Potassium bis(2-hydroxypropionate)•(2-hydroxyacetate) zincate, electrolyte, battery and preparation thereof

Abstract

The application belongs to the technical field of aqueous zinc ion batteries, and particularly relates to potassium bis(2-hydroxypropanoate)(2-hydroxyacetate) zinc (II) acid, an electrolyte, a battery and preparation thereof. 2+ Mixed coordination, forming an organic metal chelate ZGL2 electrolyte, by regulating Zn 2+ Solvation structure, reducing the activity of coordinated water, inhibiting dendrite growth and hydrogen evolution side reaction. The average coulombic efficiency of the Cu / / Zn half battery assembled by the electrolyte reaches 97.3%, and the capacity retention rate of the full battery is 76% after 4700 cycles at 1 A / g, which significantly improves the cycle stability and reversibility of the aqueous zinc ion battery. The application effectively solves the problems of low solubility (<0.2 M) of single zinc lactate and difficulty in forming a homogeneous solution of single zinc hydroxyacetate, and has a wide application prospect.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical energy storage technology, specifically relating to a potassium di(2-hydroxypropionate)·(2-hydroxyacetic acid) zinc(II) phosphate and its preparation method, an aqueous zinc-ion battery electrolyte composed of potassium di(2-hydroxypropionate)·(2-hydroxyacetic acid) zinc(II) phosphate and its preparation method, and an aqueous zinc-ion battery composed of the aqueous zinc-ion battery electrolyte. Background Technology

[0002] Aqueous zinc-ion batteries (AZIBs) are advantageous due to their inherent safety, abundant resources, low cost, and the high volumetric capacity (5855 mAh cm⁻¹) of zinc metal. -3 Its advantages, such as low redox potential (-0.76V vs. SHE), demonstrate broad application prospects in the field of large-scale energy storage.

[0003] However, the industrialization of aqueous zinc-ion batteries still faces many challenges. The zinc anode is thermodynamically unstable in aqueous electrolytes, and during charge and discharge, it is prone to uncontrolled growth of zinc dendrites, hydrogen evolution reaction (HER), and side reactions such as corrosion and passivation, which seriously affect the coulombic efficiency and cycle life of the battery, thus restricting the practical application of AZIBs.

[0004] Electrolyte additive strategies have been widely studied due to their simplicity, low cost, and significant effects. In recent years, researchers have attempted to introduce various additives into aqueous electrolytes to regulate Zn content. 2+ The solvation structure inhibits dendrite growth and side reactions. For example, patent CN116053616A uses hydroxycarboxylate salts (such as sodium tartrate, sodium gluconate, etc.) as electrolyte additives, utilizing the reaction of hydroxycarboxylate ions with Zn 2+ The complexation effect reduces the number of coordinated water molecules, inhibits the hydrogen evolution reaction, and refines the deposited grains. However, this type of additive exists only as a simple salt in the electrolyte, and its interaction with Zn... 2+ The complexation effect is limited by the solubility of the salt and the coordination equilibrium, and it relies on only a single anionic ligand, making it difficult to achieve precise control of the coordination structure.

[0005] To further enhance the functionality of additives, some studies have attempted to introduce pre-synthesized metal chelates into electrolytes. CN119852565A discloses a technical solution using non-zinc metal complexes such as Cu-EDTA as electrolyte additives, utilizing the displacement reaction between metal ions in the complex and the zinc anode to form a metal or alloy interface layer. However, the central ion of this type of additive is not Zn. 2+ Its mechanism of action depends on the displacement reaction rather than direct participation in Zn.2+ The solvation regulation is affected, and the displacement reaction may introduce impurity metal ions, affecting the purity and long-term stability of the electrolyte system.

[0006] Furthermore, CN120221824B discloses a technical solution using polysaccharide zinc chelates (such as zinc hyaluronic acid, zinc tannate, etc.) as electrolyte additives, utilizing the bifunctional sites of hydrophilic and zinc-loving coordinating groups in the polysaccharide structure to inhibit hydrogen evolution and dendrite growth. However, polysaccharide ligands have large molecular weights, complex structures, and uneven molecular weight distributions, making it difficult to form chelates with clear stoichiometry and defined structures. The number of coordinating sites and the mechanism of action are also difficult to control precisely. Simultaneously, the concentration of such additives in the electrolyte is only at the trace level (0.20–1.35 mmol / L), mainly exerting its effect through interfacial adsorption, which is insufficient for Zn. 2+ The ability to directly control the solvation structure is limited.

[0007] In summary, current technologies lack a method that can participate in and regulate Zn at sufficient concentrations. 2+ An additive system with a solvable structure and a well-defined chemical composition and coordination structure. In particular, how to utilize various anionic ligands with Zn while ensuring the homogeneous stability of the electrolyte. 2+ Forming stable mixed coordination chelates while simultaneously ensuring precise controllability of the coordination structure and meeting electrolyte concentration requirements has become a pressing technical challenge in this field. Summary of the Invention

[0008] One objective of this invention is to provide a potassium di(2-hydroxypropionate)·(2-hydroxyacetate)zinc(II) compound, which employs hydroxyacetate and lactate organic anionic ligands with Zn 2+ A mixed coordination strategy was employed to modulate the solvation structure of the electrolyte. Using potassium glycolate as a hydrophilic solubilizer effectively increased the electrolyte concentration, raising the zinc lactate concentration from 0.2 M to 0.8 M.

[0009] To achieve the above objectives, the present invention employs the following technical solution: a potassium di(2-hydroxypropionate)·(2-hydroxyacetic acid) zinc(II) compound, with the chemical formula KZnC8H. 13 O9, the molecular structure is as follows: .

[0010] A second objective of this invention is to provide a method for preparing the above-mentioned potassium di(2-hydroxypropionate)·(2-hydroxyacetic acid)zinc(II)ate, wherein the potassium di(2-hydroxypropionate)·(2-hydroxyacetic acid)zinc(II)ate is prepared by reacting lactate ions and glycolate ions with Zn. 2+ Coordination formation.

[0011] A further technical solution for the preparation method of the above-mentioned potassium di(2-hydroxypropionate)·(2-hydroxyacetic acid) zinc(II) acid: Preferably, glycolic acid is dissolved in deionized water at a concentration of 0.01–12 M, and then potassium hydroxide is added to react completely to form a potassium glycolate solution. Zinc lactate is then added to the resulting potassium glycolate solution, wherein the molar ratio of glycolic acid to potassium hydroxide and zinc lactate is 2:2:(0.4–0.8). The reaction is carried out at 40–80 °C for 2–4 h to obtain potassium di(2-hydroxypropionate)·(2-hydroxyacetic acid)zinc(II)ate, as shown in the following reaction formula: HOCH2COOK+(CH3CHOHCOO)2Zn→KZnC8H 13 O9).

[0012] A third objective of this invention is to provide an aqueous zinc-ion battery electrolyte comprising potassium di(2-hydroxypropionate)·(2-hydroxyacetic acid)zinc(II)ate as described in any one of the above-mentioned claims.

[0013] As a further technical solution for the aforementioned aqueous zinc-ion battery electrolyte: Preferably, the aqueous zinc-ion battery electrolyte has a pH value of 6-7 and its components include a solvent, other zinc salts except for potassium di(2-hydroxypropionate)·(2-hydroxyacetate)zinc(II)ate and potassium di(2-hydroxypropionate)·(2-hydroxyacetate)zinc(II)ate.

[0014] Preferably, the concentration of potassium di(2-hydroxypropionate)·(2-hydroxyacetic acid)zinc(II)ate in the aqueous zinc-ion battery electrolyte is 0.4 M to 0.8 M, and the concentration of the zinc salt is 0.01 M to 0.8 M.

[0015] Preferably, the solvent is deionized water and the zinc salt is zinc lactate.

[0016] The fourth objective of this invention is to provide an aqueous zinc-ion battery comprising any one of the aqueous zinc-ion battery electrolytes described above, including a positive electrode, a negative electrode, a separator, and an electrolyte.

[0017] As a further technical solution for the aforementioned aqueous zinc-ion battery: Preferably, the positive electrode is poly(1,5-diaminonaphthalene) (1,5-PDAN), the negative electrode is zinc foil, and the diaphragm is a glass fiber membrane.

[0018] The advantages of this invention compared to the prior art are as follows: (1) The potassium di(2-hydroxypropionate)·(2-hydroxyacetic acid) zinc(II) phosphate (ZGL2) provided by the present invention is formed by the combination of lactate ions and glycolate ions with Zn 2+ Coordination formation is an organometallic chelate with a defined chemical composition. Compared with single zinc lactate (solubility <0.2 M) and single zinc glycolate (0.1 M is a turbid solution), ZGL2 has a significantly improved solubility in water, with a concentration as high as 0.8 M and a homogeneous and transparent solution, breaking through the technical bottleneck of low solubility of single ligand zinc salts.

[0019] The preparation method of ZGL2 involves reacting glycolic acid with potassium hydroxide to generate potassium glycolate, which is then reacted with zinc lactate at 60°C. This process is simple, mild, and suitable for large-scale preparation. Furthermore, a homogeneous and transparent solution is formed when the molar ratio of potassium glycolate to zinc lactate is 2:(0.4–0.8), while a homogeneous solution cannot be formed when the molar ratio is 2:1, indicating that the formation of ZGL2 requires a specific stoichiometric ratio.

[0020] (2) The electrolyte of the present invention uses ZGL2 as a single solute and can be used directly as an electrolyte for aqueous zinc-ion batteries without the need to add additional zinc salts. The electrolyte is nearly neutral, which avoids the corrosion of electrode materials by strong acid or strong alkaline electrolytes.

[0021] ZGL2 electrolyte effectively regulates Zn 2+ The solvation structure reduces the activity of coordinated water, inhibiting the hydrogen evolution reaction and the growth of zinc anode dendrites. Cu / / Zn half-cell test results show that the average coulombic efficiency of the ZGL2 electrolyte reaches 97.3%, while that of the 0.8 M zinc sulfate electrolyte is only 88.5%, demonstrating excellent zinc deposition / dissolution reversibility.

[0022] (3) The test results of Zn / / Zn symmetric cells show that the symmetric cells using ZGL2 electrolyte can withstand 0.2 to 3 mAcm. -2 After the variable current density test, it dropped back to 0.2 mA cm⁻¹. -2 The electrolyte can still sustain zinc deposition / dissolution for up to 1300 h, indicating that it has good rate adaptability and long-term cycling stability.

[0023] Full cell test results show that the 1,5-PDAN / / Zn full cell using ZGL2 electrolyte achieves a performance of 1 A g⁻¹. -1 At a current density of 92 mAh g, it still maintains 92 mAh g after 40 cycles. -1The discharge capacity of the ZGL2 electrolyte was significantly improved, with a capacity retention of 76% after 4700 cycles. In contrast, the full cell using 0.8 M zinc sulfate electrolyte failed to operate normally after 900 cycles due to dendrite short circuits. Furthermore, the full cell cycle performance of the ZGL2 electrolyte (Example 1) was significantly better than that of the single zinc lactate electrolyte (Comparative Example 3, capacity retention of 64% after 1200 cycles) and the low-concentration ZGL2 electrolyte (Example 2, capacity retention of 71% after 3000 cycles), indicating that the specific ratio and concentration of ZGL2 electrolyte of this invention has a significant effect on improving battery cycle life. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the reaction for preparing potassium di(2-hydroxypropionate)·(2-hydroxyacetic acid) zinc(II) acid (abbreviated as ZGL2) according to the present invention.

[0025] Figure 2 The images show a comparison of the appearance of the electrolytes in the embodiments and comparative examples of the present invention; wherein, a is a photograph of the appearance of the 0.8M ZGL2 electrolyte prepared in Example 1, b is a photograph of the appearance of the turbid ZGL2 electrolyte prepared in Comparative Example 1, and c is a photograph of the appearance of the 0.1M zinc glycolate solution prepared in Comparative Example 4.

[0026] Figure 3 The graph shows the coulombic efficiency versus cycle number of Cu / / Zn half-cells assembled using the electrolytes prepared in Example 1 and Comparative Example 2 of this invention.

[0027] Figure 4 The intermediate product HOCH2COOK, the raw material (CH3CHOHCOO)2Zn, and the final product ZGL2 of Example 1 are... 1 HNMR spectrum.

[0028] Figure 5 The HRMS of the final product ZGL2 in Example 1 is shown, where a and b correspond to the cation mode and anion mode, respectively.

[0029] Figure 6 The images show the FTIR and Raman spectra of the intermediate product HOCH2COOK, the raw material (CH3CHOHCOO)2Zn, and the final product ZGL2 in Example 1; where a is a comparison of the FTIR spectra of the three substances and b is a comparison of the corresponding Raman spectra. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0031] Example 1 This embodiment provides a method for preparing potassium di(2-hydroxypropionate)·(2-hydroxyacetic acid)zinc(II)ate and 0.8 M ZGL2 electrolyte, the specific steps of which are as follows: 15.210 g of glycolic acid (HOCH2COOH) was dissolved in 80 mL of deionized water to a concentration of 2.50 M. The solution was magnetically stirred until completely dissolved, yielding a colorless and transparent solution. Then, 11.222 g of potassium hydroxide (KOH) was added, reacting completely to form a potassium glycolate (HOCH2COOK) solution. To the resulting potassium glycolate solution, 19.484 g of zinc lactate ((CH3CHOHCOO)2Zn) was added, with a molar ratio of glycolic acid to potassium hydroxide and zinc lactate of 2:2:0.8. The reaction was carried out at 60 °C for 2 hours until complete, yielding a colorless and transparent homogeneous solution, thus preparing potassium di(2-hydroxypropionate)·(2-hydroxyacetic acid)zinc(II)ate (abbreviated as ZGL2). The reaction diagram is shown below. Figure 1 As shown.

[0032] Transfer the homogeneous solution to a 100 mL volumetric flask, add deionized water to the mark, and the solution is diluted to prepare a 0.8 M ZGL2 electrolyte with a pH of approximately 6. Figure 2 a.

[0033] Example 2 This embodiment provides a method for preparing potassium di(2-hydroxypropionate)·(2-hydroxyacetic acid)zinc(II)ate and a 0.4 M ZGL2 electrolyte. The specific steps are the same as in Example 1, except that 9.742 g of zinc lactate ((CH3CHOHCOO)2Zn) is added, and the molar ratio of glycolic acid to potassium hydroxide and zinc lactate is 2:2:0.4. Potassium di(2-hydroxypropionate)·(2-hydroxyacetic acid)zinc(II)ate and a 0.4 M ZGL2 electrolyte with a pH of approximately 7 are obtained.

[0034] Comparative Example 1 This comparative example provides a method for preparing potassium di(2-hydroxypropionate)·(2-hydroxyacetic acid)zinc(II)ate. The specific steps are the same as in Example 1, except that 24.355 g of zinc lactate ((CH3CHOHCOO)2Zn) is added, and the molar ratio of the glycolic acid to potassium hydroxide and zinc lactate is 2:2:1. After the reaction, the solution is turbid and cannot form a homogeneous and transparent solution. Figure 2 b.

[0035] Comparative Example 2 At room temperature, accurately weigh 23.005 g of zinc sulfate heptahydrate (ZnSO4·7H2O) and slowly add it to a clean beaker containing 80 mL of deionized water. Stir continuously until the solid is completely dissolved, forming a transparent solution. Transfer the transparent solution to a 100 mL volumetric flask and add deionized water to accurately fill to the mark of the volumetric flask to prepare a 0.8 M ZnSO4 electrolyte.

[0036] Comparative Example 3 At room temperature, accurately weigh 4.870 g of zinc lactate (Zn(C3H5O3)2) powder and add it to a beaker containing 80 mL of deionized water. Heat and stir magnetically at 60 °C for 30 min to obtain a colorless and transparent solution. Transfer the cooled colorless and transparent solution to a 100 mL volumetric flask and accurately add deionized water to the mark to prepare a 0.2 M zinc lactate electrolyte.

[0037] Comparative Example 4 Accurately weigh 0.761 g of solid glycolic acid (HOCH₂COOH) at room temperature and add it to a beaker containing 80 mL of deionized water. Stir magnetically for 10 min at room temperature. Add 0.814 g of zinc oxide (ZnO) powder and continue stirring. No colorless, transparent homogeneous solution can be obtained; this is a turbid liquid. Transfer this turbid liquid to a 100 mL volumetric flask and add deionized water to accurately fill to the mark. This prepares a 0.1 M zinc glycolate electrolyte. Figure 2 c.

[0038] Performance testing: A uniform slurry is prepared by mixing positive electrode material, conductive carbon black, and binder in a certain proportion, which is then coated onto the positive electrode current collector. After drying, rolling, and cutting, the positive electrode sheet is obtained.

[0039] (1) Cu / / Zn half-cell test A Cu / Zn half-cell is assembled from copper foil (positive electrode), zinc sheet (negative electrode), a separator, and an electrolyte. A full cell is assembled from a positive electrode, zinc sheet (negative electrode), a separator, and an electrolyte.

[0040] The electrolytes from Example 1 and Comparative Example 2 were assembled into Cu / / Zn half-cells, and zinc deposition / dissolution reversibility tests were performed to obtain coulombic efficiency data. Then, the coulombic efficiency-cycle count curves of the two were compared to obtain... Figure 3 A comparison chart. (By...) Figure 3The comparison shows that the average coulombic efficiency using the electrolyte of Comparative Example 2 (0.8 M ZnSO4) is 88.5%, while the average coulombic efficiency using the electrolyte of Example 1 (0.8 M ZGL2) exceeds 97.3%. This indicates that compared with Comparative Example 2, the ZGL2 electrolyte of Example 1 has better zinc deposition / dissolution reversibility, with an average coulombic efficiency close to 100%.

[0041] (2) Full battery test The electrolytes from Examples 1, 2, 2, and 3 were assembled into full cells, with the positive electrode material being a 1,5-PDAN / / Zn system. The electrolytes were then used in 1 A g... -1 Long-term cycling stability tests were conducted at the specified current density. The test results are shown in Table 1.

[0042] Table 1. Cyclic performance tests of full cells assembled with electrolytes from Examples 1-2 and Comparative Examples 2-3

[0043] Note: " / " indicates that the electrolyte cannot form a uniform and transparent solution, and the battery cannot be assembled.

[0044] The test results in Table 1 show that the full cell using the electrolyte of Example 1 (0.8 M ZGL2, with a molar ratio of glycolic acid to potassium hydroxide and zinc lactate of 2:2:0.8) can achieve a high efficiency of 1 A g. -1 After 4700 cycles at a current density, the capacity retention was 76%. A full cell using the electrolyte from Example 2 (0.4 M ZGL2, with a molar ratio of glycolic acid to potassium hydroxide and zinc lactate of 2:2:0.4) was tested at 1 A g. -1 After 3000 cycles at the current density, the capacity retention was 71%. The full cell using Comparative Example 2 (0.8 M ZnSO4) electrolyte failed to operate normally after 900 cycles due to dendrite short circuits. The full cell using Comparative Example 3 (0.2 M zinc lactate) electrolyte retained 64% of its capacity after 1200 cycles.

[0045] The maximum solubility of zinc lactate is 0.8 M. In Comparative Example 1, when the molar ratio of potassium glycolate to zinc lactate is 2:1 (at which point the concentration of zinc lactate is greater than 0.8 M), a homogeneous solution cannot be formed, indicating that the formation of ZGL2 requires a specific stoichiometric ratio. In Comparative Example 3, a single lactate ion reacts with Zn... 2+ During coordination, the solubility of zinc lactate is at most 0.2 M. In Comparative Example 4, the solubility of a single glycolate ion with Zn... 2+ During coordination, zinc glycolate has extremely low solubility, becoming a turbid liquid at 0.1 M, unable to form a homogeneous and transparent solution, thus failing to meet the requirements of the electrolyte and making it impossible to conduct battery performance tests.

[0046] In Example 1, potassium glycolate and zinc lactate were reacted at a molar ratio of 2:0.8, which increased the concentration of zinc lactate to 0.8 M and kept the pH of the electrolyte system near neutral, maximizing the cycle performance of the full cell. In Example 2, when a molar ratio of 2:0.4 was used, the ZGL2 concentration was 0.4 M, and its full cell cycle performance was lower than that of Example 1.

[0047] Figure 4 The 1H NMR spectra of the intermediate product HOCH2COOK, the starting material (CH3CHOHCOO)2Zn, and the final product ZGL2 from Example 1 are shown, specifically illustrating the three substances. 1 The H NMR proton peak signals were compared. The figure shows the chemical shift of a proton in HOCH2COOK from... δ 3.934 moves to lower fields (in ZGL2) δ 3.946). This phenomenon can be attributed to Zn. 2+ The significant electron attraction effect following ion coordination leads to a deshielding effect. Test results also indicate that the chemical shifts of the two protons in ZGL2 are... δ 4.160, 4.142, 4.125, 4.180 and δ The values ​​at 1.337 and 1.320 show a ratio greater than that of (CH3CHOHCOO)2Zn ( δ 4.212, 4.195, δ 4.178 δ 4.160 and δ Higher field displacements (1.365, 1.348). This phenomenon can be attributed to HOCH2COO - and CH3CHOHCOO - Mixed coordination, in which HOCH2COO - The insertion weakens Zn 2+ The electron-withdrawing effect enhances the shielding effect.

[0048] To further determine the specific solvation structure of the ZGL2 electrolyte, HRMS testing was performed on the ZGL2 prepared in Example 1. Figure 5 In Figures a and b, the HRMS of ZGL2 in cationic and anionic modes, respectively. Figure a shows that the cationic peaks observed at m / z 394.9019 and 396.9077 correspond to C8H. 13 K2O9Zn + The molecular cation peaks (calculated values: 394.9120 and 396.9089) were observed. Additionally, anion peaks were detected at m / z 316.9851 and 318.9823 for C8H4. 13 O9Zn- The specific anionic fragments (calculated values: 316.9857 and 318.9825) are shown in Figure 5b. Analysis of the test results indicates that in the ZGL2 electrolyte, the two CH3CH2OHCOO... - And a HOCH2COO - With the center Zn 2+ The cation coordinates, and its chemical formula is KZnC8H. 13 O9.

[0049] Figure 6 Image a shows the FIIR spectra of the intermediate product HOCH2COOK, the starting material (CH3CHOHCOO)2Zn, and the final product ZGL2 in Example 1. Image b shows the Raman spectra of the three substances. At 1610 cm⁻¹ in image a... -1 and 1410 cm -1 Observed at each location corresponding to -COO - Asymmetric and symmetric stretching vibration peaks of the functional group; in (CH3CHOHCOO)2Zn, 1130 cm⁻¹ -1 The peak at 900 cm⁻¹ is attributed to the -CO- stretching vibration. Notably, this characteristic peak is also observed in the electrolyte of ZGL2, indicating the successful preparation of the ZGL2 complex. Similarly, in Figure b, the Raman spectrum of ZGL2 shows HOCH₂COOK and (CH₃CHOHCOO)₂Zn peaks at 900 cm⁻¹. -1 The nearby characteristic peaks shifted to varying degrees, which further proves the successful preparation of ZGL2 electrolyte.

[0050] The above results indicate that neither zinc lactate nor zinc glycolate alone can meet the requirements for high-concentration homogeneous electrolytes. The ZGL2 of this invention utilizes both lactate and glycolate anions with Zn... 2+ The mixed coordination overcomes the limitation of low solubility of single ligands, and can still maintain homogeneous stability at a concentration of 0.8 M, and significantly improves the cycle stability and reversibility of aqueous zinc-ion batteries.

[0051] Those skilled in the art should understand that the above descriptions are merely several specific embodiments of the present invention, and not all embodiments. It should be noted that many modifications and improvements can be made by those skilled in the art, and all modifications or improvements not exceeding the scope of the claims should be considered within the protection scope of the present invention.

Claims

1. A potassium di(2-hydroxypropionate)·(2-hydroxyacetic acid) zinc(II) compound, with the chemical formula KZnC8H 13 O9, the molecular structure is as follows: 。 2. A method for preparing potassium di(2-hydroxypropionate)·(2-hydroxyacetic acid)zinc(II)ate as described in claim 1, characterized in that, The potassium di(2-hydroxypropionate)·(2-hydroxyacetic acid) zinc(II) phosphate is formed by the combination of lactate ions and glycolate ions with Zn. 2+ Coordination formation.

3. The method for preparing potassium di(2-hydroxypropionate)·(2-hydroxyacetic acid)zinc(II)ate according to claim 2, characterized in that, Hydroxyacetic acid was dissolved in deionized water at a concentration of 0.01–12 M, and then potassium hydroxide was added. The reaction proceeded completely to form a potassium glycolate solution. Zinc lactate was added to the obtained potassium glycolate solution, with the molar ratio of glycolic acid to potassium hydroxide and zinc lactate being 2:2:(0.4–0.8). The reaction was carried out at 40–80 °C for 2–4 h to obtain potassium di(2-hydroxypropionate)·(2-hydroxyacetic acid)zinc(II)ate.

4. An aqueous zinc-ion battery electrolyte comprising potassium di(2-hydroxypropionate)·(2-hydroxyacetic acid)zinc(II)ate as described in claim 1.

5. The aqueous zinc-ion battery electrolyte according to claim 4, characterized in that, The aqueous zinc-ion battery electrolyte has a pH of 6-7 and its components include a solvent, other zinc salts except for potassium di(2-hydroxypropionate)·(2-hydroxyacetic acid)zinc(II)ate, and potassium di(2-hydroxypropionate)·(2-hydroxyacetic acid)zinc(II)ate.

6. The aqueous zinc-ion battery electrolyte according to claim 5, characterized in that, The concentration of potassium di(2-hydroxypropionate)·(2-hydroxyacetic acid)zinc(II)ate in the aqueous zinc-ion battery electrolyte is 0.4 M to 0.8 M, and the concentration of the zinc salt is 0.01 M to 0.8 M.

7. The aqueous zinc-ion battery electrolyte according to claim 5 or 6, characterized in that, The solvent is deionized water, and the zinc salt is zinc lactate.

8. A method for preparing an aqueous zinc-ion battery electrolyte as described in any one of claims 4 to 7, characterized in that, The process includes the following steps: adding potassium di(2-hydroxypropionate)·(2-hydroxyacetic acid) zinc(II) acid to deionized water and stirring until homogeneous, then adding zinc salt and stirring continuously at room temperature until completely dissolved to obtain an aqueous zinc-ion battery electrolyte.

9. An aqueous zinc-ion battery comprising the aqueous zinc-ion battery electrolyte according to any one of claims 4 to 8, comprising a positive electrode, a negative electrode, a separator, and an electrolyte.

10. The aqueous zinc-ion battery according to claim 9, characterized in that, The positive electrode is poly(1,5-diaminonaphthalene) (1,5-PDAN), the negative electrode is zinc foil, and the diaphragm is a glass fiber membrane.

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