ICOF thin film, lithium ion alternating current filter capacitor and preparation methods of iCOF thin film and lithium ion alternating current filter capacitor

Abstract

The invention belongs to the technical field of alternating current filter capacitors, and discloses an iCOF film, a lithium ion alternating current filter capacitor and a preparation method. The iCOF thin film comprises a positive electrode iCOF thin film and a negative electrode iCOF thin film; the positive electrode iCOF film is prepared by performing phase-splitting dissolution on a positive electrode monomer containing a cationic group and an amino group and a positive electrode monomer containing an aldehyde group in a mutually insoluble liquid-liquid two-phase system and performing liquid-liquid interfacial polymerization reaction under the condition of a catalyst; and the negative electrode iCOF film is prepared by performing phase-splitting dissolution on a negative electrode monomer containing a sulfonate anion group and an amino group and a negative electrode monomer containing an aldehyde group in a mutually insoluble liquid-liquid two-phase system and performing liquid-liquid interfacial polymerization reaction in the presence of a catalyst. The ordered plane structure and the one-dimensional pore channel of the positive and negative electrode iCOF thin film effectively solve the interlayer stacking defect of the block iCOF material, and the ion storage and transmission efficiency is remarkably improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of AC filter capacitors, and more specifically, relates to an iCOF thin film, a lithium-ion AC filter capacitor and a preparation method thereof. Background Art

[0002] As a new type of energy storage and filtering device, the lithium-ion AC filter capacitor has become an important development direction of the new generation of energy storage and filtering devices by integrating the high-power characteristics of supercapacitors and the high-energy density advantages of lithium-ion batteries. However, its performance is limited by the structural defects of traditional electrode materials. Covalent Organic Frameworks (COFs) are a class of porous organic polymers with uniform pores and ordered crystal forms formed by covalent bonding of light elements. Ion covalent organic frameworks (iCOFs) are functional derivatives formed by introducing charged functional groups into the COF framework, which have both high porosity, a tunable pore microenvironment, and ion conduction characteristics. However, in the prior art, iCOF materials generally exist in a bulk form, and their dense interlayer stacking results in a large number of ion active sites being buried inside the material and unable to participate in electrochemical reactions, seriously restricting the application of iCOF materials in lithium-ion AC filter capacitors.

[0003] Therefore, there is an urgent need to propose an iCOF thin film, a lithium-ion AC filter capacitor and a preparation method thereof. Summary of the Invention

[0004] The object of the present invention is to address the deficiencies of the prior art and propose an iCOF thin film, a lithium-ion AC filter capacitor and a preparation method thereof. The ordered planar structure and one-dimensional pores of the positive and negative iCOF thin films of the present invention effectively solve the interlayer stacking defects of bulk iCOF materials, and significantly improve the ion storage and transmission efficiency.

[0005] To achieve the above object, in the first aspect of the present invention, an iCOF thin film is provided, including a positive iCOF thin film and a negative iCOF thin film;

[0006] Both the positive iCOF thin film and the negative iCOF thin film have a molecular-level ordered plane and an axial one-dimensional pore;

[0007] The positive iCOF thin film is prepared by phase-separating and dissolving a positive monomer containing a cationic group and an amino group and a positive aldehyde group-containing monomer in an immiscible liquid-liquid biphasic system, and performing a liquid-liquid interface polymerization reaction under catalyst conditions;

[0008] The negative iCOF thin film is prepared by phase-separating and dissolving a negative monomer containing a sulfonate anion group and an amino group and a negative aldehyde group-containing monomer in an immiscible liquid-liquid biphasic system, and performing a liquid-liquid interface polymerization reaction under catalyst conditions.

[0009] According to the present invention, preferably, the structural formula of the monomer containing a cationic group and an amino group in the positive electrode is at least one of

[0010] According to the present invention, preferably, the structural formula of the monomer containing an aldehyde group in the positive electrode is and / or

[0011] In the present invention, the structural formula of the structural unit of the positive electrode iCOF film may be

[0012] According to the present invention, preferably, the structural formula of the monomer containing a sulfonate anion group and an amino group in the negative electrode is and / or

[0013] According to the present invention, preferably, the structural formula of the monomer containing an aldehyde group in the negative electrode is

[0014] In the present invention, the structural formula of the structural unit of the negative electrode iCOF film may be

[0015] According to the present invention, preferably, the catalyst is p-toluenesulfonic acid and / or acetic acid, preferably p-toluenesulfonic acid.

[0016] According to the present invention, preferably, the first solvent in the liquid-liquid biphasic system is at least one of water, dimethyl sulfoxide, and N,N-dimethylformamide.

[0017] According to the present invention, preferably, the second solvent in the liquid-liquid biphasic system is at least one of benzene, toluene, and hexane, preferably toluene.

[0018] According to the present invention, preferably, the thickness of the positive electrode iCOF film is 4-9 nm, and it has a positive charge distribution and large capacitance performance.

[0019] According to the present invention, preferably, the thickness of the negative electrode iCOF film is 3-6 nm, and it is rich in negative charges and oxidation active sites.

[0020] According to the present invention, preferably, the positive electrode iCOF film and the negative electrode iCOF film are prepared by a method including the following steps:

[0021] S1: Dissolve the monomer containing a cationic group and an amino group in the positive electrode and the monomer containing an aldehyde group in the positive electrode in immiscible first and second solvents respectively to form a first positive electrode monomer solution and a second positive electrode monomer solution; dissolve the monomer containing a sulfonate anion group and an amino group in the negative electrode and the monomer containing an aldehyde group in the negative electrode in immiscible first and second solvents respectively to form a first negative electrode monomer solution and a second negative electrode monomer solution.

[0022] S2: Preparation of the positive electrode iCOF film: Inject the first positive electrode monomer solution into the first reaction vessel, then inject the second positive electrode monomer solution into the first reaction vessel, inject an aqueous catalyst solution into the first reaction vessel, let it stand and react to obtain the positive electrode iCOF film.

[0023] Preparation of the negative electrode iCOF film: Inject the first negative electrode monomer solution into the second reaction vessel, then inject the second negative electrode monomer solution into the second reaction vessel, inject an aqueous catalyst solution into the second reaction vessel, let it stand and react to obtain the negative electrode iCOF film.

[0024] According to the present invention, preferably, the first solvent is at least one of water, dimethyl sulfoxide and N,N-dimethylformamide;

[0025] The second solvent is at least one of benzene, toluene and hexane, preferably toluene;

[0026] According to the present invention, preferably, the concentration of the aqueous catalyst solution is 0.05 - 0.15 mol / L.

[0027] According to the present invention, preferably, the amount of substance of the monomer containing a cationic group and an amino group in the positive electrode is 0.002 - 0.005 mmol.

[0028] According to the present invention, preferably, the amount of substance of the monomer containing an aldehyde group in the positive electrode is 0.002 - 0.006 mmol.

[0029] According to the present invention, preferably, the amount of substance of the monomer containing a sulfonate anion group and an amino group in the negative electrode is 0.002 - 0.005 mmol.

[0030] According to the present invention, preferably, the amount of substance of the monomer containing an aldehyde group in the negative electrode is 0.002 - 0.005 mmol.

[0031] According to the present invention, preferably, in the preparation of the positive electrode iCOF film: the volume ratio of the first solvent, the second solvent to the aqueous catalyst solution is (20 - 30):(1.5 - 2.5):1, the reaction temperature is 25 - 35 °C, and the time is 48 - 72 h.

[0032] According to the present invention, preferably, in the preparation of the negative electrode iCOF film, the volume ratio of the first solvent, the second solvent to the catalyst aqueous solution is (20 - 30):(1.5 - 2.5):1, the reaction temperature is 25 - 35 °C, and the reaction time is 48 - 72 h.

[0033] In the second aspect of the present invention, a lithium-ion AC filter capacitor is provided, which includes:

[0034] Pole pieces, including a positive pole piece and a negative pole piece. The positive pole piece includes a positive current collector and a positive iCOF film attached to the positive current collector. The negative pole piece includes a negative current collector and a negative iCOF film attached to the negative current collector. Optionally, the negative pole piece is pre-lithiated; the positive iCOF film and the negative iCOF film are the iCOF films described in any one of claims 1 - 6;

[0035] A separator, located between the positive pole piece and the negative pole piece, and one side of the separator is in contact with the positive iCOF film, and the other side is in contact with the negative iCOF film;

[0036] An electrolyte, uniformly distributed in the lithium-ion AC filter capacitor, and used as a medium for lithium-ion migration and charge transfer.

[0037] According to the present invention, preferably, both the positive current collector and the negative current collector are circular copper foil sheets, and the diameters of the positive current collector and the negative current collector are independently 0.5 - 3 cm.

[0038] According to the present invention, preferably, the solute of the electrolyte is at least one of lithium hexafluorophosphate, lithium bis(trifluoromethanesulfonyl)imide, and lithium perchlorate, and preferably lithium hexafluorophosphate.

[0039] According to the present invention, preferably, the solvent of the electrolyte is at least one of ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate;

[0040] According to the present invention, preferably, the solvent of the electrolyte is a mixture of ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate, and the volume ratio of ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate is 1:(0.5 - 2):(0.5 - 2), and preferably 1:1:1.

[0041] According to the present invention, preferably, the concentration of the solute of the electrolyte is 0.5 - 2 mol / L.

[0042] In the third aspect of the present invention, a preparation method of the lithium-ion AC filter capacitor is provided, and the preparation method includes:

[0043] Transfer the positive iCOF film and the negative iCOF film to the surfaces of the positive current collector and the negative current collector respectively, and vacuum dry to obtain the positive pole piece and the negative pole piece;

[0044] Pre-lithiate the negative electrode sheet to obtain a pre-lithiated negative electrode sheet;

[0045] Under an inert atmosphere, stack the positive electrode sheet, the separator, and the pre-lithiated negative electrode sheet in sequence to form an electrode separator assembly; inject the electrolyte into the electrode separator assembly to obtain the lithium-ion AC filter capacitor.

[0046] According to the present invention, preferably, the temperature of the vacuum drying is 50 - 70°C, and the time is 2 - 5 h.

[0047] According to the present invention, preferably, the pre-lithiation treatment is to perform a single charge-discharge treatment on a half-cell composed of the negative electrode sheet, a lithium sheet, and an electrolyte containing a lithium salt to obtain the pre-lithiated negative electrode sheet; preferably, the voltage of the single charge-discharge treatment is 0 - 2 V vs. Li / Li + , the charge-discharge rate is 0.01 - 0.5 C; the solute of the electrolyte containing a lithium salt is at least one of lithium hexafluorophosphate, lithium bis(trifluoromethanesulfonyl)imide, and lithium perchlorate; the solvent of the electrolyte containing a lithium salt is at least one of ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate;

[0048] In the present invention, as a preferred solution, after the single charge-discharge treatment is completed, disassemble the negative electrode sheet to obtain the pre-lithiated negative electrode sheet.

[0049] According to the present invention, preferably, the inert atmosphere is at least one of argon, helium, and nitrogen.

[0050] The beneficial effects of the technical solution of the present invention are as follows:

[0051] The positive and negative iCOF thin films of the present invention are respectively formed by the reaction of positive and negative monomers at the immiscible liquid-liquid interface. Their ordered planar structure and one-dimensional pores effectively solve the defect of dense stacking between layers of the bulk iCOF material, realize precise stacking between layers, and significantly improve the ion storage and transport efficiency. The method of the present invention realizes precise control of the thin film structure by regulating the two-phase solvent, monomer dosage, and interfacial reaction conditions, breaks through the electrochemical performance bottleneck of traditional bulk iCOF materials in capacitor applications, and the asymmetric charge group distribution of the positive and negative iCOF can form an axial self-built electric field, which can cooperate with the one-dimensional pores to accelerate the ion transport speed. Specifically:

[0052] (1) The iCOF thin film proposed by the present invention is prepared by a reaction at the immiscible liquid-liquid interface. An ordered planar structure and one-dimensional pores are formed through the liquid-liquid interface reaction, successfully breaking through the defect of pore blockage caused by dense stacking between layers of the iCOF bulk material in the prior art and improving ion transport.

[0053] (2) In the iCOF thin film proposed by the present invention, the positive iCOF thin film has large capacitance performance, the negative iCOF thin film is rich in oxidation active sites and charged groups, and the thickness of both is within 10 nm, which is particularly suitable for micro lithium-ion AC filter capacitors.

[0054] (3) For the iCOF thin film proposed by the present invention, the synthesis of the structural units of the positive iCOF thin film and the negative iCOF thin film, as well as the synthesis and ordered arrangement of the structural units, are all realized through the liquid-liquid interfacial polymerization reaction of an immiscible solvent biphasic system, making the arrangement of the structural units of the positive iCOF thin film and the negative iCOF thin film more orderly and controllable, solving the self-accumulation problem of iCOF powder in the prior art, and further improving the problems of pore blockage and ion transport retardation caused by disordered self-accumulation of iCOF bulk in the prior art.

[0055] (4) The lithium-ion AC filter capacitor of the present invention uses a positive iCOF thin film and a negative iCOF thin film with ordered planes and one-dimensional pores. Among them, the positive iCOF thin film realizes efficient charge storage through the ordered arrangement of cationic groups, and the negative iCOF thin film provides redox active sites through sulfonate anion groups; making the lithium-ion AC filter capacitor small in volume and high in energy density, and broadening the application path of COF materials in the field of lithium-ion AC filter capacitors.

[0056] (5) The preparation method of the lithium-ion AC filter capacitor of the present invention is simple, and has high energy density, high power density, fast ion transport and frequency response.

[0057] (6) The negative iCOF thin film proposed by the present invention is rich in -SO3H functional groups with strong electronegativity. The present invention uses the negative iCOF thin film and assembles a half-cell with a lithium sheet as the counter electrode for diffusion coefficient testing. The results show that the negative iCOF thin film of the present invention increases the lithium ion diffusion rate, solving the problems of kinetic imbalance caused by different energy storage methods of the positive and negative electrodes of the lithium-ion AC filter capacitor and the low frequency response of traditional carbon materials.

[0058] (7) The positive iCOF thin film proposed by the present invention is rich in N + ions. By regulating the concentrations of the monomers containing cationic groups and amino groups in the positive electrode and the aldehyde group-containing monomers in the positive electrode, the thickness of the positive iCOF thin film is achieved, and finally the capacity matching problem between the positive and negative electrodes is realized, solving the capacity mismatch problem caused by different energy storage methods of the positive and negative electrodes of the lithium-ion AC filter capacitor.

[0059] (8) Through the collaborative design of the positive electrode iCOF thin film and the negative electrode iCOF thin film, a cationic group is introduced into the positive electrode iCOF structure, and a sulfonate anion group is introduced into the negative electrode iCOF structure to form a self-built electric field across the electrodes. The direction of this electric field is consistent with the axial direction of the one-dimensional pore channels, thus accelerating ion transport.

[0060] Other features and advantages of the present invention will be described in detail in the following specific embodiments section. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] By describing the exemplary embodiments of the present invention in more detail in conjunction with the accompanying drawings, the above and other objects, features, and advantages of the present invention will become more apparent. Among them, in the exemplary embodiments of the present invention, the same reference numerals generally represent the same components.

[0062] Figure 1a -b shows the state of the positive electrode iCOF thin film and the negative electrode iCOF thin film prepared in Example 1 of the present invention existing at the immiscible liquid-liquid interface and a schematic diagram of their reaction process (1 - Schematic structure of the monomer containing a cationic group and an amino group in the positive electrode dissolved in the first solvent, 2 - Schematic structure of the monomer containing an aldehyde group in the positive electrode dissolved in the second solvent, 3 - Schematic structure of the monomer containing a sulfonate anion group and an amino group in the negative electrode dissolved in the first solvent, 4 - Schematic structure of the monomer containing an aldehyde group in the negative electrode dissolved in the second solvent).

[0063] Figure 2a -b shows the optical microscope photographs of the positive electrode iCOF thin film and the negative electrode iCOF thin film prepared in Example 1 of the present invention (iCOF DHPATG - Positive electrode iCOF thin film, iCOF TpPa-SO3H - Negative electrode iCOF thin film).

[0064] Figure 3a -b shows the scanning electron microscope photographs of the positive electrode iCOF thin film and the negative electrode iCOF thin film prepared in Example 1 of the present invention.

[0065] Figure 4a -b shows the transmission electron microscope photographs of the positive electrode iCOF thin film and the negative electrode iCOF thin film prepared in Example 1 of the present invention.

[0066] Figure 5a -b shows the atomic force microscope photographs of the positive electrode iCOF thin film and the negative electrode iCOF thin film prepared in Example 1 of the present invention.

[0067] Figure 6 Shows the time-voltage curves of the lithium-ion AC filtering capacitor prepared in Example 1 of the present invention at different current densities (Time - Time, Potential - Potential).

[0068] Figure 7Shows the capacitance performance of the lithium-ion AC filtering capacitor prepared in Example 1 of the present invention (Current density - current density, Areal capacitance - areal capacitance, Volumentric capacitance - volumetric capacitance).

[0069] Figure 8 Shows the Coulombic efficiency and cycling performance of the lithium-ion AC filtering capacitor prepared in Example 1 of the present invention (Cycle number - number of cycles, Capacitance retention - capacitance retention rate, Coulombic efficiency - Coulombic efficiency).

[0070] Figure 9 Shows the specific capacitance of the lithium-ion AC filtering capacitor prepared in Example 1 of the present invention at corresponding frequencies (Frequency - frequency, C A - areal specific capacitance, C V - volumetric specific capacitance). Detailed implementation manners

[0071] The preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to make the present invention more thorough and complete, and to fully convey the scope of the present invention to those skilled in the art.

[0072] Example 1

[0073] This example provides an iCOF film, including a positive iCOF film and a negative iCOF film, as shown in Figure 1:

[0074] 1) Preparation of the positive iCOF film: Dissolve (0.004 mmol) in water to form a first positive monomer solution; dissolve (0.006 mmol) in toluene to form a second positive monomer solution;

[0075] Inject the first positive monomer solution into a crystallization dish, then inject the second positive monomer solution into the crystallization dish, inject an aqueous solution of p-toluenesulfonic acid (0.1 mol / L) into the crystallization dish, and let it stand and react at 25 °C for 48 h to obtain a positive iCOF film (thickness: 4.5 nm);

[0076] The volume ratio of water, toluene and the aqueous solution of p-toluenesulfonic acid is 25:2:1;

[0077] 2) Preparation of the negative iCOF film: Dissolve (0.003 mmol) was dissolved in water to form the first negative electrode monomer solution; (0.002 mmol) was dissolved in toluene to form the second negative electrode monomer solution;

[0078] The first negative electrode monomer solution was injected into a crystallization dish, and then the second negative electrode monomer solution was injected into the crystallization dish. An aqueous solution of p-toluenesulfonic acid (0.1 mol / L) was injected into the crystallization dish, and it was left standing and reacted at 25 °C for 48 h to obtain a negative electrode iCOF film (thickness: 3.7 nm);

[0079] The volume ratio of water, toluene and the aqueous solution of p-toluenesulfonic acid was 25:2:1.

[0080] In this embodiment, a lithium-ion AC filter capacitor was also prepared by using the above positive and negative electrode iCOF films, including:

[0081] Pole pieces, including a positive electrode piece and a negative electrode piece; The positive electrode iCOF film and the negative electrode iCOF film were respectively transferred onto the surfaces of the positive electrode current collector copper foil and the negative electrode current collector copper foil (the areas of the positive electrode current collector and the negative electrode current collector were the same), and dried in vacuum at 60 °C for 2 h to obtain the positive electrode piece and the negative electrode piece; The pre-lithiation treatment was to perform a charge-discharge treatment on a half-cell composed of the negative electrode piece, a lithium piece and an electrolyte containing a lithium salt to obtain the pre-lithiated negative electrode piece; The voltage of the charge-discharge treatment was 0 - 2 V vs. Li / Li⁺, and the charge-discharge rate was 0.1 C; The solute of the electrolyte containing a lithium salt was lithium hexafluorophosphate, and the solvent was a mixture of ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate. The volume ratio of ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate was 1:1:1, and the concentration of the solute was 1 mol / L;

[0082] A polypropylene separator, located between the positive electrode piece and the pre-lithiated negative electrode piece, and one side of it was in contact with the positive electrode iCOF film, and the other side was in contact with the negative electrode iCOF film;

[0083] Lithium hexafluorophosphate electrolyte, the solute was lithium hexafluorophosphate, and the solvent was a mixture of ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate. The volume ratio of ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate was 1:1:1, and the concentration of the solute was 1 mol / L; The lithium hexafluorophosphate electrolyte was uniformly distributed in the lithium-ion AC filter capacitor and used as a medium for lithium-ion migration and charge transfer;

[0084] In a glove box under argon protection, the positive electrode piece, the separator and the pre-lithiated negative electrode piece were stacked in sequence to form an electrode separator assembly; The lithium hexafluorophosphate electrolyte was injected into the electrode separator assembly to obtain the lithium-ion AC filter capacitor.

[0085] As Figure 2aAs shown in -b, 3a - b, and 4a - b, the prepared positive iCOF film and negative iCOF film in this embodiment are in a uniform and complete film shape;

[0086] As Figure 5a shown in -b, the thicknesses of the prepared positive iCOF film and negative iCOF film in this embodiment are both within 10 nm;

[0087] As Figure 6 shown, the time - voltage curve of the prepared lithium - ion AC filtering capacitor with iCOF film in this embodiment is an ideal triangle, and the electrical performance is excellent;

[0088] As Figure 7 shown, the prepared lithium - ion AC filtering capacitor with iCOF film in this embodiment has a large area and volume capacitance;

[0089] As Figure 8 shown, the prepared lithium - ion AC filtering capacitor with iCOF film in this embodiment has excellent Coulomb efficiency and cycling performance;

[0090] As Figure 9 shown, under the condition of AC 120 Hz, the volume - specific capacitance of the prepared lithium - ion AC filtering capacitor with iCOF film is 1.75×104 mF cm -3 , and this lithium - ion AC filtering capacitor has a greater volume advantage than commercial filtering capacitors, is suitable for use as a miniaturized filter component in electronic circuits and energy harvesting systems, and provides opportunities for the future development of portable power electronics.

[0091] Example 2

[0092] This example provides a lithium - ion AC filtering capacitor. The difference between this example and Example 1 is only that: during the preparation of the positive iCOF film, the amount of substance of the monomer containing cationic groups and amino groups in the positive electrode is 0.5 times that in Example 1, and the amount of substance of the monomer containing aldehyde groups in the positive electrode is 0.5 times that in Example 1.

[0093] Example 3

[0094] This example provides a lithium - ion AC filtering capacitor. The difference between this example and Example 1 is only that: during the preparation of the positive iCOF film, the amount of substance of the monomer containing cationic groups and amino groups in the positive electrode is 0.75 times that in Example 1, and the amount of substance of the monomer containing aldehyde groups in the positive electrode is 0.75 times that in Example 1.

[0095] Example 4

[0096] This embodiment provides a lithium-ion AC filtering capacitor. The difference between this embodiment and Embodiment 1 is only that: during the preparation of the positive iCOF film, the amount of substance of the monomer containing cationic groups and amino groups in the positive electrode is 1.25 times that in Embodiment 1, and the amount of substance of the monomer containing aldehyde groups in the positive electrode is 1.25 times that in Embodiment 1.

[0097] Table 1 summarizes the results such as the energy density and power density of the lithium-ion AC filtering capacitors with iCOF films prepared in Embodiments 1-4. Among them, if the phase angle < -45°, there is filtering performance; if the phase angle > -45°, there is no filtering performance.

[0098] Table 1

[0099]

[0100] It can be seen from the data in Table 1 that:

[0101] As the amount of the monomer containing cationic groups and amino groups and the monomer containing aldehyde groups in the positive electrode added during the preparation of the positive iCOF film increases, the energy density and power density of the finally prepared lithium-ion AC filtering capacitor with an iCOF film do not change linearly, indicating that it is not the case that the more the monomer containing cationic groups and amino groups and the monomer containing aldehyde groups in the positive electrode for preparing the positive COF film, the better, but there is an optimal value.

[0102] For the lithium-ion AC filtering capacitor with an iCOF film prepared by the present invention, the positive iCOF film and the negative iCOF film with ordered planes and one-dimensional pores are adopted. At the same time, the internal electric field is increased in the positive and negative electrode materials, so that the lithium-ion AC filtering capacitor has a small volume and a high energy density, and broadens the application path of iCOF materials in the field of lithium-ion capacitors.

[0103] The various embodiments of the present invention have been described above. The above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations are obvious to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.

Claims

1. An iCOF film, characterized in that, It includes a positive electrode iCOF thin film and a negative electrode iCOF thin film; Both the positive electrode iCOF thin film and the negative electrode iCOF thin film have a molecular-level ordered plane and axial one-dimensional pores; The positive electrode iCOF thin film is prepared by the phase-separated dissolution of a positive electrode monomer containing a cationic group and an amino group and a positive electrode monomer containing an aldehyde group in an immiscible liquid-liquid biphasic system, and through a liquid-liquid interface polymerization reaction under the condition of a catalyst; The negative electrode iCOF thin film is prepared by the phase-separated dissolution of a negative electrode monomer containing a sulfonate anion group and an amino group and a negative electrode monomer containing an aldehyde group in an immiscible liquid-liquid biphasic system, and through a liquid-liquid interface polymerization reaction under the condition of a catalyst.

2. The iCOF thin film according to claim 1, wherein, The structural formula of the monomer containing a cationic group and an amino group in the positive electrode is at least one of; The structural formula of the positive electrode containing the aldehyde group monomer is and / or The structural formula of the monomer containing a sulfonate anion group and an amino group in the negative electrode is and / or The structural formula of the aldehyde group-containing monomer in the negative electrode is 3. The iCOF thin film according to claim 1, wherein, The catalyst is p-toluenesulfonic acid and / or acetic acid, preferably p-toluenesulfonic acid; The first solvent in the liquid-liquid biphasic system is at least one of water, dimethyl sulfoxide and N,N-dimethylformamide; The second solvent in the liquid-liquid biphasic system is at least one of benzene, toluene and hexane, preferably toluene.

4. The iCOF thin film according to claim 1, wherein, The thickness of the positive electrode iCOF thin film is 4-9 nm; The thickness of the negative electrode iCOF thin film is 3-6 nm.

5. The iCOF film according to claim 1, wherein The positive electrode iCOF thin film and the negative electrode iCOF thin film are prepared by a method including the following steps: S1: Dissolve a positive electrode monomer containing a cationic group and an amino group and a positive electrode monomer containing an aldehyde group in immiscible first and second solvents respectively to form a first positive electrode monomer solution and a second positive electrode monomer solution; dissolve a negative electrode monomer containing a sulfonate anion group and an amino group and a negative electrode monomer containing an aldehyde group in immiscible first and second solvents respectively to form a first negative electrode monomer solution and a second negative electrode monomer solution; S2: Preparation of the positive electrode iCOF thin film: Inject the first positive electrode monomer solution into a first reaction vessel, then inject the second positive electrode monomer solution into the first reaction vessel, inject an aqueous catalyst solution into the first reaction vessel, let it stand and react to obtain the positive electrode iCOF thin film; Preparation of the negative electrode iCOF thin film: Inject the first negative electrode monomer solution into a second reaction vessel, then inject the second negative electrode monomer solution into the second reaction vessel, inject an aqueous catalyst solution into the second reaction vessel, let it stand and react to obtain the negative electrode iCOF thin film.

6. The iCOF thin film according to claim 5, wherein, The first solvent is at least one of water, dimethyl sulfoxide and N,N-dimethylformamide; The second solvent is at least one of benzene, toluene and hexane, preferably toluene; The concentration of the aqueous catalyst solution is 0.05-0.15 mol / L; The amount of substance of the positive electrode monomer containing a cationic group and an amino group is 0.002-0.005 mmol; The amount of substance of the positive electrode monomer containing an aldehyde group is 0.002-0.006 mmol; The amount of substance of the negative electrode monomer containing a sulfonate anion group and an amino group is 0.002-0.005 mmol; The amount of the aldehyde group-containing monomer in the negative electrode is 0.002 - 0.005 mmol; In the preparation of the positive electrode iCOF film: the volume ratio of the first solvent, the second solvent to the catalyst aqueous solution is (20 - 30):(1.5 - 2.5):1, the reaction temperature is 25 - 35 °C, and the time is 48 - 72 h; In the preparation of the negative electrode iCOF film: the volume ratio of the first solvent, the second solvent to the catalyst aqueous solution is (20 - 30):(1.5 - 2.5):1, the reaction temperature is 25 - 35 °C, and the time is 48 - 72 h.

7. A lithium-ion AC filtering capacitor, characterized in that, The capacitor includes: Pole pieces, including a positive electrode piece and a negative electrode piece. The positive electrode piece includes a positive electrode current collector and a positive electrode iCOF film attached to the positive electrode current collector. The negative electrode piece includes a negative electrode current collector and a negative electrode iCOF film attached to the negative electrode current collector. Optionally, the negative electrode piece is pre-lithiated; the positive electrode iCOF film and the negative electrode iCOF film are the iCOF films described in any one of claims 1 - 6; A separator, located between the positive electrode piece and the negative electrode piece, and one side of it is in contact with the positive electrode iCOF film, and the other side is in contact with the negative electrode iCOF film; An electrolyte, uniformly distributed in the lithium-ion AC filter capacitor, serving as a medium for lithium-ion migration and charge transfer.

8. According to claim 1 of the lithium-ion AC filter capacitor, wherein, Both the positive electrode current collector and the negative electrode current collector are circular copper foil sheets, and the diameters of the positive electrode current collector and the negative electrode current collector are independently 0.5 - 3 cm; The solute of the electrolyte is at least one of lithium hexafluorophosphate, lithium bis(trifluoromethanesulfonyl)imide, and lithium perchlorate; The solvent of the electrolyte is at least one of ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate; Preferably, the solvent of the electrolyte is a mixture of ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate, and the volume ratio of ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate is 1:(0.5 - 2):(0.5 - 2), preferably 1:1:1; Preferably, the concentration of the solute of the electrolyte is 0.5 - 2 mol / L.

9. The preparation method of the lithium-ion AC filtering capacitor according to claim 7 or 8, characterized in that The preparation method includes: Transfer the positive electrode iCOF film and the negative electrode iCOF film to the surfaces of the positive electrode current collector and the negative electrode current collector respectively, and vacuum dry to obtain the positive electrode piece and the negative electrode piece; Pre-lithiate the negative electrode piece to obtain a pre-lithiated negative electrode piece; Under an inert atmosphere, stack the positive electrode piece, the separator, and the pre-lithiated negative electrode piece in sequence to form an electrode separator assembly; inject the electrolyte into the electrode separator assembly to obtain the lithium-ion AC filter capacitor.

10. According to claim 9 of the preparation method of the lithium-ion AC filter capacitor, wherein, The temperature of the vacuum drying is 50 - 70 °C, and the time is 2 - 5 h; The pre-lithiation treatment is to perform a charge-discharge treatment on a half-cell composed of the negative electrode sheet, a lithium sheet, and an electrolyte containing a lithium salt to obtain the pre-lithiated negative electrode sheet; preferably, the voltage of the charge-discharge treatment is 0-2V vs. Li / Li + , the charge-discharge rate is 0.01-0.5C; the solute of the electrolyte containing a lithium salt is at least one of lithium hexafluorophosphate, lithium bis(trifluoromethanesulfonyl)imide, and lithium perchlorate; the solvent of the electrolyte containing a lithium salt is at least one of ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate; The inert atmosphere is at least one of argon, helium, and nitrogen.

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