Super-amphiphilic coating capable of conducting lithium ions, preparation method and application thereof, diaphragm, pole piece and lithium-ion battery

Abstract

The present invention provides a super-amphiphilic coating that can conduct lithium ions, a preparation method and application thereof, a diaphragm, an electrode and a lithium-ion battery, and relates to the field of battery technology. The super-amphiphilic coating that can conduct lithium ions provided by the present invention comprises an amphiphilic material and a lithium-ion conductor nanomaterial; the amphiphilic material is coated on the surface of the lithium-ion conductor nanomaterial. Among them, the lithium-ion conductor nanomaterial provides good lithium-ion conductivity, and the amphiphilic material coating layer and the lithium-ion conductor nanomaterial constitute a micro-nanostructure that can provide super-oleophilic and super-hydrophilic capabilities. Therefore, the super-amphiphilic coating provided by the present invention can be used as a coating for the diaphragm and current collector of a lithium-ion battery. Its extremely strong electrolyte affinity can accelerate the back absorption of the electrolyte and improve the liquid absorption capacity of the battery core without affecting the electrochemical performance. Moreover, the micro-nanostructure and polymer components of the super-amphiphilic coating have good liquid retention capabilities, which help to alleviate the extrusion of the electrolyte during the expansion process.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a super-amphiphilic coating capable of conducting lithium ions, a preparation method and application thereof, a diaphragm, a pole piece and a lithium ion battery. Background Art

[0002] With the development of technology, lithium-ion batteries have been widely used in various fields such as consumer electronics, power, and energy storage. Due to the higher requirements of application scenarios and increasingly fierce market competition, lithium-ion batteries with high energy density, high power density, high safety, and long life have become the development focus of major battery manufacturers.

[0003] However, during the charge and discharge process of lithium-ion batteries, the electrode materials continuously expand and contract, squeezing out the electrolyte between the cell electrodes and the electrode layers. The electrolyte then flows back into the restored pores after the electrode material shrinks. During this process, uneven electrolyte reflux and localized electrolyte starvation may occur. Inadequate lithium-ion conductivity can cause lithium deposition in these locations, leading to unpredictable cycling "dives" in the battery cell, seriously impacting its cycle life.

[0004] Literature research suggests that the electrolyte first wets the separator and then diffuses into the electrode. If the electrode is not fully wetted, a non-wetting phase will be found near the electrode / current collector interface, while the separator side is relatively fully wetted. Based on this, it is crucial to improve the ability of the electrode and separator to reabsorb the electrolyte, and improving the wettability of the electrode and separator with the electrolyte is the key to improving the absorption capacity. Currently, commonly used solvents in commercial lithium-ion battery electrolytes include ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and ethyl methyl carbonate (EMC). Commercial electrolytes are a mixture of multiple solvents. Therefore, it is necessary to develop a solution that is suitable for improving the wettability of multiple electrolytes.

[0005] In view of this, the present invention is proposed. Summary of the Invention

[0006] The first object of the present invention is to provide a super-amphiphilic coating that can conduct lithium ions to solve the above technical problems.

[0007] The second object of the present invention is to provide a method for preparing the above-mentioned super-amphiphilic coating that can conduct lithium ions.

[0008] The third object of the present invention is to provide an application of the above-mentioned super-amphiphilic coating capable of conducting lithium ions in a battery.

[0009] A fourth object of the present invention is to provide a diaphragm.

[0010] A fifth object of the present invention is to provide a pole piece.

[0011] A sixth object of the present invention is to provide a lithium ion battery.

[0012] In order to achieve the above objectives, the following technical solutions are adopted:

[0013] In a first aspect, the present invention provides a super-amphiphilic coating capable of conducting lithium ions, comprising an amphiphilic material and a lithium ion conductor nanomaterial; the amphiphilic material is coated on the surface of the lithium ion conductor nanomaterial;

[0014] The amphiphilic material comprises at least one of propoxyglycerol triglycidyl ether polymer, polyvinyl pyrrolidone, polydopamine, polyethylene glycol-polytetramethyl ether glycol copolymer or polyethylene glycol-polydimethylsiloxane copolymer;

[0015] The lithium ion conductor nanomaterial includes at least one of a NASICON type oxide solid electrolyte, a LISICON type oxide electrolyte, a Garnet type oxide solid electrolyte, a Perovskite type oxide solid electrolyte or an Anti-perovskite type oxide solid electrolyte;

[0016] The particle size of the lithium ion conductor nanomaterial is 10-200 nm.

[0017] As a further technical solution, the mass ratio of the amphiphilic material to the lithium ion conductor nanomaterial is 0.01:1-10:1.

[0018] As a further technical solution, the static contact angle of the super-amphiphilic coating with water-based solvents is less than 5°, and the static contact angle of the super-amphiphilic coating with oil-based solvents is less than 5°.

[0019] As a further technical solution, the NASICON type oxide solid electrolyte includes Li 1.4 Al 0.4 Ti 1.6 (PO4)3 or Li 1.5 Al 0.5 Ge 1.5 (PO4)3;

[0020] The LISICON type oxide electrolyte includes γ-Li3PO4;

[0021] The Garnet-type oxide solid electrolyte includes Li7La3Zr2O 12 or Li5La3Ta2O 12 ;

[0022] The Perovskite-type oxide solid electrolyte includes Li 0.5 La 0.5 TiO3;

[0023] The anti-perovskite oxide solid electrolyte includes Li3OCl.

[0024] In a second aspect, the present invention provides a method for preparing the above-mentioned super-amphiphilic coating capable of conducting lithium ions, comprising the following steps:

[0025] The amphiphilic material or its precursor, a lithium ion conductor nanomaterial and a solvent are mixed to form a dispersion, and the dispersion is then applied and dried to prepare the super-amphiphilic coating capable of conducting lithium ions;

[0026] The solvent includes at least one of ethanol, deionized water, n-hexane, tetrahydrofuran (THF), heptane, isopropanol, carbon trichloride or carbon tetrachloride.

[0027] As a further technical solution, in the dispersion, the mass proportion of the lithium ion conductor nanomaterial is 0.1%-10%.

[0028] In a third aspect, the present invention provides the use of the above-mentioned super-amphiphilic coating capable of conducting lithium ions in a battery.

[0029] In a fourth aspect, the present invention provides a separator comprising a base film, wherein the surface of the base film is coated with the super-amphiphilic coating capable of conducting lithium ions.

[0030] In a fifth aspect, the present invention provides a pole piece comprising a current collector, the surface of the current collector being coated with the super-amphiphilic coating capable of conducting lithium ions.

[0031] In a sixth aspect, the present invention provides a lithium-ion battery comprising the aforementioned diaphragm and / or the aforementioned pole piece.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] The present invention provides a super-amphiphilic coating capable of conducting lithium ions, wherein the lithium ion conductor nanomaterial provides good lithium ion conductivity, and the amphiphilic coating layer and the lithium ion conductor nanomaterial constitute a micro-nanostructure, which can provide super-oleophilic and super-hydrophilic capabilities. Therefore, the super-amphiphilic coating capable of conducting lithium ions provided by the present invention can be used as a coating for the separator and current collector of a lithium ion battery. Its extremely strong electrolyte affinity can accelerate the reabsorption of the electrolyte and improve the liquid absorption capacity of the battery core without affecting the electrochemical performance. Moreover, the micro-nanostructure and polymer components of the super-amphiphilic coating have good liquid retention capacity, which helps to alleviate the extrusion of the electrolyte during the expansion process. In summary, the super-amphiphilic coating capable of conducting lithium ions provided by the present invention can effectively alleviate the lithium precipitation caused by the lack of liquid in the middle of the battery core during the cycle, thereby improving the cycle life of the battery core. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0035] Figure 1 Schematic diagram of the structure of the superamphiphilic coating that can conduct lithium ions.

[0036] Icons: 1-Lithium ion conductor nanomaterials; 2-amphiphilic materials; 10-superamphiphilic coatings that can conduct lithium ions. DETAILED DESCRIPTION

[0037] Below in conjunction with embodiment and example, embodiment of the present invention is described in detail, but those skilled in the art will appreciate that the following embodiment and example are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiment in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work premise all fall within the scope of protection of the present invention. Unspecified conditions are carried out according to the conditions of normal conditions or manufacturer's recommendations. Reagents used or instruments not specified by the manufacturer are conventional products that can be purchased commercially.

[0038] In the first aspect, the present invention provides a super-amphiphilic coating 10 that can conduct lithium ions, comprising an amphiphilic material 2 and a lithium ion conductor nanomaterial 1; the amphiphilic material 2 is coated on the surface of the lithium ion conductor nanomaterial 1, and the structural diagram of the coating is as shown in FIG. Figure 1 As shown;

[0039] The amphiphilic material 2 includes but is not limited to at least one of propoxyglycerol triglycidyl ether polymer, polyvinyl pyrrolidone, polydopamine, polyethylene glycol-polytetramethyl ether glycol copolymer or polyethylene glycol-polydimethylsiloxane copolymer, or other amphiphilic materials well known to those skilled in the art;

[0040] The lithium ion conductor nanomaterial 1 includes but is not limited to at least one of a NASICON type oxide solid electrolyte, a LISICON type oxide electrolyte, a Garnet type oxide solid electrolyte, a Perovskite type oxide solid electrolyte or an Anti-perovskite type oxide solid electrolyte;

[0041] The particle size of the lithium ion conductor nanomaterial 1 is 10-200 nm.

[0042] The lithium-ion-conducting super-amphiphilic coating provided by the present invention comprises a lithium-ion conductive nanomaterial that provides excellent lithium-ion conductivity, and an amphiphilic coating layer and the lithium-ion conductive nanomaterial form a micro-nanostructure that provides super-oleophilic and super-hydrophilic properties. Therefore, the lithium-ion-conducting super-amphiphilic coating provided by the present invention can be used as a coating for separators and current collectors in lithium-ion batteries. Its strong affinity for electrolytes can accelerate electrolyte resorption and improve the battery's liquid absorption capacity without affecting its electrochemical performance. Furthermore, the micro-nanostructure and polymer components of the super-amphiphilic coating have excellent liquid retention, helping to alleviate electrolyte extrusion during expansion.

[0043] In some optional embodiments, the mass ratio of the amphiphilic material to the lithium ion conductor nanomaterial can be, for example, but not limited to, 0.01:1, 0.1:1, 1:1 or 10:1.

[0044] In some optional embodiments, the thickness of the super-amphiphilic coating capable of conducting lithium ions is 100 nm-10 μm, for example, but not limited to 100 nm, 1 μm or 10 μm.

[0045] In some optional embodiments, the super-amphiphilic coating has a static contact angle of less than 5° for aqueous solvents, a static contact angle of less than 5° for oil-based solvents, and a static contact angle of less than 5° for various electrolytes.

[0046] In some optional embodiments, the NASICON type oxide solid electrolyte includes but is not limited to Li 1.4 Al 0.4 Ti 1.6 (PO4)3 or Li 1.5 Al 0.5 Ge 1.5 (PO4)3;

[0047] The LISICON type oxide electrolyte includes but is not limited to γ-Li3PO4;

[0048] The Garnet-type oxide solid electrolyte includes but is not limited to Li7La3Zr2O 12 or Li5La3Ta2O 12 ;

[0049] The Perovskite-type oxide solid electrolyte includes but is not limited to Li 0.5 La 0.5 TiO3;

[0050] The anti-perovskite oxide solid electrolyte includes but is not limited to Li3OCl.

[0051] In a second aspect, the present invention provides a method for preparing the above-mentioned super-amphiphilic coating capable of conducting lithium ions, comprising the following steps:

[0052] The amphiphilic material or its precursor, a lithium ion conductor nanomaterial and a solvent are mixed to form a dispersion, and the dispersion is then applied and dried to prepare the super-amphiphilic coating capable of conducting lithium ions;

[0053] The solvent includes at least one of ethanol, deionized water, n-hexane, tetrahydrofuran (THF), heptane, isopropanol, carbon trichloride or carbon tetrachloride.

[0054] The preparation method is simple and convenient, and the prepared super-amphiphilic coating capable of conducting lithium ions has good super-oleophilic and super-hydrophilic capabilities.

[0055] In some optional embodiments, in the dispersion, the mass proportion of the lithium ion conductor nanomaterial may be, for example, but not limited to, 0.1%, 1% or 10%.

[0056] In some optional embodiments, the mixing method includes one or more of magnetic stirring, vortex oscillation, ultrasonic vibration or mechanical stirring;

[0057] The mixing temperature is room temperature, and the mixing time is 1 hour to 48 hours.

[0058] In some optional embodiments, the coating method includes any one of spraying, spin coating, dipping, blade coating, and brush coating.

[0059] In some optional embodiments, the drying method includes: volatilization at room temperature for 4 hours to 24 hours; or, heat treatment in an oven at 40-120° C. for 4 hours to 24 hours.

[0060] In a third aspect, the present invention provides the use of the above-mentioned super-amphiphilic coating capable of conducting lithium ions in a battery.

[0061] Applying the lithium ion-conducting super-amphiphilic coating provided by the present invention to a battery can effectively improve the battery's liquid retention capacity.

[0062] In a fourth aspect, the present invention provides a separator comprising a base film, wherein the surface of the base film is coated with the super-amphiphilic coating capable of conducting lithium ions.

[0063] In a fifth aspect, the present invention provides a pole piece comprising a current collector, the surface of the current collector being coated with the super-amphiphilic coating capable of conducting lithium ions.

[0064] In a sixth aspect, the present invention provides a lithium-ion battery comprising the aforementioned diaphragm and / or the aforementioned pole piece.

[0065] The lithium-ion-conducting super-amphiphilic coating provided by the present invention is used as a coating for the separator and current collector of a lithium-ion battery. Its extremely strong affinity for the electrolyte can accelerate the reabsorption of the electrolyte and improve the liquid absorption capacity of the battery cell without affecting the electrochemical performance. In addition, the micro-nanostructure and polymer components of the super-amphiphilic coating have good liquid retention capabilities, which helps to alleviate the extrusion of the electrolyte during the expansion process.

[0066] The present invention is further described below by means of specific examples and comparative examples. However, it should be understood that these examples are merely provided for more detailed description and are not to be construed as limiting the present invention in any form.

[0067] Example 1

[0068] In this embodiment, the oxide solid electrolyte Li with a particle size of 50-100 nm is selected. 1.4 Al 0.4 Ti 1.6 (PO4)3 is a lithium ion conductive particle. Through coupling reaction and cross-linking reaction, an amphiphilic polymer mainly composed of propoxyglycerol triglycidyl ether (GPTE) is constructed on its surface as a coating layer, and then a super-amphiphilic coating that can conduct lithium ions is prepared on the surface of aluminum foil. The specific steps are as follows:

[0069] 1. Li with particle size of 50-100nm 1.4 Al 0.4 Ti 1.6 (PO4)3 particles were added to a mixture of anhydrous ethanol and 1-methylpyrrole (V:V = 100:0.01) and stirred rapidly at room temperature for full dispersion;

[0070] 2. Add the precursors of the amphiphilic material, propoxyglycerol triglycidyl ether (GPTE) and octadecylamine (ODA) (the mass ratio of the two is 50:1) to the dispersion. 1.4 Al 0.4 Ti 1.6 (PO4)3 particles were dispersed in a mass ratio of 1:10 and stirred at room temperature for 6 hours and at 50°C for 15 minutes to obtain a uniform dispersion. 1.4 Al 0.4 Ti 1.6 The mass proportion of (PO4)3 particles is about 0.1%;

[0071] 3. Spray the above dispersion evenly on aluminum foil;

[0072] 4. Dry the aluminum foil at room temperature for 5 minutes and heat it at 150°C for 1 hour to complete crosslinking and curing to obtain Li-ion polymer coated with amphiphilic polymer. 1.4 Al 0.4 Ti1.6 Aluminum foil with a super-amphiphilic coating that conducts lithium ions and is constructed of (PO4)3 nanoparticles. The coating thickness is 2 μm.

[0073] 5. Preparation of a lithium-ion battery comprising the above-mentioned positive electrode sheet:

[0074] (1) Preparing a positive electrode sheet with an aluminum foil surface coated with the super-amphiphilic coating capable of conducting lithium ions:

[0075] The positive electrode active material LiFePO4, conductive carbon black (Super P), and binder polytetravinylidene fluoride (PVDF) are uniformly mixed in an appropriate amount of N-methylpyrrolidone (NMP) at a mass ratio of 97.3:1.2:1.5 to prepare a positive electrode slurry. The positive electrode slurry is coated on the aluminum foil having the above-mentioned super amphiphilic coating that can conduct lithium ions. The positive electrode sheet is prepared through processes such as rolling, slitting, and punching.

[0076] (2) Preparation of negative electrode sheet:

[0077] The negative electrode active material artificial graphite, conductive agent carbon black (Super P), binder styrene-butadiene rubber (SBR) and sodium carboxymethyl cellulose (CMC-Na) were mixed uniformly in an appropriate amount of deionized water as a solvent at a mass ratio of 95.5:1.7:1.6:1.2 to obtain a negative electrode slurry. The negative electrode slurry was coated on the negative electrode current collector copper foil. The negative electrode sheet was obtained through processes such as rolling, slitting, and punching.

[0078] (3) Preparation of diaphragm:

[0079] Use commercial polypropylene diaphragms;

[0080] (4) Preparation of electrolyte:

[0081] Ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were prepared into a mixed solvent at a mass ratio of 50:50, and then fully dried electrolyte salt LiPF6 was dissolved therein (1.0 mol / L) to obtain an electrolyte solution.

[0082] (5) Preparation of lithium-ion batteries

[0083] The positive electrode sheet, separator, and negative electrode sheet are stacked in order to obtain a pole core; the pole core is placed in an outer package and baked; the electrolyte is injected into the dried lithium-ion battery, and a secondary battery is prepared through processes such as standing, formation, vacuum packaging, aging, and capacity separation.

[0084] Example 2

[0085] In this embodiment, the oxide solid electrolyte Li with a particle size of 50-100 nm is selected. 1.5 Al 0.5 Ge1.5 (PO4)3 is a lithium ion conductive particle. A polyvinyl pyrrolidone (PVP) amphiphilic polymer coating layer is constructed on its surface by a liquid phase coating method, and then a super-amphiphilic coating capable of conducting lithium ions is prepared on the surface of the polypropylene separator. The specific steps are as follows:

[0086] 1. Li with particle size of 50-100nm 1.5 Al 0.5 Ge 1.5 (PO4)3 particles are added to the PVP aqueous solution, PVP and Li 1.5 Al 0.5 Ge 1.5 The mass ratio of (PO4)3 was 1:5, and the dispersion was assisted by ultrasound at room temperature and reacted under mechanical stirring for 6 hours to obtain a uniform dispersion. 1.5 Al 0.5 Ge 1.5 The mass proportion of (PO4)3 is 1%;

[0087] 2. Prepare the coating on both sides of the polypropylene membrane by dipping it in the dispersion for 5 seconds and then take it out.

[0088] 3. The above diaphragm was placed at room temperature for 12 hours to evaporate the water, and then placed in a vacuum oven at 60°C for 24 hours to further remove the solvent, thereby obtaining the polyvinyl pyrrolidone-coated Li 1.5 Al 0.5 Ge 1.5 A separator constructed of (PO4)3 nanoparticles with a super-amphiphilic coating that can conduct lithium ions, with a coating thickness of 5 μm;

[0089] 4. Preparation of a lithium-ion battery comprising the above-mentioned separator:

[0090] (1) Preparation of positive electrode sheet:

[0091] The positive electrode active material LiFePO4, conductive carbon black (Super P) and binder polytetravinylidene fluoride (PVDF) are uniformly mixed in an appropriate amount of N-methylpyrrolidone (NMP) at a mass ratio of 97.3:1.2:1.5 to prepare a positive electrode slurry. The positive electrode slurry is coated on the current collector aluminum foil and then subjected to processes such as roller pressing, slitting, and punching to prepare a positive electrode sheet.

[0092] (2) Preparation of negative electrode sheet:

[0093] The negative electrode active material artificial graphite, conductive agent carbon black (Super P), binder styrene-butadiene rubber (SBR) and sodium carboxymethyl cellulose (CMC-Na) were mixed uniformly in an appropriate amount of deionized water as a solvent at a mass ratio of 95.5:1.7:1.6:1.2 to obtain a negative electrode slurry. The negative electrode slurry was coated on the negative electrode current collector copper foil. The negative electrode sheet was obtained through processes such as rolling, slitting, and punching.

[0094] (3) Diaphragm:

[0095] The isolation membrane adopts the membrane with a super-amphiphilic coating that can conduct lithium ions, which is constructed in the embodiment of the present application;

[0096] (4) Preparation of electrolyte:

[0097] Ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were prepared into a mixed solvent at a mass ratio of 50:50, and then fully dried electrolyte salt LiPF6 was dissolved therein (1.0 mol / L) to obtain an electrolyte solution.

[0098] (5) Preparation of lithium-ion batteries

[0099] The positive electrode sheet, separator, and negative electrode sheet are stacked in order to obtain a pole core; the pole core is placed in an outer package and baked; the electrolyte is injected into the dried lithium-ion battery, and a secondary battery is prepared through processes such as standing, formation, vacuum packaging, aging, and capacity separation.

[0100] Example 3

[0101] In this embodiment, the oxide solid electrolyte Li7La3Zr2O with a particle size of 50-100nm is selected. 12 For lithium ion conductive particles, polyethylene glycol (PEG)-polydimethylsiloxane (PDMS) copolymer is constructed on its surface as a coating layer by in situ polymerization, and then a super-amphiphilic coating that can conduct lithium ions is prepared on the surface of copper foil. The specific steps are as follows:

[0102] 1. PEG (Mn=2000) and PDMS (Mn=1810) were added in a molar ratio of 1:1 and dissolved in tetrahydrofuran solvent (10 wt / vol%);

[0103] 2. Add Li7La3Zr2O with a particle size of 50-100nm to the above solution 12 particles, as well as hexamethylene diisocyanate and dibutyltin dilaurate, polymer precursors PEG and PDMS and Li7La3Zr2O 12 The mass ratio of 1:1 was 1. The mixture was stirred at room temperature for 24 hours, and a uniform dispersion was obtained as the coupling reaction proceeded.

[0104] 3. The prepared dispersion was precipitated and washed with deionized water three times and then vacuum dried at 80 °C for 24 hours to obtain Li7La3Zr2O coated with PEG-PDMS copolymer. 12 Nanoparticles;

[0105] 4. Li7La3Zr2O coated with PEG-PDMS copolymer 12 The nanoparticles were dispersed in deionized water and the dispersion was prepared by magnetic stirring at room temperature and subsequent ultrasonic dispersion. 12 The mass share is about 5%;

[0106] 5. Use the doctor blade method to evenly apply the above dispersion on the copper foil;

[0107] 6. The above-mentioned membrane was placed at room temperature for 12 hours to evaporate the water, and then placed in a vacuum oven at 60°C for 24 hours to further remove the solvent, thereby obtaining Li7La3Zr2O coated with PEG-PDMS copolymer. 12 Copper foil with a super-amphiphilic coating that conducts lithium ions and is constructed of nanoparticles. The coating is 100 nm thick.

[0108] 7. Preparation of a lithium-ion battery comprising the above-mentioned negative electrode sheet:

[0109] (1) Preparation of positive electrode sheet:

[0110] The positive electrode active material LiFePO4, conductive carbon black (Super P), and binder polytetravinylidene fluoride (PVDF) are uniformly mixed in an appropriate amount of N-methylpyrrolidone (NMP) at a mass ratio of 97.3:1.2:1.5 to prepare a positive electrode slurry. The positive electrode slurry is coated on the aluminum foil having the above-mentioned super amphiphilic coating that can conduct lithium ions. The positive electrode sheet is prepared through processes such as rolling, slitting, and punching.

[0111] (2) Preparing a negative electrode sheet having a copper foil surface coated with the super-amphiphilic coating capable of conducting lithium ions:

[0112] The negative electrode active material artificial graphite, the conductive agent carbon black (Super P), the binder styrene-butadiene rubber (SBR), and the sodium carboxymethyl cellulose (CMC-Na) are mixed uniformly in a suitable amount of deionized water as a solvent at a mass ratio of 95.5:1.7:1.6:1.2 to obtain a negative electrode slurry. The negative electrode slurry is coated on the copper foil having the super-amphiphilic coating capable of conducting lithium ions. The negative electrode sheet is obtained through processes such as rolling, slitting, and punching.

[0113] (3) Preparation of diaphragm:

[0114] Use commercial polypropylene diaphragms;

[0115] (4) Preparation of electrolyte:

[0116] Ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were prepared into a mixed solvent at a mass ratio of 50:50, and then fully dried electrolyte salt LiPF6 was dissolved therein (1.0 mol / L) to obtain an electrolyte solution.

[0117] (5) Preparation of lithium-ion batteries

[0118] The positive electrode sheet, separator, and negative electrode sheet are stacked in order to obtain a pole core; the pole core is placed in an outer package and baked; the electrolyte is injected into the dried lithium-ion battery, and a secondary battery is prepared through processes such as standing, formation, vacuum packaging, aging, and capacity separation.

[0119] Example 4

[0120] In this embodiment, the oxide solid electrolyte Li with a particle size of 10-50 nm is selected. 0.5 La 0.5 TiO3 is a lithium ion conductive particle. A polydopamine coating is constructed on its surface by in-situ polymerization, and then a super-amphiphilic coating that can conduct lithium ions is prepared on the surface of the separator. The specific steps are as follows:

[0121] 1. Li 0.5 La 0.5 TiO3 nanoparticles were dispersed in tris(hydroxymethyl)aminomethane hydrochloride buffer solution (50.0 mmol / L, pH 8.5) at a dispersion ratio of approximately 1 g / 1000 ml;

[0122] 2. Add a certain amount of dopamine to the above dispersion, which reacts with Li 0.5 La 0.5 The mass ratio of TiO3 is about 10:1. After stirring at room temperature for 12 hours, polydopamine-coated Li 0.5 La 0.5 Uniform dispersion of TiO3, Li 0.5 La 0.5 TiO3 accounts for about 0.1% by mass;

[0123] 3. Prepare the coating on both sides of the polypropylene membrane by dipping it in the dispersion for 5 seconds and then take it out.

[0124] 4. The above-mentioned diaphragm was placed at room temperature for 12 hours to evaporate the water, and then placed in a vacuum oven at 60°C for 24 hours to further remove the solvent, thereby obtaining the polydopamine-coated Li 0.5 La 0.5 A separator constructed of TiO3 nanoparticles with a super-amphiphilic coating that can conduct lithium ions, with a coating thickness of 1 μm;

[0125] 5. Preparation of a lithium-ion battery comprising the above-mentioned separator:

[0126] (1) Preparation of positive electrode sheet:

[0127] The positive electrode active material LiFePO4, conductive carbon black (Super P) and binder polytetravinylidene fluoride (PVDF) are uniformly mixed in an appropriate amount of N-methylpyrrolidone (NMP) at a mass ratio of 97.3:1.2:1.5 to prepare a positive electrode slurry. The positive electrode slurry is coated on the current collector aluminum foil and then subjected to processes such as roller pressing, slitting, and punching to prepare a positive electrode sheet.

[0128] (2) Preparation of negative electrode sheet:

[0129] The negative electrode active material artificial graphite, conductive agent carbon black (Super P), binder styrene-butadiene rubber (SBR) and sodium carboxymethyl cellulose (CMC-Na) were mixed uniformly in an appropriate amount of deionized water as a solvent at a mass ratio of 95.5:1.7:1.6:1.2 to obtain a negative electrode slurry. The negative electrode slurry was coated on the negative electrode current collector copper foil. The negative electrode sheet was obtained through processes such as rolling, slitting, and punching.

[0130] (3) Diaphragm:

[0131] The isolation membrane adopts the membrane with a super-amphiphilic coating that can conduct lithium ions, which is constructed in the embodiment of the present application;

[0132] (4) Preparation of electrolyte:

[0133] Ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were prepared into a mixed solvent at a mass ratio of 50:50, and then fully dried electrolyte salt LiPF6 was dissolved therein (1.0 mol / L) to obtain an electrolyte solution.

[0134] (5) Preparation of lithium-ion batteries

[0135] The positive electrode sheet, separator, and negative electrode sheet are stacked in order to obtain a pole core; the pole core is placed in an outer package and baked; the electrolyte is injected into the dried lithium-ion battery, and a secondary battery is prepared through processes such as standing, formation, vacuum packaging, aging, and capacity separation.

[0136] Example 5

[0137] In this embodiment, solid electrolyte Li3OCl with a particle size of 100-200 nm is selected as lithium ion conductive particles. Polyethylene glycol (PEG)-polytetramethyl ether glycol (PTMEG) copolymer is constructed on the surface of the particles by in-situ polymerization as a coating layer, and then a super-amphiphilic coating capable of conducting lithium ions is prepared on the surface of the copper foil. The specific steps are as follows:

[0138] 1. PEG (Mn=2000) and PTMEG (Mn=2000) were added in a molar ratio of 1:1 and dissolved in tetrahydrofuran solvent (10 wt / vol%);

[0139] 2. Add Li₃OCl particles (100-200 nm in size), hexamethylene diisocyanate, and dibutyltin dilaurate to the above solution. The mass ratio of the polymer precursors PEG and PTMEG to Li₃OCl is 0.01:1. Stir at room temperature for 24 hours while the coupling reaction proceeds, ultimately obtaining a uniform dispersion.

[0140] 3. The prepared dispersion was precipitated, washed three times with deionized water, and then vacuum-dried at 80° C. for 24 hours to obtain Li3OCl nanoparticles coated with PEG-PTMEG copolymer;

[0141] 4. Li3OCl nanoparticles coated with PEG-PTMEG copolymer were dispersed in deionized water. A dispersion was prepared by magnetic stirring at room temperature and subsequent ultrasonic dispersion. The mass fraction of Li3OCl in the dispersion was approximately 10%.

[0142] 5. Use the doctor blade method to evenly apply the above dispersion on the aluminum foil;

[0143] 6. The separator was placed at room temperature for 12 hours to evaporate the water, and then placed in a vacuum oven at 60°C for 24 hours to further remove the solvent, thereby obtaining an aluminum foil having a lithium-ion conductive super-amphiphilic coating constructed of Li3OCl nanoparticles coated with PEG-PTMEG copolymer. The coating thickness was 10 μm.

[0144] 7. Preparation of a lithium-ion battery comprising the above-mentioned positive electrode sheet:

[0145] (1) Preparing a positive electrode sheet with an aluminum foil surface coated with the super-amphiphilic coating capable of conducting lithium ions:

[0146] The positive electrode active material LiFePO4, conductive carbon black (Super P), and binder polytetravinylidene fluoride (PVDF) are uniformly mixed in an appropriate amount of N-methylpyrrolidone (NMP) at a mass ratio of 97.3:1.2:1.5 to prepare a positive electrode slurry. The positive electrode slurry is coated on the aluminum foil having the above-mentioned super amphiphilic coating that can conduct lithium ions. The positive electrode sheet is prepared through processes such as rolling, slitting, and punching.

[0147] (2) Preparation of negative electrode sheet:

[0148] The negative electrode active material artificial graphite, conductive agent carbon black (Super P), binder styrene-butadiene rubber (SBR) and sodium carboxymethyl cellulose (CMC-Na) were mixed uniformly in an appropriate amount of deionized water as a solvent at a mass ratio of 95.5:1.7:1.6:1.2 to obtain a negative electrode slurry. The negative electrode slurry was coated on the negative electrode current collector copper foil. The negative electrode sheet was obtained through processes such as rolling, slitting, and punching.

[0149] (3) Preparation of diaphragm:

[0150] Use commercial polypropylene diaphragms;

[0151] (4) Preparation of electrolyte:

[0152] Ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were prepared into a mixed solvent at a mass ratio of 50:50, and then fully dried electrolyte salt LiPF6 was dissolved therein (1.0 mol / L) to obtain an electrolyte solution.

[0153] (5) Preparation of lithium-ion batteries

[0154] The positive electrode sheet, separator, and negative electrode sheet are stacked in order to obtain a pole core; the pole core is placed in an outer package and baked; the electrolyte is injected into the dried lithium-ion battery, and a secondary battery is prepared through processes such as standing, formation, vacuum packaging, aging, and capacity separation.

[0155] Comparative Example 1

[0156] A coating, which differs from Example 1 in that the particle size of the lithium ion conductive particles is 1-5 μm.

[0157] In this embodiment, the oxide solid electrolyte Li with a particle size of 1-5 μm is selected. 1.4 Al 0.4 Ti 1.6 (PO4)3 is a lithium ion conductive particle. Through coupling reaction and cross-linking reaction, an amphiphilic polymer mainly composed of propoxyglycerol triglycidyl ether (GPTE) is constructed on its surface as a coating layer, and then a super-amphiphilic coating that can conduct lithium ions is prepared on the surface of aluminum foil. The specific steps are as follows:

[0158] 1. Li particles with a size of 1-5 μm 1.4 Al 0.4 Ti 1.6 (PO4)3 particles were added to a mixture of anhydrous ethanol and 1-methylpyrrole (V:V = 100:0.01) and dispersed thoroughly by rapid stirring at room temperature. The solid content of the dispersion was 0.1%.

[0159] 2. Add the precursors of the amphiphilic material, propoxyglycerol triglycidyl ether (GPTE) and octadecylamine (ODA) (the mass ratio of the two is 50:1) to the dispersion. 1.4 Al 0.4 Ti 1.6 (PO4)3 particles were dispersed in a mass ratio of 1:10 and stirred at room temperature for 6 hours and at 50°C for 15 minutes to obtain a uniform dispersion. 1.4 Al 0.4 Ti 1.6 The mass proportion of (PO4)3 particles is about 0.1%;

[0160] 3. Spray the above dispersion evenly on aluminum foil;

[0161] 4. Dry the aluminum foil at room temperature for 5 minutes and heat it at 150°C for 1 hour to complete crosslinking and curing to obtain Li-ion polymer coated with amphiphilic polymer. 1.4 Al 0.4 Ti 1.6 Aluminum foil with a super-amphiphilic coating that conducts lithium ions and is constructed of (PO4)3 particles, with a coating thickness of 2 μm;

[0162] 5. Preparation of a lithium-ion battery comprising the above-mentioned positive electrode sheet:

[0163] (1) Preparing a positive electrode sheet with an aluminum foil surface coated with the super-amphiphilic coating capable of conducting lithium ions:

[0164] The positive electrode active material LiFePO4, conductive carbon black (Super P), and binder polytetravinylidene fluoride (PVDF) are uniformly mixed in an appropriate amount of N-methylpyrrolidone (NMP) at a mass ratio of 97.3:1.2:1.5 to prepare a positive electrode slurry. The positive electrode slurry is coated on the aluminum foil having the above-mentioned super amphiphilic coating that can conduct lithium ions. The positive electrode sheet is prepared through processes such as rolling, slitting, and punching.

[0165] (2) Preparation of negative electrode sheet:

[0166] The negative electrode active material artificial graphite, conductive agent carbon black (Super P), binder styrene-butadiene rubber (SBR) and sodium carboxymethyl cellulose (CMC-Na) were mixed uniformly in an appropriate amount of deionized water as a solvent at a mass ratio of 95.5:1.7:1.6:1.2 to obtain a negative electrode slurry. The negative electrode slurry was coated on the negative electrode current collector copper foil. The negative electrode sheet was obtained through processes such as rolling, slitting, and punching.

[0167] (3) Preparation of diaphragm:

[0168] Use commercial polypropylene diaphragms;

[0169] (4) Preparation of electrolyte:

[0170] Ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were prepared into a mixed solvent at a mass ratio of 50:50, and then fully dried electrolyte salt LiPF6 was dissolved therein (1.0 mol / L) to obtain an electrolyte solution.

[0171] (5) Preparation of lithium-ion batteries

[0172] The positive electrode sheet, separator, and negative electrode sheet are stacked in order to obtain a pole core; the pole core is placed in an outer package and baked; the electrolyte is injected into the dried lithium-ion battery, and a secondary battery is prepared through processes such as standing, formation, vacuum packaging, aging, and capacity separation.

[0173] Comparative Example 2

[0174] A coating layer, which differs from Example 1 in that it does not include a lithium ion conductor material.

[0175] In this embodiment, an amphiphilic polymer coating mainly composed of propoxyglycerol triglycidyl ether (GPTE) is constructed on the surface of aluminum foil through coupling reaction and cross-linking reaction. The specific steps are as follows:

[0176] 1. Add the precursors of the amphiphilic material, propoxyglycerol triglycidyl ether (GPTE) and octadecylamine (ODA) (mass ratio of 50:1), to a mixture of anhydrous ethanol and 1-methylpyrrole (V:V = 100:0.01) and stir at room temperature for 6 hours and at 50°C for 15 minutes to obtain a homogeneous solution.

[0177] 2. Spray the above solution evenly on aluminum foil;

[0178] 3. Dry the aluminum foil at room temperature for 5 minutes and heat at 150°C for 1 hour to complete crosslinking and curing, thereby obtaining an aluminum foil with an amphiphilic polymer coating having a thickness of 2 μm.

[0179] 4. Preparation of a lithium-ion battery comprising the above-mentioned positive electrode sheet:

[0180] (1) Preparing a positive electrode sheet with the amphiphilic polymer coating on the surface of an aluminum foil:

[0181] The positive electrode active material LiFePO4, conductive carbon black (Super P) and binder polytetravinylidene fluoride (PVDF) are uniformly mixed in an appropriate amount of N-methylpyrrolidone (NMP) at a mass ratio of 97.3:1.2:1.5 to prepare a positive electrode slurry. The positive electrode slurry is coated on the aluminum foil with the amphiphilic polymer coating and then subjected to processes such as rolling, slitting, and punching to prepare a positive electrode sheet.

[0182] (2) Preparation of negative electrode sheet:

[0183] The negative electrode active material artificial graphite, conductive agent carbon black (Super P), binder styrene-butadiene rubber (SBR) and sodium carboxymethyl cellulose (CMC-Na) were mixed uniformly in an appropriate amount of deionized water as a solvent at a mass ratio of 95.5:1.7:1.6:1.2 to obtain a negative electrode slurry. The negative electrode slurry was coated on the negative electrode current collector copper foil. The negative electrode sheet was obtained through processes such as rolling, slitting, and punching.

[0184] (3) Preparation of diaphragm:

[0185] Use commercial polypropylene diaphragms;

[0186] (4) Preparation of electrolyte:

[0187] Ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were prepared into a mixed solvent at a mass ratio of 50:50, and then fully dried electrolyte salt LiPF6 was dissolved therein (1.0 mol / L) to obtain an electrolyte solution.

[0188] (5) Preparation of lithium-ion batteries

[0189] The positive electrode sheet, separator, and negative electrode sheet are stacked in order to obtain a pole core; the pole core is placed in an outer package and baked; the electrolyte is injected into the dried lithium-ion battery, and a secondary battery is prepared through processes such as standing, formation, vacuum packaging, aging, and capacity separation.

[0190] Comparative Example 3

[0191] A coating, which differs from Example 1 in that it does not include an amphiphilic material.

[0192] In this embodiment, the oxide solid electrolyte Li with a particle size of 50-100 nm is selected. 1.4 Al 0.4 Ti 1.6 (PO4)3 is a lithium ion conductive particle. A coating containing only solid electrolyte nanoparticles is prepared on the surface of aluminum foil. The specific steps are as follows:

[0193] 1. Li with particle size of 50-100nm 1.4 Al 0.4 Ti 1.6 (PO4)3 particles were added to anhydrous ethanol solvent and dispersed rapidly with stirring at room temperature. A dispersion with a solid content of 0.1% was prepared by using polyethylene glycol as a dispersant and ultrasound.

[0194] 2. Spray the above dispersion evenly on aluminum foil;

[0195] 3. Dry the aluminum foil at room temperature for 5 minutes and heat it at 150℃ for 1 hour to further evaporate the solvent. 1.4 Al 0.4 Ti 1.6 (PO4)3 nanoparticle-coated aluminum foil with a coating thickness of 2 μm;

[0196] 4. Preparation of a lithium-ion battery comprising the above-mentioned positive electrode sheet:

[0197] (1) Preparing a positive electrode sheet with the lithium ion conductor coating coated on the surface of the aluminum foil:

[0198] The positive electrode active material LiFePO4, conductive carbon black (Super P) and binder polytetravinylidene fluoride (PVDF) are uniformly mixed in an appropriate amount of N-methylpyrrolidone (NMP) at a mass ratio of 97.3:1.2:1.5 to prepare a positive electrode slurry. The positive electrode slurry is coated on the aluminum foil coated with the lithium ion conductor and then subjected to processes such as rolling, slitting and punching to prepare a positive electrode sheet.

[0199] (2) Preparation of negative electrode sheet:

[0200] The negative electrode active material artificial graphite, conductive agent carbon black (Super P), binder styrene-butadiene rubber (SBR) and sodium carboxymethyl cellulose (CMC-Na) were mixed uniformly in an appropriate amount of deionized water as a solvent at a mass ratio of 95.5:1.7:1.6:1.2 to obtain a negative electrode slurry. The negative electrode slurry was coated on the negative electrode current collector copper foil. The negative electrode sheet was obtained through processes such as rolling, slitting, and punching.

[0201] (3) Preparation of diaphragm:

[0202] Use commercial polypropylene diaphragms;

[0203] (4) Preparation of electrolyte:

[0204] Ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were prepared into a mixed solvent at a mass ratio of 50:50, and then fully dried electrolyte salt LiPF6 was dissolved therein (1.0 mol / L) to obtain an electrolyte solution.

[0205] (5) Preparation of lithium-ion batteries

[0206] The positive electrode sheet, separator, and negative electrode sheet are stacked in order to obtain a pole core; the pole core is placed in an outer package and baked; the electrolyte is injected into the dried lithium-ion battery, and a secondary battery is prepared through processes such as standing, formation, vacuum packaging, aging, and capacity separation.

[0207] Comparative Example 4

[0208] The difference from Example 1 is that unmodified aluminum foil is used.

[0209] Preparation of lithium-ion batteries:

[0210] (1) Preparation of positive electrode sheet:

[0211] The positive electrode active material LiFePO4, conductive carbon black (Super P), and binder polytetravinylidene fluoride (PVDF) are uniformly mixed in an appropriate amount of N-methylpyrrolidone (NMP) at a mass ratio of 97.3:1.2:1.5 to prepare a positive electrode slurry. The positive electrode slurry is coated on unmodified aluminum foil and then subjected to processes such as rolling, slitting, and punching to prepare a positive electrode sheet.

[0212] (2) Preparation of negative electrode sheet:

[0213] The negative electrode active material artificial graphite, conductive agent carbon black (Super P), binder styrene-butadiene rubber (SBR) and sodium carboxymethyl cellulose (CMC-Na) were mixed uniformly in an appropriate amount of deionized water as a solvent at a mass ratio of 95.5:1.7:1.6:1.2 to obtain a negative electrode slurry. The negative electrode slurry was coated on the negative electrode current collector copper foil. The negative electrode sheet was obtained through processes such as rolling, slitting, and punching.

[0214] (3) Preparation of diaphragm:

[0215] Use commercial polypropylene diaphragms;

[0216] (4) Preparation of electrolyte:

[0217] Ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were prepared into a mixed solvent at a mass ratio of 50:50, and then fully dried electrolyte salt LiPF6 was dissolved therein (1.0 mol / L) to obtain an electrolyte solution.

[0218] (5) Preparation of lithium-ion batteries

[0219] The positive electrode sheet, separator, and negative electrode sheet are stacked in order to obtain a pole core; the pole core is placed in an outer package and baked; the electrolyte is injected into the dried lithium-ion battery, and a secondary battery is prepared through processes such as standing, formation, vacuum packaging, aging, and capacity separation.

[0220] The following is an evaluation of the separators, electrodes and lithium-ion batteries prepared in Examples 1-5 and Comparative Examples 1-4 by wettability test, 1500-cycle lithium deposition test and capacity retention test.

[0221] Performance testing methods

[0222] 1. Wettability test of diaphragm and electrode for aqueous solvent, oily solvent and electrolyte:

[0223] The present invention determines the wettability of the electrolyte by measuring the contact angles of different solvents and electrolytes on the surfaces of the diaphragm and electrode materials. A contact angle meter is used to measure the static contact angles of the solvents and electrolytes six seconds after they are dropwise applied to the sample surface. The results of five repeated tests are used as the final result.

[0224] EC was selected as the representative of the aqueous solvent, EMC as the representative of the oily solvent, and the electrolyte was represented by the following formula: ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were prepared into a mixed solvent in a mass ratio of 50:50, and then fully dried electrolyte salt LiPF6 was dissolved therein (1.0 mol / L) to obtain the electrolyte.

[0225] 2. Battery cycle lithium deposition test:

[0226] After 1500 cycles, the battery was disassembled to observe lithium deposition at the interface. The extent of lithium deposition in the center of the electrode was assessed to evaluate the effectiveness of the lithium-ion-conducting super-amphiphilic coating provided by the present invention in improving lithium deposition caused by liquid depletion in the center of the battery cell during cycling.

[0227] Cycling conditions: 25°C, 1C / 1C, 1500 cycles.

[0228] Lithium deposition degree judgment standard: the percentage of lithium deposition area in the center of the electrode to the total area of ​​the electrode:

[0229]

[0230] 3. Capacity retention rate after 1500 cycles:

[0231] The cycle capacity retention rate of the battery cell after 1500 cycles will be used as a basis to evaluate the effect of the lithium ion conductive super-amphiphilic coating provided by the present invention on improving the cycle life.

[0232] Cycling conditions: 25°C, 1C / 1C, 1500 cycles.

[0233] Capacity retention rate calculation method: 1500-cycle discharge capacity / initial discharge capacity.

[0234] Test results:

[0235]

[0236] The test results of Examples 1-5 show the technical effects of the lithium ion conductive super-amphiphilic coating on the positive and negative electrodes and battery cells when applied to aluminum foil, copper foil and separator.

[0237] (1) The positive and negative electrodes and separators using this coating have super affinity for aqueous and oily solvents in the electrolyte. The contact angles for aqueous EC and oily EMC solvents are both less than 5°, thus achieving super affinity for the electrolyte (contact angle for the electrolyte is less than 5°).

[0238] (2) Furthermore, the positive and negative electrodes and separators with this coating have good wettability during the cycle process, which can accelerate the reabsorption of electrolyte, improve the liquid absorption capacity of the battery cell, and help alleviate the extrusion of electrolyte during the expansion process. After 1500 cycles, the battery cells with positive and negative electrodes and separators with this coating all have a low degree of lithium plating.

[0239] (3) Correspondingly, its capacity retention rate for 1500 weeks is relatively excellent.

[0240] Comparison of Comparative Examples 1, 2, 3 and 4 with Example 1 illustrates the necessity of combining the amphiphilic material and the lithium ion conductor nanomaterial when constructing the super-amphiphilic coating capable of conducting lithium ions.

[0241] (1) Comparative Example 4 is a positive electrode sheet and battery cell prepared from unmodified aluminum foil. The contact angle of the positive electrode sheet to EC, EMC and electrolyte is large, corresponding to a large degree of lithium deposition after 1500 cycles, and a low cycle capacity retention rate;

[0242] (2) The coating structure of Comparative Example 1 uses 1-5 μm particle size Li coated with propoxyglycerol triglycidyl ether polymer. 1.4 Al 0.4 Ti 1.6 (PO4)3 particles, the coating formed by them lacks the micro-nanostructure required for super-amphiphilic function, and therefore only improves the affinity for oily and aqueous solvents, and electrolytes to a certain extent;

[0243] (3) Comparative Example 2 uses only propoxyglycerol triglycidyl ether polymer as a coating, and the interface constructed has only an amphiphilic function, which is far lower than the wettability of the positive electrode sheet with this coating in Example 1 to EC, EMC and electrolyte;

[0244] (4) Comparative Example 3 uses nano-Li with a particle size of 50-100 nm. 1.4 Al 0.4 Ti 1.6 The (PO4)3 electrolyte particle coating has a certain affinity for both EC solvent and electrolyte due to its polarity, but compared with the super-amphiphilic coating constructed in Example 1, its affinity is still relatively low, the degree of lithium plating during the cycle is high, and the capacity retention rate is correspondingly poor.

[0245] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A pole piece, characterized in that: The present invention comprises a current collector, wherein the surface of the current collector is coated with a super-amphiphilic coating capable of conducting lithium ions; The super-amphiphilic coating capable of conducting lithium ions comprises an amphiphilic material and a lithium ion conductor nanomaterial; the amphiphilic material is coated on the surface of the lithium ion conductor nanomaterial; the amphiphilic material coating layer and the lithium ion conductor nanomaterial constitute a micro-nano structure; The amphiphilic material comprises at least one of propoxyglycerol triglycidyl ether polymer, polyvinyl pyrrolidone, polydopamine, polyethylene glycol-polytetramethyl ether glycol copolymer or polyethylene glycol-polydimethylsiloxane copolymer; The lithium ion conductor nanomaterial includes at least one of a NASICON type oxide solid electrolyte, a LISICON type oxide electrolyte, a Garnet type oxide solid electrolyte, a Perovskite type oxide solid electrolyte or an Anti-perovskite type oxide solid electrolyte; The particle size of the lithium ion conductor nanomaterial is 10-200 nm; The static contact angle of the super-amphiphilic coating to ethylene carbonate is less than 5°; the static contact angle of the super-amphiphilic coating to ethyl methyl carbonate is less than 5°.

2. The pole piece according to claim 1, characterized in that: The mass ratio of the amphiphilic material to the lithium ion conductor nanomaterial is 0.01:1-10:

1.

3. The pole piece according to claim 1, characterized in that: The NASICON-type oxide solid electrolyte includes Li 1.4 Al 0.4 Ti 1.6 (PO4)3 or Li 1.5 Al 0.5 Ge 1.5 (PO4)3; The LISICON type oxide electrolyte includes γ-Li3PO4; The Garnet-type oxide solid electrolyte includes Li7La3Zr2O 12 or Li5La3Ta2O 12 ; The Perovskite-type oxide solid electrolyte includes Li 0.5 La 0.5 TiO3; The anti-perovskite oxide solid electrolyte includes Li3OCl.

4. The pole piece according to any one of claims 1 to 3, characterized in that: The preparation method of the super-amphiphilic coating capable of conducting lithium ions comprises the following steps: The amphiphilic material or its precursor, a lithium ion conductor nanomaterial and a solvent are mixed to form a dispersion, and the dispersion is then applied and dried to prepare the super-amphiphilic coating capable of conducting lithium ions; The solvent includes at least one of ethanol, deionized water, n-hexane, tetrahydrofuran (THF), heptane, isopropanol, carbon trichloride or carbon tetrachloride.

5. The pole piece according to claim 4, characterized in that: In the dispersion, the mass proportion of the lithium ion conductor nanomaterial is 0.1%-10%.

6. A lithium-ion battery, characterized in that: Including the pole piece according to claim 1.

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