Aqueous zinc ion battery electrolyte and preparation method and application thereof

Abstract

The invention relates to an aqueous zinc ion battery electrolyte and a preparation method and application of an aqueous zinc ion battery, an electrolyte additive is fluorinated zinc carboxylate, and the content of the additive is 1-100 mM L <-1 >. The electrolyte additive can regulate and control electrolyte zinc ion solvation, promote double anions to participate in a solvation structure and reduce to generate an amorphous solid electrolyte interface (SEI), and effectively solves the problems of zinc dendrites, zinc corrosion, hydrogen precipitation and the like, so that the cycle performance of the aqueous zinc ion battery is improved, and the service life of the aqueous zinc ion battery is prolonged. In addition, the additive provided by the invention is wide in source, green and pollution-free, and meanwhile, the zinc ion battery provided by the invention has the advantages of simple preparation process, low cost and easiness in industrialization.

Description

Technical Field

[0001] The present invention relates to the technical field of aqueous zinc ion batteries, and in particular to an aqueous zinc ion battery electrolyte, a preparation method of the aqueous zinc ion battery and applications thereof. Background Art

[0002] As an emerging energy storage technology, rechargeable aqueous zinc-ion batteries have attracted widespread attention in stationary energy storage systems in recent years. This type of battery system has shown great application potential due to its advantages such as low raw material cost, abundant resources, environmental friendliness, and high intrinsic safety. Metallic zinc has a high theoretical specific capacity (820 mAh g -1 ), abundant resources, and a moderate redox potential (0.762 V vs. standard hydrogen electrode), making zinc anodes highly promising anode materials. However, in weakly acidic electrolyte environments, zinc anodes still face a series of key challenges. During cycling, zinc anodes are subject to uncontrollable dendrite growth, severe surface corrosion, hydrogen evolution reaction (HER), and byproduct deposition. These issues are particularly exacerbated under harsh operating conditions such as high areal capacity, high current density, and a large depth of discharge (DOD), severely restricting the reversibility and cycling stability of zinc metal during the electroplating / stripping process.

[0003] Recent studies have highlighted the significant advantages of a class of functional additives that can induce the in situ formation of SEI films composed of fluoride and sulfide / chloride components on electrode surfaces. Studies have shown that the SEI films formed by these additives exhibit high mechanical modulus, good interfacial energy matching with the metal anode, and excellent ion transport kinetics. Of particular note, significant progress has been made in the development of amorphous SEI films, which exhibit isotropic ionic conductivity and mechanical properties, significantly improving the electrochemical reversibility of metal anodes and providing new design ideas for subsequent interface optimization strategies.

[0004] Therefore, there is an urgent need to develop an electrolyte additive that can synergistically regulate the solvation structure and generate a highly stable SEI film, so as to achieve stable and efficient operation of aqueous zinc-ion batteries in actual energy storage scenarios, which is of great significance to promoting the industrial application of zinc-ion batteries. Summary of the Invention

[0005] In response to the above-mentioned problems of zinc ion batteries, the present invention aims to provide an aqueous zinc ion battery electrolyte. The electrolyte additive provided by the present invention has the advantages of being non-toxic, environmentally friendly, low cost and promoting good battery cycle performance.

[0006] A first aspect of the present invention provides an aqueous zinc ion battery electrolyte.

[0007] The electrolyte comprises zinc salt, deionized water and electrolyte additives.

[0008] The zinc salt is one or more of zinc sulfate, zinc bromide, zinc nitrate, zinc chloride, zinc perchlorate and zinc trifluoromethanesulfonate, and the concentration of the zinc salt is 0.1-12mL. -1 .

[0009] The electrolyte additive is a fluorocarboxylic acid zinc salt, including one or more of zinc fluoroacetate Zn(FCH2COO)2, zinc trifluoroacetate Zn(CF3COO)2, zinc 3-fluoropropionate Zn(FCH2CH2COO)2, zinc 4-fluorobutyrate Zn(FCH2CH2CH2COO)2, and zinc 6-fluorohexanoate Zn(FCH2(CH2)4COO)2, and the concentration of the additive is 1-100 mM L -1 , preferably at a concentration of 10-80 mM L -1 .

[0010] A second aspect of the present invention provides a method for preparing an aqueous zinc ion battery, comprising the following steps: S1: prepare electrolyte; The specific steps include: S11: Add zinc salt to deionized water and continue stirring; wherein the concentration of zinc salt is 0.1-12mL -1 .

[0011] S12: Add additives to the above solution and continue stirring to obtain zinc ion battery electrolyte. The concentration of the additives is 1-100 mM L -1 The preferred concentration is 10-80 mM L -1 .

[0012] S2: Assemble zinc ion symmetric battery; The specific steps include: S21: Place the zinc foil in the positive electrode shell, and then put the diaphragm, electrolyte, zinc foil, stainless steel gasket and negative electrode shell in sequence.

[0013] S22: The assembled battery is placed in a static press for compression and sealing to obtain a zinc ion symmetrical battery.

[0014] S3: Assembling the zinc-ion full battery; The specific steps include: S31: Place the V2O5 positive electrode sheet in the positive electrode shell, and then put in the diaphragm, electrolyte, zinc foil, stainless steel gasket and negative electrode shell in sequence.

[0015] S32: The assembled battery is placed in a static press for compression and sealing to obtain a full zinc ion battery.

[0016] The third aspect of the present invention provides applications of the aqueous zinc ion full battery obtained in the second aspect, including: new energy electric vehicles, electronic product energy storage batteries, large-scale power grid energy storage systems and integrated circuit energy storage batteries, etc.

[0017] The beneficial effects of the present invention are as follows: The present invention adds fluorocarboxylic acid zinc salt to the aqueous zinc ion battery electrolyte to regulate the solvation structure of zinc ions in the electrolyte, and the fluorocarboxylate anions enter the Zn 2+ The solvation structure replaces part of the water molecules in the solvation, inhibiting the HER effect; at the same time, the strongly electronegative fluoride ions form hydrogen bonds with H2O, promoting the solvation of H2O-Zn + -H2O angle is less than 90 degrees, which promotes the anions in the zinc salt to enter the solvation structure, which further causes the uneven state of charge distribution, which is beneficial to accelerate the Zn 2+ diffusion.

[0018] This invention adds a zinc fluorocarboxylate salt to the electrolyte of an aqueous zinc-ion battery, promoting the entry of dianions into the solvent shell and successfully inducing surface reduction of the zinc negative electrode to form an amorphous two-component hybrid SEI film. This SEI film has the advantages of regulating the uniform deposition of zinc ions, reducing water activity, and inhibiting the occurrence of side reactions. Using this electrolyte can significantly improve the cycle performance and service life of aqueous zinc-ion batteries.

[0019] The present invention significantly optimizes the performance of aqueous zinc-ion batteries by precisely controlling the ratio of the zinc salt additive to the base electrolyte zinc salt. If the zinc salt ratio is too low, the SEI layer becomes too thin, failing to effectively suppress dendrite formation on the zinc negative electrode. If the zinc salt ratio is too high, the SEI layer becomes too thick, increasing interfacial impedance and reducing the rate performance of the zinc-ion battery.

[0020] The aqueous zinc ion battery electrolyte additive of the present invention has a wide range of sources and is green and pollution-free. It also has the advantages of simple preparation process, low cost, high safety, easy industrialization, and the like. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The drawings in the specification, which constitute a part of this application, are used to provide further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute improper limitations on this application.

[0022] Figure 1 Graph showing the cycle performance of the zinc ion symmetrical battery prepared in Example 1 of the present invention and Comparative Example 1.

[0023] Figure 2 This is a cycle performance diagram of the aqueous zinc ion full battery prepared in Example 1 of the present invention and Comparative Example 1.

[0024] Figure 3 (a) Cryo-transmission electron microscopy (Cryo-TEM) and cryo-high-resolution transmission electron microscopy (Cryo-HRTEM) images, and (b) EDX element distribution map of the SEI film on the zinc metal surface after cycling of the aqueous zinc ion battery prepared in Example 1 of the present invention.

[0025] Figure 4 This is a cycle performance diagram of the zinc ion symmetrical battery prepared in Comparative Examples 4-6 of the present invention. DETAILED DESCRIPTION

[0026] The present invention will be described in further detail below with reference to the embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0027] Example 1: A method for preparing an aqueous zinc ion battery, comprising the following steps: S1: prepare electrolyte; The specific steps include: S11: Add zinc sulfate to deionized water and continue stirring; wherein the concentration of zinc sulfate is 2 ML -1 ; S12: Add zinc trifluoroacetate additive to the above solution and continue stirring to obtain zinc ion battery electrolyte. The concentration of zinc trifluoroacetate additive is 80 mM L -1 .

[0028] S2: Assemble zinc ion symmetric battery; The specific steps include: S21: placing the zinc foil in the positive electrode shell, and then placing the separator, electrolyte, zinc foil, stainless steel gasket and negative electrode shell in sequence; S22: The assembled battery is placed in a static press for compression and sealing to obtain a zinc ion symmetrical battery.

[0029] S3: Assembling the zinc-ion full battery; The specific steps include: S31: Place the V2O5 positive electrode sheet in the positive electrode shell, and then put the separator, electrolyte, zinc foil, stainless steel gasket and negative electrode shell in sequence; S32: The assembled battery is placed in a static press for compression and sealing to obtain a full zinc ion battery.

[0030] Example 2: A method for preparing an aqueous zinc ion battery, comprising the following steps: S1: prepare electrolyte; The specific steps include: S11: Add zinc chloride to deionized water and continue stirring; wherein the concentration of zinc chloride is 1 ml -1 ; S12: Add zinc fluoroacetate additive to the above solution and continue stirring to obtain zinc ion battery electrolyte. The concentration of zinc fluoroacetate additive is 10 mM L -1 .

[0031] S2: Assemble zinc ion symmetric battery; The specific steps include: S21: placing the zinc foil in the positive electrode shell, and then placing the separator, electrolyte, zinc foil, stainless steel gasket and negative electrode shell in sequence; S22: The assembled battery is placed in a static press for compression and sealing to obtain a zinc ion symmetrical battery.

[0032] S3: Assembling the zinc-ion full battery; The specific steps include: S31: Place the V2O5 positive electrode sheet in the positive electrode shell, and then put the separator, electrolyte, zinc foil, stainless steel gasket and negative electrode shell in sequence; S32: The assembled battery is placed in a static press for compression and sealing to obtain a full zinc ion battery.

[0033] Example 3: A method for preparing an aqueous zinc ion battery, comprising the following steps: S1: prepare electrolyte; The specific steps include: S11: Add zinc perchlorate to deionized water and continue stirring; wherein the concentration of zinc perchlorate is 4 ml -1 ; S12: Add zinc trifluoroacetate additive to the above solution and continue stirring to obtain zinc ion battery electrolyte. The concentration of zinc trifluoroacetate additive is 50 mM L -1 .

[0034] S2: Assemble zinc ion symmetric battery; The specific steps include: S21: placing the zinc foil in the positive electrode shell, and then placing the separator, electrolyte, zinc foil, stainless steel gasket and negative electrode shell in sequence; S22: The assembled battery is placed in a static press for compression and sealing to obtain a zinc ion symmetrical battery.

[0035] S3: Assembling the zinc-ion full battery; The specific steps include: S31: Place the V2O5 positive electrode sheet in the positive electrode shell, and then put the separator, electrolyte, zinc foil, stainless steel gasket and negative electrode shell in sequence; S32: The assembled battery is placed in a static press for compression and sealing to obtain a full zinc ion battery.

[0036] Comparative Example 1: This example provides a method for preparing an aqueous zinc ion battery, the steps of which are basically the same as those in Example 1, except that zinc trifluoroacetate additive is not added to the electrolyte.

[0037] Comparative Example 2: This example provides a method for preparing an aqueous zinc ion battery, the steps of which are basically the same as those in Example 2, except that no zinc fluoroacetate additive is added to the electrolyte.

[0038] Comparative Example 3: This example provides a method for preparing an aqueous zinc ion battery, the steps of which are basically the same as those in Example 3, except that zinc trifluoroacetate additive is not added to the electrolyte.

[0039] Comparative Example 4: This example provides a method for preparing an aqueous zinc ion battery. The steps are basically the same as those in Example 1, except that the concentration of the zinc trifluoroacetate additive is 5 mM L -1 .

[0040] Comparative Example 5: This example provides a method for preparing an aqueous zinc ion battery. The steps are basically the same as those in Example 2, except that the concentration of the zinc fluoroacetate additive is 100 mM L -1 .

[0041] Comparative Example 6: This example provides a method for preparing an aqueous zinc ion battery. The steps are basically the same as those in Example 3, except that the concentration of the zinc trifluoroacetate additive is 5 mM L -1 .

[0042] The zinc ion symmetric cells in Examples 1-3 and Comparative Examples 1-6 were tested at room temperature at 2 mA cm -2 The current density and 1 mAh cm -2 The capacity of the electrochemical performance test was carried out; the zinc ion full batteries in Examples 1-3 and Comparative Examples 1-6 were heated at room temperature at 1A g -1 and 10 g -1 The current density was tested.

[0043] like Figure 1As shown, the zinc ion symmetric battery in Comparative Example 1 has a lifespan of only 72 hours (see ZS), while the zinc ion symmetric battery in Example 1 has a lifespan of up to 4600 hours (see ZSF). This shows that the addition of zinc salt additives can effectively suppress zinc dendrites and various side reactions, greatly improving the battery's service life. Furthermore, electrochemical performance tests show that the zinc ion symmetric battery in Comparative Example 2 has a lifespan of only 50 hours, while the zinc ion symmetric battery in Example 2 has a lifespan of up to 4000 hours. The zinc ion symmetric battery in Comparative Example 3 has a lifespan of only 100 hours, while the zinc ion symmetric battery in Example 3 has a lifespan of up to 5500 hours.

[0044] like Figure 2 As shown in Figure 2, the battery capacity of the zinc ion full battery in Comparative Example 1 has been decaying (see ZS), while the capacity of the zinc ion full battery in Example 1 has almost no change before and after cycling (see ZSF). It can be seen that the additive zinc salt continues to play a role in the battery cycling process, thereby promoting the stability of the battery capacity. -1 ) after 5000 cycles, there is still 80% capacity retention rate. The zinc ion full battery in Example 3 (current density is 10A g -1 ) After reaching 10,000 cycles, there is still a 75% capacity retention rate.

[0045] like Figure 3 As shown, the SEI film generated by the aqueous zinc-ion battery in Example 1 after cycling is amorphous and rich in F and S elements. This amorphous two-component hybrid SEI film has the advantages of regulating the uniform deposition of zinc ions, reducing water activity, and inhibiting the formation of zinc dendrites, thereby greatly improving the cycling performance and service life of the aqueous zinc-ion battery.

[0046] like Figure 4 As shown, the life of the zinc ion symmetrical batteries in Comparative Examples 4-6 is relatively low. It can be seen that when the ratio of the additive zinc salt to the basic electrolyte zinc salt is not within the preferred range, adding a fluorocarboxylic acid zinc salt to the aqueous zinc ion battery electrolyte cannot significantly optimize the performance of the aqueous zinc ion battery.

[0047] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. An aqueous zinc ion battery electrolyte comprising a zinc salt, deionized water and an electrolyte additive, characterized in that: The electrolyte additive is a zinc salt of fluorocarboxylic acid.

2. The aqueous zinc ion battery electrolyte according to claim 1, wherein The zinc salt is one or more of zinc sulfate, zinc bromide, zinc nitrate, zinc chloride, zinc perchlorate and zinc trifluoromethanesulfonate, and the concentration of the zinc salt is 0.1-12ML -1 .

3. The aqueous zinc ion battery electrolyte according to claim 1, wherein The fluorocarboxylic acid zinc salt includes one or more of zinc fluoroacetate, zinc trifluoroacetate, zinc 3-fluoropropionate, zinc 4-fluorobutyrate, and zinc 6-fluorohexanoate, and the additive concentration is 1-100 mM L -1 .

4. The aqueous zinc ion battery electrolyte according to claim 3, wherein The concentration of the additive is 10-80 mM L -1 .

5. A method for preparing an aqueous zinc ion battery, characterized in that: The following steps are involved: S1: preparing the aqueous zinc ion battery electrolyte according to any one of claims 1 to 4; The specific steps include: S11: adding the zinc salt to the deionized water and continuously stirring; S12: Add the additive into the above solution and continue stirring to obtain a zinc ion battery electrolyte; S2: Assemble aqueous zinc-ion batteries.

6. The preparation method according to claim 5, characterized in that The aqueous zinc ion battery is a symmetrical zinc ion battery, which specifically comprises the following steps: S21: placing the zinc foil in the positive electrode shell, and then placing the separator, the electrolyte, the zinc foil, the stainless steel gasket and the negative electrode shell in sequence; S22: The assembled battery is placed in a static press for compression and sealing to obtain a zinc ion symmetrical battery.

7. The preparation method according to claim 5, characterized in that The aqueous zinc ion battery is a full zinc ion battery, specifically comprising the following steps: S31: placing the V2O5 positive electrode sheet in the positive electrode shell, and then placing the separator, the electrolyte, the zinc foil, the stainless steel gasket and the negative electrode shell in sequence; S32: The assembled battery is placed in a static press for compression and sealing to obtain a full zinc ion battery.

8. An application of an aqueous zinc ion full battery, characterized in that: The zinc ion full battery prepared by the preparation method described in claim 7 is applied to new energy electric vehicles, electronic product energy storage batteries, large-scale power grid energy storage systems and integrated circuit energy storage batteries, etc.

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