieving a total cycle life of 7700 hours (e.g., ...). Figure 5 (As shown). The zinc-zinc symmetric battery assembled in Comparative Example 1 accumulated 48 cycles and achieved a total cycle life of 165 hours, indicating that the cycle life of the zinc-zinc symmetric battery assembled in Example 1 is better than that of Comparative Example 1.

[0103] Similarly, when the test conditions are: a current density of 6 mA / cm² 2 Constant current discharge to 6mAh / cm 2 The cutoff voltage is -0.5V (when the discharge capacity reaches 6mAh / cm³). 2 (And the effective cycle is defined as the cutoff voltage not exceeding -0.5V), and then the current density is 6mA / cm². 2 Constant current charging up to 6mAh / cm 2 The cutoff voltage is +0.5V (when the charging capacity reaches 6mAh / cm³). 2 And the effective cycle is defined as the cutoff voltage not exceeding +0.5V). This cycle is repeated, and the zinc-zinc symmetric battery assembled in Example 1 accumulates 1210 cycles, achieving a total cycle life of 2420 hours (e.g., ...). Figure 6 As shown), the total cycle life of the zinc-zinc symmetric battery assembled in Comparative Example 1 was 110 hours. The total cycle life of the zinc-zinc symmetric battery assembled in Example 2 was 280 hours (as shown). Figure 8 As shown), the total cycle life of the zinc-zinc symmetric battery assembled in Example 3 is 700 hours (as shown). Figure 9 As shown), the total cycle life of the zinc-zinc symmetric battery assembled in Example 4 is 165 hours (as shown).Figure 10 As shown), the total cycle life of the zinc-zinc symmetric battery assembled in Example 5 is 140 hours (as shown). Figure 11 As shown in the figure, this invention helps to improve the service life of zinc-based batteries by using a specific electrolyte. Furthermore, Example 1 further improves the service life of zinc-based batteries by further adjusting the composition of the electrolyte.

[0104] II. Assembly of Zinc-Copper Asymmetric Cells

[0105] A 50μm thick zinc foil was cut into a 1cm×1cm square sheet to serve as the negative electrode; a 30μm thick copper foil was cut into a 18mm diameter circle to serve as the positive electrode. The electrolytes prepared in the examples and comparative examples were injected to obtain a zinc-copper asymmetric battery.

[0106] The zinc-copper asymmetric battery was connected to a CHI 760E electrochemical workstation or a Blue Electric electrochemical tester for constant current charge-discharge testing at a current density of 5 mA / cm². 2 Constant current discharge to 5mAh / cm 2 The cutoff voltage is -0.5V (effective cycling occurs when the discharge capacity reaches 1mAh / cm² and the cutoff voltage does not exceed -0.5V), and then the current density is 5mA / cm². 2 Constant current charging to 1mAh / cm², with a cutoff voltage of +0.5V (when the charging capacity reaches 5mAh / cm²). 2 And the effective cycle is defined as the cutoff voltage not exceeding +0.5V). This cycle is repeated, and the zinc-copper asymmetric battery assembled in Example 1 achieves over 700 cycles and more than 1400 hours, with an average coulombic efficiency (total single-cycle coulombic efficiency / number of cycles) reaching 99.87% (e.g., ...). Figure 4 As shown in the figure, the zinc-copper asymmetric battery assembled in Comparative Example 1 only achieved 96 hours of cycle time, and the average coulombic efficiency (total single-cycle coulombic efficiency / number of cycles) was only 95.57%. This indicates that the present invention, by applying an electrolyte with a specific composition to zinc-based batteries, can effectively improve the cycle life and coulombic efficiency of zinc-based batteries.

[0107] III. Assembly of the Full Battery

[0108] A 50μm thick zinc foil was cut into 1cm×1cm square pieces to serve as the negative electrode; the positive electrode was Zn. 0.25 V2O5·nH2O, with a glass fiber-based membrane (Whatman GF-D), was injected into the electrolyte prepared in the examples and comparative examples to obtain a full cell.

[0109] The full cell was connected to a Blue Electric electrochemical tester for long-cycle testing under the following conditions: 2 A / g, cutoff voltage 0.3V~1.4V. The full cell assembled in Example 1 retained 94.6% capacity after 3000 cycles, while the full cell assembled in Comparative Example 1 retained only 46.7% capacity after 700 cycles (e.g., ...). Figure 7 As shown); the full cell assembled in Example 6 retained 90.7% of its capacity after 500 cycles, while the full cell assembled in Comparative Example 1 retained only 63.2% of its capacity after 500 cycles (as shown). Figure 12 As shown in the figure, the specific electrolyte of the present invention helps to improve the long cycle life of zinc-based batteries.

[0110] Based on the above test results, it can be seen that applying the electrolyte of the present invention to zinc-based batteries helps to improve the coulombic efficiency, long-cycle stability, and extend the battery's service life.

[0111] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A zinc-based battery electrolyte, characterized in that, The zinc-based battery electrolyte includes metal salts, additives, and water; The additives include complexes formed by metal ions and organic ligands. The organic ligands include , At least one of the following: the metal ion includes zinc ions; the metal salt includes a first zinc salt; the first zinc salt includes at least one of zinc sulfate, zinc chloride, zinc nitrate, zinc acetate, zinc acetate, and zinc trifluoroformyl sulfonate; the mass content of the additive in the zinc-based battery electrolyte is 0.1% to 5%.

2. The zinc-based battery electrolyte according to claim 1, characterized in that, The concentration of the metal salt in the zinc-based battery electrolyte is 0.1~5 mol / L.

3. The zinc-based battery electrolyte according to claim 1 or 2, characterized in that, The preparation method of the additive includes: mixing an organic ligand with water to obtain an organic ligand solution; adding a compound containing metal ions to the organic ligand solution, and stirring to obtain a mixture; After the mixture is allowed to stand and separate into layers, the organic phase is collected to obtain the additive.

4. The zinc-based battery electrolyte according to claim 3, characterized in that, The volume ratio of the organic ligand to the water is (1~20):(1~100); and / or, The molar ratio of the metal ion-containing compound to the organic ligand is 1:(1~3); and / or, The compound containing metal ions includes at least one of zinc sulfate, zinc chloride, zinc nitrate, zinc acetate, zinc acetate, and zinc trifluoroformyl sulfonate.

5. A zinc-based battery, characterized in that, It includes a housing and an electrode assembly and an electrolyte located within the housing; the electrolyte includes the zinc-based battery electrolyte according to any one of claims 1 to 4.

6. The zinc-based battery according to claim 5, characterized in that, The electrode assembly includes a positive electrode plate, a negative electrode plate, and a separator disposed between the positive electrode plate and the negative electrode plate. The positive electrode plate includes a positive electrode material, which includes at least one of vanadium oxide-based positive electrode materials, manganese oxide-based positive electrode materials, and Prussian blue-based positive electrode materials.

7. The zinc-based battery according to claim 6, characterized in that, The chemical formula of the cathode material includes M. x V2O5·nH2O, where 0 < x < 2, 0 < n < 20, and M includes at least one of Zn, Mn, K, Ca, Na, Li, and Al.

8. The zinc-based battery according to claim 6, characterized in that, The negative electrode comprises zinc and / or a zinc alloy, wherein the zinc alloy comprises at least one of zinc-copper alloy, zinc-tin alloy, zinc-aluminum alloy, and zinc-nickel alloy; and / or, the separator comprises at least one of glass fiber-based separator, cellulose-based separator, polyethylene-based separator, and polypropylene separator.

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