A zinc battery system based on electrochemical solid-liquid interface phase transfer and its preparation method

Abstract

The present invention belongs to the field of electrochemical technology and discloses a zinc battery system based on electrochemical solid-liquid interface phase transfer and its preparation method. The system is composed of a hydrophobic interface layer composed of a hydrophobic organic matrix and a high ionic conductivity ionic liquid and a modified electrolyte. The zinc battery system is first constructed on the surface of zinc metal with a composite coating composed of an ionic liquid and a hydrophobic organic matrix to obtain a zinc battery negative electrode; then, an organic additive is added to a soluble zinc salt to obtain a modified electrolyte, and the zinc battery negative electrode and the modified electrolyte are composited to obtain. The ionic liquid of the present invention itself has good ionic conductivity and can achieve rapid Zn 2+ Transport dynamics, through the synergistic effect of electrolyte and hydrophobic interface layer, regulate the zinc negative electrode interface chemistry to achieve a stable solid-liquid interface, thereby significantly improving the cycle stability and safety performance of the battery.

Description

Technical Field

[0001] The present invention belongs to the field of electrochemical technology, and in particular relates to a zinc battery system based on electrochemical solid-liquid interface phase transfer and a preparation method thereof. Background Art

[0002] Lithium-ion batteries are currently widely used energy storage devices, but there are major bottlenecks in their further application. First, the scarcity of lithium resources and the large-scale consumption of lithium elements have limited the total production capacity of lithium batteries, and the high cost of battery raw materials has kept battery prices high; secondly, electrolytes and battery materials are highly toxic. Once leaked, they will not only pollute the environment but also cause harm to the human body, and at the same time make battery production conditions extremely harsh. In addition, the increasingly prominent news of short-circuit and spontaneous combustion of electric vehicle batteries has also cast a shadow on the development of lithium-ion batteries. Aqueous zinc-ion batteries have the advantages of low cost, abundant raw materials, high safety, high ionic conductivity and environmental friendliness. Compared with lithium-ion batteries, they are easier to design and manufacture and do not need to be manufactured under strict water-free and oxygen-free conditions. Therefore, they are a very ideal supplementary choice for lithium-ion batteries in the future. Zinc metal has a large theoretical capacity (820 mAh·g -1 、5855 mAh·cm -3 Advantages such as low redox potential (-0.76 V vs SHE) and abundant resources have helped aqueous zinc-ion batteries achieve high energy density. However, during the charge and discharge process, the zinc anode faces a series of problems such as dendrite growth and hydrogen evolution side reactions, which seriously limit the cycle life of aqueous zinc-ion batteries.

[0003] In response to the complex and diverse problems faced by zinc metal anodes during the electrodeposition process, researchers have developed a series of strategies to solve these problems. Some strategies have been widely used to improve the cycle life of zinc, such as designing new composite electrodes, electrolyte optimization, diaphragm modification, and electrodeposition regulation. The zinc anode protective coating is in direct contact with the area of ​​zinc deposition and side reactions, which can not only regulate the diffusion of zinc ions in the electrolyte, but also act as a selector for ions entering the coating. The adaptive coating on the zinc anode can inhibit a series of side reactions, such as the formation of zinc dendrites, passivation, hydrogen evolution, corrosion and morphological changes, etc., which can optimize zinc deposition and improve the working life of aqueous zinc ion batteries. Professor Chen Shimou of the Chinese Academy of Sciences proposed a multifunctional water-blocking zwitterionic liquid coating poly ([2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)-co-tert-butyl acrylate) as a zinc metal anode protective layer. Water-blocking tert-butyl acrylate can prevent water molecules from contacting the zinc metal anode, playing a key role in inhibiting hydrogen evolution reaction and corrosion. At the same time, the zwitterionic liquid part can regulate Zn 2+The solvation environment of Zn was modified to regulate the electrode / electrolyte interface and induce dense and planar deposition of Zn metal. Professor Zaiping Guo from the University of Adelaide and Professor Baohua Li from the Shenzhen International Graduate School of Tsinghua University, along with their colleagues, increased the electron density of water protons by interacting with highly polar dimethylacetamide and trimethylphosphate molecules, thereby increasing the electrostatic attraction between OH groups and suppressing the reactivity of water. Dimethylacetamide altered the surface energy of Zn, guiding its deposition primarily on the (002) plane. Simultaneously, Zn corrosion in the mixed electrolyte was alleviated, and the electrochemical stability window and operating temperature of the electrolyte were extended.

[0004] From the above research results, it can be seen that constructing a coating on the surface of the zinc negative electrode or regulating the electrolyte components can, to a certain extent, curb the interfacial side reactions and the growth of zinc dendrites. However, the current work is limited to the single regulation of the zinc negative electrode interface and the electrolyte, focusing only on one aspect of the inhibition of zinc dendrites and the alleviation of side reactions, and the performance improvement is relatively limited. The regulation of the positive and negative electrode interfaces by trace additives is very limited, and a single hydrophobic coating will lead to slow mass transfer at the interface, reducing the battery transfer kinetics. In order to obtain high-rate and long-life zinc-based batteries, efforts should be made to achieve the synergistic effect of the negative electrode interface and the electrolyte to accelerate the Zn 2+ Phase transfer occurs at the solid-liquid interface to inhibit zinc dendrites, alleviate interfacial side reactions and achieve rapid interface transport kinetics, thereby achieving high reversibility of the zinc negative electrode. Summary of the Invention

[0005] In order to address the deficiencies and shortcomings of the above-mentioned prior art, the present invention primarily aims to provide a zinc battery system based on electrochemical solid-liquid interface phase transfer. The zinc metal surface has an oleophilic and hydrophobic layer composed of a high ionic conductivity ionic liquid and a hydrophobic organic matrix; in addition, organic additives containing different functional groups are added to the soluble zinc salt aqueous solution to regulate the electrolyte hydrogen bond network and Zn 2+ Hydrophobic ionic liquid polymer coating and modified electrolyte synergistically regulate the interface chemistry of zinc anode and accelerate Zn 2+ Conducts and reduces Zn 2+ The desolvation energy barrier was used to construct a zinc battery system based on electrochemical solid-liquid interface phase transfer.

[0006] Another object of the present invention is to provide a method for preparing the aforementioned zinc battery system based on electrochemical solid-liquid interfacial phase transfer. This method involves thoroughly mixing an ionic liquid, an organic matrix, and an organic solvent. The mixed solution is evenly spin-coated on a zinc metal surface and vacuum-dried to produce a zinc metal anode. A soluble zinc salt is then added to deionized water to form a base electrolyte. An organic additive is then added and stirred until completely dissolved to produce a modified electrolyte. The zinc metal anode and the modified electrolyte are then combined to produce a zinc battery system.

[0007] The purpose of the present invention is achieved through the following technical solutions:

[0008] A zinc battery system based on electrochemical solid-liquid interface phase transfer is disclosed. The zinc battery system first constructs a composite coating composed of a high-ionic-conductivity ionic liquid and a hydrophobic organic matrix on the surface of zinc metal to produce a zinc battery negative electrode; then, an organic additive is added to a soluble zinc salt base liquid to produce a modified electrolyte, and the zinc battery negative electrode and the modified electrolyte are composited to obtain the result.

[0009] Preferably, the thickness of the composite coating is 50-100 μm.

[0010] Preferably, the ionic liquid is 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide or 1-butyl-3-methylimidazolium hexafluorophosphate; the hydrophobic organic matrix is ​​a fluorine-containing organic matrix; the mass ratio of the ionic liquid to the hydrophobic organic matrix is ​​(1~2):(1~2), and the organic matrix has a good interaction with the ionic liquid.

[0011] More preferably, the fluorine-containing organic matrix is ​​polyvinylidene fluoride, poly(vinylidene fluoride-co-hexafluoropropylene), poly(ethylene-chlorotrifluoroethylene) or fluoropolyvinyl acetate.

[0012] Preferably, the mass concentration of the ionic liquid is 10-20%; the volume fraction of the organic additive in the modified electrolyte is 10-30%; and the organic additive is ethylene glycol, dimethyl sulfoxide or acetonitrile.

[0013] Preferably, the soluble zinc salt in the soluble zinc salt base liquid is zinc trifluoromethanesulfonate, zinc sulfate or zinc perchlorate.

[0014] The preparation method of the zinc battery system based on electrochemical solid-liquid interface phase transfer comprises the following specific steps:

[0015] S1. The ionic liquid and the hydrophobic organic matrix are dissolved in an organic solvent and mixed thoroughly to obtain a mixed solution;

[0016] S2. The mixed solution was spin-coated on the surface of the zinc negative electrode to obtain a zinc foil containing a composite coating, which was vacuum-dried to obtain a zinc battery negative electrode;

[0017] S3. The soluble zinc salt was dissolved in deionized water to obtain a soluble zinc salt base solution, and then an organic additive was added and stirred to obtain a modified electrolyte;

[0018] S4. The zinc battery negative electrode is combined with the modified electrolyte to assemble a battery to obtain a zinc battery system based on electrochemical solid-liquid interface phase transfer.

[0019] Preferably, the organic solvent in step S1 is N-methylpyrrolidone or acetone; the volume fraction of the organic solvent is 5-40%.

[0020] Preferably, the concentration of the soluble zinc salt base solution in step S3 is 1-4 mol / L.

[0021] All currently developed common aqueous zinc-ion battery cathodes can be assembled with the present invention. Commonly used cathode materials include manganese dioxide, polyaniline, sodium vanadate, and ammonium vanadate, all of which can be assembled into full batteries with excellent battery performance.

[0022] The present invention uses a simple spin coating method to construct a structure on the surface of the zinc negative electrode that can quickly conduct Zn 2+ The hydrophobic protective layer plays a direct and effective role in protecting the zinc metal negative electrode. Compared with water molecules, the ionic liquid in the hydrophobic protective layer has a strong affinity with Zn 2+ Has better affinity, can promote the desolvation process of zinc ions at the interface and Zn 2+ Fast conduction at the interface reduces the overall polarization and accelerates the Zn 2+ Transport mechanics.

[0023] Organic additives are added to the soluble zinc salt base solution to regulate the electrolyte hydrogen bond network and Zn 2+ Solvation sheath, through the synergistic effect between hydrophobic ionic liquid-based coating and organic additives, regulates the phase transfer at the electrode solid-liquid interface and promotes Zn 2+ Rapid desolvation achieves a highly stable and long-cycle zinc battery system. The main ionic liquids are 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide salt, 1-butyl-3-methylimidazolium hexafluorophosphate, and 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, all of which contain one or more of the following: imidazole group, sulfonic acid group, and carbonyl group. Nitrogen-containing imidazole group and Zn 2+ It has good affinity and can curb the specific adsorption of anions; in addition, the fluorine-containing groups in the ionic liquid and the organic matrix have a hydrophobic effect, which can exclude water from the double layer and avoid the corrosion of the zinc negative electrode by active water molecules during the desolvation process.

[0024] The system of the present invention is composed of a hydrophobic interface layer composed of a hydrophobic organic matrix and a high ionic conductivity ionic liquid and a modified electrolyte, wherein the mass ratio of the hydrophobic organic matrix to the high ionic conductivity ionic liquid is (1~2):(1~2); the electrolyte is a two-molar zinc salt aqueous solution, and organic additives containing different functional groups are added to regulate the hydrogen bond network of the electrolyte and the Zn 2+ Solvation sheath structure, the volume fraction of organic additives is controlled to 10~30%, and the zinc negative electrode interface chemistry is regulated by the synergistic effect of electrolyte and hydrophobic interface layer. The specific regulation method of this zinc battery system is as follows Figure 1On the one hand, the hydrophobic interface layer formed by the hydrophobic organic matrix and the high ionic conductivity ionic liquid containing a large number of fluorine-containing groups can isolate the direct contact between the electrolyte and the zinc metal negative electrode, thereby curbing the hydrogen evolution reaction and other interface side reactions on the surface of the zinc negative electrode; on the other hand, the polar / non-polar functional groups in the organic additives can regulate the hydrogen bond network of the electrolyte and participate in the Zn 2+ Solvation sheath reduces the activity of water molecules in the electrolyte. Through the synergistic effect of the hydrophobic interface layer and the modified additives, rapid solid-liquid interface transfer is achieved, thereby reducing the Zn 2+ At the same time, the ionic liquid itself has good ion conductivity, which can achieve rapid Zn 2+ The transfer dynamics thus significantly improve the cycle stability and safety performance of the battery.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. This invention combines a hydrophobic interface layer with a modified electrolyte to achieve a zinc battery system based on electrochemical solid-liquid interfacial phase transfer and stable electrode interface chemistry. First, the constructed hydrophobic interface layer prevents direct contact between the electrolyte and the zinc anode, preventing corrosion of the zinc anode by active water molecules during the desolvation process. Second, by introducing an organic additive into the soluble zinc salt-based liquid, the electrolyte's hydrogen bond network and solvation sheath are modulated, breaking hydrogen bonds between water molecules and limiting their activity. Finally, the synergistic effect of the hydrophobic interface layer and the modified electrolyte modulates the electrode interface chemistry and reduces the desolvation energy barrier, achieving rapid and stable interfacial phase transfer.

[0027] 2. The zinc battery system constructed by the present invention, which is based on electrochemical solid-liquid interface transfer, can be directly formed on the zinc negative electrode by simply mixing a high ionic conductivity with a hydrophobic organic matrix and then using a spin coating process; the configuration of the modified electrolyte is to add an organic additive to the soluble zinc salt base liquid to achieve Zn 2+ The optimization of electrochemical environment has realized the 2+ The rapid and stable transmission of Zn in the water phase, oil phase and interface layer was constructed based on the dynamics of phase interface transfer. 2+ However, the zinc battery system has not yet appeared in cutting-edge reports.

[0028] 3. The ionic liquid and organic matrix used in the present process are both hydrophobic. A simple mixed spin coating can create a hydrophobic protective layer of ideal thickness (50-100 μm) on the zinc foil surface. This approach, when applied to actual production, will significantly reduce production costs. The method is simple and easily scalable, and can be applied to flat zinc foil, porous zinc, zinc powder, and other materials. This process is not limited to preparing zinc battery systems based on solid-liquid two-phase interface transfer; it can also be used to prepare battery systems based on solid-liquid-solid three-phase interface transfer, for example. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a schematic diagram of the regulation of phase transfer at the solid-liquid interface of the electrode in Example 1.

[0030] Figure 2 1 is a scanning electron microscope image of the cross section of the zinc metal negative electrode prepared in Example 1 and a distribution diagram of different elements.

[0031] Figure 3 This is a photo of the contact angle test of the zinc metal negative electrode in Example 1.

[0032] Figure 4 This is an optical photograph of the modified electrolyte in Example 1.

[0033] Figure 5 The zinc metal symmetrical battery prepared in Example 1 was -2 , with an areal capacity of 1 mAhcm -2 cyclic curve.

[0034] Figure 6 This is a scanning electron microscope photograph of the zinc metal negative electrode prepared in Example 1 after 100 cycles.

[0035] Figure 7 These are optical photographs of the zinc metal negative electrodes prepared in Comparative Example 1 (left) and Example 1 (right).

[0036] Figure 8 The zinc metal symmetric battery prepared in comparative example 1 was -2 , with an areal capacity of 1 mAhcm -2 cyclic curve.

[0037] Figure 9 This is a scanning electron microscope photograph of the zinc metal negative electrode prepared in Comparative Example 1 after 100 cycles.

[0038] Figure 10 The zinc-copper half-cells prepared in Example 1 and Comparative Example 1 were tested at a current density of 5 mA cm -2 , with an areal capacity of 1 mAh cm -2 Charge and discharge efficiency curve.

[0039] Figure 11 It is a graph of the electrochemical performance of a full battery matched with the manganese dioxide positive electrode of Example 1 and Comparative Example 1. DETAILED DESCRIPTION

[0040] The present invention will be further described below in conjunction with specific examples, but should not be construed as limiting the present invention. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0041] Example 1

[0042] 1. Weigh 1.5 g of the highly conductive ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide and 1.5 g of the organic matrix poly(vinylidene fluoride-co-hexafluoropropylene) into a slurry bottle. Add 7 g of the organic solvent N-methylpyrrolidone, disperse uniformly through ultrasonication, and stir overnight on a stirrer to prepare a mixed solution.

[0043] 2. Measure a certain amount of the mixed solution and evenly spin-coat it on the surface of the zinc foil. Place it in a vacuum oven at 80℃ and dry it for 12 hours to remove the organic solvent to obtain the zinc battery negative electrode.

[0044] 3. Weigh 7.27 g of Zn(OTF)2 into 8 mL of deionized water to obtain a 2 mol / L Zn(OTF)2 base solution. Then add 2 mL of the organic additive ethylene glycol and stir thoroughly until completely dissolved to obtain a modified electrolyte.

[0045] 4. The above zinc battery negative electrode is compounded with a modified electrolyte to obtain a zinc battery system based on electrochemical solid-liquid interface phase transfer.

[0046] Figure 1 This is a schematic diagram of the control of the solid-liquid interface phase transfer at the electrode in Example 1. Figure 1 As shown, the zinc battery system based on electrochemical solid-liquid interface phase transfer consists of a hydrophobic interface layer and a modified electrolyte. Figure 2 The following is a scanning electron microscope image of the zinc metal negative electrode prepared in Example 1 and a distribution diagram of different elements (carbon, nitrogen, oxygen, fluorine, zinc). Figure 2 It can be seen that the hydrophobic interface layer has been coated on the surface of the zinc negative electrode and is evenly distributed. Figure 3 This is a contact angle test photo of Example 1. Figure 3 It can be seen that the hydrophobic interface layer has a large contact angle and can achieve the expected hydrophobic effect. Figure 4 This is an optical photograph of the modified electrolyte in Example 1. The ethylene glycol molecules can regulate the hydrogen bond network and solvation sheath of the electrolyte. Figure 5 The zinc metal symmetrical battery prepared in Example 1 was -2, with an areal capacity of 1 mAh cm -2 The cycle time-voltage curve shows that it has excellent cycle performance. Figure 6 This is a scanning electron microscope photograph of the zinc metal negative electrode prepared in Example 1 after 100 cycles. It can be seen that the surface of the zinc sheet is smooth after the cycle and no obvious dendrites are generated.

[0047] Example 2

[0048] 1. Weigh 2 g of the highly conductive ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate and 1 g of the organic matrix polyvinylidene fluoride into a slurry bottle. Add 7 g of the organic solvent acetone, disperse uniformly through ultrasonication, and stir overnight on a stirrer to obtain a mixed solution.

[0049] 2. Measure a certain amount of the mixed solution and evenly spin-coat it on the surface of the zinc foil. Place it in a vacuum oven at 80℃ and dry it for 24 hours to remove the organic solvent to obtain the zinc battery negative electrode.

[0050] 3. Weigh 5.75 g of ZnSO4·7H2O into 7 mL of deionized water to obtain a 2 mol / L ZnSO4 base solution. Then, add 3 mL of the organic additive dimethyl sulfoxide and stir thoroughly until completely dissolved to obtain a modified electrolyte.

[0051] 4. The above zinc battery negative electrode is compounded with a modified electrolyte to obtain a zinc battery system based on electrochemical solid-liquid interface phase boundary transfer.

[0052] Example 3

[0053] 1. Weigh 1 g of the highly conductive ionic liquid 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide and 2 g of the organic matrix poly(vinylidene fluoride-co-hexafluoropropylene) into a slurry bottle. Add 7 g of the organic solvent N-methylpyrrolidone, disperse uniformly through ultrasonication, and stir overnight on a stirrer to obtain a mixed solution.

[0054] 2. Measure a certain amount of the mixed solution and evenly spin-coat it on the surface of the zinc foil. Place it in a vacuum oven at 80℃ and dry it for 6 hours to remove the organic solvent to obtain the zinc battery negative electrode.

[0055] 3. Weigh 7.45 g of Zn(ClO4)2·6H2O into 9 mL of deionized water to obtain a 2 mol / L Zn(ClO4)2 base solution. Then add 1 mL of the organic additive acetonitrile and stir thoroughly until completely dissolved to obtain a modified electrolyte.

[0056] 4. The above zinc battery negative electrode is compounded with a modified electrolyte to obtain a zinc battery system based on electrochemical solid-liquid interface phase transfer.

[0057] Comparative Example 1

[0058] The zinc foil was polished with sandpaper to remove the surface oxide layer, and then ultrasonically cleaned by adding deionized water and ethanol. After drying, it was used as the zinc metal negative electrode in Comparative Example 1.

[0059] Figure 7 The optical photos of the zinc metal negative electrode prepared in Comparative Example 1 (left) and Example 1 (right) are shown. Figure 7 It can be seen that the example liquid and the organic matrix are evenly covered on the zinc metal negative electrode described in Example 1. Figure 8 The zinc metal negative electrode prepared in Example 1 assembled symmetrical battery at a current density of 1 mA cm -2 , with an areal capacity of 1 mAh cm -2 Cycle time-voltage curve. Figure 8 It can be seen that after 120 h of cycling, the symmetrical battery polarization suddenly increases, leading to battery failure. Figure 9 This is a scanning electron microscope photo of the zinc metal negative electrode prepared in Comparative Example 1 after 100 cycles. Figure 9 It can be seen that the surface of the zinc negative electrode is rough and porous and contains a large amount of hexagonal substances, indicating that zinc dendrites are generated during the cycle, accompanied by the generation of a large amount of dead zinc and basic zinc salts. Figure 10 The figure is the cycle number-charge and discharge efficiency curve of the zinc-copper half-cell assembled in Example 1 and Comparative Example 1. Figure 10 It can be seen that Example 1 can still maintain an average coulombic efficiency of 99.48% after 900 cycles, while Comparative Example 1 has a short circuit phenomenon after 50 cycles. Figure 11 is the electrochemical performance diagram of the full battery matched with the manganese dioxide positive electrode of Example 1 and Comparative Example 1, Figure 11 It can be seen that the embodiment has excellent full battery performance, with a capacity retention rate of 82% after 1000 cycles, while the cycle reversibility of comparative example 1 is poor and the capacity loss is serious.

[0060] Comparative Example 2

[0061] 1. Weigh 1.5 g of the highly conductive ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide and 1.5 g of the organic matrix poly(vinylidene fluoride-co-hexafluoropropylene) into a slurry bottle. Add 7 g of the organic solvent N-methylpyrrolidone, disperse uniformly through ultrasonication, and stir overnight on a stirrer to obtain a mixed solution.

[0062] 2. Measure a certain amount of the mixed solution and evenly spin-coat it on the surface of the zinc foil. Place it in a vacuum oven at 80℃ and dry it for 12 hours to remove the organic solvent to obtain the zinc battery negative electrode.

[0063] 3. Weigh 7.27 g Zn(OTF)2 into 10 mL deionized water and stir thoroughly until completely dissolved to obtain a 2 mol / L Zn(OTF)2 electrolyte solution.

[0064] 4. The above zinc battery negative electrode is compounded with an electrolyte to obtain a zinc battery system based on a modified zinc metal negative electrode.

[0065] Comparative Example 3

[0066] 1. Weigh 2 g of the highly conductive ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate and 1 g of the organic matrix polyvinylidene fluoride into a slurry bottle. Add 7 g of the organic solvent acetone, disperse uniformly through ultrasonication, and stir overnight on a stirrer to obtain a mixed solution.

[0067] 2. Measure a certain amount of the mixed solution and evenly spin-coat it on the surface of the zinc foil. Place it in a vacuum oven at 80℃ and dry it for 24 hours to remove the organic solvent to obtain the zinc battery negative electrode.

[0068] 3. Weigh 5.75 g of ZnSO4·7H2O into 10 mL of deionized water and stir thoroughly until completely dissolved to obtain a 2 mol / L ZnSO4 electrolyte solution.

[0069] 4. The above zinc battery negative electrode is compounded with an electrolyte to obtain a zinc battery system based on a modified zinc metal negative electrode.

[0070] Comparative Example 4

[0071] 1. Weigh 1 g of the highly conductive ionic liquid 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide and 2 g of the organic matrix poly(vinylidene fluoride-co-hexafluoropropylene) into a slurry bottle. Add 7 g of the organic solvent N-methylpyrrolidone, disperse uniformly through ultrasonication, and stir overnight on a stirrer to obtain a mixed solution.

[0072] 2. Measure a certain amount of the mixed solution and evenly spin-coat it on the surface of the zinc foil. Place it in a vacuum oven at 80℃ and dry it for 6 hours to remove the organic solvent to obtain the zinc battery negative electrode.

[0073] 3. Weigh 7.45 g Zn(ClO4)2·6H2O into 10 mL of deionized water and stir thoroughly until completely dissolved to obtain a 2 mol / L ZnSO4 electrolyte.

[0074] 4. The above zinc battery negative electrode is compounded with an electrolyte to obtain a zinc battery system based on a modified zinc metal negative electrode.

[0075] Comparative Example 5

[0076] 1. Untreated zinc foil is used as the negative electrode of zinc metal battery.

[0077] 2. Weigh 7.27 g of Zn(OTF)2 and dissolve it in 8 mL of deionized water to obtain a 2 mol / L Zn(OTF)2 base solution. Then add 2 mL of the organic additive ethylene glycol and stir thoroughly until completely dissolved to obtain a modified electrolyte.

[0078] 3. Compounding the above metal negative electrode with a modified electrolyte to obtain a zinc battery system based on the modified electrolyte.

[0079] Comparative Example 6

[0080] 1. Using untreated zinc foil as the negative electrode of zinc metal batteries;

[0081] 2. Weigh 5.75 g of ZnSO4·7H2O into 7 mL of deionized water to obtain a 2 mol / L ZnSO4 base solution. Then add 3 mL of the organic additive dimethyl sulfoxide and stir thoroughly until completely dissolved to obtain a modified electrolyte.

[0082] 4. The above metal negative electrode is compounded with a modified electrolyte to obtain a zinc battery system based on the modified electrolyte.

[0083] Comparative Example 7

[0084] 1. Untreated zinc foil is used as the negative electrode of zinc metal battery.

[0085] 2. Weigh 7.45 g of Zn(ClO4)2·6H2O into 9 mL of deionized water to obtain a 2 mol / L Zn(ClO4)2 base solution. Then add the organic additive acetonitrile and stir thoroughly until completely dissolved to obtain a modified electrolyte.

[0086] 3. Compounding the above metal negative electrode with a modified electrolyte to obtain a zinc battery system based on the modified electrolyte.

[0087] The above zinc metal negative electrode was assembled into a zinc symmetrical battery and the charge and discharge performance was tested. The test results are as follows:

[0088] Table 1 Performance of symmetrical cells assembled from zinc battery systems of Examples 1-3 and Comparative Examples 1-7

[0089]

[0090] Table 1 shows the performance of the zinc negative electrode assembled symmetrical batteries of Examples 1-3 and Comparative Examples 1-7. As can be seen from Table 1, the cycle time of the symmetrical batteries of Examples 1-3 and Comparative Examples 1-7 shows that the negative electrode life of the zinc battery system with high ionic conductivity interface composite modified electrolyte is significantly extended, indicating that the zinc battery system based on electrochemical solid-liquid interface phase transfer has a stable electrochemical interface and can inhibit interface side reactions and dendrite growth. As can be seen from the comparison of Example 1 with Example 2 and Example 3, the cycle life of the symmetrical batteries with different hydrophobic interfaces composited with different modified electrolytes is still quite different, indicating that the zinc battery system can only accelerate the Zn electrochemical reaction when there is a strong interaction between the interface and the electrolyte. 2+ Conductivity at the interface and stable electrode interface chemistry, Example 1 is preferred from this comparison.

[0091] The above electrode was used as the negative electrode of the zinc metal battery. The target organic additive was added to the soluble zinc salt solution as the electrolyte. Whatman's glass fiber membrane was used as the separator. Manganese dioxide was used as the positive electrode to assemble a full battery for constant current charge and discharge performance testing. The test results are as follows:

[0092] Table 2 Performance of full batteries assembled from zinc negative electrodes and manganese dioxide in Example 1 and Comparative Examples 1, 2, and 5

[0093]

[0094] Table 2 shows the performance of the full battery assembled with the zinc battery negative electrode and manganese dioxide of Example 1 and Comparative Examples 1, 2 and 5. As shown in Table 2, the comparison between Example 1 and Comparative Example 1 shows that the full battery cycle stability of the zinc battery system based on electrochemical solid-liquid interface phase transfer is significantly better than that of the unmodified zinc battery; the comparison between Example 1 and Comparative Example 2 shows that the addition of organic additives is beneficial to the improvement of the full battery performance, and the synergistic effect of the hydrophobic interface and the electrolyte is beneficial to stabilizing the electrode interface chemistry and accelerating the Zn 2+ The conduction at the interface has obvious advantages compared with a single regulation system; the comparison between Example 1 and Comparative Example 5 shows that simply modifying the electrolyte cannot continuously stabilize the zinc negative electrode, further illustrating that the zinc battery system based on electrochemical solid-liquid interface phase transfer can simultaneously improve the electrochemical performance of the positive and negative electrodes of the battery.

[0095] The above embodiments are preferred implementations of the present invention, but the implementations of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A zinc battery system based on electrochemical solid-liquid interface phase transfer, characterized in that: The zinc battery system comprises the following steps: first, constructing a composite coating of a high-ionic-conductivity ionic liquid and a hydrophobic organic matrix on the surface of zinc metal to obtain a zinc battery negative electrode; then, adding an organic additive to a soluble zinc salt base liquid to obtain a modified electrolyte, and then compounding the zinc battery negative electrode and the modified electrolyte; the ionic liquid is 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide salt or 1-butyl-3-methylimidazolium hexafluorophosphate; the hydrophobic organic matrix is ​​a fluorine-containing organic matrix; the mass ratio of the ionic liquid to the hydrophobic organic matrix is ​​(1-2):(1-2); the fluorine-containing organic matrix is ​​polyvinylidene fluoride, poly(vinylidene fluoride-co-hexafluoropropylene), poly(ethylene-chlorotrifluoroethylene) or fluoropolyvinyl acetate; the mass concentration of the ionic liquid is 10-20%; the volume fraction of the organic additive in the modified electrolyte is 10-30%; and the organic additive is ethylene glycol, dimethyl sulfoxide or acetonitrile.

2. The zinc battery system based on electrochemical solid-liquid interface phase transfer according to claim 1, wherein the thickness of the composite coating is 50-100 μm.

3. The zinc battery system based on electrochemical solid-liquid interface phase transfer according to claim 1, characterized in that: The soluble zinc salt in the soluble zinc salt base liquid is zinc trifluoromethanesulfonate, zinc sulfate or zinc perchlorate.

4. The method for preparing a zinc battery system based on electrochemical solid-liquid interface phase transfer according to any one of claims 1 to 3, characterized in that: The specific steps include: S1. The ionic liquid and the hydrophobic organic matrix are dissolved in an organic solvent and mixed thoroughly to obtain a mixed solution; S2. The mixed solution was spin-coated on the surface of the zinc negative electrode to obtain a zinc foil containing a composite coating, which was vacuum-dried to obtain a zinc battery negative electrode; S3. The soluble zinc salt was dissolved in deionized water to obtain a soluble zinc salt base solution, and then an organic additive was added and stirred to obtain a modified electrolyte; S4. The zinc battery negative electrode is combined with the modified electrolyte to assemble a battery to obtain a zinc battery system based on electrochemical solid-liquid interface phase transfer.

5. The method for preparing a zinc battery system based on electrochemical solid-liquid interface phase transfer according to claim 4, characterized in that: The organic solvent in step S1 is N-methylpyrrolidone or acetone; the volume fraction of the organic solvent is 5-40%.

6. The method for preparing a zinc battery system based on electrochemical solid-liquid interface phase transfer according to claim 4, characterized in that: The vacuum drying temperature in step S2 is 60-100° C., and the vacuum drying time is 6-24 h.

7. The method for preparing a zinc battery system based on electrochemical solid-liquid interface phase transfer according to claim 4, characterized in that: The concentration of the soluble zinc salt base solution in step S3 is 1-4 mol / L.

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