Electrolyte and aqueous zinc ion battery for improving battery cycle performance

Abstract

The application discloses electrolyte for improving cycle performance of a battery and a water-based zinc ion battery, and relates to the technical field of batteries.The electrolyte for improving cycle performance of a battery comprises water and an electrolyte additive, and the chemical general formula of the electrolyte additive is (N + A)I ‑ ; in the chemical general formula, N + is a positively charged nitrogen center, A is an alkyl chain, and I ‑ is an iodine ion.The electrolyte for improving cycle performance of a battery can inhibit the growth of zinc dendrites and the formation of side reactions, improves the cycle performance of the water-based zinc ion battery, and solves the problems of dendrites, hydrogen evolution and corrosion existing in the current water-based zinc ion battery.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and in particular to an electrolyte and an aqueous zinc-ion battery for improving battery cycle performance. Background Technology

[0002] Aqueous zinc-ion batteries are a new type of rechargeable metal-ion battery that uses water as the electrolyte solvent and metallic zinc as the negative electrode. The working principle of aqueous zinc-ion batteries is similar to that of lithium batteries, utilizing the reciprocating movement of zinc ions in the electrolyte between the positive and negative electrodes to store and release electrical energy.

[0003] Unlike lithium batteries, which use highly flammable organic electrolytes, aqueous zinc-ion batteries primarily use water as the electrolyte solvent. Therefore, they do not have the flammability and explosiveness issues associated with lithium batteries, giving them advantages such as high safety, environmental friendliness, and low cost. Furthermore, because zinc, the raw material for aqueous zinc-ion batteries, is abundant and battery assembly, storage, transportation, and maintenance are relatively simple, aqueous zinc-ion batteries are considered to have a broader application prospect in the field of large-scale energy storage.

[0004] Currently, the zinc anode in aqueous zinc-ion batteries suffers from severe harmful side reactions such as dendrite formation, hydrogen evolution, and metal corrosion in aqueous electrolytes, limiting the battery's cycle life and hindering its large-scale application. Dendrite formation refers to the uneven deposition of zinc ions on the zinc anode during charging and discharging, resulting in dendritic zinc crystals. These dendrites continue to grow during charging and discharging, eventually piercing the separator and contacting the positive electrode, causing the battery to fail due to internal short circuits. Hydrogen evolution occurs when water, the electrolyte solvent, decomposes and releases hydrogen gas during charging and discharging, leading to battery swelling and even explosion. Corrosion is mainly due to the high reactivity of zinc, which spontaneously reacts with water, continuously consuming the zinc anode material and electrolyte, significantly shortening battery life.

[0005] Therefore, solving the problems of dendrite growth, hydrogen evolution, and corrosion faced by aqueous zinc-ion batteries is an urgent issue that needs to be addressed. Summary of the Invention

[0006] In response to the problems raised in the background art, the purpose of this invention is to provide an electrolyte that improves the cycle performance of batteries, which can inhibit the growth of zinc dendrites and the formation of side reactions, improve the cycle performance of aqueous zinc-ion batteries, and solve the problems of dendrite formation, hydrogen evolution, and corrosion existing in current aqueous zinc-ion batteries.

[0007] Another objective of this invention is to provide an aqueous zinc-ion battery that uses the electrolyte described above to improve battery cycle performance and has the advantage of long cycle life.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] An electrolyte for improving battery cycle performance includes water and an electrolyte additive, wherein the general chemical formula of the electrolyte additive is (N... + A) - ;

[0010] In the above general chemical formula, N + A is a positively charged nitrogen center, A is an alkyl chain, and I is... - It is an iodide ion.

[0011] Furthermore, in the electrolyte, the molar concentration of the electrolyte additive is 1 mM to 100 mM.

[0012] Preferably, the alkyl chain has 1 to 4 carbon chains and 1 to 100 carbon atoms.

[0013] Furthermore, the electrolyte additive is any one of tetraethylammonium iodide, tetramethylammonium iodide, tetrabutylammonium iodide, tetra-n-dodecylammonium iodide, diisopropylammonium iodide, isopropylammonium iodide, isobutylammonium iodide, tert-butylammonium iodide, tetradecyltrimethylammonium iodide, dimethyl di(octadecyl)ammonium iodide, or dodecyltrimethylammonium iodide.

[0014] More preferably, the alkyl chain has 4 to 20 carbon atoms.

[0015] More preferably, the electrolyte additive is tetraethylammonium iodide.

[0016] Furthermore, the electrolyte also includes electrolyte salts.

[0017] Preferably, the electrolyte salt is zinc sulfate.

[0018] Furthermore, the molar concentration of zinc sulfate in the electrolyte is 1M.

[0019] An aqueous zinc-ion battery includes a positive electrode, a negative electrode, and the aforementioned electrolyte for improving battery cycle performance, wherein the negative electrode is made of zinc.

[0020] The above technical solution has the following beneficial effects: This technical solution adds a chemical formula (N...) to the electrolyte used in aqueous zinc-ion batteries. + A) - The electrolyte additive, through the synergistic effect of anions and cations, can induce uniform zinc deposition, effectively inhibit the formation and growth of zinc dendrites on the zinc anode surface, reduce side reactions in the electrolyte, significantly extend the cycle performance of aqueous zinc-ion batteries, and solve the problems of dendrite formation, hydrogen evolution, and corrosion in existing aqueous zinc-ion batteries. Attached Figure Description

[0021] Figure 1 This is a graph showing the performance test results of application embodiment 1 of the present invention;

[0022] Figure 2 This is a graph showing the performance test results of application embodiment 2 of the present invention;

[0023] Figure 3 This is a field emission scanning electron microscope image of the zinc anode of the control Zn / Zn symmetric battery in Application Example 3 of this invention;

[0024] Figure 4 This is a field emission scanning electron microscope image of the zinc anode of the experimental Zn / Zn symmetric battery in Example 3 of the present invention. Detailed Implementation

[0025] To facilitate understanding of the present invention, a more complete description is provided below. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0026] Where specific techniques or conditions are not specified in the examples, they shall be performed in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0028] The following is in conjunction with the appendix Figure 1-4 The technical solution of the present invention will be further explained in detail below with specific embodiments.

[0029] An electrolyte for improving battery cycle performance includes water and an electrolyte additive, wherein the general chemical formula of the electrolyte additive is (N... + A)I - ;

[0030] In the above general chemical formula, N + A is a positively charged nitrogen center, A is an alkyl chain, and I is... - It is an iodide ion.

[0031] Currently, the zinc anode in aqueous zinc-ion batteries suffers from severe harmful side reactions such as dendrite formation, hydrogen evolution, and metal corrosion in aqueous electrolytes, limiting the battery's cycle life and hindering its large-scale application. This technical solution addresses this by adding a chemical formula (N...) to the electrolyte used in aqueous zinc-ion batteries... + A)I - The electrolyte additive, through the synergistic effect of anions and cations, can induce uniform zinc deposition, effectively inhibit the formation and growth of zinc dendrites on the zinc anode surface, reduce side reactions in the electrolyte, significantly extend the cycle performance of aqueous zinc-ion batteries, and solve the problems of dendrite formation, hydrogen evolution, and corrosion in existing aqueous zinc-ion batteries.

[0032] Further explanation: This technical solution adds a chemical formula (N...) to the electrolyte. + A)I - Electrolyte additives, hydrophobic cations (N) in electrolyte additives + A) It can not only disrupt the hydrogen bond network between water molecules, but also preferentially adsorb onto the zinc anode surface, increasing interfacial wettability and inhibiting zinc dendrite growth and hydrogen evolution reaction. Anions (I) - This can reduce the solubility energy of hydrated zinc ions and eliminate dead zinc (dead zinc refers to elemental zinc free on the electrode surface and in the electrolyte; this elemental zinc is extremely difficult or does not participate in redox reactions during battery charging and discharging, nor does it contribute to the battery's capacity during charging and discharging) and basic zinc sulfate. Through the synergistic effect of hydrophobic cations and anions, the cycle performance of aqueous zinc-ion batteries can be significantly improved, and from... Figure 3 and Figure 4 Morphological analysis shows that the electrolyte additive in this technical solution has a good inhibitory effect on the growth of zinc dendrites and the formation of side reactions in zinc-ion batteries.

[0033] It is worth noting that this technical solution selects an electrolyte additive containing iodide ions. Iodide ions also have a certain adsorption capacity, which can further inhibit the growth of zinc dendrites and the hydrogen evolution reaction. At the same time, iodide ions have weak corrosiveness and low corrosiveness to metals. Moreover, iodide ions (I... - During charging, it can spontaneously generate triiodide ions (I3). - ), I3 - The ions can react with dead zinc or basic zinc sulfate to form zinc ions (Zn). 2+ This allows for higher utilization. Other halide ions are not easily used in this technical solution because they are highly corrosive and easily corrode the zinc anode material, leading to a significant reduction in battery life.

[0034] To further explain, alkyl-containing cations are hydrophobic, which can disrupt the hydrogen bond network between water molecules, weaken the activity of water molecules, and inhibit side reactions in the electrolyte. At the same time, they can preferentially adsorb on the zinc anode surface, isolating them from direct contact with water molecules and inhibiting side reactions on the zinc anode surface.

[0035] This technical solution uses water as a solvent in the electrolyte, giving it advantages such as high safety, good environmental protection, and low cost, and making it less prone to flammability, explosion, and other problems.

[0036] Preferably, the water used in this technical solution is deionized water.

[0037] To further explain, the molar concentration of the electrolyte additive in the electrolyte is 1 mM to 100 mM.

[0038] This technical solution, by controlling the molar concentration of the electrolyte additive within the range of 1 mM to 100 mM, achieves better suppression of zinc dendrite growth and reduction of side reactions, thereby improving the cycle performance of aqueous zinc-ion batteries. If the molar concentration (i.e., the amount of substance) of the electrolyte additive is below 1 mM, it cannot effectively suppress dendrite growth, reduce the activity of water in the electrolyte solution, or effectively suppress side reactions in the electrolyte solution. Although the battery cycle life is extended compared to batteries without additives, the cycle life is still limited. Furthermore, the molar concentration of the electrolyte additive in this technical solution should not exceed 100 mM. Since the electrolyte additive is an organic compound and flammable, if the concentration exceeds 100 mM, the flammability of the electrolyte will be further amplified, exceeding the design principle of low cost and environmental protection. Simultaneously, excessively high electrolyte additive concentrations can cause competitive adsorption of adsorbed ions, making it difficult to suppress dendrite growth. Additionally, the anions of the additive have a certain degree of corrosiveness; excessively high concentrations will exacerbate zinc electrode corrosion, leading to a decrease in cycle performance.

[0039] To further explain, the alkyl chain has 1 to 4 carbon chains and 1 to 100 carbon atoms.

[0040] Further explanation: the electrolyte additive is any one of tetraethylammonium iodide, tetramethylammonium iodide, tetrabutylammonium iodide, tetra-n-dodecylammonium iodide, diisopropylammonium iodide, isopropylammonium iodide, isobutylammonium iodide, tert-butylammonium iodide, tetradecyltrimethylammonium iodide, dimethyl di(octadecyl)ammonium iodide, or dodecyltrimethylammonium iodide.

[0041] To further clarify, the alkyl chain has 4 to 20 carbon atoms.

[0042] This technical solution selects alkyl chains with no more than 4 carbon chains and between 4 and 20 carbon chains, making the electrolyte additive relatively inexpensive. Furthermore, it enables the cations in the electrolyte additive to have a faster migration rate, thereby better inhibiting the growth of zinc dendrites and the hydrogen evolution reaction.

[0043] To further clarify, the electrolyte additive is tetraethylammonium iodide.

[0044] Preferably, the electrolyte additive in this technical solution is tetraethylammonium iodide, which is relatively inexpensive. Furthermore, tetraethylammonium iodide has a good inhibitory effect on the growth of zinc anode dendrites and the formation of side reactions in zinc-ion batteries, and can further improve the cycle performance of aqueous zinc-ion batteries.

[0045] To further clarify, the electrolyte also includes electrolyte salts.

[0046] Preferably, the electrolyte salt is a zinc salt.

[0047] To further clarify, the electrolyte salt is zinc sulfate.

[0048] The electrolyte in this technical solution is zinc sulfate electrolyte, which has good electrolytic performance.

[0049] To further clarify, the molar concentration of zinc sulfate in the electrolyte is 1M.

[0050] Specifically, the electrolyte in this technical solution is a zinc sulfate electrolyte with a zinc sulfate molar concentration of 1M, which exhibits good electrolytic performance.

[0051] An aqueous zinc-ion battery includes a positive electrode, a negative electrode, and the aforementioned electrolyte for improving battery cycle performance, wherein the negative electrode is made of zinc.

[0052] Preferably, the aqueous zinc-ion battery in this technical solution is a Zn / Zn symmetrical battery or a Zn / MnO2 full battery. Applying the electrolyte of this technical solution to the cycling of a Zn / Zn symmetrical battery can suppress the growth of zinc dendrites on the zinc anode surface and reduce side reactions in the electrolyte, significantly extending the cycle life of the symmetrical battery. Applying the electrolyte of this technical solution to a Zn / MnO2 full battery can prevent the formation and growth of zinc dendrites on the zinc anode surface, alleviate the consumption of the cathode material, and increase the capacity retention rate of the full battery.

[0053] Performance tests show that the Zn / Zn symmetric cell using the electrolyte of this technology operates at a current density of 5 mA / cm². 2 and a capacity of 1mAh / cm 2It exhibits excellent cycling stability of over 2700 h, while the Zn / MnO2 full cell shows a significant increase in capacity retention after 3000 cycles at 3 A / g.

[0054] The technical solution of the present invention will be further described below with reference to embodiments and comparative examples.

[0055] Example 1

[0056] The electrolyte components for improving battery cycle performance in this embodiment include electrolyte additives, electrolyte salts, and solvents. The electrolyte salt is zinc sulfate, the solvent is deionized water, and the electrolyte additive is tetraethylammonium iodide (chemical formula C8H20NI).

[0057] In the electrolyte of this embodiment, the molar concentration of the electrolyte additive is 50 mM (i.e., 0.05 M); the molar concentration of the electrolyte salt is 1 M.

[0058] Example 2

[0059] The electrolyte components for improving battery cycle performance in this embodiment include electrolyte additives, electrolyte salts, and solvents. The electrolyte salt is zinc sulfate, the solvent is deionized water, and the electrolyte additive is tetramethylammonium iodide (chemical formula C4H12NI).

[0060] In the electrolyte of this embodiment, the molar concentration of the electrolyte additive is 60 mM; the molar concentration of the electrolyte salt is 1 M.

[0061] Example 3

[0062] The electrolyte components for improving battery cycle performance in this embodiment include electrolyte additives, electrolyte salts, and solvents. The electrolyte salt is zinc sulfate, the solvent is deionized water, and the electrolyte additive is tetrabutylammonium iodide (chemical formula C16H36NI).

[0063] In the electrolyte of this embodiment, the molar concentration of the electrolyte additive is 100 mM; the molar concentration of the electrolyte salt is 1 M.

[0064] Example 4

[0065] The electrolyte components for improving battery cycle performance in this embodiment include electrolyte additives, electrolyte salts, and solvents. The electrolyte salt is zinc sulfate, the solvent is deionized water, and the electrolyte additive is tetra-n-dodecyl ammonium iodide (chemical formula C48H100NI).

[0066] In the electrolyte of this embodiment, the molar concentration of the electrolyte additive is 20 mM; the molar concentration of the electrolyte salt is 1 M.

[0067] Example 5

[0068] The electrolyte components for improving battery cycle performance in this embodiment include electrolyte additives, electrolyte salts, and solvents. The electrolyte salt is zinc sulfate, the solvent is deionized water, and the electrolyte additive is diisopropylammonium iodide (chemical formula C6H16NI).

[0069] In the electrolyte of this embodiment, the molar concentration of the electrolyte additive is 50 mM; the molar concentration of the electrolyte salt is 1 M.

[0070] Example 6

[0071] The electrolyte components for improving battery cycle performance in this embodiment include electrolyte additives, electrolyte salts, and solvents. The electrolyte salt is zinc sulfate, the solvent is deionized water, and the electrolyte additive is isopropylammonium iodide (chemical formula C3H10NI).

[0072] In the electrolyte of this embodiment, the molar concentration of the electrolyte additive is 40 mM; the molar concentration of the electrolyte salt is 1 M.

[0073] Example 7

[0074] The electrolyte components for improving battery cycle performance in this embodiment include electrolyte additives, electrolyte salts, and solvents. The electrolyte salt is zinc sulfate, the solvent is deionized water, and the electrolyte additive is isobutylammonium iodide (chemical formula C4H12NI).

[0075] In the electrolyte of this embodiment, the molar concentration of the electrolyte additive is 50 mM; the molar concentration of the electrolyte salt is 1 M.

[0076] Example 8

[0077] The electrolyte components for improving battery cycle performance in this embodiment include electrolyte additives, electrolyte salts, and solvents. The electrolyte salt is zinc sulfate, the solvent is deionized water, and the electrolyte additive is tert-butylammonium iodide (chemical formula C4H12NI).

[0078] In the electrolyte of this embodiment, the molar concentration of the electrolyte additive is 1 mM; the molar concentration of the electrolyte salt is 1 M.

[0079] Example 9

[0080] The electrolyte components for improving battery cycle performance in this embodiment include electrolyte additives, electrolyte salts, and solvents. The electrolyte salt is zinc sulfate, the solvent is deionized water, and the electrolyte additive is tetradecyltrimethylammonium iodide (chemical formula C17H38NI).

[0081] In the electrolyte of this embodiment, the molar concentration of the electrolyte additive is 60 mM; the molar concentration of the electrolyte salt is 1 M.

[0082] Example 10

[0083] The electrolyte components for improving battery cycle performance in this embodiment include electrolyte additives, electrolyte salts, and solvents. The electrolyte salt is zinc sulfate, the solvent is deionized water, and the electrolyte additive is dimethyl di(octadecyl)ammonium iodide (chemical formula C38H80NI).

[0084] In the electrolyte of this embodiment, the molar concentration of the electrolyte additive is 50 mM; the molar concentration of the electrolyte salt is 1 M.

[0085] Example 11

[0086] The electrolyte components for improving battery cycle performance in this embodiment include electrolyte additives, electrolyte salts, and solvents. The electrolyte salt is zinc sulfate, the solvent is deionized water, and the electrolyte additive is dodecyltrimethylammonium iodide (chemical formula C15H34NI).

[0087] In the electrolyte of this embodiment, the molar concentration of the electrolyte additive is 50 mM; the molar concentration of the electrolyte salt is 1 M.

[0088] Example 12

[0089] The electrolyte components for improving battery cycle performance in this embodiment include electrolyte additives, electrolyte salts, solvents, and manganese sulfate. The electrolyte salt is zinc sulfate, the solvent is deionized water, and the electrolyte additive is tetraethylammonium iodide (chemical formula C8H20NI).

[0090] In the electrolyte of this embodiment, the molar concentration of the electrolyte additive is 50 mM; the molar concentration of the electrolyte salt is 1 M; and the molar concentration of manganese sulfate is 0.1 M.

[0091] In this embodiment, manganese sulfate is added to the electrolyte. When the electrolyte of this embodiment is applied to a Zn / MnO2 full cell, the addition of manganese sulfate can stabilize the positive electrode material.

[0092] Application Example 1

[0093] (1) Preparation of electrolyte for the control group

[0094] Accurately weigh 71.89 g of zinc sulfate heptahydrate (ZnSO4·7H2O), add an appropriate amount of deionized water, stir at room temperature until completely dissolved, and then use a volumetric flask to make up to 250 mL to prepare a 1 M zinc sulfate electrolyte.

[0095] (2) Preparation of electrolyte for the experimental group

[0096] Accurately weigh 71.89 g of zinc sulfate heptahydrate (ZnSO4·7H2O) and an appropriate amount of electrolyte additive (tetraethylammonium iodide), then add deionized water, stir at room temperature until completely dissolved, and then use a volumetric flask to make up to 250 mL to prepare a 1 M zinc sulfate electrolyte containing the electrolyte additive. The molar concentration of tetraethylammonium iodide in the zinc sulfate electrolyte is 0.05 M (that is, the electrolyte prepared by this experimental group is the electrolyte of Example 1).

[0097] (3) Preparation of zinc electrode material

[0098] Commercial zinc sheets with a thickness of 0.2 mm were cut into 10×10 mm squares, ultrasonicated with anhydrous ethanol for 10 minutes, wiped with anhydrous ethanol 3 times, and dried to serve as the negative electrode of an aqueous zinc-ion battery.

[0099] (3) Assembly and testing of Zn / Zn symmetric cells

[0100] Zn / Zn CR2032 coin cells were assembled, with the zinc sheets prepared in step (3) used as the positive and negative electrodes, and the glass fiber membrane GF / A used as the separator. The electrolytes were the control group electrolyte prepared in step (1) and the experimental group electrolyte prepared in step (2), respectively, to prepare control Zn / Zn symmetrical cells and experimental Zn / Zn symmetrical cells. The control Zn / Zn symmetrical cells and experimental Zn / Zn symmetrical cells were tested using a CT2001A blue electric current testing system. The two cells were tested at a current density of 5 mA / cm². 2 And a capacity of 1mAh / cm 2 Under the conditions of repeated charge-discharge cycles, the test results are shown in the attached figure. Figure 1 As shown.

[0101] Analysis Appendix Figure 1 It can be observed that when using a conventional electrolyte without electrolyte additives (i.e., the control group electrolyte), zinc dendrites are formed during the cycling process. After 53 hours of cycling, the battery fails due to a short circuit caused by the zinc dendrites piercing the separator and contacting the positive electrode. In contrast, the battery containing electrolyte additives can cycle stably for more than 2700 hours.

[0102] Specifically, the battery without electrolyte additives exhibited significant voltage fluctuations and a rapid drop after 53 hours of cycling, leading to battery failure. This indicated severe zinc dendrite formation and puncture of the separator. The cause was uneven zinc deposition during the zinc deposition process. Subsequently, due to the tip effect, zinc ions tended to deposit at the protruding tips. Incomplete stripping of zinc deposited at these tips further exacerbated the problem during charge and discharge, ultimately leading to separator puncture, direct contact between the positive and negative electrodes, a sudden voltage drop, and battery failure. Therefore, it is evident that when no electrolyte additive (tetraethylammonium iodide) is added to the electrolyte used in Zn / Zn symmetric batteries, the battery's cycle performance is extremely poor, only able to cycle for 53 hours.

[0103] Application Example 2

[0104] (1) Preparation of electrolyte for the control group

[0105] Accurately weigh 71.89 g of zinc sulfate heptahydrate (ZnSO4·7H2O) and 4.23 g of manganese sulfate monohydrate (MnSO4·H2O), add an appropriate amount of deionized water, stir at room temperature until completely dissolved, and then use a volumetric flask to make up to 250 mL to prepare a 1 M zinc sulfate electrolyte (the electrolyte contains 1 M ZnSO4 + 0.1 M MnSO4).

[0106] (2) Preparation of electrolyte for the experimental group

[0107] Accurately weigh 71.89 g of zinc sulfate heptahydrate (ZnSO4·7H2O), 4.23 g of manganese sulfate monohydrate (MnSO4·H2O), and an appropriate amount of electrolyte additive (tetraethylammonium iodide). Add deionized water and stir at room temperature until completely dissolved. Then, use a volumetric flask to make up to 250 mL to prepare a 1 M zinc sulfate electrolyte containing the electrolyte additive (the electrolyte contains 1 M ZnSO4 + 0.1 M MnSO4 + 0.05 M tetraethylammonium iodide).

[0108] (3) Preparation of zinc electrode material

[0109] Commercial zinc sheets with a thickness of 0.2 mm were cut into 10×10 mm squares, ultrasonicated with anhydrous ethanol for 10 minutes, wiped with anhydrous ethanol 3 times, and dried to serve as the negative electrode of an aqueous zinc-ion battery.

[0110] (4) Synthesis of MnO2

[0111] MnO2 was prepared by a simple redox method: 1.48 g KCl and 0.632 g KMnO4 were added to 100 mL of deionized water and stirred continuously at room temperature for 10 min. Then the solution was transferred to a water bath at 60 °C, 1.014 g MnSO4·1H2O was added, and the reaction was carried out at 60 °C for 60 min. The resulting product was then washed three times with deionized water and dried in a vacuum oven at 70 °C for 12 h.

[0112] (5) Preparation of cathode materials

[0113] The MnO2, conductive agent (Ketjen Black), and binder (PVDF) prepared in step (4) were mixed in a ratio of 7:2:1 to prepare a positive electrode material slurry. The obtained slurry was then coated on a hydrophilic carbon cloth (carbon cloth area 0.7×0.9 mm) and dried in an oven for 12 hours to obtain the MnO2 positive electrode material.

[0114] (6) Assembly and testing of Zn / MnO2 full cells

[0115] A Zn / MnO2CR2032 coin cell was assembled. The positive electrode used the MnO2 positive electrode material prepared in step (5) of this embodiment, and the negative electrode used the zinc sheet prepared in step (3) of this embodiment. The separator was a glass fiber separator GF / A. The electrolytes were the control group electrolyte prepared in step (1) and the experimental group electrolyte prepared in step (2) of this embodiment, respectively, to prepare the control Zn / MnO2 full cell and the experimental Zn / MnO2 full cell. The control Zn / MnO2 full cell and the experimental Zn / MnO2 full cell were tested using a CT2001A blue electric test system. The cells were repeatedly charged and discharged at a current density of 3 A / g in a voltage range of 0.9 ~ 1.85 V. The test results are attached below. Figure 2 As shown.

[0116] Analysis Appendix Figure 2 It can be observed that when using an electrolyte without electrolyte additives, the discharge specific capacity of the Zn / MnO2 full cell drops to 55.6 mAh / g after 1000 cycles. However, the discharge specific capacity decay of the Zn / MnO2 full cell containing electrolyte additives (tetraethylammonium iodide) is significantly improved, and the capacity retention rate reaches 96% after 3000 cycles. This indicates that electrolyte additives can effectively inhibit the formation and growth of zinc dendrites and improve the cycle stability and discharge performance of the battery.

[0117] Application Example 3

[0118] (1) Preparation of electrolyte for the control group

[0119] Accurately weigh 71.89 g of zinc sulfate heptahydrate (ZnSO4·7H2O), add an appropriate amount of deionized water, stir at room temperature until completely dissolved, and then use a volumetric flask to make up to 250 mL to prepare a 1 M zinc sulfate electrolyte.

[0120] (2) Preparation of electrolyte for the experimental group

[0121] Accurately weigh 71.89 g of zinc sulfate heptahydrate (ZnSO4·7H2O) and an appropriate amount of electrolyte additive (tetraethylammonium iodide), then add deionized water, stir at room temperature until completely dissolved, and then use a volumetric flask to make up to 250 mL to prepare a 1 M zinc sulfate electrolyte containing the electrolyte additive. The molar concentration of tetraethylammonium iodide in the zinc sulfate electrolyte is 0.05 M (that is, the electrolyte prepared by this experimental group is the electrolyte of Example 1).

[0122] (3) Preparation of zinc electrode material

[0123] Commercial zinc sheets with a thickness of 0.2 mm were cut into 10×10 mm squares, ultrasonicated with anhydrous ethanol for 10 minutes, wiped with anhydrous ethanol 3 times, and dried to serve as the negative electrode of an aqueous zinc-ion battery.

[0124] (4) Field emission scanning electron microscopy was used to observe the morphology of the zinc negative electrode.

[0125] A Zn / Zn CR2032 coin cell was assembled, wherein the positive and negative electrodes were both made using zinc sheets prepared in step (3) of this embodiment, the separator was a glass fiber separator GF / A, and the electrolytes were the control group electrolyte prepared in step (1) and the experimental group electrolyte prepared in step (2), respectively, to prepare a control Zn / Zn symmetrical cell and an experimental Zn / Zn symmetrical cell. The control Zn / Zn symmetrical cell and the experimental Zn / Zn symmetrical cell were tested using a CT2001A blue electric current testing system. The two cells were tested at a current density of 1 mA / cm². 2 and a capacity of 1mAh / cm 2 Under the specified conditions, a 100-hour charge-discharge cycle was performed. The morphology of the zinc anode after cycling was investigated using field emission electron microscopy (FET) on both the control and experimental Zn / Zn symmetric cells, as shown in the attached figure. Figure 3 and attached Figure 4 As shown, where Figure 3 The image shows the morphology of the zinc anode in a Zn / Zn symmetric cell under an electron microscope. Figure 4 The image shows the morphology of the zinc anode in the experimental Zn / Zn symmetric cell under an electron microscope.

[0126] Analysis Appendix Figure 3 and 4It was observed that when using an electrolyte without the electrolyte additive (tetraethylammonium iodide), the zinc anode surface of the control Zn / Zn symmetric cell was rough, with the formation of negative reaction products and the appearance of petal-like dendrites. In stark contrast, the zinc anode surface of the experimental Zn / Zn symmetric cell remained a smooth plane without dendrites, indicating that the electrolyte additive effectively suppressed the formation of dendrites and side reactions.

[0127] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0128] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. An electrolyte for improving battery cycle performance, characterized in that, It includes water and electrolyte additives, wherein the general chemical formula of the electrolyte additives is (N + A)I - ; In the above general chemical formula, N + A is a positively charged nitrogen center, A is an alkyl chain, and I - It is an iodide ion; In the electrolyte, the molar concentration of the electrolyte additive is 1 mM to 100 mM; The alkyl chain has 1 to 4 carbon chains and 1 to 100 carbons. The electrolyte also includes an electrolyte salt, which is zinc sulfate.

2. The electrolyte for improving battery cycle performance according to claim 1, characterized in that, The electrolyte additive is any one of tetraethylammonium iodide, tetramethylammonium iodide, tetrabutylammonium iodide, tetra-n-dodecylammonium iodide, diisopropylammonium iodide, isopropylammonium iodide, isobutylammonium iodide, tert-butylammonium iodide, tetradecyltrimethylammonium iodide, dimethyl di(octadecyl)ammonium iodide, or dodecyltrimethylammonium iodide.

3. The electrolyte for improving battery cycle performance according to claim 2, characterized in that, The alkyl chain has 4 to 20 carbon atoms.

4. The electrolyte for improving battery cycle performance according to claim 3, characterized in that, The electrolyte additive is tetraethylammonium iodide.

5. The electrolyte for improving battery cycle performance according to claim 4, characterized in that, The molar concentration of zinc sulfate in the electrolyte is 1M.

6. An aqueous zinc-ion battery, characterized in that, It includes a positive electrode, a negative electrode, and an electrolyte for improving battery cycle performance as described in any one of claims 1 to 5, wherein the negative electrode is made of zinc.

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