Aqueous zinc ion electrolyte additive and its application

Abstract

The present invention relates to an aqueous zinc ion electrolyte additive and its application, belonging to the fields of electrochemical energy storage and new energy materials. The aqueous zinc ion electrolyte additive of the present invention is a pyridine derivative, wherein the pyridine derivative is 2,4-dihydroxypyridine, 2,3-dihydroxypyridine, or 2-hydroxypyridine. A certain amount of the pyridine derivative is directly added as an additive to a prepared ZnSO4 electrolyte to prepare an efficient and long-life aqueous zinc ion battery. The present invention will significantly promote the commercial application of aqueous zinc ion batteries and contribute to the upgrading of electrochemical energy storage systems.

Description

Technical Field

[0001] The present invention belongs to the field of electrochemical energy storage and new energy materials, relates to an aqueous zinc ion battery, and specifically relates to an aqueous zinc ion electrolyte additive and an application thereof. Background Art

[0002] In recent years, the rapid adoption of devices such as mobile communication terminals and electric vehicles has led to higher demands for efficient and stable electrochemical energy storage systems. Among various battery systems, lithium-ion batteries, the most technologically mature, boast long cycle life and ideal gravimetric energy density, making them widely used. However, the high cost, low safety, and environmental concerns of lithium-ion batteries have limited their further development, necessitating the urgent need for the development of novel non-lithium electrochemical energy storage systems.

[0003] Compared to flammable and toxic organic electrolyte lithium-ion batteries, recyclable aqueous zinc-ion batteries with zinc as the negative electrode are a low-cost, environmentally friendly and safe new energy storage system, and are expected to become a new type of battery to replace lithium-ion batteries. Zinc is abundant on Earth, low in cost, environmentally friendly, and has a high volumetric energy density (5855mAh cm -3 However, although aqueous zinc-ion batteries often use aqueous zinc sulfate as a weakly acidic electrolyte, dendrite growth and side reactions of the zinc anode in this electrolyte severely limit the battery's lifespan and, in turn, its commercial prospects. Dendrite growth not only leads to serious consequences such as battery short circuits but also causes the formation of "dead zinc" due to dendrite breakage. Furthermore, during the battery's cycling, hydrogen evolution reactions occur, producing large amounts of hydrogen gas, which damages the battery structure and produces byproducts.

[0004] In order to solve the above defects of aqueous zinc-ion batteries, researchers have taken a variety of measures, including the construction of zinc negative electrode protective layer, the development of new electrolytes, the modification of zinc metal and the selection of functional electrolyte additives. Among them, regulating the zinc electrode / electrolyte interface through inorganic or organic additives is one of the most effective and simplest methods to inhibit dendrite growth and side reactions. Previously, researchers added a small amount of metal salts, such as Bi, to the aqueous electrolyte. + , Pb + 、Na + 、Li +Salts of zinc and other inorganic compounds, such as MXenes, graphene oxide, and carbon, have been used. These additives not only inhibit dendrite growth and zinc corrosion but also inhibit the occurrence of hydrogen evolution reactions. However, the use of heavy metals and expensive materials poses environmental risks and increases device costs. Recently, many organic additives have also been used in aqueous zinc-ion batteries. Some of these surfactants, such as polyethylene oxide, polyacrylamide, hexadecyltrimethylammonium bromide, and glucose, can modify the morphology of zinc deposits. Summary of the Invention

[0005] To address the deficiencies in the prior art, the present invention aims, first, to provide the use of a pyridine derivative as an additive for aqueous zinc-ion battery electrolytes; second, to provide an additive for aqueous zinc-ion battery electrolytes; third, to provide an aqueous zinc-ion battery electrolyte; and fourth, to provide an aqueous zinc-ion battery. The present invention directly adds the pyridine derivatives 2,4-dihydroxypyridine, 2,3-dihydroxypyridine, or 2-hydroxypyridine as additives to a prepared ZnSO4 electrolyte to prepare a highly efficient and long-life aqueous zinc-ion battery. This invention will significantly promote the commercial application of aqueous zinc-ion batteries and contribute to the upgrading of electrochemical energy storage systems.

[0006] The specific scheme adopted in the present invention is:

[0007] The present invention provides the use of a pyridine derivative as an additive for aqueous zinc ion battery electrolyte. Further, the pyridine derivative is 2,4-dihydroxypyridine, 2,3-dihydroxypyridine or 2-hydroxypyridine.

[0008] The present invention also seeks to protect an additive for an aqueous zinc ion battery electrolyte, wherein the additive is 2,4-dihydroxypyridine, 2,3-dihydroxypyridine or 2-hydroxypyridine; the concentration of the 2,4-dihydroxypyridine in the aqueous zinc ion battery electrolyte is 1 to 3 mmol / L; the concentration of the 2,3-dihydroxypyridine or 2-hydroxypyridine is both 2 mmol / L.

[0009] The present invention seeks to protect an aqueous zinc ion battery electrolyte, which comprises a ZnSO4 aqueous electrolyte and the above-mentioned additive; the ZnSO4 aqueous electrolyte is prepared by dissolving ZnSO4 in deionized water, wherein the concentration of ZnSO4 is 1 mol / L; and the additive is dissolved in the ZnSO4 aqueous electrolyte.

[0010] The present invention further claims protection for an aqueous zinc ion battery comprising a positive electrode, a negative electrode, a separator, and the aqueous zinc ion battery electrolyte. As a further optimization, the aqueous zinc ion battery is a Zn / Zn symmetrical battery assembled with zinc metal as the negative electrode, glass fiber as the separator, zinc metal as the positive electrode, and the aqueous zinc ion battery electrolyte as the electrolyte.

[0011] Beneficial effects: The present invention uses pyridine derivatives as additives for aqueous zinc-ion battery electrolytes. Since the ZnSO4 electrolyte is weakly acidic and the pyridine additive is alkaline, during the zinc deposition process, the pyridine additive will be adsorbed at the favorable zinc nucleation sites, promoting uniform deposition of zinc ions and inhibiting the formation of zinc dendrites. At the same time, the adsorption of the additive can effectively reduce the water content at the interface between the zinc negative electrode and the electrolyte. Therefore, the use of the additive also inhibits the occurrence of hydrogen evolution reaction. In summary, the use of pyridine additives can inhibit the growth of dendrites on the surface of the zinc negative electrode and the occurrence of side reactions, thereby improving the cycle life of aqueous zinc-ion batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 The chemical structures of 2,4-dihydroxypyridine, 2,3-dihydroxypyridine, and 2-hydroxypyridine are shown below;

[0013] Figure 2 This is a graph showing the cycle life test of zinc symmetric batteries for the control sample and experimental samples 1-3;

[0014] Figure 3 This is a graph showing the cycle life test of zinc symmetric batteries of the control sample and experimental samples 2, 4, and 5;

[0015] Figure 4 This is the surface morphology of the zinc negative electrode after the control sample and the experimental sample were cycled for 100 cycles;

[0016] Figure 5 This is a light microscopic image of in-situ observation of zinc deposition using an optical microscope;

[0017] Figure 6 It is the linear voltammetric sweep test diagram of the comparison sample and the experimental sample. DETAILED DESCRIPTION

[0018] The present invention adopts a pyridine derivative as an electrolyte additive to achieve the preparation of an aqueous zinc ion battery with high efficiency and long cycle life. The electrolyte additives for the aqueous zinc ion battery are 2,4-dihydroxypyridine (2,4-DHP), 2,3-dihydroxypyridine (2,3-DHP), and 2-hydroxypyridine (2-DHP). The chemical structures are as follows: Figure 1 shown.

[0019] 1. Prepare aqueous zinc ion battery electrolyte containing additives.

[0020] Method for preparing aqueous zinc ion battery electrolyte containing additives:

[0021] (1) Dissolve 1 mol of ZnSO4 in deionized water and shake until completely dissolved to prepare a 1 mol / L ZnSO4 aqueous electrolyte.

[0022] (2) Add 1-3 mmol of 2,4-dihydroxypyridine to the aqueous electrolyte prepared above and stir magnetically until it is completely dissolved to prepare an aqueous electrolyte containing the additive.

[0023] 2. Prepare aqueous zinc ion batteries.

[0024] A Zn / Zn symmetric battery was assembled with zinc metal as the negative electrode, glass fiber as the separator, zinc metal as the positive electrode, and an aqueous solution of 1 mol / L ZnSO4 containing 2 mmol / L 2,4-dihydroxypyridine as the electrolyte.

[0025] Test Example: The electrolyte additive of the present invention was evaluated by comparing the control sample with the experimental sample.

[0026] Comparative sample: A Zn / Zn symmetrical battery was assembled with zinc metal as the negative electrode, glass fiber as the separator, zinc metal as the positive electrode, and 1 mol / L ZnSO4 aqueous solution as the electrolyte.

[0027] Experimental sample 1: A Zn / Zn symmetrical battery was assembled using zinc metal as the negative electrode, glass fiber as the separator, zinc metal as the positive electrode, and an aqueous solution of 1 mol / L ZnSO4 containing 1 mmol / L 2,4-dihydroxypyridine as the electrolyte.

[0028] Experimental sample 2: A Zn / Zn symmetrical battery was assembled using zinc metal as the negative electrode, glass fiber as the separator, zinc metal as the positive electrode, and an aqueous solution of 1 mol / L ZnSO4 containing 2 mmol / L 2,4-dihydroxypyridine as the electrolyte.

[0029] Experimental sample 3: A Zn / Zn symmetrical battery was assembled using zinc metal as the negative electrode, glass fiber as the separator, zinc metal as the positive electrode, and an aqueous solution of 1 mol / L ZnSO4 containing 3 mmol / L 2,4-dihydroxypyridine as the electrolyte.

[0030] Experimental sample 4: A Zn / Zn symmetrical battery was assembled using zinc metal as the negative electrode, glass fiber as the separator, zinc metal as the positive electrode, and an aqueous solution of 1 mol / L ZnSO4 containing 2 mmol / L 2,3-dihydroxypyridine as the electrolyte.

[0031] Experimental sample 5: A Zn / Zn symmetrical battery was assembled using zinc metal as the negative electrode, glass fiber as the separator, zinc metal as the positive electrode, and an aqueous solution of 1 mol / L ZnSO4 containing 2 mmol / L 2-hydroxypyridine as the electrolyte.

[0032] 1. The charge and discharge cycles of the control sample and the experimental sample 1 were carried out at the same time. The battery cycle life of the control sample was less than 200h, while the battery cycle life of the experimental sample exceeded 3000h. Figure 2 shown.

[0033] 2. The charge and discharge cycles of the control sample and the experimental sample 2 were carried out at the same time. The battery cycle life of the control sample was less than 200 hours, while the battery cycle life of the experimental sample exceeded 5600 hours. Figure 2 shown.

[0034] 3. The charge and discharge cycles of the control sample and the experimental sample 3 were carried out at the same time. The battery cycle life of the control sample was less than 200h, while the battery cycle life of the experimental sample exceeded 400h. Figure 2 shown.

[0035] 4. The charge and discharge cycles of the control sample and the experimental sample 4 were carried out at the same time. The battery cycle life of the control sample was less than 200h, while the battery cycle life of the experimental sample exceeded 750h. Figure 3 shown.

[0036] 5. The charge and discharge cycles of the control sample and the experimental sample 5 were carried out at the same time. The battery cycle life of the control sample was less than 200h, while the battery cycle life of the experimental sample exceeded 800h. Figure 3 shown.

[0037] 2. Cycle the control sample and the experimental sample for 100 cycles at the same time, disassemble the battery, and observe the morphology of the zinc negative electrode using a scanning electron microscope. Figure 4 By comparison, it can be found that after 100 cycles in the electrolyte with additives, the zinc deposits on the surface of the zinc negative electrode are more dense, showing an orderly stacking of layers; while after 100 cycles in the electrolyte without additives, the zinc deposits on the surface of the zinc negative electrode are disordered and there is the presence of "dead zinc".

[0038] 3. In-situ observation of zinc deposition in electrolytes with and without 2,4-DHP additive was performed using an optical microscope ( Figure 5 ), it can be seen that after 40 minutes, uneven deposition has appeared on the zinc metal surface in the electrolyte without additives, and after 60 minutes of deposition, dendrites have clearly appeared on the zinc metal surface. In contrast, during the 1-hour deposition process in the electrolyte with additives, the zinc metal surface deposition is always uniform, without dendrites.

[0039] 4. Using the electrochemical workstation, the linear voltammetry method was used to test the comparison sample and the experimental sample to determine the strength of the hydrogen evolution reaction on the zinc negative electrode surface. Figure 6 ), in the electrolyte with additives, the hydrogen evolution reaction on the surface of the zinc negative electrode is significantly reduced.

[0040] After the above comparison, the experimental samples added 2,4-dihydroxypyridine, 2,3-dihydroxypyridine and 2-hydroxypyridine to the electrolyte, which effectively inhibited the formation of dendrites and the occurrence of hydrogen evolution reaction during zinc deposition, thereby significantly improving the cycle life of the battery.

[0041] It should be noted that the above-described embodiments are to be understood as illustrative and not limiting of the scope of protection of the present invention, which is subject to the claims. It will be apparent to those skilled in the art that non-essential improvements and adjustments to the present invention, without departing from the spirit and scope of the present invention, still fall within the scope of protection of the present invention.

Claims

1. Application of pyridine derivatives as electrolyte additives for aqueous zinc ion batteries, characterized in that: The pyridine derivative is 2,4-dihydroxypyridine, 2,3-dihydroxypyridine or 2-hydroxypyridine.

2. An aqueous zinc ion battery electrolyte, characterized in that: The aqueous zinc ion battery electrolyte includes a ZnSO4 aqueous electrolyte and an additive; the ZnSO4 aqueous electrolyte is prepared by dissolving ZnSO4 in deionized water, wherein the concentration of ZnSO4 is 1 mol / L; the additive is dissolved in the ZnSO4 aqueous electrolyte, and the additive is 2,4-dihydroxypyridine, 2,3-dihydroxypyridine or 2-hydroxypyridine; the concentration of the 2,4-dihydroxypyridine in the aqueous zinc ion battery electrolyte is 1~3mmol / L; the concentrations of the 2,3-dihydroxypyridine and 2-hydroxypyridine in the aqueous zinc ion battery electrolyte are both 2mmol / L.

3. An aqueous zinc ion battery, characterized in that: The invention comprises a positive electrode, a negative electrode, a separator and the aqueous zinc ion battery electrolyte according to claim 2.

4. The aqueous zinc ion battery according to claim 3, wherein: The aqueous zinc ion battery is a Zn / Zn symmetrical battery assembled with zinc metal as the negative electrode, glass fiber as the separator, zinc metal as the positive electrode, and the aqueous zinc ion battery electrolyte according to claim 2 as the electrolyte.

Images