Aqueous zinc ion battery electrolyte additive, electrolyte and preparation method thereof

Abstract

According to the aqueous zinc ion battery electrolyte additive and the aqueous zinc ion battery disclosed by the invention, organic molecules (glucosamide / D-Glu) with polyfunctional groups and beneficial structural characteristics are added into an electrolyte as the additive, so that thermodynamic and dynamic coordinated regulation and control on a zinc deposition process can be realized; and a new normal form is provided for construction of the high-stability zinc negative electrode.

Description

Technical Field

[0001] The present invention belongs to the technical field of secondary batteries and relates to the technical field of electrolytes, and in particular to the application of a multifunctional organic molecule electrolyte additive with steric hindrance effect in aqueous zinc ion batteries. Background Art

[0002] Aqueous zinc-ion batteries (AZIBs) have a high theoretical capacity (820 mAh g -1 ), low toxicity, and low cost, it is considered a potential candidate for the next generation of high-safety energy storage technology, with broad application prospects in large-scale grid energy storage and portable electronic devices. However, zinc metal anodes face two core challenges that need to be overcome during cycling: dendrite growth and side reactions.

[0003] Various strategies have been developed to address these problems, including interface modification, separator design, structural design, and electrolyte engineering. The first three methods usually involve complex and expensive manufacturing processes. Electrolyte engineering is a direct method to regulate water activity by optimizing the electrolyte formulation. Electrolyte formulations include electrolyte additives, salt-in-water electrolytes, and deep eutectic electrolytes. Among them, electrolyte additives are considered to be one of the most promising solutions because of their high efficiency and ease of operation. Recent research has focused on small molecule organic compounds containing polar groups such as hydroxyl, carbonyl, and carboxyl groups, because their trace addition can effectively enhance the electrochemical stability and cycling reversibility of zinc anodes.

[0004] However, traditional additives often rely on a single mechanism (such as hydrogen bond networks or solvent polarity), making it difficult to simultaneously address multi-scale issues such as kinetic mismatch, interfacial side reactions, and textural disorder. For example, although some additives can reduce water activity, they may lead to delayed nucleation kinetics due to insufficient zinc affinity; and although the steric hindrance effect can homogenize the ion flux, it cannot effectively inhibit corrosion reactions involving active water. Therefore, the development of additives that combine multi-functional group synergy and molecular structure tunability has become a core strategy for achieving "dual-effect regulation" of zinc deposition kinetics. Summary of the Invention

[0005] To achieve the above objectives, the present invention proposes a D-Glu with rich functional groups (hydroxyl, carbonyl, and amide groups) and beneficial structural features as a high-efficiency electrolyte additive. This D-Glu synergistically regulates the thermodynamics (inducing (100) crystal plane growth) and kinetics (increasing the zinc ion migration number and reducing the zinc ion desolvation energy) of the zinc deposition process, significantly improving the kinetic performance of AZIBs and extending their calendar life. This, in turn, extends the cycle life of aqueous zinc-ion batteries.

[0006] Specifically, the present invention provides an aqueous zinc ion battery electrolyte additive, wherein the aqueous zinc ion battery electrolyte additive contains one, two or three of the three functional groups of hydroxyl, carbonyl and amide groups and has a steric effect, and its molecular formula is shown as follows:

[0007]

[0008] The present invention also provides an aqueous zinc ion battery electrolyte, wherein the electrolyte includes the aqueous zinc ion battery electrolyte additive as described above.

[0009] Furthermore, the concentration of the aqueous zinc ion battery electrolyte additive is 0.1 to 50 mg mL -1 .

[0010] Furthermore, the concentration of the aqueous zinc ion battery electrolyte additive is 10 mg mL -1 .

[0011] Furthermore, the electrolyte in the aqueous zinc ion battery electrolyte is zinc sulfate, zinc chloride or zinc acetate.

[0012] Furthermore, the concentration of the electrolyte is 1-3M.

[0013] The present invention also provides an aqueous zinc ion battery, which consists of a positive electrode, a negative electrode, a separator and the aqueous zinc ion battery electrolyte as described above.

[0014] Furthermore, the positive electrode material is ammonium vanadate NH4V4O 10 , the negative electrode material is zinc foil and the separator is glass fiber membrane.

[0015] The present invention also provides a method for preparing the aqueous zinc ion battery electrolyte as described above, comprising the following steps:

[0016] a) dissolving a zinc salt in deionized water and stirring to form a basic electrolyte, wherein the zinc salt is zinc sulfate, zinc chloride or zinc acetate, and the concentration of the electrolyte after dissolution is 1-3M;

[0017] b) adding the electrolyte additive according to claim 1 to the basic electrolyte, stirring for 20-60 minutes to mix uniformly, wherein the concentration of the electrolyte additive is 0.1-50 g L-1.

[0018] The present invention also provides a method for preparing the aqueous zinc ion battery as described above, comprising the following steps:

[0019] i) Preparation of positive electrode: ammonium vanadate NH4V4O 10The material, conductive agent and binder are mixed in a mass ratio of 7-8:1-2:1, coated on a carbon cloth current collector, and dried to obtain a positive electrode;

[0020] Wherein, the ammonium vanadate NH4V4O 10 The preparation of positive electrode materials includes:

[0021] Dissolve NH4VO3 and H2C2O4·2H2O in deionized water at 80-100°C and stir to form a mixed solution;

[0022] The mixed solution is hydrothermally reacted at 120-160°C for 24-48 hours, and then washed and dried to obtain NH4V4O 10 Material;

[0023] ii) using zinc foil as the negative electrode and a glass fiber membrane as the separator, injecting the electrolyte according to any one of claims 2 to 6, and assembling a battery;

[0024] Wherein, the conductive agent is acetylene black, and the binder is polyvinylidene fluoride (PVDF).

[0025] Compared with the prior art, the present invention has the following obvious outstanding substantial features and significant advantages:

[0026] 1. Molecules with one, two or three of the three functional groups of hydroxyl, carbonyl and amide and having steric effects are used as additives to the zinc sulfate electrolyte to achieve synergistic regulation of the thermodynamics (inducing (100) crystal plane growth) and kinetics (increasing the zinc ion migration number and reducing the zinc ion desolvation energy) of the zinc deposition process, thereby achieving the purpose of inhibiting dendrite growth, hydrogen evolution reaction and by-product formation.

[0027] 2. The zinc anode using this aqueous zinc ion battery electrolyte exhibits smooth, dense and uniform (100) crystal plane growth.

[0028] 3. Zn||Zn symmetric battery, Zn||Cu asymmetric battery and Zn||NH4V4O assembled using this aqueous zinc ion battery electrolyte 10 The full cell exhibits significantly enhanced long-cycle performance and excellent coulombic efficiency.

[0029] 4. The organic multifunctional molecular additive of the present invention is inexpensive and environmentally friendly.

[0030] The concept, specific structure and technical effects of the present invention will be further described below in conjunction with the accompanying drawings to fully understand the purpose, characteristics and effects of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1This is a constant current charge and discharge test diagram of a Zn||Zn symmetrical battery under high current density conditions in the ZS+D-Glu10 electrolyte and the ZS electrolyte prepared by the method of the present invention.

[0032] Figure 2 This is a constant current charge and discharge test diagram of the symmetrical battery of Example 1 at current densities of 10, 20, and 30 mA cm2 and a capacity of 1 mAh cm2.

[0033] Figure 3 This is a diagram of the shelf recovery performance of a Zn||Zn symmetric battery in the ZS+D-Glu10 electrolyte and the ZS electrolyte prepared by the method of the present invention.

[0034] Figure 4 This is a comparison chart of the rate performance of Zn||Zn symmetric batteries in ZS+D-Glu10 electrolyte and ZS electrolyte prepared by the method of the present invention.

[0035] Figure 5 This is a comparison chart of the coulombic efficiency tests of Zn||Cu asymmetric batteries in ZS+D-Glu10 electrolyte and ZS electrolyte prepared by the method of the present invention.

[0036] Figure 6 This is a comparison chart of Tafel tests of zinc metal in ZS+D-Glu10 electrolyte and ZS electrolyte prepared by the method of the present invention.

[0037] Figure 7 This is a comparison chart of linear sweep voltammetry tests of zinc metal in the ZS+D-Glu10 electrolyte and the ZS electrolyte prepared by the method of the present invention.

[0038] Figure 8 This is a comparison chart of zinc ion migration number tests in Zn||Zn symmetrical batteries in ZS+D-Glu10 electrolyte and ZS electrolyte prepared by the method of the present invention.

[0039] Figure 9 Scanning electron microscope images of the electroplating process of zinc metal in the ZS+D-Glu10 electrolyte and the ZS electrolyte prepared by the method of the present invention.

[0040] Figure 10 These are in-situ optical microscopic images of the electroplating process of zinc metal in the ZS+D-Glu10 electrolyte and the ZS electrolyte prepared by the method of the present invention.

[0041] Figure 11 This is a comparison chart of the self-discharge performance of Zn||NVO full cells in ZS+D-Glu10 electrolyte and ZS electrolyte prepared by the method of the present invention.

[0042] Figure 12This is a comparison chart of the long-cycle performance of Zn||NVO full batteries in ZS+D-Glu10 electrolyte and ZS electrolyte prepared by the method described in the present invention. DETAILED DESCRIPTION

[0043] The following describes several preferred embodiments of the present invention with reference to the accompanying drawings to make its technical content clearer and easier to understand. The present invention can be embodied in many different forms of embodiments, and the scope of protection of the present invention is not limited to the embodiments mentioned herein.

[0044] Example 1:

[0045] A method for preparing an aqueous zinc ion battery electrolyte comprises weighing 28.75 g of ZnSO4·7H2O into a beaker, adding 50 mL of deionized water, and stirring at room temperature for 20 minutes to prepare a 2M ZnSO4 electrolyte (abbreviated as ZS).

[0046] 500 mg of a molecule having three functional groups of hydroxyl, carboxyl, carbonyl and amide and having a steric effect was weighed and dissolved in the ZS electrolyte prepared above, and magnetic stirring was performed at room temperature for 30 minutes to obtain an electrolyte (D-Glu10) containing a molecule having three functional groups of hydroxyl, carboxyl, carbonyl and amide and having a steric effect.

[0047] The mixed solution prepared above was used as the electrolyte of an aqueous zinc ion battery, a commercial zinc foil with a thickness of 100 μm and a diameter of 13 mm was used as the electrode, and a glass fiber separator with a diameter of 19 mm was used as the separator to assemble a Zn||Zn symmetrical battery.

[0048] Tested using the Blue Power Battery Test System: at 5 mA cm -2 @1mAh cm -2 The symmetrical battery constant current charge and discharge test was carried out under the condition of 0.5mA cm -2 ~30mA cm -2 The battery rate performance test was carried out at a current density of 5 mA cm -2 @1mAh cm -2 The battery shelf recovery performance test was carried out at a current density of . The cycle performance of this embodiment under this test condition was better than that of the comparative example 1.

[0049] Example 2:

[0050] This embodiment was conducted in parallel with the first embodiment, and the steps were basically the same, except that:

[0051] The mixed solution prepared above was weighed and used as the electrolyte of an aqueous zinc ion battery. A commercial zinc foil with a thickness of 100 microns and a diameter of 13 mm was used as the positive electrode, a copper foil with a diameter of 16 mm was used as the negative electrode, and a glass fiber separator with a diameter of 19 mm was used as the separator to assemble a Zn||Cu asymmetric battery.

[0052] Tested using the Xinwei test system: at 1mA cm -2 The current density and 1 mAh cm -2 The Zn||Cu asymmetric battery constant current stripping / deposition test was conducted under the condition of a capacity of 1000 Ω / min. The cycle performance of this embodiment under this test condition was better than that of the comparative example 2.

[0053] Example 3:

[0054] This embodiment was conducted in parallel with the first embodiment, and the steps were basically the same, except that:

[0055] The mixed solution prepared above was weighed and used as the electrolyte of an aqueous zinc-ion battery. A commercial zinc foil with a thickness of 100 μm and a diameter of 13 mm was used as the negative electrode sheet, NVO with a diameter of 13 mm was used as the positive electrode sheet, and a glass fiber separator with a diameter of 19 mm was used as the separator to assemble a Zn||NVO full cell.

[0056] Tested using the Xinwei test system: at 5Ag -1 The full-cell constant current charge and discharge test was conducted at a current density of 1.5 V. The full-cell self-discharge test was conducted at a voltage of 0.3 to 1.4 V. The cycle performance of this embodiment under this test condition was better than that of the comparative example 3.

[0057] When the positive electrode material is NVO, the positive electrode sheet is prepared as follows: 2.340g NH4VO3 is dissolved in 70mL deionized water at 80°C to form a yellow solution, and then 3.782g H2C2O4·2H2O solid powder is added under strong stirring, and the mixture is stirred at 80°C for 30 minutes. Subsequently, the mixed solution is transferred to a 100mL Teflon-lined autoclave and transferred to a thermostat and heated at 140°C for 48 hours. After cooling, the product is collected and washed several times with deionized water, and then dried at 60°C overnight to obtain NVO material. NVO, acetylene black and PVDF (20mg mL -1 ) were mixed in N-methylpyrrolidone at a weight ratio of 8:1:1. The obtained slurry was added at a concentration of 1-3 mg cm -2 The mass loading of 200 nm was coated on a carbon cloth with a diameter of 13 mm and dried in a vacuum oven at 60 °C for 12 h to obtain the NVO cathode.

[0058] Comparative Example 1:

[0059] This embodiment was conducted in parallel with the first embodiment, and the steps were basically the same, except that:

[0060] The solution does not add molecules having hydroxyl, carboxyl, carbonyl and amide functional groups and having steric effects as electrolyte additives.

[0061] Comparative Example 2:

[0062] This embodiment and comparative example 1 were tested in parallel, with basically the same steps, except that:

[0063] At 1 mA cm -2 The current density and 1 mAh cm -2 The Zn||Cu asymmetric battery constant current stripping / deposition test was carried out under the condition of capacity.

[0064] Comparative Example 3:

[0065] This embodiment was conducted in parallel with the third embodiment, and the steps were basically the same, except that:

[0066] The solution does not add molecules having hydroxyl, carboxyl, carbonyl and amide functional groups and having steric effects as electrolyte additives.

[0067] Evaluation and analysis of test results

[0068] like Figure 1 As shown: The symmetrical cells of Example 1 and Comparative Example 1 at 10 mA cm -2 The current density is 5 mAh cm -2 The constant current charge and discharge test was conducted under the condition of the capacity of 1000A. As shown in the figure, the symmetrical battery of Example 1 showed a stable cycle of more than 1920h and a capacity of about 9.6Ah cm -2 The ultra-high cumulative electrodeposition capacity of the Zn electrode is expected to endow the Zn electrode with improved thermodynamic stability. In contrast, under the same test conditions, the symmetrical cell of Comparative Example 1 lasted less than 120 h, showing huge polarization fluctuations and a rapid overpotential increase caused by hydrogen evolution.

[0069] like Figure 2 As shown: The symmetrical battery of Example 1 at 10, 20, and 30 mA cm -2 The current density and 1 mAh cm -2 The constant current charge and discharge test was conducted under the condition of constant capacity. As shown in the figure, when the current density increases to 10.0mA cm -2 , 20.0 mA cm -2 and 30.0 mA cm -2 When , the symmetrical battery of Example 1 can still show stable cycling of up to 1890h, 1380h, and 516h.

[0070] like Figure 3 As shown: The symmetrical battery of Example 1 at 5 mA cm -2 The current density and 1 mAh cm -2 Compared with the battery of Example 2 (<100h), the battery of Example 1 exhibited an ultra-stable shelf recovery life of 2500h, showing significantly enhanced stability.

[0071] like Figure 4 As shown: the rate performance comparison of the battery in Example 1 and Comparative Example 1. When the current is increased from 0.5 to 30 mA cm -2 When the battery of Example 1 shows a stable overpotential curve in the 200h cycle, the current is restored to 0.5mA cm -2 The battery of comparative example 1 can still work stably at 5mA cm -2 The short circuit occurs at a current density that prevents it from returning to its initial state.

[0072] like Figure 5 Shown is a comparison chart of the coulombic efficiency test of the Zn||Cu asymmetric battery in Example 2 and Comparative Example 2. -2 and 1mAh cm -2 Under these conditions, the electrolyte system in Example 2 still ensured stable zinc plating / stripping operations for 2500 cycles, with an average coulombic efficiency of 99.89%. This demonstrated its ability to inhibit uneven zinc deposition and various side reactions. In contrast, the coulombic efficiency of the Zn||Cu asymmetric cell in Comparative Example 2 led to a short circuit after only 230 cycles, which was caused by the formation of dendrites and byproducts.

[0073] like Figure 6 As shown: The corrosion current and corrosion potential of zinc metal in the electrolyte of Example 1 and Comparative Example 1 were tested. The corrosion potential of Example 2 is E=0.978V, and the corrosion current is 0.241mA cm -2 In the comparative example 1, the corrosion potential of zinc metal in the electrolyte is E = 0.985 V, and the corrosion current is 0.520 mA cm -2 The increased corrosion potential and decreased corrosion current indicate that the corrosion resistance of zinc anode is improved in the electrolyte containing molecular additives with steric effects of hydroxyl, carboxyl, carbonyl and amide trifunctional groups.

[0074] like Figure 7 As shown: The hydrogen evolution performance of the zinc anode in the electrolyte of Example 1 was determined by linear sweep voltammetry. As shown in the figure, at a current density of 10 mA cm -2Under these conditions, the introduction of molecular additives with trifunctional groups of hydroxyl, carboxyl, carbonyl and amide and steric effects resulted in a lower onset potential (-1.774 V) compared with the overpotential of hydrogen evolution at zinc anode in Na2SO4 (-1.654 V), indicating that the water splitting activity was reduced, which was beneficial to inhibiting hydrogen evolution.

[0075] like Figure 8 The figure shows the comparison of the zinc ion transference number of the symmetrical battery in Example 1 and Comparative Example 1. The zinc ion transference number of the symmetrical battery in Example 1 is 31.896 kJ mol -1 , which is greater than the zinc ion transference number of the symmetrical battery in Comparative Example 1 (24.03 kJ mol -1 ), indicating that the molecular additives with steric effects of hydroxyl, carboxyl, carbonyl and amide functional groups added to the electrolyte effectively increased the cation flow and reduced the Zn 2+ Concentration polarization.

[0076] like Figure 9 As shown: The morphological changes of zinc during the deposition process in the electrolyte of Example 1 and Comparative Example 1 were studied by scanning electron microscopy. -2 At a current density of , uniform and dense vertical growth of zinc was observed in the electrolyte of Example 1, and it became more dense as the deposition time increased. This is because the crystal plane shielding effect causes the added hydroxyl, carboxyl, carbonyl, and amide trifunctional molecules with steric effects to selectively adsorb on the Zn (002) and (101) crystal planes, which is conducive to the deposition of zinc on the Zn (100) plane. In contrast, the anode surface in the electrolyte of Comparative Example 1 showed a random and irregular distribution of zinc.

[0077] like Figure 10 Figure 2 shows in-situ optical observation of the zinc metal electroplating process in the electrolytes of Example 1 and Comparative Example 1 using an optical microscope. In the electrolyte of Comparative Example 1, as the constant current plating process progresses, a "tip" position is generated after 15 minutes of deposition. When the deposition time is increased to 60 minutes, sharp dendrites grow. In contrast, in the electrolyte of Example 1, the deposition process is characterized by uniform and dense deposition, even after 60 minutes of deposition of 10 mAh cm -2 , the sedimentary morphology remains smooth.

[0078] like Figure 11 Figure 2 shows a comparison of the self-discharge performance of the Zn||NVO full cells from Example 3 and Comparative Example 3. The test results show that after 96 hours of storage, the full cell from Example 3 retained 82.2% of its charge capacity, while the full cell from Comparative Example 3 retained only 76.2%. This result further demonstrates the significant enhancement of the stability of aqueous zinc-ion batteries by the addition of a molecular additive with steric effects, including trifunctional groups of hydroxyl, carboxyl, carbonyl, and amide.

[0079] like Figure 12 Shown: Comparison of the long cycle performance of the Zn||NVO full battery in Example 3 and Comparative Example 3. -1 After 2000 consecutive operations, the capacity remains at 218.36 mAh g -1 This retention rate is significantly higher than that of Comparative Example 3, which only retained 102.44 mAh g -1 capacity.

[0080] The above describes in detail the preferred embodiments of the present invention. It should be understood that those skilled in the art can make numerous modifications and variations based on the concepts of the present invention without inventive effort. Therefore, any technical solutions that can be derived by those skilled in the art through logical analysis, reasoning, or limited experimentation based on the concepts of the present invention and the prior art should be within the scope of protection defined by the claims.

Claims

1. An aqueous zinc ion battery electrolyte additive, characterized in that The aqueous zinc ion battery electrolyte additive contains one, two or three of the three functional groups of hydroxyl, carbonyl and amide groups and has a molecular structure with a steric hindrance effect. Its molecular formula is shown below:

2. An aqueous zinc ion battery electrolyte, characterized in that The aqueous zinc ion battery electrolyte comprises the aqueous zinc ion battery electrolyte additive according to claim 1.

3. The aqueous zinc ion battery electrolyte according to claim 2, wherein The concentration of the aqueous zinc ion battery electrolyte additive is 0.1 to 50 g L -1 .

4. The aqueous zinc ion battery electrolyte according to claim 3, wherein The concentration of the aqueous zinc ion battery electrolyte additive is 20 g L -1 .

5. The aqueous zinc ion battery electrolyte according to claim 2, wherein The electrolyte in the aqueous zinc ion battery electrolyte is zinc sulfate, zinc chloride or zinc acetate.

6. The aqueous zinc ion battery electrolyte according to claim 5, wherein The concentration of the electrolyte is 1-3M.

7. An aqueous zinc ion battery, characterized in that The aqueous zinc ion battery consists of a positive electrode, a negative electrode, a separator and the aqueous zinc ion battery electrolyte according to any one of claims 2 to 6.

8. The aqueous zinc ion battery according to claim 7, wherein The positive electrode material is ammonium vanadate NH4V4O 10 , the negative electrode material is zinc foil and the separator is glass fiber membrane.

9. A method for preparing the aqueous zinc ion battery electrolyte according to any one of claims 2 to 6, characterized in that: The following steps are involved: a) dissolving a zinc salt in deionized water and stirring to form a basic electrolyte, wherein the zinc salt is zinc sulfate, zinc chloride or zinc acetate, and the concentration of the electrolyte after dissolution is 1-3M; b) adding the electrolyte additive according to claim 1 to the basic electrolyte, stirring for 20-60 minutes to mix uniformly, wherein the concentration of the electrolyte additive is 0.1-50 g L-1.

10. A method for preparing an aqueous zinc ion battery according to any one of claims 7 to 8, characterized in that: The following steps are involved: i) Preparation of positive electrode: ammonium vanadate NH4V4O 10 The material, conductive agent and binder are mixed in a mass ratio of 7-8:1-2:1, coated on a carbon cloth current collector, and dried to obtain a positive electrode; Wherein, the ammonium vanadate NH4V4O 10 The preparation of positive electrode materials includes: Dissolve NH4VO3 and H2C2O4·2H2O in deionized water at 80-100°C and stir to form a mixed solution; The mixed solution is hydrothermally reacted at 120-160°C for 24-48 hours, and then washed and dried to obtain NH4V4O 10 Material; ii) using zinc foil as the negative electrode and a glass fiber membrane as the separator, injecting the electrolyte according to any one of claims 2 to 6, and assembling a battery; Wherein, the conductive agent is acetylene black, and the binder is polyvinylidene fluoride (PVDF).

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