WO2024027499A1 - 一种基于物理过程形成sei膜的宽电压窗口水系电解液及其制备方法和应用 - Google Patents

一种基于物理过程形成sei膜的宽电压窗口水系电解液及其制备方法和应用 Download PDF

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WO2024027499A1
WO2024027499A1 PCT/CN2023/107849 CN2023107849W WO2024027499A1 WO 2024027499 A1 WO2024027499 A1 WO 2024027499A1 CN 2023107849 W CN2023107849 W CN 2023107849W WO 2024027499 A1 WO2024027499 A1 WO 2024027499A1
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aqueous electrolyte
voltage window
sei film
electrolyte
physical process
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PCT/CN2023/107849
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English (en)
French (fr)
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薄拯
杨化超
周美琪
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浙江大学
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/54—Electrolytes
    • H01G11/58—Liquid electrolytes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/54—Electrolytes
    • H01G11/58—Liquid electrolytes
    • H01G11/62—Liquid electrolytes characterised by the solute, e.g. salts, anions or cations therein
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/54—Electrolytes
    • H01G11/58—Liquid electrolytes
    • H01G11/64—Liquid electrolytes characterised by additives
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/84—Processes for the manufacture of hybrid or EDL capacitors, or components thereof
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/13—Energy storage using capacitors

Definitions

  • the invention belongs to the field of electrochemical energy storage, and in particular relates to a wide voltage window aqueous electrolyte that forms an SEI film based on a physical process and its preparation method and application.
  • the energy density E of the supercapacitor is proportional to the square of the operating voltage V, where V is mainly determined by the irreversible decomposition of the electrolyte at the interface. Therefore, in order to increase the energy density of supercapacitors, increasing the electrochemical stability window of the electrolyte is a very effective way.
  • organic electrolytes have been widely used in the development of commercial electrochemical energy storage devices. However, the use of organic electrolytes poses huge safety, environmental, and cost issues due to their toxic, hygroscopic, flammable, and volatile shortcomings.
  • aqueous electrolytes have outstanding characteristics such as good safety, environmental friendliness, high ionic conductivity, low manufacturing costs, and reliable operation under various operating conditions, and are considered to be the most promising alternatives to organic electrolytes.
  • traditional aqueous electrolytes are limited by the low decomposition voltage of water (1.23V), resulting in a narrow electrochemical stability window, which is very unfavorable for practical application in electrochemical devices with high energy density.
  • the purpose of the present invention is to provide a wide voltage window aqueous electrolyte that forms an SEI film based on a physical process, to overcome the shortcomings of a super-concentrated high-voltage aqueous electrolyte that forms an SEI film based on a chemical process, consuming electrolyte and having low ionic conductivity of the solution, and is suitable for In a water-based electrochemical energy storage device that is safe, environmentally friendly, and has high rate performance; the invention also provides a preparation method of the above-mentioned water-based electrolyte and its application in an electrochemical energy storage device.
  • a wide voltage window aqueous electrolyte that forms an SEI film based on a physical process, including additives, electrolytes and water;
  • the additive is a long-chain compound with oppositely charged functional groups and opposite wettability
  • the electrolyte is a soluble inorganic salt of an alkali metal.
  • the long-chain compound with oppositely charged functional groups and opposite wettability is 3-[dimethyl(n-octyl)ammonium]propane-1-sulfonate (C 13 H 29 NO 3 S ), 3-(decyldimethylammonium)propane-1-sulfonic acid inner salt (C 15 H 33 NO 3 S), dodecyldimethyl (3-sulfopropyl) ammonium hydroxide inner salt ( At least one of C 17 H 37 NO 3 S).
  • aqueous electrolyte that forms the SEI film based on the physical process provided by the present invention: 3-[dimethyl(n-octyl)ammonium]propane-1-sulfonate, 3- One or more functional additives of (decyldimethylammonium) propane-1-sulfonic acid inner salt and dodecyldimethyl (3-sulfopropyl) ammonium hydroxide inner salt, when the device is charged , under the action of the electric field, the positively charged long-chain hydrophobic structure in the additive will be preferentially adsorbed on the surface of the negative electrode.
  • the water molecules on the electrode surface will be attracted by the negatively charged hydrophilic end of the additive and stay away from the electrode surface due to electrostatic repulsion. . Subsequently, due to the electrostatic attraction between molecules, more and more long-chain additive molecules accumulate end-to-end on the electrode surface.
  • a waterproof layer will be formed at the interface between the negative electrode material and the electrolyte through a physical electrostatic adsorption process, similar to the SEI film in organic electrolyte systems and super-concentrated aqueous electrolyte systems, which hinders the electrolysis of water molecules on the electrolytic surface, thereby improving This increases the electrochemical stability window of the electrolyte; at the same time, in the bulk solution, additive molecules tend to self-aggregate to form clusters due to the electrostatic interaction of their own positive and negative charges, rather than combining with water molecules and ions in the solution. Therefore, the addition of additives will hardly destroy the original ion coordination structure in the solution, which is conducive to the rapid transmission of ions and maintains a high conductivity of the solution.
  • the electrolyte provided by the present invention can form an SEI film through a pure physical electrostatic adsorption process, effectively broadening the voltage window of the aqueous electrolyte, while maintaining a high ionic conductivity, and can effectively improve the rate performance and cycle of the aqueous electrochemical energy storage device. life, giving it excellent electrochemical properties.
  • the soluble inorganic salt of alkali metal includes at least one of sodium nitrate, potassium nitrate, lithium nitrate and lithium sulfate.
  • the additive is 3-(decyldimethylammonium)propane-1-sulfonate inner salt
  • the soluble inorganic salt of alkali metal is sodium nitrate
  • the electrolyte composed of the additive has more optimized comprehensive performance.
  • the mass ratio of inorganic salt to water is 0.1:1 to 0.3:1.
  • the mass ratio of the additive to water is 0.5:1 to 1.5:1, more preferably 0.6:1 to 1.4:1.
  • the electrochemical window of the wide voltage window aqueous electrolyte that forms the SEI film based on a physical process is greater than 1.5V.
  • the invention also provides a method for preparing a wide voltage window aqueous electrolyte based on a physical process to form an SEI film, which includes the following steps:
  • step (2) Add additives to the salt solution obtained in step (1) and mix evenly to obtain the wide voltage window aqueous electrolyte that forms an SEI film based on a physical process.
  • the present invention also provides the application of the wide voltage window aqueous electrolyte based on the physical process to form the SEI film in electrochemical energy storage devices.
  • the present invention also provides an electrochemical energy storage device, which includes a wide voltage window aqueous electrolyte that forms an SEI film based on the physical process as described above.
  • the electrochemical energy storage device is a button supercapacitor, a button ion capacitor or a soft-packed supercapacitor.
  • the button-type supercapacitor is a symmetrical activated carbon button capacitor pressed by a tablet press. It is composed of a positive electrode shell, a negative electrode shell, a gasket, a shrapnel, a positive electrode material, a negative electrode material, a diaphragm, an electrolyte and Current collector composition.
  • the positive electrode shell, negative electrode shell, gasket, and shrapnel are made of stainless steel, the electrode material is a commercial YP-50F activated carbon electrode, the separator is a glass fiber separator, and the electrolyte is the above-mentioned wide SEI film based on the physical process.
  • the voltage window is a water-based electrolyte, and the current collector is a stainless steel mesh.
  • the button-type supercapacitor has a capacity retention rate of 81.7% (from 36.6 to 29.9F g -1 ) under a large current density change from 0.5A g -1 to 20A g -1 .
  • a button-type ion capacitor which is an activated carbon//Ni-Fe Prussian blue (NiHCF) button ion capacitor pressed by a tablet press. It consists of positive electrode shell, negative electrode shell, gasket, shrapnel, positive electrode material, negative electrode material, separator, electrolyte and current collector.
  • the positive electrode shell, negative electrode shell, gasket, and shrapnel are made of stainless steel, the positive electrode is a NiHCF electrode, the negative electrode is a commercial YP-50F activated carbon electrode, the separator is a glass fiber separator, and the electrolyte is the above-mentioned physically based
  • the process forms a wide voltage window aqueous electrolyte of SEI film, and the current collector is aluminum foil and titanium foil.
  • the button-type ion capacitor can be cycled for 1000 cycles at a low current density of 0.5A g -1 and the capacity is maintained.
  • the holding rate is 81.5%.
  • the soft-packed supercapacitor is a symmetrical activated carbon soft-packed supercapacitor manufactured at the industrial level. It is composed of an aluminum plastic film casing, a positive electrode plate, a negative electrode plate, a pole lug, an electrolyte and a positive electrode plate. and the separator between the negative electrode piece.
  • the separator is a glass fiber separator
  • the electrolyte is the above-mentioned wide voltage window aqueous electrolyte that forms an SEI film based on physical processes
  • the current collector is aluminum foil.
  • the capacity retention rate of the soft-packed supercapacitor reaches 77% when the rate is increased from 2C to 100C.
  • the present invention has the following beneficial effects:
  • the wide voltage window aqueous electrolyte that forms the SEI film based on the physical process provided in the present invention uses safe, non-toxic, low-cost soluble inorganic salts and additives, so that the aqueous electrolyte has better economy, safety and sustainability.
  • the present invention has no special restrictions on the preparation method of the wide voltage window aqueous electrolyte that forms the SEI film based on physical processes. It is easy to operate, does not require any purification and drying facilities in the preparation and assembly process, and is easy to produce on a large scale.
  • the wide voltage window aqueous electrolyte provided by the present invention based on the physical process to form the SEI film accurately controls the free water at the interface between the electrode and the electrolyte through a pure physical electrostatic adsorption process, effectively inhibiting the electrolysis of water molecules on the electrode surface, thus obtaining It achieves a wide voltage window while maintaining high ionic conductivity. In addition, it has good universality and can be applied to most traditional commonly used salt solutions.
  • the button-type symmetrical activated carbon supercapacitor provided by the present invention can achieve a high rate performance of 81.7% when the current density is increased by 40 times.
  • the button-type ion capacitor provided by the present invention can maintain a capacity retention rate of more than 80% after 1000 cycles at a low current density of 0.5A g -1 , reflecting excellent electrochemical performance.
  • Figure 1 is a schematic structural diagram of the wide voltage window aqueous electrolyte forming the SEI film based on the physical process provided by the present invention at the interface and bulk phase in the device;
  • Figure 2 shows the chemical structural formula of the additive provided by the present invention
  • FIG. 3 is a schematic structural diagram of the button capacitor provided in Embodiments 8-9;
  • Figure 4 is a constant current charge and discharge curve of the button-type supercapacitor provided in Embodiment 8;
  • Figure 5 is a Nyquist plot of the button supercapacitor obtained from the EIS test provided in Example 8;
  • Figure 6 shows the cycle life curves of the button ion capacitors provided in Example 9 and Comparative Example 2;
  • FIG. 7 is a schematic structural diagram of a soft-pack capacitor provided in Embodiment 10.
  • the wide voltage window aqueous electrolyte provided by the present invention to form an SEI film based on a physical process includes additives, electrolytes and water.
  • Additives are long-chain compounds with oppositely charged functional groups and opposite wettability; when the electrode is negatively charged, the positively charged hydrophobic groups in the additive molecules will be preferentially adsorbed on the electrode under the action of Coulomb force. On the negatively charged electrode surface, water molecules are repelled away from the electrode surface along with the negatively charged hydrophilic groups in the additive molecules. Subsequently, due to the Coulomb attraction between molecules, a large number of additive molecules aggregate on the electrode surface to form clusters.
  • a hydrophobic and waterproof SEI film is formed on the electrode surface through the physical adsorption process, which inhibits the electrolysis of water molecules on the electrode surface; in addition, in the bulk solution, long-chain additive molecules tend to They aggregate end-to-end on themselves to form clusters, rather than combining with water molecules and electrolyte ions in the solution. Therefore, they will not affect the original ion hydration structure in the solution and are conducive to maintaining high ionic conductivity.
  • Electrochemical stability window Use an electrochemical workstation, model PGSTAT302N (Metrohm Autolab BV), to test the electrochemical stability window of the aqueous electrolyte. Specifically, a three-electrode system composed of an aqueous electrolyte, a stainless steel electrode, and an Ag/AgCl reference electrode was used for linear scan voltammetry testing, and it was determined that the current threshold for hydrolysis reaction was 0.3 mA cm -2 .
  • Ion conductivity Use a conductivity meter, model DDSJ-308F, to measure the ion conductivity of the wide voltage window aqueous electrolyte that forms the SEI film based on the physical process.
  • Electrochemical performance Use an electrochemical workstation, model PGSTAT302N (Metrohm Autolab B.V.), to test the electrochemical performance of button capacitors and soft-pack capacitors to obtain performance information such as impedance, rate performance or cycle life.
  • the specific composition of the electrolyte of this comparative example is the solvent is water, the solute is sodium nitrate, and the specific preparation method is as follows: Add sodium nitrate to the water at a sodium nitrate/water weight ratio of 0.17/1 to dissolve, and mix evenly to obtain the NaNO 3 solution in this comparative example.
  • the performance test of the NaNO 3 electrolyte obtained in this comparative example is performed as follows: Ag/AgCl is used as the reference electrode, and the stainless steel sheet is used as the working electrode and counter electrode. A three-electrode system is used to conduct an electrochemical window stability test on the aqueous electrolyte. The test results show that the electrochemical window is 1.39V.
  • the specific composition of the electrolyte in this embodiment is: the solvent is water, the solute is sodium nitrate, and the additive is 3-[dimethyl(n-octyl)ammonium]propane-1-sulfonate.
  • the specific preparation method is as follows: add nitric acid Sodium is added to the water at a sodium nitrate/water weight ratio of 0.17/1 to dissolve it to obtain a NaNO 3 solution, and then 3-[dimethyl(n-octyl)ammonium]propane-1-sulfonate is dissolved in the water with 3-[dimethyl(n-octyl)ammonium]propane-1-sulfonate. Methyl(n-octyl)ammonium]propane-1-sulfonate/water weight ratio was added to the NaNO 3 solution at a weight ratio of 0.9/1 and mixed evenly to obtain the solution in this example.
  • Example 2 The conductivity of the NaNO 3 -based electrolyte obtained in Example 1 was tested using a conductivity meter, and the conductivity was 29 mS cm -1 .
  • the voltage window of the NaNO 3- based electrolyte obtained in Example 1 was tested according to the method of Comparative Example 1, and the voltage window was 2.71V.
  • the specific composition of the electrolyte in this embodiment is: the solvent is water, the solute is sodium nitrate, and the additive is 3-[dimethyl(n-octyl)ammonium]propane-1-sulfonate.
  • the specific preparation method is as follows: add nitric acid Sodium is added to the water at a sodium nitrate/water weight ratio of 0.17/1 to dissolve it to obtain a NaNO 3 solution, and then 3-[dimethyl(n-octyl)ammonium]propane-1-sulfonate is dissolved in the water with 3-[dimethyl(n-octyl)ammonium]propane-1-sulfonate. Methyl(n-octyl)ammonium]propane-1-sulfonate/water weight ratio was added to the NaNO 3 solution at a weight ratio of 1.4/1 and mixed evenly to obtain the solution in this example.
  • the conductivity of the NaNO 3 -based electrolyte obtained in Example 2 was tested using a conductivity meter, and the conductivity was 11 mS cm -1 .
  • the voltage window of the NaNO 3- based electrolyte obtained in Example 2 was tested according to the method of Comparative Example 1, and the voltage window was 2.76V.
  • the specific composition of the electrolyte in this embodiment is: the solvent is water, the solute is sodium nitrate, and the additive is 3-(decyldimethylammonium)propane-1-sulfonic acid inner salt.
  • the specific preparation method is as follows: sodium nitrate is prepared according to nitric acid Sodium/water weight ratio 0.17/1 The proportion of 3-(decyldimethylammonium)propane-1-sulfonic acid inner salt was added to water to dissolve it to obtain a NaNO 3 solution, and then 3-(decyldimethylammonium)propane-1-sulfonic acid inner salt was used. /Water weight ratio of 0.7/1 was added to the NaNO 3 solution and mixed evenly to obtain the solution in this example.
  • the conductivity of the NaNO 3 -based electrolyte obtained in Example 3 was tested using a conductivity meter, and the conductivity was 42 mS cm -1 .
  • the voltage window of the NaNO 3 -based electrolyte obtained in Example 3 was tested according to the method of Comparative Example 1, and the voltage window was 2.72V.
  • the specific composition of the electrolyte in this embodiment is: the solvent is water, the solute is sodium nitrate, and the additive is dodecyldimethyl (3-sulfopropyl) ammonium hydroxide internal salt.
  • the specific preparation method is as follows: add sodium nitrate according to Sodium nitrate/water weight ratio of 0.17/1 was added to the water and dissolved to obtain a NaNO 3 solution, and then the dodecyldimethyl (3-sulfopropyl) ammonium hydroxide inner salt was dissolved in the water with dodecyldimethyl (3-sulfopropyl) ammonium hydroxide inner salt.
  • 3-Sulfopropyl) ammonium hydroxide internal salt/water weight ratio was added to the NaNO 3 solution and mixed evenly to obtain the solution in this example.
  • the conductivity of the NaNO 3 -based electrolyte obtained in Example 4 was tested using a conductivity meter, and the conductivity was 46 mS cm -1 .
  • the voltage window of the NaNO 3- based electrolyte obtained in Example 4 was tested according to the method of Comparative Example 1, and the voltage window was 2.66V.
  • the specific composition of the electrolyte in this embodiment is: the solvent is water, the solute is potassium nitrate, and the additive is 3-(decyldimethylammonium)propane-1-sulfonic acid inner salt.
  • the specific preparation method is as follows: potassium nitrate is prepared according to the method of nitric acid The potassium/water weight ratio is 0.202/1. Add it to the water and dissolve it to obtain a KNO 3 solution. Then add 3-(decyldimethylammonium)propane-1-sulfonic acid inner salt to 3-(decyldimethylammonium). Add the propane-1-sulfonic acid inner salt/water weight ratio of 0.7/1 to the KNO 3 solution and mix evenly to obtain the solution in this example.
  • the conductivity of the KNO 3 -based electrolyte obtained in Example 5 was tested using a conductivity meter, and the conductivity was 50 mS cm -1 .
  • the voltage window of the KNO 3- based electrolyte obtained in Example 5 was tested according to the method of Comparative Example 1, and the voltage window was 2.68V.
  • the specific composition of the electrolyte in this embodiment is: the solvent is water, the solute is lithium nitrate, and the additive is 3-(decyldimethylammonium)propane-1-sulfonic acid inner salt.
  • the specific preparation method is as follows: lithium nitrate is prepared according to nitric acid Add the lithium/water weight ratio of 0.13788/1 to the water and dissolve it to obtain a LiNO 3 solution, and then dissolve 3-(decyldimethylammonium) propane-1-sulfonic acid inner salt with 3-(decyldimethylammonium) Add the propane-1-sulfonic acid inner salt/water weight ratio of 0.7/1 to the LiNO 3 solution and mix evenly to obtain the solution in this example.
  • the conductivity of the LiNO 3 -based electrolyte obtained in Example 6 was tested using a conductivity meter, and the conductivity was 39 mS cm -1 .
  • the voltage window of the LiNO 3- based electrolyte obtained in Example 6 was tested according to the method of Comparative Example 1, and the voltage window was 2.75V.
  • the specific composition of the electrolyte in this embodiment is: the solvent is water, the solute is lithium sulfate, and the additive is 3-(decyldimethylammonium)propane-1-sulfonic acid inner salt.
  • the specific preparation method is as follows: add lithium sulfate according to the method of sulfuric acid Add the lithium/water weight ratio of 0.1011/1 into the water and dissolve it to obtain a Li 2 SO 4 solution, and then dissolve 3-(decyldimethylammonium)propane-1-sulfonic acid inner salt with 3-(decyldimethylammonium) Ammonium) propane-1-sulfonic acid inner salt/water weight ratio was added to the Li 2 SO 4 solution at a weight ratio of 0.7/1 and mixed evenly to obtain the solution in this example.
  • the conductivity of the Li 2 SO 4 -based electrolyte obtained in Example 7 was tested using a conductivity meter.
  • the conductivity was 25 mS cm -1 .
  • the voltage window of the Li 2 SO 4 -based electrolyte obtained in Example 7 was tested according to the method of Comparative Example 1, and the voltage window was 2.83V.
  • the windows and conductivities of aqueous electrolytes prepared with different electrolyte types are different for sodium nitrate, potassium nitrate, lithium nitrate and sulfuric acid.
  • Lithium is 2.72V/42mS cm -1 , 2.68V/50mS cm -1 , 2.75V/39mS cm -1 and 2.83V/25mS cm -1 respectively.
  • the sodium nitrate-based electrolyte has better performance than other electrolytes. More optimized overall performance.
  • Embodiment 8 is a symmetrical activated carbon button supercapacitor assembled using commercial YP-50F activated carbon as the electrode. Its internal structure is shown in Figure 3, including: button capacitor metal shell 1, spring piece 2, stainless steel gasket 3, activated carbon positive electrode It consists of material 4, glass fiber separator 5, activated carbon negative electrode material 6 and the wide voltage window aqueous electrolyte 7 based on the physical process to form the SEI film in Example 3.
  • the wide voltage window aqueous electrolyte in which the SEI film is formed based on a physical process is prepared by the method in Example 3.
  • the electrochemical performance test was performed on the symmetric buckle supercapacitor prepared in Example 8.
  • the voltage window of the charge and discharge test is set to 0 ⁇ 2V, and the current density range is 0.5 ⁇ 20A g -1 .
  • the mass specific capacitance of the symmetrical supercapacitor at different scan speeds can be calculated, and then the rate performance of the capacitor can be obtained.
  • the capacity retention rate is 81.7% (36.6 to 29.9F g -1 ).
  • EIS testing shows that the equivalent series resistance of symmetrical supercapacitors is very small.
  • the Nyquist plot shows almost vertical lines that are characteristic of capacitive behavior.
  • smaller semicircles indicate less resistance to ion transport. Therefore, the wide voltage window aqueous electrolyte provided by the present invention to form an SEI film based on a physical process significantly improves the impedance and rate performance of the aqueous energy storage device while increasing the voltage window.
  • Comparative Example 2 uses commercial YP-50F activated carbon as the negative electrode and Ni-Fe Prussian Blue (NiHCF) as the positive electrode to assemble an activated carbon//Ni-Fe Prussian Blue button-type ion capacitor.
  • the internal structure is shown in Figure 3, including : Button capacitor metal shell 1, shrapnel 2, stainless steel gasket 3, NiHCF positive electrode material 4, glass fiber separator Membrane 5, activated carbon negative electrode material 6 and NaNO 3 aqueous electrolyte 7 in Comparative Example 1.
  • the NaNO 3 aqueous electrolyte solution was prepared by the method in Comparative Example 1.
  • the activated carbon//Ni-Fe Prussian blue button-type ion capacitor prepared in Comparative Example 2 was charged and discharged at 0 to 2V. As shown in Figure 6, when the current density was 0.5A g -1 , at room temperature After 1000 cycles, the capacity retention rate is only 25.7%.
  • Embodiment 9 uses commercial YP-50F activated carbon as the negative electrode and Ni-Fe Prussian blue (NiHCF) as the positive electrode to assemble an activated carbon//Ni-Fe Prussian blue button-type ion capacitor.
  • the internal structure is shown in Figure 3, including : Composition of button capacitor metal case 1, shrapnel 2, stainless steel gasket 3, NiHCF positive electrode material 4, glass fiber separator 5, activated carbon negative electrode material 6 and the wide voltage window aqueous electrolyte 7 based on the physical process to form the SEI film in Example 3 .
  • the wide voltage window aqueous electrolyte in which the SEI film is formed based on a physical process is prepared by the method in Example 3.
  • the activated carbon//Ni-Fe Prussian blue button-type ion capacitor prepared in Example 9 was charged and discharged at 0 to 2V. As shown in Figure 6, when the current density was 0.5A g -1 , at room temperature After 1000 cycles, the capacity retention rate was 81.5%, showing excellent electrochemical performance.
  • the capacity and cycle life of the aqueous energy storage device are significantly improved.
  • Embodiment 10 is a symmetrical activated carbon soft-packed supercapacitor assembled using commercial YP-50F activated carbon as electrodes. Its internal structure is shown in Figure 7, including: an aluminum plastic film shell 1, a positive electrode plate 2, and a negative electrode plate 3 , tab 4, separator 5 located between the positive electrode piece and the negative electrode piece, and the wide voltage window aqueous electrolyte 6 based on the physical process to form the SEI film in Example 3.
  • the wide voltage window aqueous electrolyte in which the SEI film is formed based on a physical process is achieved by the method in Example 3.
  • the thickness of the activated carbon electrode is 93 ⁇ m, and the area loading capacity is 10.1 mg cm -2 .
  • the electrochemical performance test was performed on the symmetrical activated carbon soft-packed supercapacitor prepared in Example 10.
  • the voltage window of the charge and discharge test was set to 0 ⁇ 2V, and it was found that from the rate of 2C to the rate of 100C, the capacity retention rate reached 77%, proving that the aqueous electrolyte in Example 1 has good practical application performance.
  • the wide voltage window aqueous electrolyte provided by the present invention based on the formation of SEI film based on the physical process can not only broaden the voltage window of the aqueous electrolyte, but also maintain good ionic conductivity and provide excellent rate of electrochemical devices. performance and cycle performance.
  • the aqueous electrolyte provided by the present invention can also be used in button capacitors and industrial-grade soft-packed supercapacitors, and can maintain excellent electrochemical performance under various environmental conditions.

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Abstract

本发明公开了一种基于物理过程形成SEI膜的宽电压窗口水系电解液：添加剂、电解质和水；添加剂为同时带有异性电荷官能团且润湿性相反的长链化合物；电解质为碱金属的可溶性无机盐。本发明还提供了上述水系电解液的制备方法及在电化学储能器件中的应用，电化学储能器件包括扣式超级电容器、扣式离子电容器或软包超级电容器。该发明通过纯物理静电吸附过程在界面处形成SEI层，精确减少界面处自由水含量来抑制了水分解，从而在拓宽了电压窗口的同时还保持较高的离子电导率，有效地克服了传统高电压水系电解液电导率低和基于化学过程形成SEI膜消耗电解液的问题，在水系储能器件中实现了高容量、长循环寿命和优异的倍率性能。

Description

一种基于物理过程形成SEI膜的宽电压窗口水系电解液及其制备方法和应用 技术领域
本发明属于电化学储能领域，尤其涉及一种基于物理过程形成SEI膜的宽电压窗口水系电解液及其制备方法和应用。
背景技术
在高效利用间歇性可再生能源和电动汽车的需求推动下，开发性能卓越的电池和超级电容器等电化学储能装置一直走在能源技术的最前沿。其中，超级电容器由于具有较高的功率密度和超长的循环寿命，在电动汽车、电网、港口、重型机械和可再生能源的大规模部署等领域中都具有广泛的实际应用前景。然而，面对日益增长的高能量应用需求，超级电容器能量密度较低的缺点导致其面临巨大的挑战。
根据E∝V2，超级电容器的能量密度E与工作电压V的平方成正比，其中V主要是由电解液在界面处的不可逆分解决定的。因此，要想提高超级电容器的能量密度，提高电解液的电化学稳定性窗口是十分有效的途径。目前，有机电解液已经被广泛用于商用电化学储能器件的开发。然而，由于具有毒性、吸湿、易燃和易挥发的缺点，有机电解液的使用会带来巨大的安全、环境和成本问题。相比之下，水系电解液具有安全性好、环境友好、离子电导率高、制造成本低以及在各种操作条件下可靠运行等突出特点，被认为是有机电解液的最有前景的替代品。但是传统水系电解液受限于水较低的分解电压(1.23V)，导致电化学稳定窗口较窄，这对实际应用于高能量密度的电化学器件是十分不利的。
近年来，通过添加超高浓度溶质来形成SEI膜和减少游离水分子以获得高电压水系电解液的策略取得了重大突破。然而，这种超浓缩的电解液具有两个主要问题：(1)基于化学过程形成的SEI膜：传统通过添加极高浓度的盐来生成SEI膜是基于化学反应过程的方法，因此会伴随着消耗电解液和反应过程不可逆的问题。此外，这种SEI膜由于自身的水溶性和不稳定等问题在水溶液环境中容易被破坏，对电化学器件的寿命和安全造成不利影响。(2)离子电导率较低：超浓缩溶液中用来解离导电离子的溶剂水含量过少，导致阴阳离子之间静电吸引力很强，形成了大量的阴阳离子配位对。这种配对的出现阻碍了带电离子向两极运输，因此大大降低了溶液电导率，对器件的功率和倍率性能造成了损害。
发明内容
本发明的目的在于提供一种基于物理过程形成SEI膜的宽电压窗口水系电解液，克服超浓缩高电压水系电解液基于化学过程形成SEI膜消耗电解液以及溶液离子电导率低的缺点，适用于安全环保、高倍率性能的水系电化学储能器件中；本发明还提供了上述水系电解液的制备方法及在电化学储能器件中的应用。
本发明采用下述技术方案：
一种基于物理过程形成SEI膜的宽电压窗口水系电解液，包括添加剂、电解质和水；其中，
所述添加剂为同时带有异性电荷官能团且润湿性相反的长链化合物；
所述电解质为碱金属的可溶性无机盐。
优选的，所述同时带有异性电荷官能团且润湿性相反的长链化合物为3-[二甲基(正辛基)铵基]丙烷-1-磺酸酯(C13H29NO3S)、3-(癸基二甲基铵)丙烷-1-磺酸内盐(C15H33NO3S)、十二烷基二甲基(3-磺丙基)氢氧化铵内盐(C17H37NO3S)中的至少一种。
对于本发明提供的基于物理过程形成SEI膜的宽电压窗口水系电解液：在传统水系电解液中添加3-[二甲基(正辛基)铵基]丙烷-1-磺酸酯、3-(癸基二甲基铵)丙烷-1-磺酸内盐、十二烷基二甲基(3-磺丙基)氢氧化铵内盐的一种或几种功能性添加剂，当器件充电时，在电场的作用下，添加剂中带正电荷的长链疏水结构会优先吸附在负电极表面，电极表面的水分子会被添加剂中带负电荷的亲水端吸引，由于静电排斥而远离电极表面。随后，由于分子间的静电吸引，越来越多的长链添加剂分子首尾相接聚集在电极表面。因此，负极材料和电解液界面处会通过物理静电吸附过程形成一层防水层，类似于有机电解液体系和超浓缩水系电解液体系中的SEI膜，阻碍水分子在电解表面的电解，从而提高了电解液的电化学稳定窗口；同时，在体相溶液中，添加剂分子由于自身正负电荷静电相互作用更加倾向于自聚集形成团簇，而不是与溶液中的水分子和离子结合。因此，添加剂的加入几乎不会破坏溶液中原本的离子配位结构，有利于离子的快速传输，使溶液保持了较高的电导率。因此，本发明提供的电解液能够通过纯物理静电吸附过程形成SEI膜有效拓宽水系电解液的电压窗口，同时保持较高的离子电导率，能够有效改善水系电化学储能器件的倍率性能和循环寿命，使其具有优异的电化学性能。
优选的，所述碱金属的可溶性无机盐包括硝酸钠、硝酸钾、硝酸锂和硫酸锂中的至少一种。
进一步优选的，所述添加剂为3-(癸基二甲基铵)丙烷-1-磺酸内盐，碱金属的可溶性无机盐为硝酸钠，其组成的电解液具有更优化的综合性能。
优选的，无机盐与水的质量比为0.1:1～0.3:1。
优选的，添加剂与水的质量比为0.5:1～1.5:1，进一步优选为0.6:1～1.4:1。
优选的，所述的基于物理过程形成SEI膜的宽电压窗口水系电解液的电化学窗口大于1.5V。
本发明还提供了一种基于物理过程形成SEI膜的宽电压窗口水系电解液的制备方法，包括如下步骤：
(1)将碱金属的可溶性无机盐和水混合，搅拌配制成盐溶液；
(2)将添加剂加入步骤(1)得到的盐溶液混合均匀，得到所述的基于物理过程形成SEI膜的宽电压窗口水系电解液。
本发明还提供如上所述的基于物理过程形成SEI膜的宽电压窗口水系电解液在电化学储能器件中的应用。
本发明还提供电化学储能器件，其包括如上所述的基于物理过程形成SEI膜的宽电压窗口水系电解液。
优选的，所述电化学储能器件为扣式超级电容器、扣式离子电容器或软包超级电容器。
一种扣式超级电容，所述扣式超级电容为通过压片机压制成的对称式活性炭纽扣电容器，由正极壳、负极壳、垫片、弹片、正极材料、负极材料、隔膜、电解液和集流体组成。所述正极壳、负极壳、垫片、弹片为不锈钢材质，所述电极材料为商用YP-50F活性炭电极，所述隔膜为玻璃纤维隔膜，所述电解液为上述基于物理过程形成SEI膜的宽电压窗口水系电解液，所述集流体为不锈钢网。
优选的，所述扣式超级电容在从0.5A g-1到20A g-1的大幅度电流密度变化下，容量保持率为81.7％(从36.6到29.9F g-1)。
一种扣式离子电容器，所述扣式离子电容器为通过压片机压制成的活性炭//Ni-Fe普鲁士蓝(NiHCF)纽扣离子电容器。由正极壳、负极壳、垫片、弹片、正极材料、负极材料、隔膜、电解液和集流体组成。所述正极壳、负极壳、垫片、弹片为不锈钢材质，所述正极为NiHCF电极，所述负极为商用YP-50F活性炭电极，所述隔膜为玻璃纤维隔膜，所述电解液为上述基于物理过程形成SEI膜的宽电压窗口水系电解液，所述集流体为铝箔和钛箔。
优选的，所述扣式离子电容器在0.5A g-1的低电流密度下循环1000圈，容量保 持率为81.5％。
一种软包超级电容器，所述软包超级电容器为工业级制造的对称式活性炭软包超级电容器，由铝塑膜外壳、正极极片、负极极片、极耳、电解液和位于正极极片和负极极片之间的隔膜组成。所述电极片为按照YP-50F活性炭材料/炭黑/SBR/CMC＝85/10/3/2的重量比混合制成浆料，再经过涂布辊压工序大规模生产得到。所述隔膜为玻璃纤维隔膜，所述电解液为上述基于物理过程形成SEI膜的宽电压窗口水系电解液，所述集流体为铝箔。
优选的，所述软包超级电容器在倍率从2C提高到100C时，容量保持率达到77％。
与现有技术相比，本发明具有的有益效果如下：
本发明中提供的基于物理过程形成SEI膜的宽电压窗口水系电解液采用安全无毒、成本低廉的可溶性无机盐和添加剂，使水系电解液具有较好的经济性和安全可持续性。
本发明对所述基于物理过程形成SEI膜的宽电压窗口水系电解液的制备方法没有特殊的限制，操作简便，制备和装配过程不需要任何净化和干燥的设施，易于规模化生产。
本发明中提供的基于物理过程形成SEI膜的宽电压窗口水系电解液，通过纯物理静电吸附过程精确控制电极和电解液界面处的自由水，有效地抑制了水分子在电极表面的电解，得到了宽电压窗口的同时保持了较高的离子电导率。此外，还具有较好的普遍性，能够应用于大多数传统的常用盐溶液。
本发明提供的扣式对称活性炭超级电容，在40倍的电流密度提高下，可实现81.7％的高倍率性能。本发明提供的扣式离子电容器在0.5A g-1的低电流密度下经过1000次循环后容量保持率能够超过80％，体现出了优异的电化学性能。
附图说明
图1为本发明提供的基于物理过程形成SEI膜的宽电压窗口水系电解液在器件中界面处和体相处的结构示意图；
图2位本发明提供的添加剂的化学结构式；
图3是实施例8-9提供的扣式电容器的结构示意图；
图4为实施例8提供的扣式超级电容器的恒电流充放电曲线图；
图5为实施例8提供的EIS测试得到的扣式超级电容器的奈奎斯特图；
图6实施例9和对比例2提供的扣式离子电容器的循环寿命曲线图；
图7是实施例10提供的软包电容器的结构示意图。
具体实施方式
为使本发明更明显易懂，以下结合附图和具体实施例对本发明的技术方案作进一步的说明。以下描述的实施例仅用于解释本发明，并非对本发明任何形式上和实质上的限制。
如图1所示，本发明提供的基于物理过程形成SEI膜的宽电压窗口水系电解液包括了添加剂、电解质和水。添加剂为同时带有异性电荷官能团且润湿性相反的长链化合物；当电极带负电时，在库仑力的作用下，所述的添加剂分子中的带正电荷的疏水基团会优先吸附在带负电的电极表面，水分子随着添加剂分子中的带负电荷的亲水基团被排斥远离电极表面。随后，由于分子间的库仑吸引力，大量的添加剂分子在电极表面聚集形成团簇。因此，电极表面通过物理吸附过程形成了一层疏水的防水SEI膜，抑制了水分子在电极表面的电解；另外，体相溶液中，长链添加剂分子由于自身正负电荷的静电相互作用而倾向于自身首尾相接聚集形成团簇，而不是与溶液中的水分子和电解质离子结合，因此不会对溶液中原本的离子水合结构造成影响，有利于保持高离子电导率。
对本发明提供的基于物理过程形成SEI膜的宽电压窗口水系电解液进行如下性能测试：
1、电化学稳定窗口：利用电化学工作站，型号为PGSTAT302N(Metrohm Autolab B.V.)，对水系电解液进行电化学稳定窗口测试。具体地，将水系电解液与不锈钢电极、Ag/AgCl参比电极组成三电极体系进行线性扫描伏安法测试，判定发生水解反应的电流阈值为0.3mA cm-2。
2、离子电导率：利用电导率仪，型号为DDSJ-308F，测量基于物理过程形成SEI膜的宽电压窗口水系电解液的离子电导率。
3、电化学性能：利用电化学工作站，型号为PGSTAT302N(Metrohm Autolab B.V.)，对扣式电容器和软包电容器进行电化学性能测试，得到其阻抗、倍率性能或循环寿命等性能信息。
对比例1
本对比例的电解液具体组成：溶剂为水，溶质为硝酸钠，其具体制备方法如下： 将硝酸钠按照硝酸钠/水重量比0.17/1的比例加入到水中溶解，混合均匀得到本对比例中NaNO3溶液。
对本对比例得到的NaNO3电解液进行性能测试，具体如下：以Ag/AgCl为参比电极，不锈钢片为工作电极和对电极，采用三电极体系对水系电解液进行电化学窗口稳定性测试，测试结果显示电化学窗口为1.39V。
实施例1
本实施例的电解液具体组成：溶剂为水，溶质为硝酸钠，添加剂为3-[二甲基(正辛基)铵基]丙烷-1-磺酸酯，其具体制备方法如下：将硝酸钠按照硝酸钠/水重量比0.17/1的比例加入到水中溶解得到NaNO3溶液，然后将3-[二甲基(正辛基)铵基]丙烷-1-磺酸酯以3-[二甲基(正辛基)铵基]丙烷-1-磺酸酯/水重量比0.9/1的比例加入到NaNO3溶液混合均匀得到本例中的溶液。
利用电导率仪测试实施例1得到的NaNO3基电解液的电导率，电导率为29mS cm-1.
按照对比例1的方法测试实施例1得到的NaNO3基电解液的电压窗口，电压窗口为2.71V。
实施例2
本实施例的电解液具体组成：溶剂为水，溶质为硝酸钠，添加剂为3-[二甲基(正辛基)铵基]丙烷-1-磺酸酯，其具体制备方法如下：将硝酸钠按照硝酸钠/水重量比0.17/1的比例加入到水中溶解得到NaNO3溶液，然后将3-[二甲基(正辛基)铵基]丙烷-1-磺酸酯以3-[二甲基(正辛基)铵基]丙烷-1-磺酸酯/水重量比1.4/1的比例加入到NaNO3溶液混合均匀得到本例中的溶液。
利用电导率仪测试实施例2得到的NaNO3基电解液的电导率，电导率为11mS cm-1.
按照对比例1的方法测试实施例2得到的NaNO3基电解液的电压窗口，电压窗口为2.76V。
实施例3
本实施例的电解液具体组成：溶剂为水，溶质为硝酸钠，添加剂为3-(癸基二甲基铵)丙烷-1-磺酸内盐，其具体制备方法如下：将硝酸钠按照硝酸钠/水重量比0.17/1 的比例加入到水中溶解得到NaNO3溶液，然后将3-(癸基二甲基铵)丙烷-1-磺酸内盐以3-(癸基二甲基铵)丙烷-1-磺酸内盐/水重量比0.7/1的比例加入到NaNO3溶液混合均匀得到本例中的溶液。
利用电导率仪测试实施例3得到的NaNO3基电解液的电导率，电导率为42mS cm-1。
按照对比例1的方法测试实施例3得到的NaNO3基电解液的电压窗口，电压窗口为2.72V。
实施例4
本实施例的电解液具体组成：溶剂为水，溶质为硝酸钠，添加剂为十二烷基二甲基(3-磺丙基)氢氧化铵内盐，其具体制备方法如下：将硝酸钠按照硝酸钠/水重量比0.17/1的比例加入到水中溶解得到NaNO3溶液，然后将十二烷基二甲基(3-磺丙基)氢氧化铵内盐以十二烷基二甲基(3-磺丙基)氢氧化铵内盐/水重量比0.6/1的比例加入到NaNO3溶液混合均匀得到本例中的溶液。
利用电导率仪测试实施例4得到的NaNO3基电解液的电导率，电导率为46mS cm-1.
按照对比例1的方法测试实施例4得到的NaNO3基电解液的电压窗口，电压窗口为2.66V。
实施例5
本实施例的电解液具体组成：溶剂为水，溶质为硝酸钾，添加剂为3-(癸基二甲基铵)丙烷-1-磺酸内盐，其具体制备方法如下：将硝酸钾按照硝酸钾/水重量比0.202/1的比例加入到水中溶解得到KNO3溶液，然后将3-(癸基二甲基铵)丙烷-1-磺酸内盐以3-(癸基二甲基铵)丙烷-1-磺酸内盐/水重量比0.7/1的比例加入到KNO3溶液混合均匀得到本例中的溶液。
利用电导率仪测试实施例5得到的KNO3基电解液的电导率，电导率为50mS cm-1.
按照对比例1的方法测试实施例5得到的KNO3基电解液的电压窗口，电压窗口为2.68V。
实施例6
本实施例的电解液具体组成：溶剂为水，溶质为硝酸锂，添加剂为3-(癸基二甲基铵)丙烷-1-磺酸内盐，其具体制备方法如下：将硝酸锂按照硝酸锂/水重量比0.13788/1的比例加入到水中溶解得到LiNO3溶液，然后将3-(癸基二甲基铵)丙烷-1-磺酸内盐以3-(癸基二甲基铵)丙烷-1-磺酸内盐/水重量比0.7/1的比例加入到LiNO3溶液混合均匀得到本例中的溶液。
利用电导率仪测试实施例6得到的LiNO3基电解液的电导率，电导率为39mS cm-1.
按照对比例1的方法测试实施例6得到的LiNO3基电解液的电压窗口，电压窗口为2.75V。
实施例7
本实施例的电解液具体组成：溶剂为水，溶质为硫酸锂，添加剂为3-(癸基二甲基铵)丙烷-1-磺酸内盐，其具体制备方法如下：将硫酸锂按照硫酸锂/水重量比0.1011/1的比例加入到水中溶解得到Li2SO4溶液，然后将3-(癸基二甲基铵)丙烷-1-磺酸内盐以3-(癸基二甲基铵)丙烷-1-磺酸内盐/水重量比0.7/1的比例加入到Li2SO4溶液混合均匀得到本例中的溶液。
利用电导率仪测试实施例7得到的Li2SO4基电解液的电导率，电导率为25mS cm-1.
按照对比例1的方法测试实施例7得到的Li2SO4基电解液的电压窗口，电压窗口为2.83V。
表1对比例1和实施例1-7制备的水系电解液的性能测试结果
制备得到的基于物理过程形成SEI膜的宽电压窗口水系电解液几种性能参数如表1所示，使用同种添加剂3-[二甲基(正辛基)铵基]丙烷-1-磺酸酯时，添加剂与水的比例为0.9时的获得水系电解液的电导率显著高于添加比例为1.4时的电导率。不同种类的添加剂下，基于3-(癸基二甲基铵)丙烷-1-磺酸内盐的电解液电导率和电压窗口的综合性能优于基于其他两种添加剂的电解液。当使用同种添加剂3-(癸基二甲基铵)丙烷-1-磺酸内盐时，不同的电解质种类所制备的水系电解液窗口和电导率对于硝酸钠、硝酸钾、硝酸锂和硫酸锂分别是2.72V/42mS cm-1、2.68V/50mS cm-1、2.75V/39mS cm-1和2.83V/25mS cm-1，其中，基于硝酸钠的电解液具有与其他电解液相比更优化的综合性能。
实施例8
实施例8是使用商用YP-50F活性炭作为电极，组装的对称活性炭扣式超级电容器，其内部结构如图3所示，包括了：纽扣电容金属外壳1、弹片2、不锈钢垫片3、活性炭正极材料4、玻璃纤维隔膜5、活性炭负极材料6和实施例3中的基于物理过程形成SEI膜的宽电压窗口水系电解液7组成。
其中基于物理过程形成SEI膜的宽电压窗口水系电解液是通过实施例3中的方法制备的。活性炭电极按照YP-50F活性炭材料/炭黑/SBR/CMC＝85/10/3/2的重量比混合制成浆料，涂覆在不锈钢网集流体上，经过烘干制得。对实施例8所制备的对称扣式超级电容进行电化学性能测试。充放电测试的电压窗口设置为0～2V，电流密度范围为0.5～20A g-1。由恒电流充放电曲线可计算对称超级电容在不同扫速下的质量比电容，进而得到电容器的倍率性能。如图4所示，在从0.5A g-1到20A g-1的大幅度电流密度变化下，容量保持率为81.7％(36.6到29.9F g-1)。如图5所示，EIS测试表明，对称超级电容等效串联电阻很小。在低频范围内，奈奎斯特图显示出几乎垂直的线，是电容行为的特征。在高频范围内，较小半圆表明离子传输的电阻较小。因此，本发明提供的基于物理过程形成SEI膜的宽电压窗口水系电解液在提高电压窗口的情况下，显著改善了水系储能器件的阻抗和倍率性能。
对比例2
对比例2是使用商用YP-50F活性炭作为负极，Ni-Fe普鲁士蓝(NiHCF)为正极，组装的活性炭//Ni-Fe普鲁士蓝扣式离子电容器，其内部结构如图3所示，包括了：纽扣电容金属外壳1、弹片2、不锈钢垫片3、NiHCF正极材料4、玻璃纤维隔 膜5、活性炭负极材料6和对比例1中的NaNO3水系电解液7组成。
其中NaNO3水系电解液是通过对比例1中的方法制备的。所述活性炭电极按照YP-50F活性炭材料/炭黑/SBR/CMC＝85/10/3/2的重量比混合制成浆料，涂覆在铝箔上，经过烘干制得。所述Ni-Fe普鲁士蓝(NiHCF)是按照NiHCF材料/炭黑/SBR/CMC＝85/10/3/2的重量比混合制成浆料，涂覆在钛箔上，经过烘干制得。对对比例2所制备的活性炭//Ni-Fe普鲁士蓝扣式离子电容器进行在0～2V下进行充放电测试，如图6所示，在电流密度为0.5A g-1时，在室温下循环1000次，容量保持率仅为25.7％。
实施例9
实施例9是使用商用YP-50F活性炭作为负极，Ni-Fe普鲁士蓝(NiHCF)为正极，组装的活性炭//Ni-Fe普鲁士蓝扣式离子电容器，其内部结构如图3所示，包括了：纽扣电容金属外壳1、弹片2、不锈钢垫片3、NiHCF正极材料4、玻璃纤维隔膜5、活性炭负极材料6和实施例3中的基于物理过程形成SEI膜的宽电压窗口水系电解液7组成。
其中基于物理过程形成SEI膜的宽电压窗口水系电解液是通过实施例3中的方法制备的。活性炭电极按照YP-50F活性炭材料/炭黑/SBR/CMC＝85/10/3/2的重量比混合制成浆料，涂覆在铝箔上，经过烘干制得。所述Ni-Fe普鲁士蓝(NiHCF)是按照NiHCF材料/炭黑/SBR/CMC＝85/10/3/2的重量比混合制成浆料，涂覆在钛箔上，经过烘干制得。对实施例9所制备的活性炭//Ni-Fe普鲁士蓝扣式离子电容器进行在0～2V下进行充放电测试，如图6所示，在电流密度为0.5A g-1时，在室温下循环1000次，容量保持率为81.5％，表现出了优异的电化学性能。
本发明提供的基于物理过程形成SEI膜的宽电压窗口水系电解液的情况下，显著改善了水系储能器件的容量和循环寿命。
实施例10
实施例10是使用商用YP-50F活性炭作为电极，组装的对称活性炭软包超级电容器，其内部结构如图7所示，包括了：由铝塑膜外壳1、正极极片2、负极极片3、极耳4、位于正极极片和负极极片之间的隔膜5和实施例3中的基于物理过程形成SEI膜的宽电压窗口水系电解液6组成。
其中基于物理过程形成SEI膜的宽电压窗口水系电解液是通过实施例3中的方法 制备的。所述活性炭电极按照YP-50F活性炭材料/炭黑/SBR/CMC＝85/10/3/2的重量比混合制成浆料，涂覆在铝箔上，再经过涂布辊压制备。活性炭电极的厚度为93μm，面积负载量为10.1mg cm-2。对实施例10所制备的对称活性炭软包超级电容器进行电化学性能测试。充放电测试的电压窗口设置为0～2V，发现从2C的倍率到100C的倍率，容量保持率达到77％，证明了实施例1中的水系电解液具有很好的实际应用性能。
从以上可以看出，本发明提供的基于物理过程形成SEI膜的宽电压窗口水系电解液不仅能够拓宽水系电解液的电压窗口，还能够保持较好的离子电导率，提供电化学器件优异的倍率性能和循环性能。另外，本发明提供的水系电解液还能够适用于扣式电容器以及工业级软包超级电容器中，能够在多种环境条件下保持优异的电化学性能。
上述是结合实施例对本发明作出的详细说明，但是本发明的实施方式并不受上述实施例的限制，其它任何在本发明专利核心指导思想下所作的改变、替换、组合简化等都包含在本发明专利的保护范围之内。

Claims (10)

  1. 一种基于物理过程形成SEI膜的宽电压窗口水系电解液，其特征在于，所述水系电解液包括添加剂、电解质和水；
    所述添加剂为同时带有异性电荷官能团且润湿性相反的长链化合物；
    所述电解质为碱金属的可溶性无机盐。
  2. 根据权利要求1所述的基于物理过程形成SEI膜的宽电压窗口水系电解液，其特征在于，所述同时带有异性电荷官能团且润湿性相反的长链化合物为3-[二甲基(正辛基)铵基]丙烷-1-磺酸酯、3-(癸基二甲基铵)丙烷-1-磺酸内盐、十二烷基二甲基(3-磺丙基)氢氧化铵内盐中的至少一种。
  3. 根据权利要求1所述的基于物理过程形成SEI膜的宽电压窗口水系电解液，其特征在于，所述碱金属的可溶性无机盐包括硝酸钠、硝酸钾、硝酸锂和硫酸锂中的至少一种。
  4. 根据权利要求1所述的基于物理过程形成SEI膜的宽电压窗口水系电解液，其特征在于，所述碱金属的可溶性无机盐与水的质量比为0.1:1～0.3:1。
  5. 根据权利要求1所述的基于物理过程形成SEI膜的宽电压窗口水系电解液，其特征在于，所述添加剂与水的质量比为0.5:1～1.5:1。
  6. 根据权利要求1所述的基于物理过程形成SEI膜的宽电压窗口水系电解液，其特征在于，所述水系电解液的电化学窗口大于1.5V。
  7. 一种制备权利要求1-6任一所述的基于物理过程形成SEI膜的宽电压窗口水系电解液的方法，其特征在于，所述制备方法包括如下步骤：
    (1)将碱金属的可溶性无机盐和水混合，搅拌配制成盐溶液；
    (2)将添加剂加入步骤(1)得到的盐溶液混合均匀，得到所述的基于物理过程形成SEI膜的宽电压窗口水系电解液。
  8. 一种权利要求1-6任一所述的基于物理过程形成SEI膜的宽电压窗口水系电解液在电化学储能器件中的应用。
  9. 根据权利要求8所述的基于物理过程形成SEI膜的宽电压窗口水系电解液在电化学储能器件中的应用，其特征在于，所述电化学储能器件为扣式超级电容器、扣式离子电容器或软包超级电容器。
  10. 根据权利要求8所述的基于物理过程形成SEI膜的宽电压窗口水系电解液在电化学储能器件中的应用，其特征在于，
    所述扣式超级电容为对称式活性炭纽扣超级电容器，电极为商用的YP-50F活性炭电极，电解液采用权利要求1-6任一所述的基于物理过程形成SEI膜的宽电压窗口 水系电解液；
    所述扣式离子电容器为活性炭//Ni-Fe普鲁士蓝NiHCF纽扣离子电容器，正极为NiHCF电极，负极为YP-50F活性炭电极，电解液采用权利要求1-6任一所述的基于物理过程形成SEI膜的宽电压窗口水系电解液；
    所述软包超级电容为对称式活性炭软包超级电容器，电极为工业级大规模生产的YP-50F活性炭电极，所述YP-50F活性炭电极厚度为80～110μm，面积负载量为9～12mg cm-2，电解液采用权利要求1-6任一所述的基于物理过程形成SEI膜的宽电压窗口水系电解液。
PCT/CN2023/107849 2022-08-05 2023-07-18 一种基于物理过程形成sei膜的宽电压窗口水系电解液及其制备方法和应用 WO2024027499A1 (zh)

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