An additive for an aqueous zinc-ion battery electrolyte, an electrolyte, and an aqueous zinc-ion battery.

Abstract

This invention relates to an additive for an aqueous zinc-ion battery electrolyte, an electrolyte, and an aqueous zinc-ion battery, belonging to the technical field of aqueous zinc-ion batteries. The electrolyte additive is a water-soluble fluorinated amino acid, and the current density of the aqueous zinc-ion battery is 5–10 mA cm⁻¹. ‑2 The cathode material of the aqueous zinc-ion battery is a transition metal-based cathode material. The fluorinated amino acid additive described in this invention effectively solves the problems of microcrack formation in cathode material particles, dissolution of transition metal ions, zinc dendrite formation, and zinc corrosion. It also has advantages such as simple preparation process, high safety, and environmental friendliness, and has broad application prospects in the field of aqueous zinc-ion batteries.

Description

Technical Field

[0001] This invention relates to an additive for an aqueous zinc-ion battery electrolyte, an electrolyte, and an aqueous zinc-ion battery, belonging to the technical field of aqueous zinc-ion batteries. Background Technology

[0002] Aqueous zinc-ion batteries (AZIBs) have attracted attention from researchers in recent years due to their advantages such as high theoretical capacity, abundant resources, low cost, and high safety.

[0003] However, both the positive and negative electrode materials are significant factors limiting the further development of aqueous zinc-ion batteries. The negative electrode material is primarily affected by the hydrogen evolution reaction (HER) and the formation of zinc dendrites. The HER consumes electrons used for zinc deposition during charging, thus reducing the coulombic efficiency of zinc ion deposition / dissolution. On the other hand, the HER irreversibly consumes electrolyte, reducing battery lifespan. Furthermore, as H2 accumulates during electrolyte decomposition, the battery expands under increasing internal pressure, potentially leading to explosion and compromising safe operation. Additionally, the HER reaction is accompanied by OH... - The formation of zinc dendrites alters the local pH of the electrolyte, leading to the generation of byproducts such as Zn₄SO₄(OH)₆·xH₂O, Zn(OH)₂, and ZnO. Zinc dendrites primarily affect battery performance in two ways: First, during repeated charging, the generated zinc dendrites easily detach from the zinc negative electrode surface, forming dead zinc that no longer participates in the electrode reaction, thus affecting the battery's capacity and coulombic efficiency. Second, the generated zinc dendrites can easily puncture the separator, causing a short circuit and leading to safety issues. Currently, research on zinc-ion battery cathode materials focuses on manganese-based and vanadium-based materials. Because Zn… 2+ The larger ionic radius of Zn increases with charge-discharge cycles. 2+ The continuous insertion and extraction of metal ions into and out of the cathode material can easily cause structural changes in the cathode material, leading to the shedding of cathode material from the current collector surface and affecting battery performance. Furthermore, as the battery undergoes charge-discharge cycles, transition metal ions such as Mn and V dissolve from the cathode material, causing the cathode material structure to collapse, thus affecting battery performance.

[0004] To date, researchers have proposed various strategies to address the aforementioned problems encountered in aqueous zinc-ion batteries, including material structure design, material surface modification, and electrolyte engineering optimization. Among these, electrolyte additives have emerged as a promising modification method for large-scale application due to their simple processing and low cost. Considering the complexity of the problems in aqueous zinc-ion batteries, developing multifunctional electrolyte additives that simultaneously suppress the collapse of the positive electrode material structure and the dissolution of transition metal ions, as well as the hydrogen evolution reaction and zinc dendrite formation on the negative electrode side, is crucial for the rapid development of aqueous zinc-ion batteries. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide an additive for an aqueous zinc-ion battery electrolyte, an electrolyte, and an aqueous zinc-ion battery, which can simultaneously suppress the dissolution of transition metal ions on the positive electrode side and the hydrogen evolution reaction and zinc dendrites on the negative electrode side.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows.

[0007] An electrolyte additive for aqueous zinc-ion batteries, wherein the electrolyte additive is a water-soluble fluorinated amino acid, and the current density of the aqueous zinc-ion battery is 5–10 mA cm⁻¹. -2 The positive electrode material of the aqueous zinc-ion battery is a transition metal-based positive electrode material.

[0008] Preferably, the water-soluble fluoroamino acid is difluoromethylornithine, 3-fluoroalanine, or 3,5-difluorophenylalanine.

[0009] An electrolyte for use in aqueous zinc-ion batteries, the electrolyte comprising a soluble zinc salt, H2O, and the additives described in this invention.

[0010] Preferably, the soluble zinc salt in the electrolyte is one or more selected from zinc sulfate, zinc sulfate hydrate, zinc chloride and its hydrate, and zinc trifluoromethanesulfonate and its hydrate. More preferably, the soluble zinc salt is zinc sulfate.

[0011] Preferably, the molar concentration of the soluble zinc salt in the electrolyte is 1–3 mol / L. Most preferably, it is 2 mol / L.

[0012] Preferably, the molar concentration of the additive in the electrolyte is 1–20 mmol / L. More preferably, the molar concentration of the additive is 8–12 mmol / L.

[0013] Preferably, the electrolyte further includes a manganese ion additive. More preferably, the manganese ion additive is one or more selected from manganese nitrate, manganese sulfate, and manganese chloride. Most preferably, manganese sulfate is used.

[0014] Preferably, the molar concentration of manganese ion additive in the electrolyte is 0.05–0.5 mol / L. Most preferably, it is 0.1 mol / L.

[0015] An aqueous zinc-ion battery includes the electrolyte, transition metal-based positive electrode material, negative electrode material, and separator described in this invention.

[0016] Preferably, the negative electrode material includes zinc sheet, zinc foil, zinc powder, or zinc foam. Most preferably, it is commercial zinc foil with a thickness of 100 nm.

[0017] Preferably, the positive electrode material is lithium manganese oxide, manganese dioxide, vanadium pentoxide, or sodium vanadate. Sodium vanadate is the most preferred.

[0018] Preferably, the diaphragm is made of glass fiber.

[0019] Beneficial effects

[0020] This invention uses water-soluble fluorinated amino acids as additives for aqueous zinc-ion batteries, which can, on the one hand, modify Zn 2+ In the solvation structure, the carboxyl group will partially replace Zn. 2+ The additive solubilizes water molecules in the shell, reducing the water content in the zinc complex and thus inhibiting hydrogen evolution reaction, corrosion passivation, and the formation of the byproduct basic zinc sulfate. Furthermore, under high current densities, this additive can adsorb onto the zinc anode surface and form a ZnF2 inorganic layer during cycling, reducing the local current density on the zinc anode surface and regulating Zn... 2+ Two-dimensional diffusion inhibits dendrite growth.

[0021] This invention uses water-soluble fluorinated amino acids as additives for aqueous zinc-ion batteries. These additives can generate a fluorine-rich CEI film in situ on the surface of the cathode material during battery charge-discharge cycles, effectively stabilizing the cathode material structure, inhibiting the collapse of the cathode material structure and the dissolution of transition metal ions in the cathode material, thereby improving the cycle stability of the battery. Attached Figure Description

[0022] Figure 1 The contact angles of a 2 mol / L zinc sulfate solution (Comparative Example 1) and a modified electrolyte with a difluoromethylornithine concentration of 10 mmol / L (Example 2) on a commercial zinc foil substrate are shown.

[0023] Figure 2 The Zn||Zn symmetric cell obtained in Application Example 2 and Comparative Application Example 1 is used at a current density of 5 mA cm⁻¹ -2 The surface capacity is 1mAh cm -2 Cyclic performance under certain conditions.

[0024] Figure 3For the Zn||Zn symmetric cells obtained in Application Example 2 and Comparative Application Example 1, at a current density of 1 mA cm⁻¹ -2 The surface capacity is 1mAh cm -2 XPS image of the zinc anode surface after 50 cycles under the specified conditions.

[0025] Figure 4 For the Zn||Zn symmetric cells obtained in Application Example 2 and Comparative Application Example 1, at a current density of 1 mA cm⁻¹ -2 The surface capacity is 1mAh cm -2 SEM image of the zinc anode surface after 50 cycles under the specified conditions.

[0026] Figure 5 The rate performance graphs of the Zn||NVO full cell obtained from Application Example 2 and Comparative Application Example 1 are shown.

[0027] Figure 6 The Zn||NVO full cell obtained in Application Example 2 and Comparative Application Example 1 in 2Ag -1 Cyclic performance at current density. Detailed Implementation

[0028] To better understand the present invention, the following embodiments further illustrate the invention. These embodiments are merely illustrative and, obviously, represent only a portion of the embodiments described in this application, not all of them. Based on the embodiments in this application, and all other embodiments obtained by those skilled in the art without inventive effort, should fall within the scope of protection of this application.

[0029] Example 1

[0030] A fluorinated amino acid additive aqueous zinc-ion battery electrolyte, its preparation method, and its application, comprising the following steps:

[0031] (1) Weigh 2.88g of solid ZnSO4·7H2O and add it to 3.68ml of deionized water. Stir thoroughly until completely dissolved to obtain a zinc sulfate solution with a concentration of 2mol / L.

[0032] (2) Weigh 4.55 mg of difluoromethylornithine powder and add it to the zinc sulfate solution obtained in (1). Stir it thoroughly at 25°C until it is completely dissolved to obtain a modified electrolyte with a difluoromethylornithine concentration of 5 mmol / L, which is denoted as ZnSO4+5mM DFMO.

[0033] Example 2

[0034] A fluorinated amino acid additive aqueous zinc-ion battery electrolyte, its preparation method, and its application, comprising the following steps:

[0035] (1) Weigh 2.88g of solid ZnSO4·7H2O and add it to 3.68ml of deionized water. Stir thoroughly until completely dissolved to obtain a zinc sulfate solution with a concentration of 2mol / L.

[0036] (2) Weigh 9.1 mg of difluoromethylornithine powder and add it to the zinc sulfate solution obtained in (1). Stir it thoroughly at 25°C until it is completely dissolved to obtain a modified electrolyte with a difluoromethylornithine concentration of 10 mmol / L, which is denoted as ZnSO4+10mM DFMO.

[0037] Example 3

[0038] A fluorinated amino acid additive aqueous zinc-ion battery electrolyte, its preparation method, and its application, comprising the following steps:

[0039] (1) Weigh 2.88g of solid ZnSO4·7H2O and add it to 3.68ml of deionized water. Stir thoroughly until completely dissolved to obtain a zinc sulfate solution with a concentration of 2mol / L.

[0040] (2) Weigh 18.2 mg of difluoromethylornithine powder and add it to the zinc sulfate solution obtained in (1). Stir it thoroughly at 25°C until it is completely dissolved to obtain a modified electrolyte with a difluoromethylornithine concentration of 20 mmol / L, which is denoted as ZnSO4+20mM DFMO.

[0041] Example 4

[0042] A fluorinated amino acid additive aqueous zinc-ion battery electrolyte, its preparation method, and its application, comprising the following steps:

[0043] (1) Weigh 2.88g of solid ZnSO4·7H2O and add it to 3.68ml of deionized water. Stir thoroughly until completely dissolved to obtain a zinc sulfate solution with a concentration of 2mol / L.

[0044] (2) Weigh 2.68 mg of 3-fluoroalanine powder and add it to the zinc sulfate solution obtained in (1). Stir thoroughly at 25°C until completely dissolved to obtain a modified electrolyte with a 3-fluoroalanine concentration of 5 mmol / L, denoted as ZnSO4+5mM 3-FDA.

[0045] Example 5

[0046] A fluorinated amino acid additive aqueous zinc-ion battery electrolyte, its preparation method, and its application, comprising the following steps:

[0047] (1) Weigh 2.88g of solid ZnSO4·7H2O and add it to 3.68ml of deionized water. Stir thoroughly until completely dissolved to obtain a zinc sulfate solution with a concentration of 2mol / L.

[0048] (2) Weigh 5.354 mg of 3-fluoroalanine powder and add it to the zinc sulfate solution obtained in (1). Stir thoroughly at 25°C until completely dissolved to obtain a modified electrolyte with a 3-fluoroalanine concentration of 10 mmol / L, denoted as ZnSO4+10mM 3-FDA.

[0049] Example 6

[0050] A fluorinated amino acid additive aqueous zinc-ion battery electrolyte, its preparation method, and its application, comprising the following steps:

[0051] (1) Weigh 2.88g of solid ZnSO4·7H2O and add it to 3.68ml of deionized water. Stir thoroughly until completely dissolved to obtain a zinc sulfate solution with a concentration of 2mol / L.

[0052] (2) Weigh 10.71 mg of 3-fluoroalanine powder and add it to the zinc sulfate solution obtained in (1). Stir thoroughly at 25°C until completely dissolved to obtain a modified electrolyte with a 3-fluoroalanine concentration of 20 mmol / L, denoted as ZnSO4+20mM 3-FDA.

[0053] Example 7

[0054] A fluorinated amino acid additive aqueous zinc-ion battery electrolyte, its preparation method, and its application, comprising the following steps:

[0055] (1) Weigh 2.88g of solid ZnSO4·7H2O and add it to 3.68ml of deionized water. Stir thoroughly until completely dissolved to obtain a zinc sulfate solution with a concentration of 2mol / L.

[0056] (2) Weigh 5.03 mg of 3,5-difluorophenylalanine powder and add it to the zinc sulfate solution obtained in (1). Stir thoroughly at 25°C until completely dissolved to obtain a modified electrolyte with a 3,5-difluorophenylalanine concentration of 5 mmol / L, denoted as ZnSO4+5mM 3,5-DDL.

[0057] Example 8

[0058] A fluorinated amino acid additive aqueous zinc-ion battery electrolyte, its preparation method, and its application, comprising the following steps:

[0059] (1) Weigh 2.88g of solid ZnSO4·7H2O and add it to 3.68ml of deionized water. Stir thoroughly until completely dissolved to obtain a zinc sulfate solution with a concentration of 2mol / L.

[0060] (2) Weigh 10.06 mg of 3,5-difluorophenylalanine powder and add it to the zinc sulfate solution obtained in (1). Stir thoroughly at 25°C until completely dissolved to obtain a modified electrolyte with a 3,5-difluorophenylalanine concentration of 10 mmol / L, denoted as ZnSO4+10mM 3,5-DDL.

[0061] Example 9

[0062] A fluorinated amino acid additive aqueous zinc-ion battery electrolyte, its preparation method, and its application, comprising the following steps:

[0063] (1) Weigh 2.88g of solid ZnSO4·7H2O and add it to 3.68ml of deionized water. Stir thoroughly until completely dissolved to obtain a zinc sulfate solution with a concentration of 2mol / L.

[0064] (2) Weigh 20.12 mg of 3,5-difluorophenylalanine powder and add it to the zinc sulfate solution obtained in (1). Stir thoroughly at 25°C until completely dissolved to obtain a modified electrolyte with a 3,5-difluorophenylalanine concentration of 20 mmol / L, denoted as ZnSO4+20mM 3,5-DDL.

[0065] Comparative Example 1

[0066] This comparative example provides an electrolyte, its preparation method, and its application, including the following steps:

[0067] Weigh 2.88g of solid ZnSO4·7H2O and add it to 3.68ml of deionized water. Stir thoroughly until completely dissolved to obtain a zinc sulfate solution with a concentration of 2mol / L, denoted as ZnSO4.

[0068] Figure 1 The contact angles of the electrolytes obtained in Example 2 and Comparative Example 1 on a commercial zinc foil substrate are shown. The contact angle of the 2 mol / L zinc sulfate electrolyte without additives in Comparative Example 1 on the zinc foil surface is 99.02°, and the contact angle of the modified electrolyte with a difluoromethylornithine concentration of 10 mmol / L in Example 2 on the zinc foil surface is 85.59°. This indicates that the addition of difluoromethylornithine is beneficial to improving the wettability of the electrolyte, which will be beneficial to the ion transfer of the interfacial reaction.

[0069] The contact angle test results of Examples 2-9 show that the addition of water-soluble fluoroamino acids improves the wettability of the electrolyte.

[0070] Application Example 1

[0071] Preparation of Zn||Zn symmetric cells: A commercial CR2025 electrode shell was used, with both positive and negative electrodes being commercial zinc foil (11 mm in diameter), and a glass fiber membrane (19 mm in diameter) as the separator. 150 μL of the modified electrolyte obtained in Example 1 was dropwise added onto the separator. The cells were assembled in the following order: positive electrode shell - zinc foil - separator - electrolyte - zinc foil - spring sheet - gasket - gasket - negative electrode shell. After assembly, the cells were pressurized and sealed to prepare the Zn||Zn symmetric cells.

[0072] Preparation of Zn||Cu half-cell: A commercial CR2025 electrode shell was used, with a commercial copper foil (11 mm in diameter) as the positive electrode and a commercial zinc foil (11 mm in diameter) as the negative electrode. A glass fiber membrane (19 mm in diameter) was used as the separator. 150 μL of the modified electrolyte obtained in Example 1 was dropped onto the separator. The cell was assembled in the following order: positive electrode shell - copper foil - separator - electrolyte - zinc foil - spring sheet - gasket - gasket - negative electrode shell. After assembly, the cell was pressurized and sealed to prepare the Zn||Cu half-cell.

[0073] Preparation of Zn||NVO full cells: A commercial CR2025 electrode shell was used. The positive electrode was carbon paper coated with sodium vanadate (11 mm in diameter), the negative electrode was commercial zinc foil (11 mm in diameter), and the separator was a glass fiber membrane (19 mm in diameter). 150 μL of the modified electrolyte obtained in Example 1 was dropped onto the separator. The battery was assembled in the following order: positive electrode shell - positive electrode - separator - electrolyte - zinc foil - spring sheet - gasket - gasket - negative electrode shell. After assembly, the battery was pressurized and sealed to prepare a Zn||NVO full cell.

[0074] Application Example 2

[0075] Preparation of Zn||Zn symmetric cells: Replace 150 μL of the modified electrolyte obtained in Example 1 with 150 μL of the modified electrolyte obtained in Example 2, and keep other conditions the same as in Application Example 1.

[0076] Preparation of Zn||Cu half-cell: Replace 150 μL of the modified electrolyte obtained in Example 1 with 150 μL of the modified electrolyte obtained in Example 2, and keep other conditions the same as in Application Example 1.

[0077] Preparation of Zn||NVO full cells: Replace 150 μL of the modified electrolyte obtained in Example 1 with 150 μL of the modified electrolyte obtained in Example 2, and keep other conditions the same as in Application Example 1.

[0078] Application Example 3

[0079] Preparation of Zn||Zn symmetric cells: Replace 150 μL of the modified electrolyte obtained in Example 1 with 150 μL of the modified electrolyte obtained in Example 3, and keep other conditions the same as in Application Example 1.

[0080] Preparation of Zn||Cu half-cell: Replace 150 μL of the modified electrolyte obtained in Example 1 with 150 μL of the modified electrolyte obtained in Example 3, and keep other conditions the same as in Application Example 1.

[0081] Preparation of Zn||NVO full cells: Replace 150 μL of the modified electrolyte obtained in Example 1 with 150 μL of the modified electrolyte obtained in Example 3, and keep other conditions the same as in Application Example 1.

[0082] Application Example 4

[0083] Preparation of Zn||Zn symmetric cells: Replace 150 μL of the modified electrolyte obtained in Example 1 with 150 μL of the modified electrolyte obtained in Example 4, and keep other conditions the same as in Application Example 1.

[0084] Preparation of Zn||Cu half-cell: Replace 150 μL of the modified electrolyte obtained in Example 1 with 150 μL of the modified electrolyte obtained in Example 4, and keep other conditions the same as in Application Example 1.

[0085] Preparation of Zn||NVO full cells: Replace 150 μL of the modified electrolyte obtained in Example 1 with 150 μL of the modified electrolyte obtained in Example 4, and keep other conditions the same as in Application Example 1.

[0086] Application Example 5

[0087] Preparation of Zn||Zn symmetric cells: Replace 150 μL of the modified electrolyte obtained in Example 1 with 150 μL of the modified electrolyte obtained in Example 5, and keep other conditions the same as in Application Example 1.

[0088] Preparation of Zn||Cu half-cell: Replace 150 μL of the modified electrolyte obtained in Example 1 with 150 μL of the modified electrolyte obtained in Example 5, and keep other conditions the same as in Application Example 1.

[0089] Preparation of Zn||NVO full cells: Replace 150 μL of the modified electrolyte obtained in Example 1 with 150 μL of the modified electrolyte obtained in Example 5, and keep other conditions the same as in Application Example 1.

[0090] Application Example 6

[0091] Preparation of Zn||Zn symmetric cells: Replace 150 μL of the modified electrolyte obtained in Example 1 with 150 μL of the modified electrolyte obtained in Example 6, and keep other conditions the same as in Application Example 1.

[0092] Preparation of Zn||Cu half-cell: Replace 150 μL of the modified electrolyte obtained in Example 1 with 150 μL of the modified electrolyte obtained in Example 6, and keep other conditions the same as in Application Example 1.

[0093] Preparation of Zn||NVO full cells: Replace 150 μL of the modified electrolyte obtained in Example 1 with 150 μL of the modified electrolyte obtained in Example 6, and keep other conditions the same as in Application Example 1.

[0094] Application Example 7

[0095] Preparation of Zn||Zn symmetric cells: Replace 150 μL of the modified electrolyte obtained in Example 1 with 150 μL of the modified electrolyte obtained in Example 7, and keep other conditions the same as in Application Example 1.

[0096] Preparation of Zn||Cu half-cell: Replace 150 μL of the modified electrolyte obtained in Example 1 with 150 μL of the modified electrolyte obtained in Example 7, and keep other conditions the same as in Application Example 1.

[0097] Preparation of Zn||NVO full cells: Replace 150 μL of the modified electrolyte obtained in Example 1 with 150 μL of the modified electrolyte obtained in Example 7, and keep other conditions the same as in Application Example 1.

[0098] Application Example 8

[0099] Preparation of Zn||Zn symmetric cells: Replace 150 μL of the modified electrolyte obtained in Example 1 with 150 μL of the modified electrolyte obtained in Example 8, and keep other conditions the same as in Application Example 1.

[0100] Preparation of Zn||Cu half-cell: Replace 150 μL of the modified electrolyte obtained in Example 1 with 150 μL of the modified electrolyte obtained in Example 8, and keep other conditions the same as in Application Example 1.

[0101] Preparation of Zn||NVO full cells: Replace 150 μL of the modified electrolyte obtained in Example 1 with 150 μL of the modified electrolyte obtained in Example 8, and keep other conditions the same as in Application Example 1.

[0102] Application Example 9

[0103] Preparation of Zn||Zn symmetric cells: Replace 150 μL of the modified electrolyte obtained in Example 1 with 150 μL of the modified electrolyte obtained in Example 9, and keep other conditions the same as in Application Example 1.

[0104] Preparation of Zn||Cu half-cell: Replace 150 μL of the modified electrolyte obtained in Example 1 with 150 μL of the modified electrolyte obtained in Example 9, and keep other conditions the same as in Application Example 1.

[0105] Preparation of Zn||NVO full cells: Replace 150 μL of the modified electrolyte obtained in Example 1 with 150 μL of the modified electrolyte obtained in Example 9, and keep other conditions the same as in Application Example 1.

[0106] Comparative Application Example 1

[0107] Preparation of Zn||Zn symmetric cells: Replace 150 μL of the modified electrolyte obtained in Example 1 with 150 μL of the modified electrolyte obtained in Comparative Example 1, and keep other conditions the same as in Application Example 1.

[0108] Preparation of Zn||Cu half-cell: Replace 150 μL of the modified electrolyte obtained in Example 1 with 150 μL of the modified electrolyte obtained in Comparative Example 1, and keep other conditions the same as in Application Example 1.

[0109] Preparation of Zn||NVO full cells: Replace 150 μL of the modified electrolyte obtained in Example 1 with 150 μL of the modified electrolyte obtained in Comparative Example 1, and keep other conditions the same as in Application Example 1.

[0110] The electrochemical performance of the prepared aqueous zinc-ion battery was tested using a LAND CT2001A tester (Wuhan Landian Electronics Co., Ltd.).

[0111] The Zn||Zn symmetric cell was subjected to constant current charge-discharge testing at 30℃, with a current density of 0.25 mA / cm². -2 ~5mA cm -2 The surface capacity is 0.25mAh cm -2 ~1mAh cm -2 .

[0112] The Zn||Cu half-cell was subjected to constant current charge-discharge testing at 30℃, with a current density of 0.25 mA cm⁻¹. -2 ~5mA cm -2 The surface capacity is 0.25mAh cm -2 ~1mAh cm -2 The cutoff voltage is 0.5V.

[0113] The Zn||NVO full cell was tested for charge and discharge at 30°C with a current density of 0.1Ag. -1 ~5Ag -1 .

[0114] Figure 2 To illustrate Application Example 2 and compare it with Application Example 1, the Zn||Zn symmetric cell assembled at a current density of 5 mA cm⁻¹ -2 The surface capacity is 1mAh cm -2 Cyclic performance under the above test conditions. Compared with the symmetric battery assembled with 2 mol / L zinc sulfate electrolyte in Application Example 1, which had a cycle life of only 190 hours, the symmetric battery assembled with modified electrolyte of 10 mmol / L difluoromethylornithine in Application Example 2 could cycle stably for 1954 hours, increasing the cycle life of the zinc anode by 9 times. This shows that the presence of additives significantly improves the long-term cycle stability of the zinc anode.

[0115] Figure 3 XPS images of the zinc anode surface after cycling in Application Example 2 and Comparative Application Example 1, obtained from Zn||Zn symmetrical cells. (Image taken at a current density of 1 mA / cm²). -2 The surface capacity is 1mAh cm -2 After 50 cycles under the specified conditions, the Zn 2P signal on the zinc anode surface of the symmetric battery assembled with 2 mol / L zinc sulfate electrolyte only showed two characteristic peaks of Zn at 1044 eV and 1021 eV. However, after cycling, the broadening of the typical characteristic peak of the Zn 2P signal on the zinc anode surface of the symmetric battery assembled with a modified electrolyte of 10 mmol / L difluoromethylornithine was attributed to the formation of Zn-F bonds. The appearance of two new peaks at 1046 eV and 1023 eV indicated the formation of a ZnF2 layer on the zinc anode surface.

[0116] Figure 4 SEM images of the zinc anode surface after cycling of the Zn||Zn symmetric cells assembled in Application Example 2 and Comparative Application Example 1. (Image taken at a current density of 1 mA cm⁻¹) -2 The surface capacity is 1mAh cm -2 After 50 cycles under the test conditions, the zinc anode surface of the symmetrical battery assembled with 2 mol / L zinc sulfate electrolyte exhibited a significantly uneven surface, and a large number of zinc dendrites could be observed, indicating that Zn 2 Irregular deposition was observed in the zinc anode of the symmetrical battery assembled with a modified electrolyte containing 10 mmol / L difluoromethylornithine. However, after cycling, the zinc anode surface was smooth and uniform with no obvious dendrites, indicating that difluoromethylornithine effectively suppressed the formation of zinc dendrites.

[0117] Figure 5 The figure shows the rate performance of the Zn||NVO full cells assembled in Application Example 2 and Comparative Application Example 1. As shown, the Zn||NVO full cells from Application Example 2 and Comparative Application Example 1 were subjected to current densities of 0.1, 0.2, 0.5, 1, 2, and 52 A / g, respectively. -1 The battery discharge capacity was tested after 5 charge-discharge cycles with a charge-discharge cutoff voltage range of 0.3V-1.5V. Due to the dissolution of the NVO cathode material, the current of the full cell assembled using 2mol / L zinc sulfate electrolyte returned to 0.1A / g. -1 The specific capacity decayed rapidly, but the full cell assembled using a modified electrolyte with a difluoromethylornithine concentration of 10 mmol / L showed improved performance due to the formation of a CEI film on the surface of the positive electrode material, which inhibited the dissolution of the NVO positive electrode material, allowing the current to return to 0.1 A / g. -1 The specific capacity remains stable.

[0118] Figure 6The figure shows the cycling performance of the Zn||NVO full cells assembled in Application Example 2 and Comparative Application Example 1. As shown in the figure, at 2A / g... -1 At the specified current density, the specific capacity of the full cell assembled using 2 mol / L zinc sulfate electrolyte gradually decreased during 2500 charge-discharge cycles; while the specific capacity of the full cell assembled using a modified electrolyte with a difluoromethylornithine concentration of 10 mmol / L decreased slowly throughout the entire charge-discharge cycle, and the capacity retention rate was 71% after 2500 cycles. This indicates that the difluoromethylornithine additive can effectively improve the stability of the NVO cathode material, thereby improving the cycle stability of the full cell.

[0119] The zinc-ion batteries assembled in Application Examples 1-9 and Comparative Application Example 1 were subjected to electrochemical performance tests. The Zn||Zn symmetric battery was tested at a current density of 5 mA / cm². -2 The surface capacity is 1mAh cm -2 Cycling was performed under the specified conditions; the Zn||NVO full cell was charged and discharged at 30℃, with a charge / discharge cutoff voltage range of 0.3V-1.5V and a current density of 2A / g. -1 The test results are shown in Table 1.

[0120] Table 1

[0121]

[0122]

[0123] Therefore, it can be seen that the fluorinated amino acid additive in this invention can be adsorbed on the zinc anode surface, thereby regulating the Zn content. 2+ Deposition behavior during charge and discharge processes, inhibiting Zn 2+ Two-dimensional diffusion to suppress dendrite growth; fluorinated amino acid additives can improve Zn 2+ The coordination environment of Zn changes 2+ The solvation structure reduces Zn 2+ The reduced water content in the complex inhibits side reactions. Furthermore, the introduction of fluorinated amino acid additives can form a CEI layer on the surface of the cathode material, with an outer organic layer enriched and an inner layer enriched with F-containing inorganic matter. This can suppress the dissolution of transition metal ions and improve the stability of the cathode material. Therefore, using fluorinated amino acid additives as electrolyte additives for zinc-ion batteries can significantly improve the cycle life of zinc-ion batteries. The fluorinated amino acid additives described in this invention effectively solve the problems of microcrack formation in cathode material particles, transition metal ion dissolution, zinc dendrite formation, and zinc corrosion. They also have advantages such as simple preparation process, high safety, and environmental friendliness, and have broad application prospects in the field of aqueous zinc-ion batteries.

[0124] In summary, the invention includes, but is not limited to, the above embodiments. Any equivalent substitutions or partial improvements made under the spirit and principles of this invention shall be considered to be within the protection scope of this invention.

Claims

1. An electrolyte additive for aqueous zinc-ion batteries, characterized in that: The electrolyte additive is a water-soluble fluorinated amino acid, and the current density of the aqueous zinc-ion battery is 5~10 mA cm⁻¹. -2 The positive electrode material of the aqueous zinc-ion battery is a transition metal-based positive electrode material; The water-soluble fluoroamino acid is difluoromethylornithine, 3-fluoroalanine, or 3,5-difluorophenylalanine; the molar concentration of the additive is 1~20 mmol / L.

2. An electrolyte for aqueous zinc-ion batteries, characterized in that: The electrolyte comprises soluble zinc salt, H2O, and the additives described in claim 1.

3. The electrolyte for an aqueous zinc-ion battery as described in claim 2, characterized in that: The electrolyte contains one or more of the following soluble zinc salts: zinc sulfate, zinc sulfate hydrate, zinc chloride and its hydrate, and zinc trifluoromethanesulfonate and its hydrate.

4. The electrolyte for an aqueous zinc-ion battery as described in claim 3, characterized in that: The electrolyte contains a soluble zinc salt with a molar concentration of 1-3 mol / L.

5. The electrolyte for an aqueous zinc-ion battery as described in claim 2, characterized in that: In the electrolyte, the molar concentration of the additive is 8~12 mmol / L.

6. The electrolyte for an aqueous zinc-ion battery as described in claim 2, characterized in that: The electrolyte also includes manganese ion additives.

7. The electrolyte for an aqueous zinc-ion battery as described in claim 6, characterized in that: The manganese ion additive is one or more of manganese nitrate, manganese sulfate, and manganese chloride; the molar concentration of the manganese ion additive is 0.05 mol / L to 0.5 mol / L.

8. An aqueous zinc-ion battery, characterized in that: It includes the electrolyte, transition metal-based positive electrode material, negative electrode material, and separator as described in any one of claims 2 to 7.

9. The aqueous zinc-ion battery as described in claim 8, characterized in that: The negative electrode material includes zinc sheet, zinc foil, zinc powder, and zinc foam; The positive electrode material is lithium manganese oxide, manganese dioxide, vanadium pentoxide, or sodium vanadate. The diaphragm is made of glass fiber.

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