Self-repairing artificial interfacial layer modified copper-based current collector, preparation method thereof and application thereof in negative electrode-free lithium battery

Abstract

The application discloses a self-repairing artificial interface layer modified copper-based current collector and a preparation method and application thereof in a negative electrode-free lithium battery. The self-repairing artificial interface layer is prepared from nitrogen-containing water-soluble comonomer, quaternary ammonium salt monomer, double bond-terminated polyethylene oxide and dopamine self-repairing monomer by a solution polymerization method to obtain an ionomer with a self-repairing function. The ionomer is prepared into a solution and used as an electrophoretic liquid, and an electrophoretic deposition method is adopted to deposit the ionomer on the exposed copper-based current collector. The artificial interface layer obtained by the method is dense, uniform and adjustable in thickness, and can accelerate lithium ion transmission, homogenize lithium deposition and self-repair, etc. The copper-based current collector modified by the self-repairing artificial interface layer is used in the negative electrode-free lithium battery, and the cycle life of the battery is obviously improved, thereby providing a new solution for developing high-performance negative electrode-free lithium batteries.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of new energy materials, and particularly relates to a self-repairing artificial interface layer modified copper-based current collector, a preparation method thereof and application thereof in a negative electrode-free lithium battery. BACKGROUND

[0002] Recently, the scheme of replacing the existing lithium-ion battery with a lithium metal battery using lithium as the negative electrode has attracted attention in the academic field, but the high reactivity of lithium leads to problems such as electrolyte decomposition and dendrite growth piercing the separator. In addition, the preparation of thin lithium foil with a capacity comparable to that of the positive electrode also faces challenges such as complex process and high cost in industrial production. In view of this, a negative electrode-free lithium battery composed of a lithium-rich positive electrode and a copper-based current collector negative electrode without metal lithium is proposed.

[0003] The so-called negative electrode-free lithium battery is actually an ideal lithium metal battery in a fully discharged state, that is, the lithium in the initial battery is all stored in the active material on the positive electrode side according to the electrochemical stoichiometric ratio. During the first charge, lithium migrates from the positive electrode side to the copper-based current collector. This will bring the following problems: (1) the nucleation barrier of lithium on the copper current collector is high, which will greatly reduce the deposition / stripping reversibility of lithium. (2) During the deposition and stripping of lithium, it will react with the electrolyte to form a solid electrolyte interface (SEI), and the SEI layer has poor mechanical properties, which will cause lithium dendrites to pierce the layer, leading to continuous rupture and regeneration of the SEI layer, accelerating the irreversible consumption of lithium and electrolyte; moreover, there are a large number of defects in the formed SEI film, which will cause uneven electric field and ion flux, thus accelerating uncontrollable lithium dendrite growth, and ultimately leading to the shortening of the cycle life of the negative electrode-free lithium battery. Therefore, improving the cycle life and stability of the negative electrode-free lithium battery has become a major challenge.

[0004] To solve these problems, the current research of scientists mainly focuses on electrolyte optimization, copper-based current collector modification and control of cut-off voltage / discharge depth, etc. For an anode-free lithium battery, lithium is directly deposited on the surface of the copper-based current collector, and the initial nucleation condition between them directly affects the subsequent deposition behavior of lithium, so the modification of the copper-based current collector is more important. This modification method not only can enhance the interfacial compatibility between lithium and the copper-based current collector, but also can inhibit the decomposition of the electrolyte and the corrosion of lithium, thereby prolonging the cycle life of the battery. The reconstruction of the copper-based current collector mainly includes three aspects of setting an artificial interface layer, designing a three-dimensional structure and replacing the current collector material. Among them, the artificial interface layer is realized by coating, polymerization, calcination and other methods on the copper-based current collector. This method can reduce the direct contact between lithium and electrolyte to promote the formation of stable SEI, and can also regulate the desolvation kinetics of lithium ions to reduce the nucleation barrier. Therefore, in recent years, researchers have shown increasing interest in setting an artificial interface layer to construct high-performance lithium batteries. Patent CN118198375A discloses setting an ultra-thin and ultra-light interface layer composed of DNA on the copper-based current collector to promote the adsorption of lithium ions. Patent CN117438533A sets an ion layer and an electron conducting layer on the copper-based current collector, which respectively reduces the nucleation barrier of lithium ions and inhibits the excessive reduction and decomposition of the electrolyte, effectively regulating the deposition and stripping behavior of lithium ions. However, the currently reported artificial interface layer has single functionality, lacks self-repairing functional monomers, and cannot meet the long cycle requirements of the battery. Therefore, it is necessary to develop a copper-based current collector modified by a self-repairing artificial interface layer. SUMMARY

[0005] In view of the deficiencies of the prior art, the present application discloses a copper-based current collector modified by a self-repairing artificial interface layer and a preparation method thereof. The self-repairing artificial interface layer is prepared by solution polymerization of four functional monomers, which is composed of a self-repairing ionomer and deposited on the copper-based current collector by electrophoretic deposition. The artificial interface layer has good mechanical properties, high ionic conductivity and self-repairing property, which can improve the cycle performance of the anode-free lithium battery.

[0006] To achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0007] The first aspect of the present application provides a copper-based current collector modified by a self-repairing artificial interface layer, which is prepared by solution polymerization of A, B, C and D four components to obtain a self-repairing ionomer modified on the bare copper-based current collector, wherein the A component is a nitrogen-containing water-soluble comonomer, which is 20-45 parts by weight, the B component is a quaternary ammonium salt monomer, which is 20-40 parts by weight, the C component is a double bond-terminated polyethylene oxide, which is 30-45 parts by weight, and the D component is a dopamine self-repairing monomer, which is 0.5-1.0 parts by weight.

[0008] The thickness of the self-repairing artificial interface layer is 5-10 microns.

[0009] The nitrogen-containing water-soluble comonomer is one of acrylamide, N-methyl methacrylamide and methacrylamide.

[0010] The quaternary ammonium salt monomer is one of methacryloyloxyethyl trimethyl ammonium chloride, methacryloyloxypropyl trimethyl ammonium chloride and acryloyloxyethyl trimethyl ammonium chloride.

[0011] The double bond-terminated polyethylene oxide is polyethylene glycol monomethyl ether methacrylate.

[0012] The dopamine self-repairing monomer is 3-methacrylamido dopamine.

[0013] The second aspect of the present application provides a preparation method of the copper-based current collector modified by the self-repairing artificial interface layer, comprising the following steps.

[0014] First, the nitrogen-containing water-soluble comonomer, the quaternary ammonium salt monomer, the double bond-terminated polyethylene oxide, the dopamine self-repairing monomer and the partial reducing agent component of the redox initiator are added to deionized water, stirred and mixed uniformly, then under the protection of inert atmosphere, the temperature is increased to 30-50 DEG C, and the half amount of the oxidant component of the redox initiator is slowly added, and the reaction is carried out for 1-3 hours; then the other half amount of the oxidant and the reducing agent component of the redox initiator is slowly added, and the reaction is carried out for 2-10 hours; the temperature is increased to 60-80 DEG C, and the reaction is carried out for 1-3 hours, so as to obtain the target product, the ionomer solution with self-repairing function, and the solid content of the ionomer solution is 10-30 wt%.

[0015] Then, the ionomer solution with self-repairing function prepared above is diluted with deionized water and ethanol to the solid content of 2-10 wt%, and the ionomer with self-repairing function is deposited on the bare copper current collector by electrophoretic deposition method, the electrophoretic voltage is controlled to be 0.4-1.2 V, and the electrophoresis time is 240-420 s, so as to obtain the copper-based current collector modified by the self-repairing artificial interface layer.

[0016] The third aspect of the present application provides a negative electrode-free lithium metal battery, which comprises the copper-based current collector modified by the self-repairing artificial interface layer, and other components, including the lithium-rich positive electrode, the separator and the electrolyte, are not particularly limited.

[0017] Compared with the prior art, the present application has at least the following beneficial effects.

[0018] (1) The two hydroxyl groups in the catechol group of the dopamine self-repairing monomer can participate in the formation of multiple hydrogen bonds, so that the artificial interface layer can be repaired in time after being damaged by lithium dendrites, which helps to improve the cycle life and rate performance of the battery.

[0019] (2) The double bond-terminated polyethylene oxide can form a uniform lithium ion migration channel, improve the ionic conductivity of the artificial interface layer, improve the rate performance of the battery; and enhance the flexibility of the polymer chain, so that the artificial interface layer can adapt to the periodic strain caused by the repeated deposition and stripping of lithium, thereby prolonging the cycle life of the battery.

[0020] (3) The quaternary ammonium salt monomer contains an ionizable cationic group, so that the method of electrophoretic deposition for constructing the artificial interface layer can be realized, which helps to form an artificial interface layer with controllable thickness and good density, and plays the role of cationic ionomer in homogenizing the electric field.

[0021] (4) The nitrogen-containing water-soluble comonomer not only helps other functional monomers to form copolymers to exert the synergistic effect of each component, but also contains nitrogen elements that can promote the formation of stable SEI, so that the electrochemical performance of the anode-free lithium metal battery is comprehensively improved. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 Scanning electron microscope images of scratches on the surface of the copper-based current collector modified with the self-repairing artificial interface layer described in Example 1 at different self-repairing times, at a magnification of 200 times.

[0023] Figure 2 LiNi 0.8 Co 0.1 Mn 0.1 O2 ternary cathode || copper full cell assembled for Example 1 and Comparative Example 1, Comparative Example 2, Comparative Example 3 was subjected to constant current charge-discharge cycling at a rate of 0.5C. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical scheme and beneficial technical effects of the present application clearer, the following embodiments will be further described. It should be understood by those skilled in the art that the embodiments are only to help understand the present application and should not be regarded as a specific limitation on the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the present application.

[0025] Example 1.

[0026] In this embodiment, a copper-based current collector modified with a self-repairing artificial interface layer for an anode-free lithium battery is provided, and the preparation method of the copper-based current collector modified with a self-repairing artificial interface layer for an anode-free lithium battery comprises.

[0027] Take 2.0 g of acrylamide, 3.4 g of methacryloyloxyethyl trimethyl ammonium chloride, 4.5 g of polyethylene glycol monomethyl ether methacrylate and 0.08 g of 3-methacrylamidopamine and 0.04 g of sodium bisulfite into deionized water, stir and mix uniformly, then heat to 50℃ under argon protection, slowly add 0.08 g of ammonium persulfate, react for 3 h; then slowly add 0.04 g of sodium bisulfite and 0.08 g of ammonium persulfate, react for 2 h; increase the temperature to 60℃, react for 1 h, to obtain the target product, a self-repairing ionomer solution, the solid content of which is 20 wt%.

[0028] The prepared self-repairing ionomer solution is diluted with deionized water and ethanol to a solid content of 6 wt%, and the self-repairing ionomer is deposited on the bare copper current collector by electrophoresis, with a copper electrode as the cathode and a stainless steel sheet as the anode, the electrophoresis voltage is controlled at 0.6 V, and the electrophoresis time is 300 s, to obtain a copper current collector modified with a self-repairing artificial interface layer. The thickness of the artificial interface layer is 5 um.

[0029] The applicant further assembles the self-repairing artificial interface layer modified copper current collector and the positive electrode into a negative electrode-free lithium battery. The positive electrode is prepared by dispersing LiNi 0.8 Co 0.1 Mn 0.1 O2 ternary positive electrode material powder, LiNiO2 lithium nickel oxide powder, conductive carbon black particles and polyvinylidene fluoride emulsion binder in a mass ratio of 77:19:2:2 in N-methyl pyrrolidone, grinding the mixture until the particles are uniformly dispersed, to obtain a positive electrode slurry. Then the positive electrode slurry is coated on an aluminum foil and dried in a vacuum oven at 100℃ overnight, and punched into a circular sheet with a diameter of 12 mm, to prepare a positive electrode sheet.

[0030] The applicant performs microscopic examination on the self-repairing polymer modified copper current collector obtained, and obtains the scanning electron microscope image shown in FIG. 1. The self-repairing ionomer described in Example 1 exhibits excellent self-repairing performance in a short time, which has a significant effect on the timely repair of the subsequent artificial interface layer. Figure 1

[0031] Example 2.

[0032] In this embodiment, a self-repairing artificial interface layer modified copper current collector for a negative electrode-free lithium battery is provided, and a preparation method of the self-repairing artificial interface layer modified copper current collector for a negative electrode-free lithium battery includes.

[0033] ​Take 4.5 g N-methyl methacrylamide, 2.0 g methacryloyloxypropyl trimethyl ammonium chloride, 3.0 g polyethylene glycol monomethyl ether methacrylate and 0.05 g 3-methacrylamidodopamine and 0.024 g sodium thiosulfate into deionized water, stir and mix uniformly, then under argon protection, slowly add 0.024 g potassium persulfate, react for 3 h; then slowly add 0.024 g sodium thiosulfate and 0.024 g potassium persulfate, react for 6 h; increase the temperature to 70℃, react for 3 h, to obtain the target product, a ionomer solution with self-repairing function, the solid content of the ionomer solution being 10 wt%.

[0034] Dilute the prepared ionomer solution with self-repairing function to a solid content of 2 wt% with deionized water and ethanol, deposit the ionomer with self-repairing function on a bare copper current collector by electrophoresis, take the copper electrode as the cathode, take the stainless steel sheet as the anode, control the electrophoresis voltage to be 0.8 V, and the electrophoresis time to be 420 s, to obtain a copper current collector modified by an artificial interface layer with self-repairing function. The thickness of the artificial interface layer is 8 um.

[0035] The applicant further assembles the copper current collector modified by the artificial interface layer with self-repairing function of the embodiment and a positive electrode into a negative electrode-free lithium battery, and the positive electrode material is prepared as in Embodiment 1.

[0036] Embodiment 3.

[0037] In this embodiment, a copper current collector modified by an artificial interface layer with self-repairing function for a negative electrode-free lithium battery is provided, and the preparation method of the copper current collector modified by the artificial interface layer with self-repairing function for the negative electrode-free lithium battery comprises.

[0038] Take 2.0 g methacrylamide, 4.0 g acryloyloxyethyl trimethyl ammonium chloride, 4.0 g polyethylene glycol monomethyl ether methacrylate and 0.06 g 3-methacrylamidodopamine and 0.075 g sodium bisulfite into deionized water, stir and mix uniformly, then under argon protection, increase the temperature to 40℃, slowly add 0.075 g ammonium persulfate, react for 1 h; then slowly add 0.075 g sodium bisulfite and 0.075 g ammonium persulfate, react for 10 h; increase the temperature to 80℃, react for 2 h, to obtain the target product, an ionomer solution with self-repairing function, the solid content of the ionomer solution being 30 wt%.

[0039] The prepared self-repairing ionomer solution with a solid content of 10wt% was diluted with deionized water and ethanol, and was deposited on the exposed copper-based current collector by electrophoresis, with a copper electrode as the cathode and a stainless steel sheet as the anode, the electrophoresis voltage was controlled at 0.4V, and the electrophoresis time was 420s, to obtain a copper-based current collector modified with a self-repairing artificial interface layer. The thickness of the artificial interface layer was 9um.

[0040] The applicant further assembled the self-repairing artificial interface layer modified copper-based current collector of the present embodiment and a positive electrode into a negative electrode-free lithium battery, and the positive electrode material was prepared as in Embodiment 1.

[0041] Embodiment 4.

[0042] In the present embodiment, a self-repairing artificial interface layer modified copper-based current collector for a negative electrode-free lithium battery is provided, and the preparation method of the self-repairing artificial interface layer modified copper-based current collector for a negative electrode-free lithium battery comprises.

[0043] 3.0g of N-methyl methacrylamide, 3.0g of methacryloyloxyethyl trimethylammonium chloride, 3.5g of polyethylene glycol monomethyl ether methacrylate, 0.07g of 3-methacrylamidodopamine, and 0.035g of sodium thiosulfate were added to deionized water, stirred and mixed uniformly, then heated to 50℃ under argon protection, 0.075g of potassium persulfate was slowly added, and reacted for 2h; then 0.035g of sodium thiosulfate and 0.075g of potassium persulfate were slowly added, and reacted for 8h; the temperature was increased to 65℃, and reacted for 1h, to obtain the target product, a self-repairing ionomer solution, with a solid content of 15wt%.

[0044] The prepared self-repairing ionomer solution with a solid content of 10wt% was diluted with deionized water and ethanol, and was deposited on the exposed copper-based current collector by electrophoresis, with a copper electrode as the cathode and a stainless steel sheet as the anode, the electrophoresis voltage was controlled at 0.4V, and the electrophoresis time was 420s, to obtain a copper-based current collector modified with a self-repairing artificial interface layer. The thickness of the artificial interface layer was 9um.

[0045] The applicant further assembled the self-repairing artificial interface layer modified copper-based current collector of the present embodiment and a positive electrode into a negative electrode-free lithium battery, and the positive electrode material was prepared as in Embodiment 1.

[0046] Embodiment 5.

[0047] In the present embodiment, a self-repairing artificial interface layer modified copper-based current collector for a negative electrode-free lithium battery is provided, and the preparation method of the self-repairing artificial interface layer modified copper-based current collector for a negative electrode-free lithium battery comprises.

[0048] Take 2.0 g of methacrylamide, 3.4 g of methacryloyloxyethyl trimethyl ammonium chloride, 4.5 g of polyethylene glycol monomethyl ether methacrylate and 0.09 g of 3-methacrylamido dopamine and 0.04 g of sodium thiosulfate into deionized water, stir and mix uniformly, then under argon protection, heat to 50℃, slowly add 0.08 g of potassium persulfate, react for 3 h; then slowly add 0.04 g of sodium thiosulfate and 0.08 g of potassium persulfate, react for 2 h; increase the temperature to 60℃, react for 1 h, to obtain the target product, a solution of ionomer with self-repairing function, the solid content of the ionomer solution being 20 wt%.

[0049] The prepared solution of ionomer with self-repairing function is diluted with deionized water and ethanol to a solid content of 6 wt%, and the ionomer with self-repairing function is deposited on the exposed copper-based current collector by electrophoresis, with a copper electrode as the cathode and a stainless steel sheet as the anode, the electrophoresis voltage being controlled at 0.6 V and the electrophoresis time being 360 s, to obtain a copper-based current collector modified with a self-repairing artificial interface layer. The thickness of the artificial interface layer is 10 um.

[0050] The applicant further assembles the copper-based current collector modified with the self-repairing artificial interface layer of the present embodiment and a positive electrode into a negative electrode-free lithium battery, and the positive electrode material is prepared as in Embodiment 1.

[0051] Embodiment 6.

[0052] In the present embodiment, a copper-based current collector modified with a self-repairing artificial interface layer for a negative electrode-free lithium battery is provided, and the preparation method of the copper-based current collector modified with a self-repairing artificial interface layer for a negative electrode-free lithium battery comprises.

[0053] Take 2.0 g of methacrylamide, 3.4 g of methacryloyloxyethyl trimethyl ammonium chloride, 4.5 g of polyethylene glycol monomethyl ether methacrylate and 0.09 g of 3-methacrylamido dopamine and 0.04 g of sodium thiosulfate into deionized water, stir and mix uniformly, then under argon protection, heat to 50℃, slowly add 0.08 g of potassium persulfate, react for 3 h; then slowly add 0.04 g of sodium thiosulfate and 0.08 g of potassium persulfate, react for 2 h; increase the temperature to 60℃, react for 1 h, to obtain the target product, a solution of ionomer with self-repairing function, the solid content of the ionomer solution being 20 wt%.

[0054] The prepared solution of ionomer with self-repairing function is diluted with deionized water and ethanol to a solid content of 6 wt%, and the ionomer with self-repairing function is deposited on the exposed copper-based current collector by electrophoresis, with a copper electrode as the cathode and a stainless steel sheet as the anode, the electrophoresis voltage being controlled at 0.6 V and the electrophoresis time being 360 s, to obtain a copper-based current collector modified with a self-repairing artificial interface layer. The thickness of the artificial interface layer is 10 um.

[0055] Applicant further assembles the self-repairing artificial interface layer modified copper-based current collector and the positive electrode of the present example into a negative electrode-free lithium battery, and the preparation of the positive electrode material is the same as that in Example 1.

[0056] Comparative Example 1.

[0057] Comparative Example 1 refers to the preparation of the positive electrode sheet according to the positive electrode material preparation method in “Example 1”, but no deposition of the ionomer solution is performed during the preparation of the negative electrode current collector, and the negative electrode only uses a bare copper-based current collector. The negative electrode-free lithium battery thus assembled is used as the test sample.

[0058] Comparative Example 2.

[0059] Comparative Example 2 refers to the ionomer and the preparation of the positive electrode sheet according to the self-repairing ionomer synthesis method and the positive electrode material preparation method in “Example 1”, but during the preparation of the negative electrode, the ionomer solution is uniformly coated on the copper-based current collector using a 10-μm doctor blade. The negative electrode-free lithium battery thus assembled is used as the test sample.

[0060] Comparative Example 3.

[0061] In the present comparative example, a self-repairing artificial interface layer modified copper-based current collector for a negative electrode-free lithium battery is provided, and the preparation method of the self-repairing artificial interface layer modified copper-based current collector for a negative electrode-free lithium battery comprises.

[0062] Take 2.0 g of acrylamide, 3.4 g of methacryloyloxyethyl trimethylammonium chloride, 4.5 g of polyethylene glycol monomethyl ether methacrylate, and 0.04 g of sodium bisulfite into deionized water, stir and mix uniformly, then under argon protection, slowly add 0.08 g of ammonium persulfate, and react for 3 h; then slowly add 0.04 g of sodium bisulfite and 0.08 g of ammonium persulfate, and react for 2 h; then increase the temperature to 60℃, and react for 1 h to obtain the target product, an ionomer solution, which has a solid content of 20 wt%.

[0063] Dilute the prepared ionomer solution with deionized water and ethanol to a solid content of 6 wt%, and deposit the ionomer on a bare copper-based current collector by electrophoresis, with a copper electrode as the cathode and a stainless steel sheet as the anode, and control the electrophoresis voltage to be 0.6 V and the electrophoresis time to be 300 s to obtain a self-repairing artificial interface layer modified copper-based current collector. The thickness of the artificial interface layer is 7 μm.

[0064] Applicant further assembles the self-repairing artificial interface layer modified copper-based current collector and the positive electrode of the present example into a negative electrode-free lithium battery, and the preparation of the positive electrode material is the same as that in Example 1.

[0065] Figure 2 As shown in the figure, the LiNi 0.8Co 0.1 Mn 0.1 The specific capacity and coulombic efficiency curve of the copper full cell at a current density of 0.5C (charge / discharge rate) after 100 charge / discharge cycles. The coulombic efficiency of Example 1 is maintained at 99%, and the capacity retention rate is 47%. The cycle performance of the full cell assembled using the copper-based current collector negative electrode with a self-repairing functional interface layer described in Example 1 is better, significantly better than Comparative Examples 1-3, which is mainly because the ionomer deposited by electrophoresis can promote the transmission of lithium ions, inhibit the growth of lithium dendrites and timely self-repair, thus having a positive effect on the improvement of the cycle performance of the full cell.

[0066] In the above examples and comparative examples, the reagents, materials and instruments used are commercially available unless otherwise specified.

[0067] Verification example:

[0068] The self-repairing efficiency, room temperature ionic conductivity and tensile strength of the ionomers described in Examples 1-6 and Comparative Examples 1-3 were obtained to obtain the test results shown in Table 1.

[0069] Self-repairing efficiency: The ionomer was dried into a film at 100°C, cut into a dumbbell-shaped sample with a length of 15mm and a width of 2mm, and fixed along the length direction between the upper and lower clamps of a universal testing machine. The lower clamp was stationary, and the upper clamp was stretched at a constant rate of 20mm / min until the sample broke, and the stress was recorded as σ1. A notch was made on the thinnest part of another identical sample, and the sample was transferred to a mold for self-repairing. After 2h, the self-repaired sample was subjected to the above stretching test again, and the stress was recorded as σ2. The self-repairing efficiency = (σ2-σ1) / σ1 x 100%.

[0070] Ionic conductivity: The ionomer was dried into a film at 100°C, and cut into a circular sheet with a diameter of 12mm. The circular sheet was sandwiched between two stainless steel gaskets to assemble a symmetrical battery, and an alternating current impedance test was performed. The room temperature (25°C) ionic conductivity was calculated and shown in Table 1.

[0071] Tensile strength: universal testing machine; tensile mode test. The self-repairing artificial interface layer was dried at 100°C, cut into a dumbbell-shaped sample with a length of 15mm and a width of 2mm, and fixed along the length direction between the upper and lower clamps of a universal testing machine. The lower clamp was stationary, and the upper clamp was stretched at a constant rate of 20mm / min until the sample broke, and the stress was recorded as σ.

[0072] Table 1 Physical property indexes of ionomers

[0073]

[0074]

[0075] As can be seen from the data in Table 1, the self-repairing efficiency of the ionomers described in Examples 1-6 is 82% to 95%, the ionic conductivity can reach 0.82 to 1.39 x 10 -3 S cm -1 , and the mechanical strength is 8.6 to 11.5 MPa. And with the increase of dopamine self-repairing monomer, the self-repairing efficiency and tensile strength of the interface layer gradually increase. However, when the weight fraction of the self-repairing monomer is 0.9 wt%, the viscosity of the system is too large, which is not conducive to the subsequent steps. Although the self-repairing rate and mechanical strength are the highest when the weight fraction of the self-repairing monomer is 1 wt%, but due to the gelation phenomenon at this ratio, the subsequent electrophoretic deposition process cannot be carried out. It can also be found from the table that the double bond-terminated polyethylene oxide can improve the ionic conductivity of the interface layer. In Comparative Example 1, there is no artificial interface layer, so there is no self-repairing property; in Comparative Example 2, the artificial interface layer prepared by blade coating has a self-repairing rate of 87%, and the ionic conductivity and mechanical strength are lower than those of the artificial interface layer obtained by electrophoretic deposition, because the electrophoretic deposition process helps to arrange the molecular chains regularly, thereby improving the uniformity and electrochemical performance of the interface layer. In Comparative Example 3, the absence of self-repairing monomers not only leads to the almost complete loss of self-repairing property, but also reduces the mechanical strength, and the ionic conductivity of the interface layer also decreases slightly.

[0076] The copper-based current collectors with self-repairing functional interface layers prepared in Examples 1-6 and Comparative Examples 1-3 were cut into round pieces with a diameter of 12 mm, and their mass and thickness were recorded. The test results shown in Table 2 were obtained.

[0077] Table 2 Mass and thickness of self-repairing functional interface layer

[0078]

[0079]

[0080] As can be seen from the data in Table 2, the composition of the polymer, the time and voltage of electrophoresis will affect the mass and thickness of the interface layer. In Example 1, the thickness of the interface layer is only 5 um. However, when the weight fraction of the dopamine self-repairing monomer is 1 wt%, due to the gelation phenomenon, the polymer will agglomerate unevenly on the copper-based current collector, and the uniform electrophoretic deposition process cannot be carried out.

[0081] The LiNi 0.8 Co 0.1 Mn 0.1 O2 ternary positive electrode||copper full cell batteries assembled with the different copper-based current collectors of Examples 1-6 and Comparative Examples 1-3 were tested for charge-discharge performance and cycle performance, and the test results shown in Table 3 were obtained.

[0082] Table 3 LiNi 0.8 Co 0.1 Mn 0.1 O2 ternary cathode || Discharge capacity and coulombic efficiency of copper full cell

[0083]

[0084]

[0085] As can be seen from the data in Table 3, the LiNi assemblies assembled with different copper-based current collectors in Examples 1-6... 0.8 Co 0.1 Mn 0.1 The initial discharge capacity of the O2 ternary cathode || copper full cell was significantly higher than that of Comparative Examples 1-3. Meanwhile, the LiNi cells assembled using the copper-based current collector anode with the self-healing functional interface layer described in Examples 1-6... 0.8 Co 0.1 Mn 0.1 After 100 cycles, the coulombic efficiency of the O2 ternary cathode copper full cell is above 89%, significantly higher than the highest value of Comparative Examples 1-3. This demonstrates that the present invention, by introducing a self-healing artificial interface layer, can facilitate the rapid transport of lithium ions at high current densities, thereby increasing the number of lithium ions participating in the reaction and improving the specific capacity of the battery at high current densities.

[0086] The present invention has been described by the above-described embodiments; however, these embodiments are merely examples for implementing the present invention. It must be noted that the disclosed embodiments do not limit the scope of the present invention. Conversely, modifications and equivalents contained within the spirit and scope of the claims are included within the scope of the present invention.

Claims

1. A self-healing artificial interfacial layer-modified copper-based current collector, characterized in that, The self-repairing artificial interface layer is prepared by solution polymerization of four components A, B, C and D, wherein the A component is a nitrogen-containing water-soluble comonomer, the B component is a quaternary ammonium salt monomer, the C component is a double bond-terminated polyethylene oxide, and the D component is a dopamine self-repairing monomer; the thickness of the self-repairing artificial interface layer is 5-10 microns; and the copper-based current collector modified by the self-repairing artificial interface layer is prepared by the following steps: (1) adding the nitrogen-containing water-soluble comonomer, the quaternary ammonium salt monomer, the double bond-terminated polyethylene oxide, the dopamine self-repairing monomer and part of the reducing agent component of the redox initiator into deionized water, stirring and uniformly mixing, then slowly adding half of the oxidant component of the redox initiator under the protection of an inert atmosphere, and reacting for 1-3 hours; then slowly adding the other half of the oxidant and reducing agent components of the redox initiator, and reacting for 2-10 hours; increasing the temperature to 60-80 DEG C, and reacting for 1-3 hours to obtain the target product, i.e. the ionomer solution with self-repairing function, wherein the solid content of the ionomer solution is 10-30 wt%; (2) diluting the ionomer solution with self-repairing function prepared in step (1) with deionized water and ethanol to a solid content of 2-10 wt%, and depositing the ionomer with self-repairing function on the bare copper current collector by electrophoretic deposition, wherein the electrophoretic voltage is controlled to be 0.4-1.2 V, and the electrophoresis time is 240-420 seconds to obtain the copper-based current collector modified by the self-repairing artificial interface layer.

2. The self-healing artificial interfacial layer modified copper-based current collector of claim 1, and a method of making the same, wherein, The nitrogen-containing water-soluble comonomer is one of acrylamide, N-methyl methacrylamide and methacrylamide.

3. The self-healing artificial interfacial layer modified copper-based current collector of claim 1, and a method of making the same, wherein, The quaternary ammonium salt monomer is one of methacryloyloxyethyl trimethyl ammonium chloride, methacryloyloxypropyl trimethyl ammonium chloride and acryloyloxyethyl trimethyl ammonium chloride.

4. The self-healing artificial interfacial layer modified copper-based current collector of claim 1, and a method of making the same, wherein, The double bond-terminated polyethylene oxide is polyethylene glycol monomethyl ether methacrylate.

5. The self-healing artificial interfacial layer modified copper-based current collector of claim 1, and a method of making the same, wherein, The dopamine self-repairing monomer is 3-methacrylamidodopamine.

6. The self-repairing artificial interfacial layer modified copper-based current collector of claim 1, and a method of making the same, wherein, The oxidant component of the redox initiator is one of ammonium persulfate and potassium persulfate; the reducing agent component is one of sodium bisulfite and sodium thiosulfate; and the mass ratio of the oxidant component to the reducing agent component is 1:0.5-1:

1.

7. The self-healing artificial interfacial layer modified copper-based current collector of claim 1, and a method of making the same, wherein, The amount of the redox initiator used in the preparation method is 1.0 wt%-3.0 wt% of the total amount of the four component monomers.

8. The self-repairing artificial interface layer modified copper-based current collector according to any one of claims 1-7 is applied in a negative electrode-free lithium battery.

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