Preparation method and application of hydrophobic zinc ion conductor perfluorotetradecanoic acid-LaF3 film

Abstract

A preparation method and application of a hydrophobic zinc ion conductor perfluorotetradecanoic acid-LaF3 film, which belongs to the field of metallic zinc negative electrodes of aqueous zinc ion batteries. The present invention aims to solve the problem that the existing protective layer with nanometer-scale thickness cannot effectively guarantee rapid zinc ion transmission dynamics and uniform zinc ion deposition. Method: perfluorotetradecanoic acid solution is dripped onto the surface of a lanthanum nitrate aqueous solution, and then a sodium fluoride aqueous solution is injected into the bottom of the solution and allowed to stand at room temperature to obtain a hydrophobic zinc ion conductor perfluorotetradecanoic acid-LaF3 film at the interface between air and water. Application: It is used as an interface protective layer for zinc negative electrodes in aqueous zinc ion batteries. The present invention is used for the preparation of a hydrophobic zinc ion conductor perfluorotetradecanoic acid-LaF3 film and its application.

Description

Technical Field

[0001] The invention belongs to the field of metallic zinc negative electrodes of aqueous zinc ion batteries. Background Art

[0002] Aqueous zinc-ion batteries (Zn-ion batteries) have become a growing research hotspot due to their safety and low cost. However, the slow Zn-ion transport dynamics and uneven electric field distribution on the Zn negative electrode surface can lead to uncontrolled dendrite growth, seriously affecting the cycle life of aqueous Zn-ion batteries. To effectively suppress dendrite growth at the source, existing technologies often construct an artificial Zn negative electrode interface protective layer on the Zn surface. However, the thickness of existing Zn negative electrode artificial interface protective layers is typically in the micrometer range, which lengthens the Zn-ion transport path and affects the battery's volumetric energy density. Even nanometer-thick protective layers cannot effectively guarantee fast Zn-ion transport dynamics and uniform Zn-ion deposition. Summary of the Invention

[0003] The present invention aims to solve the problem that the existing nanometer-thick protective layer cannot effectively ensure rapid zinc ion transmission dynamics and uniform zinc ion deposition, and further provides a preparation method and application of a hydrophobic zinc ion conductor perfluorotetradecanoic acid-LaF3 film.

[0004] A method for preparing a hydrophobic zinc ion conductor perfluorotetradecanoic acid-LaF3 film is carried out according to the following steps:

[0005] 1. Add perfluorotetradecanoic acid to a mixed solution of chloroform and methanol, stir and dissolve to obtain a perfluorotetradecanoic acid solution; add lanthanum nitrate powder to secondary water, stir and dissolve to obtain a lanthanum nitrate aqueous solution; add sodium fluoride powder to secondary water, stir and dissolve to obtain a sodium fluoride aqueous solution;

[0006] Second, a perfluorotetradecanoic acid solution was added dropwise onto the surface of the lanthanum nitrate aqueous solution at a drop rate of 2 μL / s to 5 μL / s, and then a sodium fluoride aqueous solution was injected into the bottom of the solution at an injection rate of 1 mL / s to 2 mL / s and allowed to stand at room temperature to obtain a hydrophobic zinc ion conductor perfluorotetradecanoic acid-LaF3 film at the air-water interface;

[0007] The molar ratio of lanthanum nitrate in the lanthanum nitrate aqueous solution to perfluorotetradecanoic acid in the perfluorotetradecanoic acid solution is 1:(0.0001-0.0002); the molar ratio of lanthanum nitrate in the lanthanum nitrate aqueous solution to sodium fluoride in the sodium fluoride aqueous solution is 1:(3-4).

[0008] Application of hydrophobic zinc ion conductor perfluorotetradecanoic acid-LaF3 membrane, which is used as the interfacial protective layer of zinc negative electrode in aqueous zinc ion batteries.

[0009] The beneficial effects of the present invention are:

[0010] The present invention uses a surfactant as a soft template to induce LaF3 to connect into a dense and uniform nanofilm at the air-water interface, providing an organic-inorganic composite material and a hydrophobic zinc ion conductor membrane CF-LaF3 that can be prepared on a large scale for zinc negative electrode protection in aqueous zinc ion batteries. It should be emphasized that the template agent perfluorotetradecanoic acid used in the present invention induces lanthanum fluoride to form a continuous nanofilm with a crystalline structure and continuous zinc transfer channels. Its composition structure is perfluorotetradecanoic acid on the surface and lanthanum fluoride at the bottom. The surface perfluorotetradecanoic acid active agent monolayer is exposed, which is hydrophobic and promotes Zn(H2O)6 2+ After desolvation, the lanthanum fluoride at the bottom has a uniform zinc ion transmission channel, which accelerates zinc ion transmission and induces uniform zinc ion deposition. The two components synergistically improve the zinc ion transmission kinetics.

[0011] The present invention transfers the CF-LaF3 nanofilm to the surface of the zinc foil. Due to the zinc-affinity transmission channel inside the CF-LaF3 nanofilm, CF-LaF3 as a zinc negative electrode protective layer can significantly improve the Zn 2+ Transport dynamics. In addition, the hydrophobic properties of the CF-LaF3 nanomembrane surface accelerate the desolvation process of zinc ions at the interface, and further prevent the direct contact between the zinc negative electrode and active water, thereby inhibiting the corrosion of the zinc surface by the electrolyte. Due to the dense uniformity of the CF-LaF3 nanomembrane and the special zinc transport path, the overall electrochemical performance of the CF-LaF3 / Zn electrode is significantly improved. The hydrophobic zinc ion conductor perfluorotetradecanoic acid-LaF3 film is transferred to the surface of a zinc foil with a thickness of 150μm to 250μm to obtain CF-LaF3 / Zn. CF-LaF3 / Zn is used as the positive and negative electrodes to assemble a CF-LaF3 / Zn||CF-LaF3 / Zn symmetrical battery. At a current density of 5mA / cm 2 and an area capacity of 1 mAh / cm 2 The symmetrical battery was stably cycled for more than 4000h under the condition of 100 nm. The hydrophobic zinc ion conductor perfluorotetradecanoic acid-LaF3 film was transferred to the surface of a thin zinc foil with a thickness of 30 μm to obtain CF-LaF3 / Zn. CF-LaF3 / Zn was used as the positive and negative electrodes to assemble the CF-LaF3 / Zn||CF-LaF3 / Zn symmetrical battery. At a current density of 2 mA / cm 2 and area capacity of 10 mAh / cm 2Under the condition that the zinc utilization rate is 67%, the symmetrical battery can be stably cycled for more than 240h; the hydrophobic zinc ion conductor perfluorotetradecanoic acid-LaF3 film is transferred to the surface of zinc foil with a thickness of 150μm to 250μm to obtain CF-LaF3 / Zn, and the hydrophobic zinc ion conductor perfluorotetradecanoic acid-LaF3 film is transferred to the surface of titanium foil with a thickness of 5μm to 15μm to obtain CF-LaF3 / Ti. CF-LaF3 / Ti is used as the positive electrode and CF-LaF3 / Zn as the negative electrode to assemble the CF-LaF3 / Zn||CF-LaF3 / Ti half-cell. At a current density of 5mA / cm 2 and area capacity of 1 mAh / cm 2 The half-cell can be stably cycled for more than 6000 times, with a cumulative cycle area capacity of 6000mAh / cm 2 In summary, the CF-LaF3 nanofilm prepared by the present invention has a good zinc negative electrode protection effect.

[0012] Figures in the specification

[0013] Figure 1 This is an optical microscope photograph of the CF-LaF3 nanofilm prepared in Example 1 over a large area;

[0014] Figure 2 Transmission electron microscopy of the CF-LaF3 nanofilm prepared in Example 1 and the corresponding element distribution map;

[0015] Figure 3 This is an atomic force microscope image of the CF-LaF3 nanofilm prepared in Example 1;

[0016] Figure 4 The powder X-ray diffraction and transmission electron microscopy images of the CF-LaF3 nanofilm prepared in Example 1;

[0017] Figure 5 This is a three-dimensional time-of-flight secondary ion mass spectrometry spectrum of the zinc negative electrode with a CF-LaF3 protective layer prepared in Example 2;

[0018] Figure 6 XPS graphs of different depths of the zinc negative electrode with a CF-LaF3 protective layer prepared in Example 2, a is the F1s spectrum, b is the La3d spectrum, and c is the Zn2p spectrum;

[0019] Figure 7 Static contact angle test of the zinc negative electrode with CF-LaF3 protective layer prepared in Example 2 and bare zinc;

[0020] Figure 8 SEM images of the zinc negative electrode with a CF-LaF3 protective layer and bare zinc prepared in Example 2 after being immersed in a 2 mol / L zinc sulfate aqueous solution for 6 days;

[0021] Figure 9 This is a DFT theoretical calculation simulation diagram of the CF-LaF3 nanofilm prepared in Example 1;

[0022] Figure 10 The CF-LaF3 / Zn||CF-LaF3 / Zn symmetrical battery (zinc foil thickness of 200 μm) assembled in Example 2 was tested at a current density of 5 mA / cm 2 and an area capacity of 1 mAh / cm 2 The long cycle diagram below;

[0023] Figure 11 For comparison, the Zn||Zn symmetric battery (Zn foil thickness is 200 μm) assembled in experiment 1 was tested at a current density of 5 mA / cm 2 and an area capacity of 1 mAh / cm 2 The cycle diagram below;

[0024] Figure 12 At a current density of 2 mA / cm 2 and an area capacity of 10 mAh / cm 2 Below is the cycle performance diagram of the deep charge and discharge zinc utilization rate of 67% of the CF-LaF3 / Zn||CF-LaF3 / Zn symmetrical battery (zinc foil thickness is 30 μm) assembled in Example 2;

[0025] Figure 13 At a current density of 2 mA / cm 2 and an area capacity of 10 mAh / cm 2 Below is the cycle performance diagram of the Zn||Zn symmetric battery (zinc foil thickness is 30μm) assembled in comparative experiment 1 with a deep charge and discharge zinc utilization rate of 67%;

[0026] Figure 14 The CF-LaF3 / Zn||CF-LaF3 / Ti half-cell assembled in Example 3 was tested at a current density of 5 mA / cm 2 and area capacity of 1 mAh / cm 2 The long cycle diagram below;

[0027] Figure 15 For comparison, the Zn||Ti half-cell assembled in Experiment 2 was tested at a current density of 5 mA / cm 2 and area capacity of 1 mAh / cm 2 The cycle diagram below;

[0028] Figure 16 Linear sweep voltammetry (LSV) test diagrams of the CF-LaF3 / Zn||CF-LaF3 / Ti half-cell assembled in Example 3 and the Zn||Ti half-cell assembled in Comparative Experiment 2, a is hydrogen evolution, b is oxygen evolution;

[0029] Figure 17 Activation energy test results for the CF-LaF3 / Zn||CF-LaF3 / Zn symmetrical battery (zinc foil thickness of 200 μm) assembled in Example 2 and the Zn||Zn symmetrical battery (zinc foil thickness of 200 μm) assembled in Comparative Experiment 1;

[0030] Figure 18 Scanning morphology images of the negative electrode after cycling of the CF-LaF3 / Zn||CF-LaF3 / Zn symmetric battery (zinc foil thickness is 200 μm) assembled in Example 2 and the Zn||Zn symmetric battery (zinc foil thickness is 200 μm) assembled in Comparative Experiment 1;

[0031] Figure 19 These are in-situ optical microscope images of the negative electrode deposition after cycling of the CF-LaF3 / Zn||CF-LaF3 / Zn symmetric battery (zinc foil thickness is 200 μm) assembled in Example 2 and the Zn||Zn symmetric battery (zinc foil thickness is 200 μm) assembled in Comparative Experiment 1. DETAILED DESCRIPTION

[0032] Specific embodiment 1: This embodiment is a method for preparing a hydrophobic zinc ion conductor perfluorotetradecanoic acid-LaF3 film, which is carried out according to the following steps:

[0033] 1. Add perfluorotetradecanoic acid to a mixed solution of chloroform and methanol, stir and dissolve to obtain a perfluorotetradecanoic acid solution; add lanthanum nitrate powder to secondary water, stir and dissolve to obtain a lanthanum nitrate aqueous solution; add sodium fluoride powder to secondary water, stir and dissolve to obtain a sodium fluoride aqueous solution;

[0034] Second, a perfluorotetradecanoic acid solution was added dropwise onto the surface of the lanthanum nitrate aqueous solution at a drop rate of 2 μL / s to 5 μL / s, and then a sodium fluoride aqueous solution was injected into the bottom of the solution at an injection rate of 1 mL / s to 2 mL / s and allowed to stand at room temperature to obtain a hydrophobic zinc ion conductor perfluorotetradecanoic acid-LaF3 film at the air-water interface;

[0035] The molar ratio of lanthanum nitrate in the lanthanum nitrate aqueous solution to perfluorotetradecanoic acid in the perfluorotetradecanoic acid solution is 1:(0.0001-0.0002); the molar ratio of lanthanum nitrate in the lanthanum nitrate aqueous solution to sodium fluoride in the sodium fluoride aqueous solution is 1:(3-4).

[0036] The beneficial effects of this embodiment are:

[0037] This embodiment uses a surfactant as a soft template to induce LaF3 to connect into a dense and uniform nanofilm at the air-water interface, providing an organic-inorganic composite material and a hydrophobic zinc ion conductor membrane CF-LaF3 that can be prepared on a large scale for zinc negative electrode protection in aqueous zinc ion batteries. It should be emphasized that the template agent perfluorotetradecanoic acid used in this embodiment induces lanthanum fluoride to form a continuous nanofilm with a crystalline structure and continuous zinc transfer channels. Its composition structure is perfluorotetradecanoic acid on the surface and lanthanum fluoride at the bottom. The surface perfluorotetradecanoic acid active agent monolayer is exposed, which is hydrophobic and promotes Zn(H2O)6 2+ After desolvation, the lanthanum fluoride at the bottom has a uniform zinc ion transmission channel, which accelerates zinc ion transmission and induces uniform zinc ion deposition. The two components synergistically improve the zinc ion transmission kinetics.

[0038] In this embodiment, the CF-LaF3 nanofilm is transferred to the surface of the zinc foil. Due to the zinc-affinity transmission channel inside the CF-LaF3 nanofilm, CF-LaF3 as a zinc negative electrode protective layer can significantly increase the Zn 2+ Transport dynamics. In addition, the hydrophobic properties of the CF-LaF3 nanomembrane surface accelerate the desolvation process of zinc ions at the interface, and further prevent the direct contact between the zinc negative electrode and active water, thereby inhibiting the corrosion of the zinc surface by the electrolyte. Due to the dense uniformity of the CF-LaF3 nanomembrane and the special zinc transport path, the overall electrochemical performance of the CF-LaF3 / Zn electrode is significantly improved. The hydrophobic zinc ion conductor perfluorotetradecanoic acid-LaF3 film is transferred to the surface of a zinc foil with a thickness of 150μm to 250μm to obtain CF-LaF3 / Zn. CF-LaF3 / Zn is used as the positive and negative electrodes to assemble a CF-LaF3 / Zn||CF-LaF3 / Zn symmetrical battery. At a current density of 5mA / cm 2 and an area capacity of 1 mAh / cm 2 The symmetrical battery was stably cycled for more than 4000h under the condition of 100 nm. The hydrophobic zinc ion conductor perfluorotetradecanoic acid-LaF3 film was transferred to the surface of a thin zinc foil with a thickness of 30 μm to obtain CF-LaF3 / Zn. CF-LaF3 / Zn was used as the positive and negative electrodes to assemble the CF-LaF3 / Zn||CF-LaF3 / Zn symmetrical battery. At a current density of 2 mA / cm 2 and area capacity of 10 mAh / cm 2Under the condition that the zinc utilization rate is 67%, the symmetrical battery can be stably cycled for more than 240h; the hydrophobic zinc ion conductor perfluorotetradecanoic acid-LaF3 film is transferred to the surface of zinc foil with a thickness of 150μm to 250μm to obtain CF-LaF3 / Zn, and the hydrophobic zinc ion conductor perfluorotetradecanoic acid-LaF3 film is transferred to the surface of titanium foil with a thickness of 5μm to 15μm to obtain CF-LaF3 / Ti. CF-LaF3 / Ti is used as the positive electrode and CF-LaF3 / Zn as the negative electrode to assemble the CF-LaF3 / Zn||CF-LaF3 / Ti half-cell. At a current density of 5mA / cm 2 and area capacity of 1 mAh / cm 2 The half-cell can be stably cycled for more than 6000 times, with a cumulative cycle area capacity of 6000mAh / cm 2 In summary, the CF-LaF3 nanofilm prepared by the present invention has a good zinc negative electrode protection effect.

[0039] Specific embodiment 2: This embodiment differs from specific embodiment 1 in that the concentration of the perfluorotetradecanoic acid solution in step 1 is 1.5 mmol / mL to 2.5 mmol / mL; and the volume ratio of chloroform to methanol in the mixed solution of chloroform and methanol in step 1 is (2-4):1. Other aspects are the same as specific embodiment 1.

[0040] Specific embodiment 3: This embodiment differs from specific embodiment 1 or 2 in that the concentration of the lanthanum nitrate aqueous solution in step 1 is 150 mmol / mL to 250 mmol / mL. Other aspects are the same as specific embodiment 1 or 2.

[0041] Specific embodiment 4: This embodiment differs from specific embodiments 1 to 3 in that the concentration of the sodium fluoride aqueous solution in step 1 is 150 mmol / mL to 250 mmol / mL. Other aspects are the same as specific embodiments 1 to 3.

[0042] Specific embodiment 5: This embodiment differs from specific embodiments 1 to 4 in that the step 2 is left to stand at room temperature for 20 to 28 hours. Other aspects are the same as specific embodiments 1 to 4.

[0043] Specific embodiment 6: This embodiment differs from specific embodiments 1 to 5 in that the hydrophobic zinc ion conductor perfluorotetradecanoic acid-LaF3 membrane described in step 2 is composed of perfluorotetradecanoic acid on the surface and lanthanum fluoride on the bottom. Other aspects are the same as specific embodiments 1 to 5.

[0044] Specific embodiment seven: This embodiment differs from any one of specific embodiments one to six in that: the bottom lanthanum fluoride has a uniform zinc ion transmission channel, which improves the Zn 2+Transport dynamics; the surface perfluorotetradecanoic acid is hydrophobic, promoting Zn(H2O)6 2+ Desolvation. Other aspects are the same as those of the first to sixth embodiments.

[0045] Specific embodiment 8: This embodiment differs from specific embodiments 1 to 7 in that the thickness of the hydrophobic zinc ion conductor perfluorotetradecanoic acid-LaF3 film in step 2 is 60 nm to 80 nm. Other aspects are the same as specific embodiments 1 to 7.

[0046] Specific embodiment 9: The application of the hydrophobic zinc ion conductor perfluorotetradecanoic acid-LaF3 membrane of this embodiment is characterized in that it is used as an interface protection layer of the zinc negative electrode in an aqueous zinc ion battery.

[0047] Specific embodiment ten: This embodiment differs from specific embodiment nine in that: a hydrophobic zinc ion conductor perfluorotetradecanoic acid-LaF3 film is transferred to the surface of a zinc foil with a thickness of 150 μm to 250 μm to obtain CF-LaF3 / Zn, and CF-LaF3 / Zn is used as the positive and negative electrodes to assemble a CF-LaF3 / Zn||CF-LaF3 / Zn symmetrical battery. At a current density of 5 mA / cm 2 and an area capacity of 1 mAh / cm 2 Under this condition, the symmetrical battery can cycle stably for more than 4000h;

[0048] The hydrophobic zinc ion conductor perfluorotetradecanoic acid-LaF3 film was transferred to the surface of a thin zinc foil with a thickness of 30 μm to obtain CF-LaF3 / Zn. CF-LaF3 / Zn was used as the positive and negative electrodes to assemble a CF-LaF3 / Zn||CF-LaF3 / Zn symmetrical battery. At a current density of 2 mA / cm 2 and area capacity of 10 mAh / cm 2 Under this condition, when the zinc utilization rate is 67%, the symmetrical battery can be stably cycled for more than 240 hours;

[0049] The hydrophobic zinc ion conductor perfluorotetradecanoic acid-LaF3 film was transferred to the surface of zinc foil with a thickness of 150μm to 250μm to obtain CF-LaF3 / Zn. The hydrophobic zinc ion conductor perfluorotetradecanoic acid-LaF3 film was transferred to the surface of titanium foil with a thickness of 5μm to 15μm to obtain CF-LaF3 / Ti. CF-LaF3 / Ti was used as the positive electrode and CF-LaF3 / Zn as the negative electrode to assemble the CF-LaF3 / Zn||CF-LaF3 / Ti half-cell. The reaction was carried out at a current density of 5mA / cm 2 and area capacity of 1 mAh / cm 2 The half-cell can be stably cycled for more than 6000 times, with a cumulative cycle area capacity of 6000mAh / cm 2The rest is the same as the ninth embodiment.

[0050] The following examples are used to verify the beneficial effects of the present invention:

[0051] Example 1:

[0052] A method for preparing a hydrophobic zinc ion conductor perfluorotetradecanoic acid-LaF3 film is carried out according to the following steps:

[0053] 1. Add perfluorotetradecanoic acid to a mixed solution of chloroform and methanol, stir and dissolve to obtain a perfluorotetradecanoic acid solution; add lanthanum nitrate powder to secondary water, stir and dissolve to obtain a lanthanum nitrate aqueous solution; add sodium fluoride powder to secondary water, stir and dissolve to obtain a sodium fluoride aqueous solution;

[0054] Second, a lanthanum nitrate aqueous solution was added to a culture dish with a diameter of 6 cm. A perfluorotetradecanoic acid solution was added dropwise onto the surface of the lanthanum nitrate aqueous solution at a drop rate of 5 μL / s. Then, a sodium fluoride aqueous solution was injected into the bottom of the solution at an injection rate of 2 mL / s and the solution was allowed to stand at room temperature for 20 hours to obtain a hydrophobic zinc ion conductor perfluorotetradecanoic acid-LaF3 film, i.e., a CF-LaF3 nanomembrane, at the air-water interface.

[0055] The molar ratio of lanthanum nitrate in the lanthanum nitrate aqueous solution to perfluorotetradecanoic acid in the perfluorotetradecanoic acid solution is 1:0.00012; the molar ratio of lanthanum nitrate in the lanthanum nitrate aqueous solution to sodium fluoride in the sodium fluoride aqueous solution is 1:3.

[0056] The concentration of the perfluorotetradecanoic acid solution described in step 1 is 1.8 mmol / mL; the volume ratio of chloroform to methanol in the mixed solution of chloroform and methanol described in step 1 is 3:1.

[0057] The concentration of the lanthanum nitrate aqueous solution described in step 1 is 200 mmol / mL.

[0058] The concentration of the sodium fluoride aqueous solution described in step 1 is 200 mmol / mL.

[0059] The hydrophobic zinc ion conductor perfluorotetradecanoic acid-LaF3 membrane described in step 2 is composed of perfluorotetradecanoic acid on the surface and lanthanum fluoride on the bottom;

[0060] The bottom lanthanum fluoride has a uniform zinc ion transmission channel, which improves the Zn 2+ Transport dynamics; the surface perfluorotetradecanoic acid is hydrophobic, promoting Zn(H2O)6 2+ Desolvation.

[0061] The diameter of the CF-LaF3 nanofilm described in step 2 is 6 cm, the thickness is 70 nm and the thickness is uniform, and the roughness is about 1 nm.

[0062] In the second embodiment, the aqueous zinc ion battery is a Zn||Zn symmetrical battery:

[0063] 1. The surface of the zinc sheet was polished smooth using 800-mesh and 2000-mesh sandpaper, respectively. The CF-LaF3 nanofilm prepared in Example 1 was then transferred to the polished surface of the zinc sheet and cut into small discs with an area of ​​0.785 square centimeters to obtain a zinc negative electrode with a CF-LaF3 protective layer and a zinc positive electrode with a CF-LaF3 protective layer;

[0064] 2. Assemble a button cell in the order of a negative electrode, a negative electrode shell, a spring, a gasket, a separator, an electrolyte, a positive electrode, and a positive electrode shell, wherein the positive electrode is a zinc positive electrode with a CF-LaF3 protective layer, the separator is a glass fiber membrane, the electrolyte is a 2 mol / L zinc sulfate aqueous solution, and the negative electrode is a zinc negative electrode with a CF-LaF3 protective layer, to obtain a CF-LaF3 / Zn||CF-LaF3 / Zn symmetrical cell;

[0065] The thickness of the zinc sheets are 200 μm and 30 μm respectively;

[0066] When a symmetrical battery is assembled using a 200 μm thick zinc sheet, the current density is 5 mA / cm 2 and an area capacity of 1 mAh / cm 2 The CF-LaF3 / Zn||CF-LaF3 / Zn symmetrical battery assembled in Example 2 was subjected to a constant current charge-discharge long cycle test.

[0067] When a symmetrical battery is assembled using a zinc sheet with a thickness of 30 μm, the current density is 2 mA / cm 2 and area capacity of 10 mAh / cm 2 Under the conditions of CF-LaF3||CF-LaF3 symmetrical battery assembled in Example 2, a deep charge and discharge cycle test was carried out, and the DOD value was as high as 67%.

[0068] Example 3: Aqueous zinc ion battery is a Zn||Ti half-cell:

[0069] 1. The CF-LaF3 nanofilm prepared in Example 1 was transferred onto a titanium foil with a thickness of 10 μm to obtain a titanium positive electrode protected by the CF-LaF3 nanofilm; the surface of a zinc sheet with a thickness of 200 μm was polished smooth using sandpaper, and then the CF-LaF3 nanofilm prepared in Example 1 was transferred onto the polished zinc sheet to obtain a zinc negative electrode protected by the CF-LaF3 nanofilm;

[0070] 2. Assemble a button cell in the order of negative electrode, negative electrode shell, spring, gasket, separator, electrolyte, positive electrode and positive electrode shell, wherein the negative electrode is a zinc negative electrode protected by a CF-LaF3 nanofilm, the separator is a glass fiber membrane, the electrolyte is a 2 mol / L zinc sulfate aqueous solution, and the positive electrode is a titanium positive electrode protected by a CF-LaF3 nanofilm, and assemble a CF-LaF3 / Zn||CF-LaF3 / Ti half-cell;

[0071] At a current density of 5 mA / cm 2 and area capacity of 1 mAh / cm 2 The CF-LaF3 / Zn||CF-LaF3 / Ti half-cell assembled in Example 3 was subjected to a constant current charge-discharge long cycle test.

[0072] Comparative Experiment 1: This embodiment differs from the second embodiment in that the positive and negative electrodes are both polished ordinary zinc sheets. Other aspects are the same as the second embodiment.

[0073] Comparative Experiment 2: This embodiment differs from the third embodiment in that the positive electrode is a common titanium foil and the negative electrode is a polished common zinc sheet. Other aspects are the same as the third embodiment.

[0074] CF-LaF3 nanofilm transfer process prepared by embodiment one: to be prepared with CF-LaF3 nanofilm culture dish (diameter is 6cm) slowly put into the large glass watch glass container that is 20cm in diameter, secondary water is slowly injected along the edge of the 6cm culture dish, along with the continuous adding of secondary water, CF-LaF3 nanofilm interface is slowly lifted and rises to the height consistent with the 6cm culture dish.Then in the 20cm watch glass container, inject secondary water until the water surface does not cover the 6cm culture dish, now CF-LaF3 nanofilm will slowly drift out from the 6cm culture dish and float on the interface of the 20cm watch glass water, successfully nanofilm is transferred out, subsequently solid substrate (such as zinc sheet, titanium foil) is slowly extended into the CF-LaF3 bottom of nanofilm floating on the water surface, slowly upwards lift and break away from the water surface, CF-LaF3 nanofilm will be transferred to the solid substrate, and bottom lanthanum fluoride contacts the solid substrate.

[0075] Figure 1 This is an optical microscope photograph of a large area of ​​the CF-LaF3 nanofilm prepared in Example 1. As can be seen from the figure, the nanofilm has a uniform morphology over a large area.

[0076] Figure 2 This is a transmission electron microscope image of the CF-LaF3 nanofilm prepared in Example 1 and the corresponding element distribution diagram; it can be seen from the figure that the elements La, F and C are evenly distributed in the nanofilm.

[0077] Depend on Figure 2 and Figure 3 It can be seen that the CF-LaF3 nanofilm prepared in Example 1 forms a uniform and continuous zinc ion transmission channel.

[0078] Figure 3 This is an atomic force microscope image of the CF-LaF3 nanofilm prepared in Example 1; as can be seen from the image, the thickness of the nanofilm is 70nm.

[0079] Figure 4 The powder X-ray diffraction and transmission electron microscopy images of the CF-LaF3 nanofilm prepared in Example 1 are shown. As can be seen from the figure, the prepared CF-LaF3 nanofilm has a good correspondence with the hexagonal phase LaF3 of the standard card. At the same time, the clear lattice fringes in the transmission electron microscope also prove that the prepared film is polycrystalline.

[0080] Figure 5 This is a three-dimensional spectrum of the time-of-flight secondary ion mass spectrometry of the zinc negative electrode with a CF-LaF3 protective layer prepared in Example 2; as can be seen from the figure, the CF-LaF3 nanofilm on the surface of the zinc substrate shows a visualized organic-inorganic hybrid component, which is composed of perfluorotetradecanoic acid on the surface and lanthanum fluoride at the bottom.

[0081] Figure 6 The XPS images of the zinc negative electrode with a CF-LaF3 protective layer prepared in Example 2 at different depths are shown in Figures a and c. The F1s spectrum, b, La3d spectrum, and Zn2p spectrum are shown. The organic CF bond (689.5 eV) and the inorganic La-F bond (685.29 eV) appear first, followed by the disappearance of the organic CF bond and the enhancement of the inorganic La-F bond over time. Furthermore, as etching time increases, the peaks of the zinc substrate (1044 eV, 1021 eV) become increasingly prominent. These characterizations demonstrate the organic-inorganic hybrid composition of the CF-LaF3 nanofilm on the zinc substrate.

[0082] Figure 7 Static contact angle test of the zinc negative electrode with CF-LaF3 protective layer and bare zinc prepared in Example 2; as can be seen from the figure, the contact angles of the zinc sheet protected by CF-LaF3 nanofilm and bare zinc with 2 mol / L zinc sulfate aqueous solution are 116° and 74°, respectively, indicating that the nanofilm surface is hydrophobic.

[0083] Figure 8SEM images of the zinc anode with a CF-LaF3 protective layer prepared in Example 2 and bare zinc after being immersed in a 2 mol / L zinc sulfate solution for 6 days. The images show that the bare zinc surface forms a byproduct, Zn4SO4(OH)6·5H2O (ZHS), due to direct corrosion from the electrolyte. In contrast, the CF-LaF3 / Zn layer effectively suppresses the formation of ZHS byproducts, demonstrating the electrolyte barrier properties of the CF-LaF3 nanofilm.

[0084] Figure 9 This is a DFT theoretical calculation simulation diagram of the CF-LaF3 nanomembrane prepared in Example 1; it simulates the diffusion path of zinc ions in the LaF3 open framework within the nanomembrane, among which the migration path of zinc ions from Zn1 to Zn9 is simulated, proving the orderly migration of zinc ions through the LaF3 pores.

[0085] Figure 10 The CF-LaF3 / Zn||CF-LaF3 / Zn symmetrical battery (zinc foil thickness of 200 μm) assembled in Example 2 was tested at a current density of 5 mA / cm 2 and an area capacity of 1 mAh / cm 2 The long cycle diagram below; it can be seen from the figure that the CF-LaF3 / Zn||CF-LaF3 / Zn symmetric battery has a cycle life of up to 4000h, proving that the CF-LaF3 protective layer can effectively improve the performance of the symmetric battery.

[0086] Figure 11 For comparison, the Zn||Zn symmetric battery (Zn foil thickness is 200 μm) assembled in experiment 1 was tested at a current density of 5 mA / cm 2 and an area capacity of 1 mAh / cm 2 The cycle diagram below; it can be seen from the figure that the Zn||Zn symmetric battery has a cycle life of only 550h.

[0087] Figure 12 At a current density of 2 mA / cm 2 and an area capacity of 10 mAh / cm 2 Below is the cycle performance diagram of the deep charge and discharge zinc utilization rate of the CF-LaF3 / Zn||CF-LaF3 / Zn symmetrical battery (zinc foil thickness is 30μm) assembled in Example 2; it can be seen from the figure that the CF-LaF3 / Zn||CF-LaF3 / Zn symmetrical battery can still operate stably for 240h under relatively harsh conditions, proving the ability of the CF-LaF3 nanofilm to effectively inhibit dendrites on the metallic zinc negative electrode.

[0088] Figure 13 At a current density of 2 mA / cm 2 and an area capacity of 10 mAh / cm 2Below is a cycle performance diagram of the Zn||Zn symmetrical battery (zinc foil thickness is 30μm) assembled in comparative experiment 1 with a deep charge and discharge zinc utilization rate of 67%; it can be seen from the figure that the Zn||Zn symmetrical battery assembled with bare zinc is difficult to operate normally under harsh conditions.

[0089] Figure 14 The CF-LaF3 / Zn||CF-LaF3 / Ti half-cell assembled in Example 3 was tested at a current density of 5 mA / cm 2 and area capacity of 1 mAh / cm 2 The long cycle diagram below shows that the CF-LaF3 / Zn||CF-LaF3 / Ti half-cell can operate stably for more than 6000 cycles, with a cumulative capacity of more than 6000 mAh / cm 2 , proving that the CF-LaF3 nanofilm can quickly conduct uniform zinc ion flux deposited on the titanium foil, and effectively inhibit the dendrite growth on the zinc negative electrode side. At the same time, the hydrophobic protective layer can effectively inhibit the corrosion of the electrolyte on the electrode, thereby significantly improving the cycle life of the zinc ion battery.

[0090] Figure 15 For comparison, the Zn||Ti half-cell assembled in Experiment 2 was tested at a current density of 5 mA / cm 2 and area capacity of 1 mAh / cm 2 The cycle diagram below shows that due to the slow accumulation of zinc dendrites and the generation of insulating byproducts, the Zn||Ti half-cell assembled with unprotected titanium foil and zinc foil can only cycle normally for 187 cycles.

[0091] Figure 16 The linear sweep voltammetry test diagram (LSV) of the CF-LaF3 / Zn||CF-LaF3 / Ti half-cell assembled in Example 3 and the Zn||Ti half-cell assembled in Comparative Experiment 2, a is hydrogen evolution, b is oxygen evolution; it can be seen from the figure that compared with the unprotected bare zinc battery system, the CF-LaF3 nanofilm protected zinc battery body has a wider electrochemical window, which widens the hydrogen evolution potential from -85mV to -100mV and the oxygen evolution potential from 2.55V to 2.7V.

[0092] Figure 17 The activation energy test results of the CF-LaF3 / Zn||CF-LaF3 / Zn symmetrical battery (zinc foil thickness of 200μm) assembled in Example 2 and the Zn||Zn symmetrical battery (zinc foil thickness of 200μm) assembled in Comparative Experiment 1 are shown in the figure. As shown in the figure, the activation energy obtained by fitting the impedance at different temperatures based on the Arrhenius equation is smaller than the activation energy of bare zinc (57J / mol) in the activation energy of CF-LaF3 / Zn interface desolvation (45kJ / mol), indicating that the CF-LaF3 nanofilm accelerates the Zn(H2O)62+ The process of desolvation.

[0093] The symmetrical CF-LaF3 / Zn||CF-LaF3 / Zn battery (zinc foil thickness of 200 μm) assembled in Example 2 and the symmetrical Zn||Zn battery (zinc foil thickness of 200 μm) assembled in Comparative Experiment 1 were tested at a current density of 10 mA / cm 2 and area capacity of 1 mAh / cm 2 30 and 60 cycles respectively under the conditions of Figure 18 The negative electrode scanning morphology of the CF-LaF3 / Zn||CF-LaF3 / Zn symmetrical battery (zinc foil thickness of 200μm) assembled in Example 2 and the Zn||Zn symmetrical battery (zinc foil thickness of 200μm) assembled in Comparative Experiment 1 after cycling; the scanning image shows that compared with bare zinc, the electrode surface protected by the CF-LaF3 nanofilm is smooth and flat, and no by-products are generated. This indicates that the nanofilm with uniformly distributed zinc ion transport channels is beneficial to Zn 2+ Uniform deposition of ions and effective suppression of the generation of by-products.

[0094] The symmetrical CF-LaF3 / Zn||CF-LaF3 / Zn battery (zinc foil thickness of 200 μm) assembled in Example 2 and the symmetrical Zn||Zn battery (zinc foil thickness of 200 μm) assembled in Comparative Experiment 1 were tested at a current density of 20 mA / cm 2 and area capacity of 1 mAh / cm 2 The cycles were 30 min and 50 min respectively under the conditions of Figure 19 In-situ optical microscopy images of the negative electrode deposition after cycling for the CF-LaF3 / Zn||CF-LaF3 / Zn symmetric cell (zinc foil thickness 200μm) assembled in Example 2 and the Zn|Zn symmetric cell (zinc foil thickness 200μm) assembled in Comparative Experiment 1. As can be seen from the figure, tiny protrusions appear on the surface of the bare zinc electrode at 30 minutes. After 50 minutes, the protrusions become significantly larger, accompanied by continuous gas evolution. In contrast, the CF-LaF3 / Zn electrode maintains a uniform and dense zinc deposition morphology for up to 50 minutes, indicating that the CF-LaF3 nanofilm can induce uniform zinc deposition and effectively inhibit hydrogen evolution.

Claims

1. A method for preparing a hydrophobic zinc ion conductor perfluorotetradecanoic acid-LaF3 film, characterized in that It is carried out in the following steps:

1. Add perfluorotetradecanoic acid to a mixed solution of chloroform and methanol, stir and dissolve to obtain a perfluorotetradecanoic acid solution; add lanthanum nitrate powder to secondary water, stir and dissolve to obtain a lanthanum nitrate aqueous solution; add sodium fluoride powder to secondary water, stir and dissolve to obtain a sodium fluoride aqueous solution; Second, a perfluorotetradecanoic acid solution was added dropwise onto the surface of the lanthanum nitrate aqueous solution at a drop rate of 2 μL / s to 5 μL / s, and then a sodium fluoride aqueous solution was injected into the bottom of the solution at an injection rate of 1 mL / s to 2 mL / s and allowed to stand at room temperature to obtain a hydrophobic zinc ion conductor perfluorotetradecanoic acid-LaF3 film at the air-water interface; The molar ratio of lanthanum nitrate in the lanthanum nitrate aqueous solution to perfluorotetradecanoic acid in the perfluorotetradecanoic acid solution is 1:(0.0001-0.0002); the molar ratio of lanthanum nitrate in the lanthanum nitrate aqueous solution to sodium fluoride in the sodium fluoride aqueous solution is 1:(3-4).

2. The method for preparing a hydrophobic zinc ion conductor perfluorotetradecanoic acid-LaF3 film according to claim 1, characterized in that The concentration of the perfluorotetradecanoic acid solution described in step 1 is 1.5 mmol / mL to 2.5 mmol / mL; the volume ratio of chloroform to methanol in the mixed solution of chloroform and methanol described in step 1 is (2 to 4):

1.

3. The method for preparing a hydrophobic zinc ion conductor perfluorotetradecanoic acid-LaF3 film according to claim 1, characterized in that The concentration of the lanthanum nitrate aqueous solution described in step 1 is 150 mmol / mL to 250 mmol / mL.

4. The method for preparing a hydrophobic zinc ion conductor perfluorotetradecanoic acid-LaF3 film according to claim 1, characterized in that The concentration of the sodium fluoride aqueous solution in step 1 is 150 mmol / mL to 250 mmol / mL.

5. The method for preparing a hydrophobic zinc ion conductor perfluorotetradecanoic acid-LaF3 film according to claim 1, characterized in that In step 2, let it stand at room temperature for 20 to 28 hours.

6. The method for preparing a hydrophobic zinc ion conductor perfluorotetradecanoic acid-LaF3 film according to claim 1, characterized in that The hydrophobic zinc ion conductor perfluorotetradecanoic acid-LaF3 membrane described in step 2 is composed of perfluorotetradecanoic acid on the surface and lanthanum fluoride on the bottom.

7. The method for preparing a hydrophobic zinc ion conductor perfluorotetradecanoic acid-LaF3 film according to claim 6, characterized in that The bottom lanthanum fluoride has a uniform zinc ion transmission channel, which improves the Zn 2+ Transport dynamics; the surface perfluorotetradecanoic acid is hydrophobic, promoting Zn(H2O)6 2+ Desolvation.

8. The method for preparing a hydrophobic zinc ion conductor perfluorotetradecanoic acid-LaF3 film according to claim 1, characterized in that The thickness of the hydrophobic zinc ion conductor perfluorotetradecanoic acid-LaF3 film described in step 2 is 60nm to 80nm.

9. Use of the hydrophobic zinc ion conductor perfluorotetradecanoic acid-LaF3 membrane prepared as claimed in claim 1, characterized in that It is used as an interfacial protective layer for zinc anodes in aqueous zinc-ion batteries.

10. Use of the hydrophobic zinc ion conductor perfluorotetradecanoic acid-LaF3 membrane according to claim 9, characterized in that The hydrophobic zinc ion conductor perfluorotetradecanoic acid-LaF3 film was transferred to the surface of zinc foil with a thickness of 150μm to 250μm to obtain CF-LaF3 / Zn. CF-LaF3 / Zn was used as the positive and negative electrodes to assemble the CF-LaF3 / Zn||CF-LaF3 / Zn symmetrical battery. The battery was heated at a current density of 5mA / cm 2 and an area capacity of 1 mAh / cm 2 Under this condition, the symmetrical battery can cycle stably for more than 4000h; The hydrophobic zinc ion conductor perfluorotetradecanoic acid-LaF3 film was transferred to the surface of a thin zinc foil with a thickness of 30 μm to obtain CF-LaF3 / Zn. CF-LaF3 / Zn was used as the positive and negative electrodes to assemble a CF-LaF3 / Zn||CF-LaF3 / Zn symmetrical battery. At a current density of 2 mA / cm 2 and area capacity of 10 mAh / cm 2 Under this condition, when the zinc utilization rate is 67%, the symmetrical battery can be stably cycled for more than 240 hours; The hydrophobic zinc ion conductor perfluorotetradecanoic acid-LaF3 film was transferred to the surface of zinc foil with a thickness of 150μm to 250μm to obtain CF-LaF3 / Zn. The hydrophobic zinc ion conductor perfluorotetradecanoic acid-LaF3 film was transferred to the surface of titanium foil with a thickness of 5μm to 15μm to obtain CF-LaF3 / Ti. CF-LaF3 / Ti was used as the positive electrode and CF-LaF3 / Zn as the negative electrode to assemble the CF-LaF3 / Zn||CF-LaF3 / Ti half-cell. The reaction was carried out at a current density of 5mA / cm 2 and area capacity of 1 mAh / cm 2 The half-cell can be stably cycled for more than 6000 times, with a cumulative cycle area capacity of 6000mAh / cm 2 above.

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