Solid electrolyte coating diaphragm, preparation method thereof and lithium ion battery

Abstract

The invention discloses a solid-state electrolyte coating diaphragm. The solid-state electrolyte coating diaphragm comprises a base membrane and a plurality of solid-state electrolyte coating layers, at least one surface of the base membrane is coated with the solid electrolyte composite coating, and the solid electrolyte composite coating at least comprises a binder and a solid electrolyte coated with ionic liquid. Cracks are generated in the preparation process of the solid electrolyte, mechanical stress caused by volume expansion of the electrode can be absorbed and relieved, the ionic liquid and the cracks on the surface of the solid electrolyte can effectively adsorb, contain and package the electrolyte, when the volume of the electrode changes, the packaged electrolyte is gradually released, continuity of an ion conduction channel is maintained, and therefore the solid electrolyte is prevented from being damaged. And the cycling stability and safety of the battery are improved.

Description

Technical Field

[0001] The present invention relates to the field of electrochemical technology, and in particular to a solid electrolyte coating diaphragm, a preparation method thereof, and a lithium ion battery. Background Art

[0002] Lithium-ion batteries are widely used in portable electronic devices and new energy vehicles due to their high energy density and long cycle life. However, during the battery cycle, electrode materials (such as silicon-based, lithium metal, graphite, etc.) often experience significant volume expansion and contraction due to the insertion and deinsertion of lithium ions. This volume change not only leads to mechanical stress concentration between electrode particles, but may also cause electrode structure rupture, conductive network breakage, and detachment between the electrode and the current collector, thereby affecting the overall cycle stability and safety of the battery. Especially under high-rate charge and discharge and deep cycle conditions, the problem of electrode volume expansion is more prominent, becoming one of the main technical difficulties restricting the long-term stable operation of lithium-ion batteries. Summary of the Invention

[0003] The purpose of the present invention is to overcome the defect that the electrodes of existing lithium-ion batteries are prone to volume expansion, and to provide a solid electrolyte coating membrane that can alleviate the volume expansion of the electrodes, so that the lithium-ion battery prepared therefrom can maintain electrochemical stability and safety during the entire cycle.

[0004] In order to achieve the above-mentioned object, the present invention provides a solid electrolyte coating diaphragm, which comprises: a base membrane; a solid electrolyte composite coating coated on at least one side of the base membrane, wherein the solid electrolyte composite coating comprises at least a binder and an ionic liquid-coated solid electrolyte.

[0005] Optionally, the material of the base film includes any one or a combination of any two or more of polyethylene, polypropylene, polyolefin, polyvinylidene fluoride, polytetrafluoroethylene and derivatives thereof.

[0006] Optionally, the ionic liquid includes at least 1-butyl-3-methylimidazolium trifluoromethanesulfonate, 1-ethyl-3-methylimidazolium bistrifluoromethanesulfonyl imide, 1-ethyl-1-methylpyrrolidine bistrifluoromethanesulfonyl imide, 1-methyl-1-propylpyrrolidinium bis(fluorosulfonyl)imide, tributylmethylammonium bistrifluoromethanesulfonyl imide, 1-propyl-1-methylpiperidinium bistrifluoromethanesulfonyl imide, and 1-butyl-1-methylpiperidinium bistrifluoromethanesulfonyl imide, or any combination of more than one of the above.

[0007] Optionally, the solid electrolyte comprises at least Li3Si2Zr2PO 12 , Li4Zr2(SiO4)3, LiZr2(PO4)3, Li3Hf2Si2PO12 、Li3La(PO4)2、Li 1.3 Ti 1.7 Al 0.3 (PO4)3、Li3V2(PO4)3、Li 2.96 Nb 0.04 Zr 1.96 Si2PO 12 Any one of .

[0008] Optionally, the solid electrolyte contains a plurality of cracks, and the size of the cracks is 10 nm to 100 nm.

[0009] Optionally, in the solid electrolyte composite coating, the mass proportion of the binder is 5wt.% to 20wt.%, and the mass proportion of the ionic liquid-coated solid electrolyte is 80wt.% to 95wt.%.

[0010] Optionally, the adhesive comprises any one or a combination of any two or more of an acrylic water-based adhesive, a polyacrylamide adhesive, a polyacrylate adhesive, a polyvinyl alcohol adhesive, and an alkoxy terpolymer.

[0011] The present invention also provides a method for preparing the solid electrolyte coating membrane as described above, comprising the following steps:

[0012] S1, Preparation of ionic liquid-coated solid electrolyte:

[0013] The sodium ion solid electrolyte is mixed with LiTFSI and ionic liquid, and the mixture is placed in a reactor for reaction. The reactor is placed in a homogeneous reactor and stirred in rotation for 72 to 144 hours at a temperature of 180°C.

[0014] The reaction product in the reactor is taken out, centrifuged and then dried to obtain the ionic liquid-coated solid electrolyte;

[0015] S2, preparation of solid electrolyte coating membrane:

[0016] Adding the ionic liquid-coated solid electrolyte and the binder to deionized water and stirring to obtain a solid electrolyte slurry, coating the solid electrolyte slurry on a base film, and drying to obtain a solid electrolyte coating membrane with a coating thickness of 5 μm to 12 μm;

[0017] Wherein, the sodium ion solid electrolyte comprises Na3Si2Zr2PO 12 , Na4Zr2(SiO4)3, NaZr2(PO4)3, Na3Hf2Si2PO 12 、Na3La(PO4)2、Na 1.3 Ti1.7 Al 0.3 (PO4)3、Na3V2(PO4)3、Na 2.96 Nb 0.04 Zr 1.96 Si2PO 12 Any one of .

[0018] Optionally, the thickness of the ionic liquid coating is 10 nm to 20 nm.

[0019] The present invention also provides a lithium-ion battery, which comprises at least the solid electrolyte coating separator described above.

[0020] Compared with the prior art, the beneficial effects of the present invention include at least:

[0021] (1) The solid electrolyte coating diaphragm of the present invention comprises a base film and a solid electrolyte composite coating coated on at least one side of the base film, wherein the solid electrolyte composite coating comprises a solid electrolyte coated with an ionic liquid, wherein the solid electrolyte naturally forms cracks during the lithium-sodium ion exchange preparation process, and the cracks are evenly distributed inside the solid electrolyte particles, playing a role similar to a reserved buffer zone. When the electrode material expands in volume during the charge-discharge cycle, these cracks can effectively disperse and absorb the local mechanical stress caused by the expansion, preventing the electrode particles from breaking or falling off due to stress concentration, thereby greatly reducing the risk of damage to the electrode structure and ensuring the stability and integrity of the overall electrode system.

[0022] (2) The solid electrolyte is formed in a liquid phase with an ionic liquid as the solvent. Due to the interaction of chemical bonds, a thin ionic liquid coating is formed on the surface. Because it has abundant polar groups, a thin film with strong adsorption properties is formed on the surface of the solid electrolyte, which significantly improves the adsorption and encapsulation ability of the diaphragm for the electrolyte. This encapsulation effect allows a portion of the electrolyte to be embedded in the cracks formed by the solid electrolyte. When the volume of the electrode expands, these encapsulated electrolytes will be gradually squeezed and released, ensuring the continuous supply and uniform distribution of the electrolyte inside the battery, thereby maintaining a stable ion conduction channel and improving the electrochemical performance and overall safety of the battery during the cycle.

[0023] (3) The present invention uses an aqueous slurry to prepare a solid electrolyte composite coating. This process helps to achieve a close bond between the base film and the coating, ensuring the interfacial bonding strength and the continuity of the ion conduction channel. The aqueous system not only reduces the environmental and safety risks during the preparation process, but also makes the coating preparation process simpler and easier to control. During long-term cycling, this stable interface structure effectively resists delamination or peeling caused by electrode volume expansion and other mechanical stresses, thereby significantly improving the cycle life and safety performance of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The solid electrolyte Li3Si2Zr2PO prepared in Example 1 of the present invention 12 SEM image of .

[0025] Figure 2 The solid electrolyte Li3Si2Zr2PO4 coated with ionic liquid prepared in Example 1 of the present invention 12 Local TEM image of.

[0026] Figure 3 This is a cross-sectional SEM image of the solid electrolyte coating membrane prepared in Example 1 of the present invention.

[0027] Figure 4 This is a comparison chart of the cycle performance of the lithium metal soft-pack batteries prepared in Example 2 of the present invention and Comparative Example 1.

[0028] Figure 5 This is a needle penetration test diagram of the soft-pack battery prepared in Example 3 of the present invention in a fully charged state. DETAILED DESCRIPTION

[0029] The technical solution of the present invention is further described below with reference to the accompanying drawings and embodiments.

[0030] Currently, alleviating the volume expansion of lithium-ion battery electrodes is an urgent problem that needs to be solved. The impact of volume expansion is usually reduced by optimizing the electrode formulation and structural design. For example, the use of a binder with high elasticity and flexibility can improve the structural stability within the electrode. The patent "A lithium-sulfur battery binder, its preparation method and application" uses a large number of nitrogen-rich functional groups contained in a binder composed of a methylated amino resin and a solvent to buffer the volume expansion of the electrode and inhibit the lithium polysulfide shuttle effect. By designing nanostructured or porous electrode materials, the damage to the overall conductive network caused by volume changes can be alleviated. The patent "A carbon-silicon composite material with an elastic nanostructure, its preparation method and application" states that the carbon-silicon composite material with an elastic nanostructure can constrain the volume expansion of silicon-containing particles during the electrochemical charge and discharge process within the elastic unit, without generating macroscopic strain and stress accumulation. The addition of flexible conductive materials such as carbon nanotubes or graphene also helps maintain good conductivity during electrode expansion, thereby improving the cycle life and safety of the battery. The patent "A silicon-based negative electrode material for lithium-ion batteries with small volume expansion and its preparation method" improves the cycle stability and rate performance of lithium-ion batteries by coating the surface of carbon nanotubes with silicon material, then chemically depositing carbon material on the outer layer, and using a special process to arrange the carbon nanotubes in an orderly manner.

[0031] Although the above methods can alleviate volume expansion, starting from the electrode materials, it is usually necessary to adjust the proportion of traditional electrode materials and introduce additional buffer or elastic materials, which may lead to a reduction in the content of active substances in the electrode, thereby sacrificing some energy density and power performance. In addition, improving electrode formulations and structural designs often involves complex manufacturing processes and strict quality control, which not only increases production costs but also may pose challenges to process repeatability and stability. Moreover, in large-scale production, how to maintain uniformity and long-term stability has also become a problem that needs to be solved urgently.

[0032] In order to solve the above technical problems, a functional diaphragm is proposed as a new type of battery component to improve the adverse effects of electrode volume expansion. The present invention provides a solid electrolyte coating diaphragm that alleviates the volume expansion of the electrode, comprising a base film and a solid electrolyte composite coating coated on the surface of the base film, wherein the solid electrolyte composite coating is composed of a binder and an ionic liquid-coated solid electrolyte. The ionic liquid-coated solid electrolyte is prepared by a lithium-sodium ion exchange reaction. During the preparation process, cracks are generated inside the solid electrolyte by the lithium-sodium ion exchange reaction. These cracks can serve as "reserved space" when the volume of the electrode material expands, absorbing the mechanical stress generated during the electrode expansion process, thereby reducing the risk of local stress concentration and structural damage caused by the expansion of the electrode material. At the same time, the ionic liquid coated on the surface of the solid electrolyte contains rich polar groups, which can significantly improve the adsorption and encapsulation ability of the composite coating on the electrolyte, so that a portion of the electrolyte can be firmly retained in the cracks of the solid electrolyte. When the volume of the electrode changes during the charge and discharge cycle, these encapsulated electrolytes will be gradually squeezed and released, thereby compensating for the electrolyte loss or local insufficient liquid supply caused by volume expansion, further maintaining the continuity of the ion conduction channel, and ensuring the electrochemical stability and safety of the battery throughout the cycle.

[0033] The present invention applies the prepared solid electrolyte coating diaphragm to lithium ion batteries and lithium metal batteries to evaluate their performance. The preparation process of the solid electrolyte coating diaphragm and its use process fully consider the compatibility with the existing lithium battery production process, and do not require the introduction of additional special equipment or changes in process parameters. In addition, the solid electrolyte, binder and ionic liquid materials used are all well compatible with the existing system and can be directly replaced or integrated into the current production process without the need to significantly change the existing process flow, thereby not bringing additional burden to production. In the embodiments of the present invention, there are no special restrictions on the positive and negative electrodes of the lithium battery, and the positive and negative electrodes can be prepared using conventional processes.

[0034] The method for preparing the solid electrolyte coating membrane of the present invention comprises the following steps:

[0035] S1, Preparation of ionic liquid-coated solid electrolyte:

[0036] The sodium ion solid electrolyte, LiTFSI and ionic liquid are mixed evenly and placed in a reactor for reaction. The reactor is placed in a homogeneous reactor and rotated and stirred for 72h to 144h at a temperature of 180°C.

[0037] The reaction product in the reactor is taken out, centrifuged and then dried to obtain the ionic liquid-coated solid electrolyte.

[0038] S2, preparation of solid electrolyte coating membrane:

[0039] The ionic liquid-coated solid electrolyte and binder are added to deionized water and stirred to obtain a solid electrolyte slurry, which is coated on a base film and dried to obtain a solid electrolyte coating membrane with a coating thickness of 5 μm to 12 μm.

[0040] The sodium ion solid electrolyte comprises Na3Si2Zr2PO 12 , Na4Zr2(SiO4)3, NaZr2(PO4)3, Na3Hf2Si2PO 12 、Na3La(PO4)2、Na 1.3 Ti 1.7 Al 0.3 (PO4)3、Na3V2(PO4)3、Na 2.96 Nb 0.04 Zr 1.96 Si2PO 12 Any one of .

[0041] The concentration of the lithium salt in the ionic liquid is 0.1 mol / L to 0.5 mol / L, the molar ratio of LiTFSI to sodium ion solid electrolyte is 3:1, the particle size of the solid electrolyte material is 5 μm to 10 μm, the thickness of the base film is 10 μm to 15 μm, and the solid content of the solid electrolyte slurry is 35% to 45%.

[0042] Example 1

[0043] (1) Preparation of positive electrode sheet: The binder PVDF, the conductive agent Super P, and the main material lithium nickel cobalt manganese oxide are mixed in NMP solvent in a mass ratio of 96:2:2, and then coated on aluminum foil, dried, rolled, and cut to make positive electrode sheets.

[0044] (2) Preparation of negative electrode sheets: Dry powders of silicon carbon, conductive agent Super P, styrene-butadiene rubber, and sodium carboxymethyl cellulose are mixed with an aqueous solvent in a mass ratio of 95:2:1:2. The slurry is then coated on copper foil and dried, rolled, and cut to make negative electrode sheets.

[0045] (3) Preparation of ionic liquid coated solid electrolyte: Sodium ion solid electrolyte Na3Si2Zr2PO 12 Mix LiTFSI and ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt evenly and put them into the reactor. The concentration of lithium salt in the ionic liquid is 0.5 mol / L. LiTFSI and Na3Si2Zr2PO 12 The molar ratio of the reaction kettle is 3:1; the reactor is placed in a homogeneous reactor and rotated and stirred at a speed of 50 rpm / min for 144 hours at a temperature of 180°C; the reaction product in the reactor is taken out and centrifuged and dried to obtain the ionic liquid-coated solid electrolyte Li3Si2Zr2PO 12 .

[0046] (4) Preparation of solid electrolyte coating membrane: solid electrolyte Li3Si2Zr2PO coated with ionic liquid 12 , a binder polyacrylic siloxane ternary copolymer emulsion is added to deionized water in a mass ratio of 90:10 and mixed and stirred to prepare a solid electrolyte slurry with a solid content of 40%. The evenly dispersed solid electrolyte slurry is applied on one side of a polypropylene base film with a thickness of 20 μm and dried to obtain a solid electrolyte coating membrane with a coating thickness of 12 μm.

[0047] (5) Preparation of electrolyte: 1.0 M LiPF6 was dissolved in EC:EMC solvent with a volume ratio of 3:7, and 2 wt% FEC and 0.5 wt% LiDFOB were added.

[0048] (6) Battery assembly: The positive electrode sheet, solid electrolyte coating separator and negative electrode sheet are stacked in a Z-shaped stacking manner, and a soft-pack battery is made after the tabs are welded and the aluminum-plastic film is encapsulated, with the solid electrolyte composite coating facing the negative electrode side.

[0049] Depend on Figure 1 It can be seen that the prepared solid electrolyte Li3Si2Zr2PO 12 The particle size is 8μm, and there are regular cracks, the size of which is 100nm, which can "reserve space" for subsequent relief of volume expansion; Figure 2 It can be seen that the solid electrolyte Li3Si2Zr2PO coated with ionic liquid was prepared 12 , it can be seen that the surface of the solid electrolyte is coated with ionic liquid, and the thickness of the ionic liquid coating layer is about 20nm; Figure 3 It can be seen that the total thickness of the prepared solid electrolyte coating membrane is about 30 μm, and the coating thickness on one side is about 12 μm.

[0050] Example 2

[0051] (1) Preparation of positive electrode sheet: The binder PVDF, the conductive agent Super P, and the main material lithium nickel cobalt manganese oxide are mixed in NMP solvent in a mass ratio of 96:2:2, and then coated on aluminum foil, dried, rolled, and cut to make positive electrode sheets.

[0052] (2) Preparation of negative electrode sheet: The negative electrode sheet is a 100 μm thick metal lithium strip.

[0053] (3) Preparation of ionic liquid-coated solid electrolyte: The sodium ion solid electrolyte Na3La(PO4)2 was mixed evenly with LiTFSI and ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, and placed in a reactor. The concentration of lithium salt in the ionic liquid was 0.5 mol / L, and the molar ratio of LiTFSI to Na3La(PO4)2 was 5:1. The reactor was placed in a homogeneous reactor and rotated and stirred at a speed of 50 rpm / min for 96 hours at a temperature of 180°C. The reaction product in the reactor was taken out and centrifuged and dried to obtain the ionic liquid-coated solid electrolyte Li3La(PO4)2.

[0054] (4) Preparation of solid electrolyte coating membrane: The solid electrolyte Li3La(PO4)2 coated with ionic liquid and the binder polyacrylic siloxane ternary copolymer emulsion were added into deionized water at a mass ratio of 85:15 and mixed to prepare a solid electrolyte slurry with a solid content of 38%. The evenly dispersed solid electrolyte slurry was applied on one side of a polyvinylidene fluoride film with a thickness of 10 μm and dried to obtain a solid electrolyte coating membrane with a coating thickness of 8 μm.

[0055] (5) Preparation of electrolyte: 3M LiFSI was dissolved in DME:TTE solvent with a volume ratio of 1:3, and 2 wt% FEC was added.

[0056] (6) Battery assembly: The positive electrode sheets, solid electrolyte coating separators and lithium ribbons are stacked in a Z-shaped stacking manner, and then the tabs are welded and encapsulated with aluminum-plastic film to form a soft-pack battery, with the solid electrolyte composite coating facing the positive electrode side.

[0057] Comparative Example 1

[0058] (1) Preparation of positive electrode sheet: The binder PVDF, the conductive agent Super P, and the main material lithium nickel cobalt manganese oxide are mixed in NMP solvent in a mass ratio of 96:2:2, and then coated on aluminum foil, dried, rolled, and cut to make positive electrode sheets.

[0059] (2) Preparation of negative electrode sheet: The negative electrode sheet is a 100 μm thick metal lithium strip.

[0060] (3) Preparation of ionic liquid-coated solid electrolyte: The sodium ion solid electrolyte Na3La(PO4)2 was mixed evenly with LiTFSI and ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, and placed in a reactor. The concentration of lithium salt in the ionic liquid was 0.5 mol / L, and the molar ratio of LiTFSI to Na3La(PO4)2 was 5:1. The reactor was placed in a homogeneous reactor and rotated and stirred at a speed of 50 rpm / min for 96 hours at a temperature of 180°C. The reaction product in the reactor was taken out and centrifuged and dried to obtain the ionic liquid-coated solid electrolyte Li3La(PO4)2.

[0061] (4) Preparation of diaphragm: A polyvinylidene fluoride film with a thickness of 10 μm was used.

[0062] (5) Preparation of electrolyte: 3M LiFSI was dissolved in DME:TTE solvent with a volume ratio of 1:3, and 2 wt% FEC was added.

[0063] (6) Battery assembly: The positive electrode sheets, solid electrolyte coating separators and lithium ribbons are stacked in a Z-shaped stacking manner, and then the tabs are welded and encapsulated with aluminum-plastic film to form a soft-pack battery.

[0064] Depend on Figure 4 It can be seen that the cycle performance comparison diagrams of the lithium metal soft-pack batteries prepared in Example 2 (B) of the present invention and Comparative Example 1 (A) respectively show that the cycle performance of the battery using the solid electrolyte coating separator is significantly improved, with a capacity retention rate of 90.1% after 130 cycles, while the performance of the metal lithium soft-pack battery using the ordinary separator "dives" after 70 cycles, the battery fails, and the capacity retention rate is 85.1%.

[0065] Example 3

[0066] (1) Preparation of positive electrode sheet: The binder PVDF, the conductive agent Super P, and the main material lithium cobalt oxide are mixed in NMP solvent in a mass ratio of 96:2:2, and then coated on aluminum foil, dried, rolled, and cut to make positive electrode sheets.

[0067] (2) Preparation of negative electrode sheets: Dry powders of silicon carbon, conductive agent Super P, styrene-butadiene rubber, and sodium carboxymethyl cellulose are mixed with an aqueous solvent in a mass ratio of 95:2:1:2. The slurry is then coated on copper foil and dried, rolled, and cut to make negative electrode sheets.

[0068] (3) Preparation of ionic liquid coated solid electrolyte: Sodium ion solid electrolyte Na 2.96 Nb 0.04 Zr 1.96 Si2PO 12 Mix LiTFSI and ionic liquid 1-butyl-3-methylimidazolium trifluoromethanesulfonate evenly and put them into the reactor. The concentration of lithium salt in the ionic liquid is 0.5 mol / L. LiTFSI and Na 2.96 Nb 0.04 Zr 1.96 Si2PO 12 The molar ratio of the reaction kettle is 3:1; the reactor is placed in a homogeneous reactor, and the reaction mixture is stirred at a speed of 50 rpm / min for 144 hours at a temperature of 180°C; the reaction product in the reactor is taken out and centrifuged and dried to obtain the ionic liquid-coated solid electrolyte Li 2.96 Nb 0.04 Zr 1.96 Si2PO 12 .

[0069] (4) Preparation of solid electrolyte coating membrane: solid electrolyte Li coated with ionic liquid 2.96 Nb 0.04 Zr 1.96 Si2PO 12 , a binder polyacrylic siloxane ternary copolymer emulsion is added to deionized water in a mass ratio of 90:10 and mixed and stirred to prepare a solid electrolyte slurry with a solid content of 40%. The evenly dispersed solid electrolyte slurry is applied on both sides of a polypropylene base film with a thickness of 12 μm and dried to obtain a solid electrolyte coating diaphragm with a coating thickness of 10 μm on both sides.

[0070] (5) Preparation of electrolyte: 1.0 M LiPF6 was dissolved in EC:EMC solvent with a volume ratio of 3:7.

[0071] (6) Battery assembly: The positive electrode sheet, solid electrolyte coating separator and negative electrode sheet are stacked in a Z-shaped stacking manner, and then the tabs are welded and encapsulated with aluminum-plastic film to form a soft-pack battery.

[0072] Figure 5This image shows a fully charged soft-pack battery prepared in Example 3 of the present invention undergoing a needle penetration test. The battery successfully passed the needle penetration safety test without catching fire or exploding. This demonstrates that the solid-state electrolyte-coated separator can significantly improve battery safety performance, primarily by effectively alleviating the mechanical stress generated by volume changes in the electrodes during charge and discharge cycles. This reduces the risk of localized stress concentration and structural damage, thereby mitigating potential safety hazards such as internal short circuits and overheating.

[0073] In summary, the present invention provides a solid electrolyte coating membrane comprising a base membrane and a solid electrolyte composite coating applied to at least one side of the base membrane, wherein the solid electrolyte composite coating comprises at least a binder and a solid electrolyte coated with an ionic liquid. The solid electrolyte forms cracks during the preparation process, which can absorb and alleviate the mechanical stress caused by the volume expansion of the electrode. The ionic liquid on the surface of the solid electrolyte can effectively adsorb and encapsulate the electrolyte. When the electrode volume changes, the encapsulated electrolyte is gradually released, maintaining the continuity of the ion conduction channel, thereby improving the battery cycle stability and safety.

[0074] Although the present invention has been described in detail through the above preferred embodiments, it should be understood that the above description is not intended to limit the present invention. After reading the above description, various modifications and substitutions of the present invention will become apparent to those skilled in the art. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A solid electrolyte coating membrane, characterized in that: The solid electrolyte coating membrane comprises: a base membrane; A solid electrolyte composite coating is coated on at least one side of the base membrane, wherein the solid electrolyte composite coating comprises at least a binder and an ionic liquid-coated solid electrolyte.

2. The solid electrolyte coating membrane according to claim 1, characterized in that The material of the base film includes any one or a combination of any two or more of polyethylene, polypropylene, polyolefin, polyvinylidene fluoride, polytetrafluoroethylene and derivatives thereof.

3. The solid electrolyte coating membrane according to claim 1, characterized in that The ionic liquid includes at least one of 1-butyl-3-methylimidazolium trifluoromethanesulfonate, 1-ethyl-3-methylimidazolium bistrifluoromethanesulfonyl imide, 1-ethyl-1-methylpyrrolidinium bistrifluoromethanesulfonyl imide, 1-methyl-1-propylpyrrolidinium bis(fluorosulfonyl)imide, tributylmethylammonium bistrifluoromethanesulfonyl imide, 1-propyl-1-methylpiperidinium bistrifluoromethanesulfonyl imide, and 1-butyl-1-methylpiperidinium bistrifluoromethanesulfonyl imide, or any combination of more than one of the above.

4. The solid electrolyte coating membrane according to claim 1, wherein The solid electrolyte comprises at least Li3Si2Zr2PO 12 , Li4Zr2(SiO4)3, LiZr2(PO4)3, Li3Hf2Si2PO 12 、Li3La(PO4)2、Li 1.3 Ti 1.7 Al 0.3 (PO4)3、Li3V2(PO4)3、Li 2.96 Nb 0.04 Zr 1.96 Si2PO 12 Any one of .

5. The solid electrolyte coating membrane according to claim 1, wherein The solid electrolyte contains a plurality of cracks, and the size of the cracks is 10 nm to 100 nm.

6. The solid electrolyte coating membrane according to claim 1, characterized in that In the solid electrolyte composite coating, the mass proportion of the binder is 5 wt.% to 20 wt.%, and the mass proportion of the solid electrolyte coated with the ionic liquid is 80 wt.% to 95 wt.%.

7. The solid electrolyte coating membrane according to claim 1, characterized in that The adhesive comprises any one or a combination of any two or more of an acrylic acid water-based adhesive, a polyacrylamide adhesive, a polyacrylate adhesive, a polyvinyl alcohol adhesive, and an alkoxy terpolymer.

8. A method for preparing a solid electrolyte coating membrane according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1, Preparation of ionic liquid-coated solid electrolyte: The sodium ion solid electrolyte is mixed with LiTFSI and an ionic liquid, and the mixture is placed in a reactor for reaction. The reactor is placed in a homogeneous reactor and subjected to rotary stirring for 72 to 144 hours at a temperature of 180° C. The reaction product in the reactor is taken out, centrifuged, and then dried to obtain the ionic liquid-coated solid electrolyte; S2, preparation of solid electrolyte coating membrane: Adding the ionic liquid-coated solid electrolyte and the binder to deionized water and stirring to obtain a solid electrolyte slurry, coating the solid electrolyte slurry on a base film, and drying to obtain a solid electrolyte coating membrane with a coating thickness of 5 μm to 12 μm; Wherein, the sodium ion solid electrolyte comprises Na3Si2Zr2PO 12 , Na4Zr2(SiO4)3, NaZr2(PO4)3, Na3Hf2Si2PO 12 、Na3La(PO4)2、Na 1.3 Ti 1.7 Al 0.3 (PO4)3、Na3V2(PO4)3、Na 2.96 Nb 0.04 Zr 1.96 Si2PO 12 Any one of .

9. The preparation method according to claim 8, wherein The thickness of the ionic liquid coating is 10 nm to 20 nm.

10. A lithium ion battery, characterized in that: The lithium-ion battery comprises at least the solid electrolyte coating separator according to any one of claims 1 to 7.

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