Electrolyte separator for copper-ion battery and preparation method and application thereof

Abstract

The application discloses an electrolyte diaphragm for a copper ion battery and a preparation method and application thereof, and the electrolyte diaphragm comprises zeolite, copper salt and a binder, wherein the mass ratio of the zeolite, the copper salt and the binder is (1-9):(1-9):(1-9). The electrolyte diaphragm for the copper ion battery is prepared by mixing the zeolite, the copper salt and the binder, compression molding and drying, the preparation process is simple, the operation is convenient, the prepared electrolyte diaphragm has good ion transmission performance when being used in an aqueous copper ion battery, the iodine negative ion shuttling effect can be prevented, and the cycle efficiency and stability of the copper iodine battery are greatly improved. The electrolyte diaphragm can be used to construct the aqueous copper iodine battery with high capacity and high stability.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of copper ion battery materials, in particular to an electrolyte separator for a copper ion battery and a preparation method and application thereof. BACKGROUND

[0002] In recent years, aqueous ion batteries have attracted widespread attention due to their low cost, high safety and small environmental impact. Among various aqueous ion batteries, aqueous copper ion batteries have become a key research direction. First, the abundance and easy availability of copper resources give copper ion batteries a natural advantage in material sources. Second, the high specific capacity (837.5 mAh / g) of copper ion batteries means that they can store a large amount of electrical energy, which is particularly important for application scenarios that require large-capacity storage. More importantly, the chemical properties of copper in aqueous solution are extremely stable, which is crucial for ensuring the long-term service life and safety of the battery.

[0003] The electrode material for storing copper ions is mainly a chalcogen element. A sulfur (S) electrode can provide an ultra-high specific capacity of 3044 mAh / g when storing copper ions (Angew. Chem. 2019, 131, 12770), and in order to address the problem of sulfur shuttling and expansion, Wang et al. proposed a self-supporting CuS electrode (ACS Nano 2021, 15, 5420). In order to improve the rate performance of the CuS electrode, a preparation method for a Se-doped CuS electrode is disclosed in a Chinese patent (Patent Publication No. CN115028189A), and doping can expand the ion transmission channel and also enhance the electronic conductivity of the CuS electrode. A Chinese patent (Patent Publication No. CN115133109A) discloses a Te positive electrode obtained by fully mixing elemental Te powder with a conductive agent and a binder. These materials, when paired with metallic copper, all achieve good electrochemical performance.

[0004] In addition to chalcogen electrodes, iodine (I2) electrodes are also applied to aqueous battery systems such as zinc-iodine (Zn / / I2) batteries due to their high capacity and low cost. In Zn / / I2 batteries, Zn serves as the negative electrode due to its low potential, while I2 serves as the positive electrode due to its high potential. Similarly, a copper-iodine (Cu / / I2) battery can also be designed. In Cu / / I2 batteries, Cu 2+ has a standard potential of 0.34 V, which is lower than the standard potential of I2 / I - , which is 0.54 V. This reaction appears to be non-spontaneous, but due to the difficulty of dissolving the product CuI, Cu 2+ can oxidize I - ions, and the reaction that occurs at this time is 2Cu 2+ + 4I -→ 2CuI + I2, the standard potential can reach 0.86V, and the reaction is the redox titration method commonly used in analytical chemistry, namely iodometric titration. However, due to the poor solubility of CuI and I - The shuttle property of ions (i.e. the generated polyiodide will shuttle to the negative electrode and be directly reduced), thereby causing the problems of low coulombic efficiency and capacity decay, and the iodometric titration reaction is difficult to be used to construct a battery. SUMMARY

[0005] To solve the above technical problems, the application provides an electrolyte separator for a copper ion battery and a preparation method and application thereof, the preparation process is simple and convenient to operate, and the prepared electrolyte separator can improve the coulombic efficiency and cycle stability of the battery when used in a water-based copper ion battery, and solve the problem of the shuttle effect of polyiodide in a water-based copper-iodine battery.

[0006] The application is implemented by the following technical solutions:

[0007] The application provides an electrolyte separator for a copper ion battery, which comprises zeolite, copper salt and a binder, and the mass ratio of the zeolite, copper salt and binder is (1-9):(1-9):(1-9).

[0008] In the electrolyte separator provided by the application, the natural pore structure of the zeolite helps to improve the ion transmission speed, the limited pore size and the negative charge state can effectively prevent the passage of iodine negative ions with large size, thereby inhibiting the shuttle effect of iodine negative ions. In addition, the zeolite powder has good chemical stability in the water-based electrolyte, which helps to enhance the long-term cycle stability of the battery. The addition of copper salt helps to increase the concentration of copper ions in the separator, thereby enhancing the ion transmission speed of the separator. The addition of the binder helps to connect the zeolite powder particles, thereby reducing the transmission distance of copper ions and improving the ion transmission capacity of the electrolyte separator.

[0009] Further, the chemical formula of the zeolite is A m B q O 2q ·nH2O, wherein A is selected from one or more of calcium (Ca), sodium (Na), potassium (K), barium (Ba) and strontium (Sr), and B is aluminum (Al) and silicon (Si).

[0010] Further, in the chemical formula of the zeolite, q is the valence of the cation, q is 1-2, m is the number of cations, m is 1-5, preferably 2-5, and n is the number of water molecules, n is 1-20, preferably 4.5-14.

[0011] Further, the structural formula of the zeolite is A m [(AlO2) x (SiO2)y ]·n(H2O), wherein x is the number of Al atoms, x is 1-5, preferably 2-5, y is the number of Si atoms, y is 1-15, preferably 2-13, y / x (Si / Al ratio) is 1-5, preferably 1-2.6, and x+y is the number of tetrahedrons in a unit cell.

[0012] Further, the mass ratio of the zeolite, the copper salt and the binder is preferably (2-5):(2-5):(1-3), more preferably (3-5):(3-5):(1-3).

[0013] Further, the copper salt is selected from one or more of copper sulfate, copper chloride, copper bromide, copper acetate and copper trifluoromethylsulfonate.

[0014] Further, the binder is selected from one or more of polytetrafluoroethylene (PTFE), polyacrylonitrile (PAN) and polypropylene (PAA).

[0015] Further, the thickness of the electrolyte separator is 10-50 μm.

[0016] The second aspect of the present application provides a preparation method of an electrolyte separator for a copper ion battery, comprising the following steps:

[0017] (1) mixing a zeolite, a copper salt, a binder and water to obtain a mixture;

[0018] (2) performing compression molding on the mixture obtained in step (1) to obtain the electrolyte separator after drying.

[0019] Further, in step (1), the zeolite is subjected to a vacuum activation treatment, the temperature of the activation treatment is 100-200 °C, and the activation treatment time is 1-10 h, i.e. the zeolite is placed in a vacuum at 100-200 °C for 1-10 h.

[0020] In a specific embodiment, in step (1), the activated zeolite powder and the copper salt powder are first ground and stirred, and then the binder powder and water are added and mixed uniformly.

[0021] Further, the particle size of the zeolite powder is 2-5 μm.

[0022] Further, in step (2), the compression molding pressure is 1-10 MPa.

[0023] Further, in step (2), the drying is performed by vacuum drying.

[0024] Further, in step (2), the drying temperature is 50-150 °C.

[0025] Further, the drying time in step (2) is 1-10 hours.

[0026] The electrolyte separator of the first aspect is used in the preparation of a copper ion battery, especially a copper-iodine battery.

[0027] The electrolyte separator of the present application has good ion transmission performance when used in aqueous copper ion batteries, can prevent the shuttle effect of iodine anions, greatly improves the cycle efficiency and stability of copper-iodine batteries, and can construct high-capacity and high-stability aqueous copper-iodine batteries using the electrolyte separator of the present application.

[0028] The present application provides a highly reversible Cu / / I2 battery, which uses a composite electrode of iodine and carbon black to solve the reversibility problem of CuI, and uses a zeolite-based electrolyte separator with high ionic conductivity and anion shuttle inhibition characteristics, thereby greatly improving the cycle efficiency and stability of the copper-iodine battery. The Cu / / I2 battery is significantly different from the Zn / / I2 battery. On the one hand, in the Zn / / I2 battery, Zn 2+ ions are only carriers, while in the Cu / / I2 battery, Cu 2+ ions are not only carriers, but also redox active centers, which can be further reduced to Cu + ions; on the other hand, in the Zn / / I2 battery, I2 oxidizes Zn to generate I - ions and Zn 2+ ions, and I2 is the positive electrode; while in the Cu / / I2 battery, I2 is first reduced to I - ions by obtaining electrons, and then is oxidized by Cu 2+ ions in the electrolyte to generate I2 and Cu + ions, so I2 and Cu 2+ ions in the electrolyte are both positive electrode materials.

[0029] The present application has the following advantages:

[0030] The preparation process of the electrolyte separator provided by the present application is simple and convenient to operate. When the electrolyte separator prepared is used in aqueous copper ion batteries, the addition of zeolite and copper salt can significantly improve the ion transmission capacity of the electrolyte separator. The natural pore structure of the zeolite is a fast ion transmission channel, and the addition of copper salt helps to increase the copper ion concentration of the electrolyte separator, further improving the transmission performance of copper ions, thereby improving the coulomb efficiency and cycle stability of the battery. The rigid crystal framework of the zeolite has a natural negative charge, which can repel polyiodide ions with the same negative charge, and its limited pore size can prevent the passage of iodine anions with larger size, so the problem of polyiodide shuttle effect in aqueous copper-iodine batteries can be solved. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 Optical photograph of electrolyte separator of Example 1.

[0032] Figure 2 Charge-discharge curve of aqueous copper-iodine battery assembled with electrolyte separator of Example 1 and glass fiber separator at 0.2 A / g.

[0033] Figure 3 Cycle performance comparison of aqueous copper-iodine battery assembled with electrolyte separator of Example 1 and glass fiber separator at 1 A / g.

[0034] Figure 4 Cycle performance of aqueous copper-iodine battery assembled with electrolyte separator of Example 1 at 2.0 A / g.

[0035] Figure 5 Ion conductivity data chart of electrolyte separator of Examples 1-9. DETAILED DESCRIPTION

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0037] The present application will be further described with reference to the drawings and specific examples, so that those skilled in the art can better understand the present application and implement it.

[0038] The experimental methods used in the following examples are conventional methods unless otherwise specified, and the materials, reagents, etc. used are commercially available unless otherwise specified.

[0039] The test method of electrochemical performance of electrolyte separator in the following examples is as follows:

[0040] Ion conductivity: Apply a pressure of 0-5 MPa to the electrolyte separator, then make a blocking electrode by clamping stainless steel sheets with a diameter of 16 mm and a thickness of 100 μm on both sides of the electrolyte separator, and then perform electrochemical impedance spectroscopy test, and input the measured results into the formula δ=d / RA, wherein δ in the formula represents ion conductivity, d is the thickness of the separator, R is the resistance, and A is the interface area of the separator.

[0041] The electrolyte separator in the following examples is assembled into an aqueous copper-iodine battery, and the assembly method is as follows:

[0042] The composite electrode prepared by uniformly mixing iodine, carbon black and a binder at a mass ratio of 8:1:1 is used as a working electrode, a pure copper sheet is used as a counter electrode, a 0.5M CuSO4 aqueous solution is used as an electrolyte, and the electrolyte separator is combined to assemble a water-based copper-iodine battery.

[0043] The voltage range of the assembled water-based copper-iodine battery in the charge-discharge test is 0.1-0.6V.

[0044] Example 1

[0045] An electrolyte separator comprises Na2[Al2Si2O8]·4.5H2O, copper sulfate and polytetrafluoroethylene, wherein the mass ratio of Na2[Al2Si2O8]·4.5H2O, copper sulfate and polytetrafluoroethylene is 4:5:1, and the preparation method comprises the following steps:

[0046] (1) The zeolite powder (Na2[Al2Si2O8]·4.5H2O) is activated at 200°C in a vacuum for 1h, 640mg of the activated zeolite powder and 800mg of copper sulfate powder are placed in a mortar and stirred, then 160mg of polytetrafluoroethylene powder and water are added and uniformly mixed to obtain a paste-like mixture.

[0047] (2) The paste-like mixture obtained in step (1) is pressed into an electrolyte separator with a thickness of 15μm under a pressure of 8MPa, and the electrolyte separator is vacuum dried at 50°C for 5h to obtain the electrolyte separator, as shown in Figure 1 .

[0048] The electrolyte separator is subjected to a pressure of 3MPa, and the ionic conductivity of the electrolyte separator of Example 1 is measured to be 3.1mS / cm by a blocking electrode test.

[0049] Figure 2 The charge-discharge curve of the water-based copper-iodine battery assembled with the electrolyte separator of Example 1 and a glass fiber separator at a current density of 0.2A / g can be seen from Figure 2 , wherein the first cycle discharge capacity of the water-based copper-iodine battery based on the electrolyte separator of Example 1 is 347mAh / g, and the first cycle coulombic efficiency is 97%; the first cycle discharge capacity of the water-based copper-iodine battery based on the glass fiber separator is 198mAh / g, and the first cycle coulombic efficiency is 61%.

[0050] Figure 3 The cycle performance comparison chart of the water-based copper-iodine battery assembled with the electrolyte separator of Example 1 and a glass fiber separator at 1A / g can be seen from Figure 3 , wherein the capacity retention rate of the water-based copper-iodine battery based on the electrolyte separator of Example 1 after 100 cycles is as high as 92%, and the capacity retention rate of the water-based copper-iodine battery based on the glass fiber separator after 100 cycles is only 12%.

[0051] Figure 4 The cycle performance plot of the aqueous copper-iodine battery assembled with the electrolyte separator of Example 1 at 2.0 A / g shows that the copper-iodine battery still maintains 95.7% of the initial capacity after 600 cycles. Figure 4

[0052] Example 2

[0053] An electrolyte separator comprising Na2[Al2Si2O8]·4.5H2O, copper sulfate and polytetrafluoroethylene, wherein the mass ratio of Na2[Al2Si2O8]·4.5H2O, copper sulfate and polytetrafluoroethylene is 3:3:1, and the preparation method is basically the same as that of Example 1.

[0054] Example 3

[0055] An electrolyte separator comprising Na2[Al2Si2O8]·4.5H2O, copper sulfate and polytetrafluoroethylene, wherein the mass ratio of Na2[Al2Si2O8]·4.5H2O, copper sulfate and polytetrafluoroethylene is 3:4:2, and the preparation method is basically the same as that of Example 1.

[0056] Example 4

[0057] An electrolyte separator comprising Na2[Al2Si2O8]·4.5H2O, copper sulfate and polytetrafluoroethylene, wherein the mass ratio of Na2[Al2Si2O8]·4.5H2O, copper sulfate and polytetrafluoroethylene is 3:5:3, and the preparation method is basically the same as that of Example 1.

[0058] Example 5

[0059] An electrolyte separator comprising Na2[Al2Si2O8]·4.5H2O, copper sulfate and polytetrafluoroethylene, wherein the mass ratio of Na2[Al2Si2O8]·4.5H2O, copper sulfate and polytetrafluoroethylene is 4:3:2, and the preparation method is basically the same as that of Example 1.

[0060] Example 6

[0061] An electrolyte separator comprising Na2[Al2Si2O8]·4.5H2O, copper sulfate and polytetrafluoroethylene, wherein the mass ratio of Na2[Al2Si2O8]·4.5H2O, copper sulfate and polytetrafluoroethylene is 4:4:3, and the preparation method is basically the same as that of Example 1.

[0062] Example 7

[0063] ​An electrolyte separator comprising Na2[Al2Si2O8]·4.5H2O, copper sulfate, and polytetrafluoroethylene, wherein the mass ratio of Na2[Al2Si2O8]·4.5H2O, copper sulfate, and polytetrafluoroethylene is 5:4:1, and the preparation method is substantially the same as that of Example 1.

[0064] Example 8

[0065] An electrolyte separator comprising Na2[Al2Si2O8]·4.5H2O, copper sulfate, and polytetrafluoroethylene, wherein the mass ratio of Na2[Al2Si2O8]·4.5H2O, copper sulfate, and polytetrafluoroethylene is 5:5:2, and the preparation method is substantially the same as that of Example 1.

[0066] Example 9

[0067] An electrolyte separator comprising Na2[Al2Si2O8]·4.5H2O, copper sulfate, and polytetrafluoroethylene, wherein the mass ratio of Na2[Al2Si2O8]·4.5H2O, copper sulfate, and polytetrafluoroethylene is 5:5:3, and the preparation method is substantially the same as that of Example 1.

[0068] Figure 5 A graph of ion conductivity data for the electrolyte separators of Examples 1-9.

[0069] Example 10

[0070] An electrolyte separator comprising Na2[Al2Si2O8]·4.5H2O, copper acetate, and polyacrylic acid, wherein the mass ratio of Na2[Al2Si2O8]·4.5H2O, copper acetate, and polyacrylic acid is 5:4:1, and the preparation method comprises the following steps:

[0071] (1) Activating zeolite powder (Na2[Al2Si2O8]·4.5H2O) at 100°C in a vacuum for 10 h, placing 800 mg of the activated zeolite powder and 640 mg of copper acetate powder in a mortar and stirring, then adding 160 mg of polyacrylic acid powder and water to mix uniformly to obtain a paste-like mixture.

[0072] (2) Pressing the paste-like mixture obtained in step (1) into an electrolyte separator with a thickness of 50 μm under a pressure of 1 MPa, and vacuum drying at 100°C for 2 h to obtain an electrolyte separator.

[0073] The ionic conductivity of the electrolyte separator of Example 10 was measured to be 3.7 mS / cm by the blocking electrode test with a pressure of 3 MPa applied to the electrolyte separator. The water-based copper-iodine battery assembled with the electrolyte separator of Example 10 had a first circle discharge capacity of 345 mAh / g at a current density of 0.2 A / g, and a first circle coulombic efficiency of 96%; the capacity retention rate was as high as 91% at a current density of 1 A / g after 100 circles.

[0074] Example 11

[0075] An electrolyte separator comprising NaCa2[Al5Si 13 O 36 ]·14H2O, copper bromide, and polyacrylonitrile, wherein the mass ratio of NaCa2[Al5Si 13 O 36 ]·14H2O, copper bromide, and polyacrylonitrile is 5:3:2, and the preparation method comprises the following steps:

[0076] (1) Activating zeolite powder (NaCa2[Al5Si 13 O 36 ]·14H2O) at 150°C in a vacuum for 5 h, grinding and stirring 800 mg of the activated zeolite powder and 480 mg of copper bromide powder in a mortar, then adding 320 mg of polyacrylonitrile powder and water to mix uniformly to obtain a paste-like mixture.

[0077] (2) Pressing the paste-like mixture obtained in step (1) into an electrolyte separator with a thickness of 35 μm under a pressure of 5 MPa, and vacuum drying at 80°C for 3 h to obtain an electrolyte separator.

[0078] The ionic conductivity of the electrolyte separator of Example 11 was measured to be 4.9 mS / cm by the blocking electrode test with a pressure of 3 MPa applied to the electrolyte separator. The water-based copper-iodine battery assembled with the electrolyte separator of Example 11 had a first circle discharge capacity of 355 mAh / g at a current density of 0.2 A / g, and a first circle coulombic efficiency of 97%; the capacity retention rate was as high as 91% at a current density of 1 A / g after 100 circles.

[0079] Example 12

[0080] An electrolyte separator comprising NaCa2[Al5Si 13 O 36 ]·14H2O, copper trifluoromethylsulfonate, and polytetrafluoroethylene, wherein the mass ratio of NaCa2[Al5Si 13 O 36 ]·14H2O, copper trifluoromethylsulfonate, and polytetrafluoroethylene is 4:5:1, and the preparation method comprises the following steps:

[0081] (1) Zeolite powder (NaCa2[Al5Si 13 O 36 ]·14H2O) was activated at 180°C in vacuum for 2h, 640mg of the activated zeolite powder and 800mg of copper trifluoromethyl sulfonate powder were ground in a mortar, then 160mg of polytetrafluoroethylene powder was added and mixed with water to obtain a paste-like mixture.

[0082] (2) The paste-like mixture obtained in step (1) was pressed into an electrolyte separator with a thickness of 10μm under a pressure of 10MPa, and vacuum dried at 150°C for 1h to obtain an electrolyte separator.

[0083] The electrolyte separator was applied with a pressure of 3MPa, and tested by blocking electrode test, and the ionic conductivity of the electrolyte separator of Example 12 was 3.2mS / cm. The water-based copper-iodine battery assembled with the electrolyte separator of Example 12 had a first circle discharge capacity of 350mAh / g and a first circle coulombic efficiency of 93% at a current density of 0.2A / g, and a capacity retention rate of up to 90% after 100 circles at a current density of 1A / g.

[0084] Obviously, the above embodiments of the present application are only examples for clearly illustrating the present application, and are not intended to limit the embodiments of the present application. It should be understood by those skilled in the art that other different forms of changes or variations can be made on the basis of the above description. Here, it is not necessary and also impossible to enumerate all the embodiments. Any modification, equivalent replacement and improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the claims of the present application.

Claims

1. An aqueous copper-iodine battery, characterized in that: The invention comprises a positive electrode and an electrolyte membrane, wherein a composite electrode of iodine and carbon black is used as the positive electrode, and the electrolyte membrane comprises zeolite, copper salt and a binder, wherein the mass ratio of zeolite, copper salt and binder is (1-9):(1-9):(1-9).

2. The aqueous copper-iodine battery according to claim 1, wherein The chemical formula of the zeolite is A m B q O 2q •nH2O, wherein A is selected from one or more of calcium, sodium, potassium, barium and strontium, B is aluminum and silicon, m is 1 to 5, q is 1 to 2, and n is 1 to 20.

3. The aqueous copper-iodine battery according to claim 1, wherein The copper salt is selected from one or more of copper sulfate, copper chloride, copper bromide, copper acetate and copper trifluoromethanesulfonate.

4. The aqueous copper-iodine battery according to claim 1, wherein The binder is selected from one or more of polytetrafluoroethylene, polyacrylonitrile and polyacrylic acid.

5. The aqueous copper-iodine battery according to claim 1, wherein The thickness of the electrolyte separator is 10-50 μm.

6. The aqueous copper-iodine battery according to claim 1, characterized in that The preparation method of the electrolyte membrane comprises the following steps: (1) mixing zeolite, copper salt, a binder and water to obtain a mixture; (2) The mixture obtained in step (1) is pressed and molded, and dried to obtain the electrolyte membrane.

7. The aqueous copper-iodine battery according to claim 6, wherein In step (1), the zeolite is subjected to vacuum activation treatment, the activation treatment temperature is 100-200°C, and the activation treatment time is 1-10 h.

8. The aqueous copper-iodine battery according to claim 6, wherein In step (2), the pressing pressure is 1-10 MPa.

9. The aqueous copper-iodine battery according to claim 6, wherein In step (2), the drying temperature is 50-150°C.

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