Electrolyte additive, aqueous electrolyte and zinc-based energy storage device

Abstract

The invention discloses an electrolyte additive, an aqueous electrolyte and a zinc-based energy storage device. The electrolyte additive comprises an azo organic matter with at least one functional group of carboxyl, acetamido, carbonyl, sulfonate radical, phenolic hydroxyl, ammonia radical or methoxyl and salt of the azo organic matter. The electrolyte additive can improve the stability and the service life of the zinc-based energy storage device.

Description

Technical Field

[0001] The present application relates to the field of electrochemical energy storage technology, and in particular to an electrolyte additive, an aqueous electrolyte, and a zinc-based energy storage device. Background Art

[0002] In recent years, multivalent ion electrochemical energy storage systems based on aqueous electrolytes are considered to be the next generation of energy storage devices that meet the requirements of sustainable development. Among them, aqueous zinc-based energy storage devices with metallic zinc as the negative electrode are expected to be used for large-scale energy storage due to their abundant reserves, low cost, high safety and good rate performance. However, the problems of dendrite growth, hydrogen evolution corrosion and low service life of zinc-based energy storage devices have not been completely solved. Summary of the invention

[0003] In view of this, the present application provides an electrolyte additive, an aqueous electrolyte and a zinc-based energy storage device that can solve the above-mentioned technical problems.

[0004] In a first aspect, the present application provides an electrolyte additive, which includes an azo organic compound and a salt thereof having at least one functional group selected from the group consisting of a carboxyl group, an acetamide group, a carbonyl group, a sulfonate group, a phenolic hydroxyl group, an amino group or a methoxy group.

[0005] Further, the electrolyte additive is acid red 1, acid red 4, acid red 7, acid red 9, acid red 17, acid red 18, acid red 26, acid red 27, acid red 35, acid red 73, acid red 88, acid red 89, acid red 177, acid red 188, acid red 249, acid red 266, acid orange 7, acid black 1, acid orange 10, acid blue 92, orange yellow I, orange yellow IV, benzopurpurogen 4B, Evans blue, ethyl orange sodium salt, basic orange 2 , sodium p-sulfophenylazo chromotropic acid, sunset yellow, Congo red, brilliant yellow, methyl red, methoxy red, methyl orange, 4-aminoazobenzene-3,4'-disulfonic acid, chromotropic acid 2B, diphenylamine yellow, 4-(2-pyridylazo)resorcinol monosodium salt, chrome black T, chrome black R, scarlet S, basic brown 1, direct black 38, azo blue, 2-hydroxy-5-[(E)-phenylazo]benzaldehyde or (E)-1-(4-isocyanatophenyl)-2-phenyldiazene.

[0006] Furthermore, the electrolyte additive includes an azo organic compound and a salt thereof having an azo group and at least one functional group selected from the group consisting of a carboxyl group, an acetamide group, a carbonyl group, a sulfonate group, a phenolic hydroxyl group, an amino group, and a methoxy group.

[0007] The second aspect of the present application provides the use of the above-mentioned electrolyte additive in a zinc-based energy storage device.

[0008] The third aspect of the present application provides an aqueous electrolyte containing the above electrolyte additive, wherein the concentration of the electrolyte additive in the aqueous electrolyte is 0.1 mmol L -1 ~1000mmol L -1 .

[0009] Furthermore, the concentration of the electrolyte additive in the aqueous electrolyte is 1 mmol L -1 ~50mmolL -1 .

[0010] Furthermore, the aqueous electrolyte also includes a soluble zinc salt, and the soluble zinc salt is ZnSO4, Zn(CF3SO3)2, ZnCl2, Zn(NO3)2, Zn(ClO4)2, Zn(CH3COO)2, ZnF2, Zn(BF4)2, Zn(C6H 11 At least one of O7)2, ZnSiF6 and Zn[N(SO2CF3)2]2.

[0011] Furthermore, the concentration of the soluble zinc salt in the aqueous electrolyte is 0.1 mmol L -1 ~10mmolL -1 .

[0012] A fourth aspect of the present application provides a zinc-based energy storage device, which includes the above-mentioned aqueous electrolyte.

[0013] Furthermore, the zinc-based energy storage device also includes a negative electrode, a positive electrode and a separator.

[0014] Furthermore, the zinc-based energy storage device is at least one of a zinc-ion symmetrical battery, a zinc-ion hybrid capacitor or a zinc-ion full battery.

[0015] The electrolyte additive provided in the present application can be adsorbed on the "electrode-electrolyte" interface to form a double electric layer, homogenize the interfacial electric field, prevent side reactions caused by free water, inhibit the growth of dendrites, delay hydrogen evolution corrosion, and ultimately improve the stability and service life of zinc-based energy storage devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 These are optical photographs of the electrolytes prepared in Comparative Example 1 and Examples 1 to 5.

[0017] Figure 2 The zinc ion symmetric battery prepared in Comparative Example 1 was -2 The dough capacity is 0.5 mAh cm -2 Time-voltage curve under the same conditions.

[0018] Figure 3The zinc ion symmetric battery prepared in Example 1 was subjected to a current density of 1 mA cm -2 The dough capacity is 0.5 mAh cm -2 Time-voltage curve under the same conditions.

[0019] Figure 4 The zinc ion symmetric battery prepared in Example 2 was subjected to a current density of 1 mA cm -2 The dough capacity is 0.5 mAh cm -2 Time-voltage curve under the same conditions.

[0020] Figure 5 The zinc ion symmetric battery prepared in Example 3 was subjected to a current density of 1 mA cm -2 The dough capacity is 0.5 mAh cm -2 Time-voltage curve under the same conditions.

[0021] Figure 6 The zinc ion symmetric battery prepared in Example 4 was subjected to a current density of 1 mA cm -2 The dough capacity is 0.5 mAh cm -2 Time-voltage curve under the same conditions.

[0022] Figure 7 The zinc ion symmetric battery prepared in Example 5 was subjected to a current density of 1 mA cm -2 The dough capacity is 0.5 mAh cm -2 Time-voltage curve under the same conditions.

[0023] Figure 8 The electrochemical impedance curves of the zinc ion hybrid capacitors prepared in Comparative Example 1 and Example 1.

[0024] Fig. 9A and Fig. 9B The electrodes of the zinc ion symmetrical batteries prepared in Comparative Example 1 and Example 1 are photographs after 200 hours of cycle testing.

[0025] Fig.10 This is a scanning electron microscope image of the electrode of the zinc ion symmetric battery prepared in Comparative Example 1 after 200 hours of cycle testing.

[0026] Fig.11 This is a scanning electron microscope image of the electrode of the zinc ion symmetric battery prepared in Example 1 after 200 hours of cycle testing.

[0027] Fig.12 In-situ optical microscope images of the electrode cross-sections of the zinc ion symmetric batteries prepared in Comparative Example 1 and Example 1 during a cycle period of 0 to 12 hours.

[0028] Fig.13This is a scanning electron microscope image of the α-MnO2 material prepared in this application.

[0029] Fig.14 This is a graph showing the rate performance test data of the zinc ion hybrid capacitor prepared in Comparative Example 1 and Example 1.

[0030] Fig.15 This is a test diagram of the cycle performance of the zinc ion full battery prepared in Comparative Example 1 and Example 1. DETAILED DESCRIPTION

[0031] The embodiments of the present application are described in detail below. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limiting the present application. The reagents and materials described in the following embodiments can all be obtained from commercial sources.

[0032] An electrolyte additive comprises an azo organic compound having at least one functional group selected from the group consisting of a carboxyl group, an acetamide group, a carbonyl group, a sulfonate group, a phenolic hydroxyl group, an amino group or a methoxy group, and a salt thereof.

[0033] The electrolyte additive described in this application can form an electrostatic shielding layer through ion adsorption, reshape the charge distribution of the "electrode-electrolyte" interface, homogenize the surface electric field, optimize the deposition site of zinc ions, thereby inhibiting the growth of zinc dendrites and obtaining a more uniform deposition layer. At the same time, the polar functional groups of carboxyl, acetamide, carbonyl, sulfonate, phenolic hydroxyl, and amino groups in the electrolyte additive can form hydrogen bonds with water molecules, reduce the solvation interaction between zinc ions and water molecules, bind the activity of water molecules, delay the hydrogen evolution corrosion of the zinc electrode, and achieve the purpose of effectively protecting the zinc negative electrode. In addition, the azo and phenolic hydroxyl functional groups in the electrolyte additive have good redox properties, which can provide additional capacity for zinc-based energy storage devices and improve the energy density of zinc-based energy storage devices.

[0034] In some specific embodiments, the electrolyte additive includes an azo organic compound and a salt thereof having an azo group and at least one functional group selected from the group consisting of a carboxyl group, an acetamide group, a carbonyl group, a sulfonate group, a phenolic hydroxyl group, an amino group, and a methoxy group. It is understood that the electrolyte additive has an azo group and at least one functional group selected from the group consisting of a carboxyl group, an acetamide group, a carbonyl group, a sulfonate group, a phenolic hydroxyl group, an amino group, and a methoxy group.

[0035] In some specific embodiments, the electrolyte additive is acid red 1, acid red 4, acid red 7, acid red 9, acid red 17, acid red 18, acid red 26, acid red 27, acid red 35, acid red 73, acid red 88, acid red 89, acid red 177, acid red 188, acid red 249, acid red 266, acid orange 7, acid black 1, acid orange 10, acid blue 92, orange yellow I, orange yellow IV, benzopurpurogen 4B, Evans blue, ethyl orange sodium salt, alkali At least one of chromatic orange 2, sodium p-sulfophenylazo chromotropic acid, sunset yellow, Congo red, brilliant yellow, methyl red, methoxy red, methyl orange, 4-aminoazobenzene-3,4'-disulfonic acid, chromotropic acid 2B, diphenylamine yellow, 4-(2-pyridylazo)resorcinol monosodium salt, chrome black T, chrome black R, scarlet S, basic brown 1, direct black 38, azo blue, 2-hydroxy-5-[(E)-phenylazo]benzaldehyde or (E)-1-(4-isocyanatophenyl)-2-phenyldiazene.

[0036] In some specific embodiments, the above electrolyte additives can be used in zinc-based energy storage devices.

[0037] An aqueous electrolyte containing the electrolyte additive, wherein the concentration of the electrolyte additive in the aqueous electrolyte is 0.1 mmol L -1 ~1000mmol L -1 , for example 0.1 mmol L -1 , 1mmol L -1 、10mmol L -1 , 50mmolL -1 、100mmol L -1 , 200mmol L -1 、300mmol L -1 、400mmol L -1 、500mmol L -1 、600mmol L -1 、700mmol L -1 、800mmol L -1 , 900mmol L -1 、1000mmol L -1 .

[0038] In some specific embodiments, the concentration of the electrolyte additive in the aqueous electrolyte is 1 mmol / L -1 ~50mmol L -1 , for example 1mmol L -1 , 5mmol L -1 、10mmol L -1 、15mmol L-1 , 20mmol L -1 , 25mmol L -1 、30mmol L -1 、35mmol L -1 , 40mmol L -1 、45mmol L -1 , 50mmol L -1 The concentration of the electrolyte additive in the aqueous electrolyte is preferably 5 mmol L -1 .

[0039] In some specific embodiments, the soluble zinc salt is ZnSO4, Zn(CF3SO3)2, ZnCl2, Zn(NO3)2, Zn(ClO4)2, Zn(CH3COO)2, ZnF2, Zn(BF4)2, Zn(C6H 11 O7)2, ZnSiF6 and Zn[N(SO2CF3)2]2, and the soluble zinc salt is preferably ZnSO4.

[0040] In some specific embodiments, the concentration of the soluble zinc salt in the aqueous electrolyte is 0.1 mmol / L -1 ~10mmol L -1 Preferably, the concentration of the soluble zinc salt in the aqueous electrolyte is 2 mmol L -1 .

[0041] A zinc-based energy storage device comprises the above-mentioned aqueous electrolyte.

[0042] In some specific embodiments, the zinc-based energy storage device is at least one of a zinc ion symmetric battery, a zinc ion hybrid capacitor, or a zinc ion full battery.

[0043] In the present application, a zinc ion hybrid capacitor refers to a capacitor having a zinc electrode.

[0044] In some specific embodiments, the zinc-based energy storage device further comprises a negative electrode, a positive electrode and a separator.

[0045] In some specific embodiments, the negative electrode is metallic zinc or a zinc alloy.

[0046] In some specific embodiments, the positive electrode is at least one of activated carbon, manganese-based oxides, Prussian blue and its analogs, vanadium-based materials, or organic positive electrode materials.

[0047] In some specific embodiments, the activated carbon includes but is not limited to at least one of activated carbon, foamed carbon, nitrogen-phosphorus co-doped porous carbon, conductive carbon black (ketjen black), sulfur-doped porous carbon or graphene.

[0048] In some specific embodiments, the manganese-based oxide includes but is not limited to at least one of MnO2, Mn2O3 and Mn3O4.

[0049] In some specific embodiments, the MnO2 can be selected from at least one of 2×2 tunnel-shaped α-MnO2, 1×1 tunnel-shaped β-MnO2 or layered δ-MnO2, preferably α-MnO2.

[0050] In some specific embodiments, the Prussian blue and its analogs include at least one of Fe4[Fe(CN)6]3·nH2O, NiHCF and CuHCF.

[0051] In some specific embodiments, the vanadium-based material includes at least one of NaV3O8, V2O5, VO2, and VS2.

[0052] In some specific embodiments, the organic cathode material includes p-chloranil, p-benzoquinone, and 5,7,12,14-tetraaza-6,13-pentacenequinone (TAPQ).

[0053] In some specific embodiments, the separator includes but is not limited to glass fiber separator, cellulose separator, C9HF 17 At least one of O5S (Nafion membrane), polyethylene membrane, polypropylene polyolefin microporous membrane, porous polymer membrane and non-woven fabric membrane, and the membrane is preferably a glass fiber membrane.

[0054] In some specific embodiments, the packaging form of the zinc-based energy storage device includes packaging into button batteries, soft-pack batteries, cylindrical batteries, square batteries or stacked batteries, preferably button batteries.

[0055] The present application is described in detail below through specific embodiments.

[0056] Comparative Example 1

[0057] At 25°C, prepare 2 mol L -1 The ZnSO4 solution is set aside.

[0058] A zinc ion symmetric battery was assembled using sandpaper-polished zinc foil as the positive and negative electrodes, glass fiber as the separator, and 50 μL of the above ZnSO4 solution as the electrolyte.

[0059] A zinc ion hybrid capacitor was assembled using a sandpaper-polished zinc foil as the negative electrode, a carbon electrode as the positive electrode, a glass fiber as the separator, and 50 μL of the above ZnSO4 solution as the electrolyte.

[0060] A zinc ion full battery was assembled using the sandpaper-polished zinc foil as the negative electrode, α-MnO2 as the positive electrode, glass fiber as the separator, and 50 μL of the above ZnSO4 solution as the electrolyte.

[0061] The preparation process of the carbon electrode is as follows: 160 mg of activated carbon, 20 mg of conductive carbon black and 20 mg of polyvinylidene fluoride (PVDF) are weighed into a sample bottle, and a stirring bar is added and then 2 mL of N-methylpyrrolidone (NMP) solvent is added for slurry stirring. The slurry is stirred for 60 minutes until it becomes a uniform slurry. The slurry is evenly coated on the surface of a stainless steel sheet with a coater to control the coating thickness. The loading amount of the material after drying is 1-2 mg cm -2 , then put it into a drying oven at 60℃ for 12 hours, then take it out and cut it into positive electrode sheets with a diameter of 12mm, and put it into a moisture-proof cabinet for standby use.

[0062] The synthesis process of α-MnO2 material: First, oxalic acid was dissolved in deionized water and stirred evenly with a magnetic stirrer to prepare 100 mL of 0.15 mol L -1 Then dissolve potassium permanganate in deionized water to prepare 100 mL of 0.1 mol L -1 Prepare a water bath and keep the oxalic acid solution at a constant temperature of 60°C. Then use a peristaltic pump to pump the potassium permanganate solution at a rate of 0.1 mL min. -1 The oxalic acid solution was added at a rate of , and stirred evenly with a magnetic stirrer. After the potassium permanganate solution was completely added, the obtained brown turbid liquid was stirred at 60°C for 30 minutes. Finally, the brown turbid liquid was filtered, and the obtained brown precipitate was washed with distilled water and ethanol several times, and dried at 120°C for 6 hours. The obtained dry powder was the birnessite sample. The obtained birnessite sample was placed in a muffle furnace and calcined at 600°C for 4 hours to be converted into α-MnO2 material. The scanning electron microscope image of the α-MnO2 material is shown in the figure Fig.13 shown.

[0063] Preparation process of α-MnO2 electrode: 160 mg α-MnO2, 20 mg conductive carbon black, and 20 mg PVDF were weighed into a sample bottle, and 2 mL NMP solvent was added after adding a stirring bar to stir the slurry. The slurry was stirred for 60 minutes until it became a uniform slurry. The slurry was evenly coated on the surface of the stainless steel sheet with a coater to control the coating thickness. The loading amount of the material after drying was about 1-2 mg cm -2 , then put it into a drying oven at 60℃ for 12 hours, then take it out and cut it into positive electrode sheets with a diameter of 12mm, and put it into a moisture-proof cabinet for standby use.

[0064] Preparation process of the diaphragm: Cut the uncontaminated glass fiber diaphragm into discs with a diameter of 16 mm and put them in a moisture-proof cabinet for use.

[0065] Preparation process of zinc electrode: Use 800-8000 mesh sandpaper to grind the zinc foil in sequence to reduce surface defects, then cut it into discs with a diameter of 12 mm, add acetone for ultrasonic cleaning, put it in a drying oven to dry, and then put it in a moisture-proof cabinet for use.

[0066] The negative electrode shell and the positive electrode shell are commercially available CR2032 button battery shells, and the gasket and the spring play a supporting and stabilizing role. Among them, the thickness of the gasket is 1.0mm, and the spring is made of corrugated 304 stainless steel.

[0067] The assembly process of zinc ion symmetrical battery, zinc ion hybrid capacitor and zinc ion full battery: assemble in the order of negative electrode shell, negative electrode, diaphragm, positive electrode, gasket, shrapnel and positive electrode shell, and the electrolyte used in assembly is fixed at 50μL. The assembled zinc-based energy storage devices are packaged with a hydraulic packaging machine with a pressure of 1.5GPa, and a multimeter is used to test whether a short circuit occurs. Finally, the assembled devices are placed in a drying oven and left to stand for 3 hours.

[0068] Example 1

[0069] Acid Red 9 was added to the ZnSO4 solution provided in Comparative Example 1 and dissolved evenly to obtain an electrolyte. The concentration of Acid Red 9 in the electrolyte was 5 mmol L -1 .

[0070] The electrolyte is made into a zinc ion symmetrical battery, a zinc ion hybrid capacitor and a zinc ion full battery in the manner shown in Comparative Example 1. The difference between this embodiment 1 and Comparative Example 1 is only that the electrolyte is different, and the remaining steps are the same as Comparative Example 1.

[0071] Example 2

[0072] Acid Red 27 was added to the ZnSO4 solution provided in Comparative Example 1 and dissolved evenly to obtain an electrolyte. The concentration of Acid Red 27 in the electrolyte was 5 mmol L -1 .

[0073] The electrolyte is made into a zinc ion symmetrical battery, a zinc ion hybrid capacitor and a zinc ion full battery in the manner shown in Comparative Example 1. The difference between this Example 2 and Comparative Example 1 is only that the electrolyte is different, and the remaining steps are the same as Comparative Example 1.

[0074] Example 3

[0075] Sodium p-sulfophenylazo chromotropic acid was added to the ZnSO4 solution provided in Comparative Example 1 and dissolved evenly to obtain an electrolyte. The concentration of sodium p-sulfophenylazo chromotropic acid in the electrolyte was 5 mmol L -1 .

[0076] The electrolyte is made into a zinc ion symmetrical battery, a zinc ion hybrid capacitor and a zinc ion full battery in the manner shown in Comparative Example 1. The difference between this Example 3 and Comparative Example 1 is only the electrolyte, and the remaining steps are the same as Comparative Example 1.

[0077] Example 4

[0078] Congo red was added to the ZnSO4 solution provided in Comparative Example 1 and dissolved evenly to obtain an electrolyte. The concentration of Congo red in the electrolyte was 5 mmol L -1 .

[0079] The electrolyte is made into a zinc ion symmetrical battery, a zinc ion hybrid capacitor and a zinc ion full battery in the manner shown in Comparative Example 1. The difference between this Example 4 and Comparative Example 1 is only the different electrolytes, and the remaining steps are the same as Comparative Example 1.

[0080] Example 5

[0081] Sunset yellow was added to the ZnSO4 solution provided in Comparative Example 1 and dissolved evenly to obtain an electrolyte. The concentration of sunset yellow in the electrolyte was 5 mmol L -1 .

[0082] The electrolyte is made into a zinc ion symmetrical battery, a zinc ion hybrid capacitor and a zinc ion full battery in the manner shown in Comparative Example 1. The difference between this Example 5 and Comparative Example 1 is only the different electrolytes, and the remaining steps are the same as Comparative Example 1.

[0083] See also Figure 1 , Figure 1 From left to right in the figure are optical photographs of the electrolytes configured in Comparative Example 1 and Examples 1-5.

[0084] The electrochemical workstation CHI660E was used to test the current density of 1 mA cm -2 , surface capacity is 0.5 mAh cm -2 Under the conditions of , the zinc ion symmetrical batteries prepared in Comparative Example 1 and each embodiment were subjected to constant current charge and discharge tests to test the cycle performance of the batteries. The test results are shown in Tables 1 and Figures 2 to 7 .

[0085] Table 1

[0086]

[0087]

[0088] Figure 2 The time-voltage curve of the zinc ion symmetric battery prepared in Comparative Example 1 is shown in FIG. Figure 2It can be seen that under the test conditions, the battery cycle life of the zinc ion symmetric battery prepared in Comparative Example 1 is only 168 hours, and the polarization voltage is 93.4 mV. After the test time reaches 168 hours, the zinc ion symmetric battery of Comparative Example 1 short-circuit occurs, and the voltage fluctuates greatly, indicating that the performance of the zinc ion symmetric battery of Comparative Example 1 is unstable.

[0089] Figure 3 The battery cycle performance test results of the zinc ion symmetrical battery prepared in Example 1 are as follows: Figure 3 It can be seen that the battery cycle life of the zinc ion symmetrical battery prepared in Example 1 is 2296 hours, and the polarization voltage is 89.0 mV. The battery cycle stability and service life of Example 1 are better than those of Comparative Example 1.

[0090] Figure 4 The battery cycle performance test results of the zinc ion symmetrical battery prepared in Example 2 are as follows: Figure 4 It can be seen that the battery cycle life of the zinc ion symmetrical battery prepared in Example 2 is 326 hours, and the polarization voltage is 70.7 mV. The battery cycle stability and service life of Example 2 are better than those of Comparative Example 1.

[0091] Figure 5 The battery cycle performance test results of the zinc ion symmetrical battery prepared in Example 3 are as follows: Figure 5 It can be seen that the battery cycle life of the zinc ion symmetrical battery prepared in Example 3 is 608 hours, and the polarization voltage is 45.0 mV. The battery cycle stability and service life of Example 3 are better than those of Comparative Example 1.

[0092] Figure 6 The battery cycle performance test results of the zinc ion symmetrical battery prepared in Example 4 are as follows: Figure 6 It can be seen that the battery cycle life of the zinc ion symmetrical battery prepared in Example 4 is 614 hours, and the polarization voltage is 65.5 mV. The battery cycle stability and service life of Example 4 are better than those of Comparative Example 1.

[0093] Figure 7 The battery cycle performance test results of the zinc ion symmetrical battery prepared in Example 5 are as follows: Figure 7 It can be seen that the battery cycle life of the zinc ion symmetrical battery prepared in Example 5 is 328 hours, and the polarization voltage is 51.1 mV. The battery cycle stability and service life of Example 5 are better than those of Comparative Example 1.

[0094] From the test results in Table 1 and Figures 2 to 7From the comparison, it can be concluded that the battery life of Examples 1-5 of the present application is longer than that of Comparative Example 1, and Examples 1-5 of the present application show a smaller polarization voltage. The small polarization voltage is beneficial to promote the electron transfer of zinc ions and the cycle stability of the battery.

[0095] The electrochemical AC impedance test was performed on the zinc ion hybrid capacitors prepared in Comparative Example 1 and Example 1 using a blue battery test system (CT3004A). The test frequency range was between 0.01 and 100 kHz. The test results are shown in Figure 8 . Figure 8 In the figure, curve A is the test result of comparative example 1, and curve B is the test result of embodiment 1. Figure 8 The horizontal axis is the inductive reactance, and the vertical axis is the capacitive reactance. The electrochemical AC impedance curve consists of a semicircular curve and an upward sloping linear curve. The semicircular curve is divided into a high-frequency region and a medium-frequency region, and the linear curve is a low-frequency region. The semicircular part corresponds to the charge transfer resistance, and the linear part corresponds to the ion diffusion resistance. The intersection of the semicircular curve in the high-frequency region and the horizontal axis represents the ohmic impedance of the electrolyte, which characterizes the inherent electrochemical contact characteristics of the "electrode-electrolyte" interface. The smaller the ohmic impedance, the better. Figure 8 It can be seen that the ohmic impedance of Example 1 is smaller than that of the comparative example, indicating that the zinc ion hybrid capacitor of Example 1 has a lower charge transfer resistance than that of Comparative Example 1. This is attributed to the high π electron delocalization effect of the electrolyte additive, which accelerates the transfer of electrons, adjusts the solvation structure and hydrogen bond network of the electrolyte, and accelerates ion migration. The rate performance test of the zinc ion hybrid capacitor prepared in Comparative Example 1 and Example 1 was carried out using a blue battery test system (CT3004A), and the test current was 0.1, 0.3, 0.5, 0.7, 0.9, 1.2, 1.5, 0.1A g -1 , test results see Fig.14 . Fig.14 In the figure, curve A is the test result of comparative example 1, and curve B is the test result of embodiment 1. It can be seen that embodiment 1 exhibits higher capacity, better rate performance and stability.

[0096] Next, the morphology of the zinc ion symmetrical batteries prepared in Example 1 and Comparative Example 1 was observed.

[0097] The zinc ion symmetrical batteries prepared in Example 1 and Comparative Example 1 were tested in a blue battery test system (CT3004A) at a current density of 1 mA cm -2 、Surface capacity 0.5mAh cm -2 After 200 hours of cycling under the test conditions, the zinc ion symmetrical battery was disassembled, the positive electrode and the negative electrode were taken out, and the samples to be observed were obtained. The appearance of the samples to be observed in Comparative Example 1 and Example 1 was photographed with a SLR camera (model: Canon EOS 6D Mark II). Fig. 9AThis is a photo of the positive electrode and negative electrode of the zinc ion symmetric battery of Example 1 ( Fig. 9A The left disc is the positive electrode, and the right disc is the negative electrode). Fig. 9B is a photograph of the positive electrode and negative electrode of the zinc ion symmetric battery of Example 1 ( Fig. 9B The left disc is the positive electrode, and the right disc is the negative electrode). Fig. 9A and Fig. 9B It can be seen that after 200 hours of testing, the surface of the zinc electrode of Comparative Example 1 after the cycle is rough, with many cracks and defects, while the surface of the zinc electrode of Example 1 remains relatively smooth after 200 hours of cycle testing, indicating that the battery stability of Example 1 is better. The sample to be observed is placed under a cold field scanning electron microscope (model: SU8010) for observation, and the Fig.10 and Fig.11 . Fig.10 This is a scanning electron microscope image of the electrode of the zinc ion symmetric battery of comparative example 1, Fig.11 This is a scanning electron microscope image of the electrode of the zinc ion symmetric battery in Example 1. Fig.10 and Fig.11 It can be seen that after 200 hours of cycling, zinc dendrites deposited in the vertical direction can be seen in the zinc electrode of the zinc ion symmetric battery in Comparative Example 1. The flaky, randomly distributed zinc dendrites eventually pierce the separator and cause a short circuit in the battery. Fig.11 It was observed that zinc ions grew hexagonally along the (002) crystal plane, which promoted the long cycle life of the battery.

[0098] The morphological evolution of the electrode cross section during the zinc stripping / deposition process was observed using an in-situ optical microscope (model: Vision MV-EM200C, lens: Vision BT-TML20X110S). Fig.12 In the figure, A is an in-situ optical microscope image of the zinc electrode cross section of the zinc ion symmetrical battery prepared in comparative example 1 during a 0-12 hour cycle test, and B is an in-situ optical microscope image of the zinc electrode cross section of the zinc ion symmetrical battery prepared in example 1 during a 0-12 hour cycle test. Fig.12 It can be seen that irregular growth of zinc dendrites can be observed in the cross section of the zinc electrode of Comparative Example 1, while no obvious zinc dendrites appear in the cross section of the zinc electrode of Example 1. It can be seen that the zinc dendrites of the zinc electrode of Example 1 are effectively suppressed.

[0099] The cycling performance of the zinc ion full batteries prepared in Example 1 and Comparative Example 1 was tested using a Blue Electric Battery Test System (CT3004A) at a test current of 0.2A g -1 , test results see Fig.15 As shown by Fig.15It can be seen that under the same number of cycles, the capacity of Example 1 is higher than that of Comparative Example 1, and the coulombic efficiency of Example 1 is also higher than that of Comparative Example 1.

[0100] In summary, the electrolyte additive provided in the present application is applied to zinc-based energy storage devices such as zinc-ion symmetrical batteries, zinc-ion hybrid capacitors and zinc-ion full batteries, and has the advantages of inhibiting the growth of zinc dendrites and improving the stability and service life of zinc-based energy storage devices.

[0101] The above implementation modes are only used to illustrate the technical solutions of the present application and are not intended to limit the present application. Although the present application is described in detail with reference to the above implementation modes, a person skilled in the art should understand that the technical solutions of the present application may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present application.

Claims

1. An electrolyte additive, characterized in that: The electrolyte additive includes an azo organic compound and a salt thereof having at least one functional group selected from the group consisting of a carboxyl group, an acetamide group, a carbonyl group, a sulfonate group, a phenolic hydroxyl group, an amino group or a methoxy group.

2. The electrolyte additive according to claim 1, characterized in that: The electrolyte additives are acid red 1, acid red 4, acid red 7, acid red 9, acid red 17, acid red 18, acid red 26, acid red 27, acid red 35, acid red 73, acid red 88, acid red 89, acid red 177, acid red 188, acid red 249, acid red 266, acid orange 7, acid black 1, acid orange 10, acid blue 92, orange yellow I, orange yellow IV, benzopurpurogen 4B, Evans blue, ethyl orange sodium salt, basic orange 2, sulfonic acid At least one of sodium phenylazo chromotropic acid, sunset yellow, Congo red, brilliant yellow, methyl red, methoxy red, methyl orange, 4-aminoazobenzene-3,4'-disulfonic acid, chromotropic acid 2B, diphenylamine yellow, 4-(2-pyridylazo)resorcinol monosodium salt, chrome black T, chrome black R, scarlet S, basic brown 1, direct black 38, azo blue, 2-hydroxy-5-[(E)-phenylazo]benzaldehyde or (E)-1-(4-isocyanatophenyl)-2-phenyldiazene.

3. The electrolyte additive according to claim 1, characterized in that: The electrolyte additive includes an azo organic compound and a salt thereof which has an azo group and at least one functional group selected from the group consisting of a carboxyl group, an acetamide group, a carbonyl group, a sulfonate group, a phenolic hydroxyl group, an amino group and a methoxy group.

4. Use of the electrolyte additive according to any one of claims 1 to 3 in a zinc-based energy storage device.

5. An aqueous electrolyte containing the electrolyte additive according to any one of claims 1 to 3, characterized in that: The concentration of the electrolyte additive in the aqueous electrolyte is 0.1 mmol L -1 ~1000mmol L -1 .

6. The aqueous electrolyte according to claim 5, characterized in that: The concentration of the electrolyte additive in the aqueous electrolyte is 1 mmol L -1 ~50mmol L -1 .

7. The aqueous electrolyte according to claim 5, characterized in that The aqueous electrolyte also includes a soluble zinc salt, which is ZnSO4, Zn(CF3SO3)2, ZnCl2, Zn(NO3)2, Zn(ClO4)2, Zn(CH3COO)2, ZnF2, Zn(BF4)2, Zn(C6H 11 At least one of O7)2, ZnSiF6 and Zn[N(SO2CF3)2]2.

8. The aqueous electrolyte according to claim 7, characterized in that The concentration of the soluble zinc salt in the aqueous electrolyte is 0.1 mmol L -1 ~10mmol L -1 .

9. A zinc-based energy storage device, characterized in that: The zinc-based energy storage device comprises an aqueous electrolyte as described in any one of claims 5-8.

10. The zinc-based energy storage device according to claim 9, characterized in that: The zinc-based energy storage device is at least one of a zinc-ion symmetrical battery, a zinc-ion hybrid capacitor or a zinc-ion full battery.

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