Electrolyte composite separator, preparation method, and lithium battery

Abstract

The present invention relates to the technical field of lithium batteries, and in particular, to an electrolyte composite separator, a preparation method, and a lithium battery. The electrolyte composite separator comprises a base film, a solid electrolyte layer disposed on at least one side of the base film, and a resin layer disposed on at least the side of the solid electrolyte layer away from the base film. The peel strength between the solid electrolyte layer and the base film is greater than the peel strength between the solid electrolyte layer and the resin layer. When a lithium battery is prepared by using the electrolyte composite separator provided in the examples of the present application, due to the fact that the peel strength between the resin layer and a solid electrolyte is relatively small, the resin layer can be partially integrated into the electrode material after hot pressing, so that the solid electrolyte layer can be in full contact with the electrode material, resin content in the contact interface between the solid electrolyte layer and the electrode material is reduced, and the internal resistance of the lithium battery can be reduced.

Description

Electrolyte composite diaphragm, preparation method and lithium battery

[0001] Cross-references

[0002] This application claims priority to Chinese patent application No. 202311006763.2, filed on August 11, 2023, entitled “An electrolyte composite membrane, preparation method and lithium battery”, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present application relates to the technical field of lithium batteries, and in particular to an electrolyte composite diaphragm, a preparation method and a lithium battery. Background Art

[0004] As the demand for lithium-ion batteries continues to grow, consumers are placing increasingly higher demands on the performance of lithium-ion batteries. Among them, solid-state or semi-solid-state lithium-ion batteries are expected to significantly improve the safety issues of lithium-ion batteries.

[0005] In solid-state or semi-solid-state lithium batteries, the problem of insufficient contact between the solid electrolyte and the electrode is easy to occur, and the solid-liquid interface between the electrode material and the electrolyte will partially transform into the solid-solid interface between the electrode material and the solid electrolyte. The mutual diffusion and even reaction between the components will form vacancy charge layers, etc., which will lead to increased internal resistance of the lithium battery and poor battery cycle performance.

[0006] Currently, in order to improve the interface bonding problem between the solid electrolyte layer and the electrode, a thermal adhesive layer can be introduced on the surface of the solid electrolyte layer. However, the introduction of the thermal adhesive layer will increase the internal resistance of the lithium battery.

[0007] Summary of the Invention

[0008] Based on the above-mentioned deficiencies, the present application provides a composite electrolyte membrane, a preparation method and a lithium battery to partially or completely improve the problem of excessive internal resistance of lithium batteries containing a thermal adhesive layer in the related art.

[0009] This application is implemented as follows:

[0010] In a first aspect, examples of the present application provide an electrolyte composite membrane comprising a base membrane, a solid electrolyte layer disposed on at least one side of the base membrane, and a resin layer disposed on at least one side of the solid electrolyte layer facing away from the base membrane. The peel strength between the solid electrolyte layer and the base membrane is greater than the peel strength between the solid electrolyte layer and the resin layer.

[0011] In the above implementation process, a solid electrolyte layer is provided on the base film, and a resin layer is provided on the solid electrolyte layer, which can improve the ionic conductivity of the electrolyte composite membrane. In addition, the resin layer is provided on the surface of the solid electrolyte layer, which can make the contact between the solid electrolyte layer and the electrode more complete and tight during the hot pressing process. The peel strength between the resin layer and the solid electrolyte is relatively low. When preparing a lithium battery, the resin layer can be partially integrated into the electrode material after hot pressing, so that the electrolyte layer and the electrode material are in full contact, and the resin content at the contact interface between the electrolyte layer and the electrode material is reduced, thereby reducing the internal resistance of the lithium battery.

[0012] In combination with the first aspect, in an optional embodiment of the present application, the peel strength between the solid electrolyte layer and the base film is 80-220 N / m.

[0013] In the above implementation process, the peel strength between the solid electrolyte layer and the base membrane is 80-220 N / m, which can improve the stability of the electrolyte composite membrane and reduce the probability of solid electrolyte falling off.

[0014] In combination with the first aspect, in an optional embodiment of the present application, the peel strength between the solid electrolyte layer and the resin layer is 20-50 N / m.

[0015] In the above implementation process, the peel strength between the solid electrolyte layer and the resin layer is 20-50 N / m, which can reduce the internal resistance of the electrolyte composite membrane while ensuring the adhesion between the electrolyte composite membrane and the electrode sheet.

[0016] In combination with the first aspect, in an optional embodiment of the present application, the thickness of the solid electrolyte layer is 1-5 μm.

[0017] In the above implementation process, the thickness of the solid electrolyte layer is 1-5 μm, which can further improve the ionic conductivity of the electrolyte composite membrane.

[0018] In combination with the first aspect, in an optional embodiment of the present application, the thickness of the resin layer is 0.5-3 μm.

[0019] In the above implementation process, the thickness of the resin layer is 0.5-3 μm, which can further reduce the transmission distance between the solid electrolyte and the electrode and further increase the overall internal resistance of the lithium battery.

[0020] In combination with the first aspect, in an optional embodiment of the present application, a solid electrolyte layer is provided on one side of the base film, and a resin layer is provided on the other side of the base film.

[0021] In combination with the first aspect, in an optional embodiment of the present application, the electrolyte composite membrane includes a resin layer, a base membrane, a solid electrolyte layer and a resin layer stacked in sequence.

[0022] In the above implementation process, a resin layer is directly set on the other side of the base film. The two resin layers on the surface of the electrolyte composite diaphragm can be used to stick the electrolyte composite diaphragm between the positive and negative electrodes of the lithium battery to reduce the internal resistance of the lithium battery.

[0023] In combination with the first aspect, in an optional embodiment of the present application, a ceramic layer is arranged between the base film and the resin layer; and / or, a ceramic layer is arranged between the base film and the solid electrolyte layer, the base film and the ceramic layer have a first peel strength, the ceramic layer and the solid electrolyte layer have a second peel strength, and the peel strength between the solid electrolyte layer and the base film is the minimum of the first peel strength and the second peel strength.

[0024] In the above implementation process, providing a ceramic layer on one side or both sides of the base membrane can improve the safety of the electrolyte composite membrane.

[0025] In combination with the first aspect, in an optional embodiment of the present application, the material forming the solid electrolyte layer includes an oxide solid electrolyte.

[0026] In the above implementation process, oxide solid electrolytes such as lithium titanium aluminum phosphate, lithium lanthanum zirconium oxide and lithium lanthanum titanium oxide have good structural stability and can further improve the ionic conductivity of the electrolyte composite membrane.

[0027] In combination with the first aspect, in an optional embodiment of the present application, the material forming the resin layer includes at least one of acrylic resin and polyvinylidene fluoride.

[0028] In the above implementation process, thermo-adhesive resins such as acrylic resin and polyvinylidene fluoride can improve the interface bonding performance between the solid electrolyte layer and the electrode.

[0029] In a second aspect, an example of the present application provides a method for preparing an electrolyte composite membrane, the electrolyte composite membrane comprising a base membrane, a solid electrolyte layer disposed on at least one side of the base membrane, and a resin layer disposed at least on a side of the solid electrolyte layer facing away from the base membrane; the preparation method comprises:

[0030] The solid electrolyte layer is prepared by obtaining a first slurry containing a solid electrolyte material and a first adhesive, and applying the first slurry to at least one side of the base film to prepare the solid electrolyte layer;

[0031] The steps for preparing the resin layer are as follows: obtaining a second slurry containing a thermo-viscous resin material and a second adhesive, and applying the second slurry to at least the other side of the solid electrolyte layer to obtain a resin layer; wherein the first adhesive and the second adhesive have the same bonding strength, and the mass content of the first adhesive in the first slurry is higher than the mass content of the second adhesive in the second slurry; or, the bonding strength of the first adhesive and the second adhesive is different, and the bonding strength of the first adhesive is higher than the bonding strength of the second adhesive.

[0032] In the above implementation process, the mass content of the first adhesive in the first slurry is higher than the mass content of the second adhesive in the second slurry, and the bonding strength of the first adhesive is higher than the bonding strength of the second adhesive. After the first slurry is applied to the base film and the second slurry is applied to the surface of the solid electrolyte layer, an electrolyte composite membrane having the characteristic that the peel strength between the base film and the solid electrolyte layer is greater than the peel strength between the solid electrolyte layer and the resin layer can be obtained. This can not only improve the ionic conductivity of the electrolyte composite membrane, but also reduce the internal resistance of the electrolyte composite membrane.

[0033] In combination with the second aspect, in an optional embodiment of the present application, the first adhesive is selected from two-component polyurethane glue.

[0034] In the above implementation process, the two-component polyurethane glue has high bonding strength and can improve the structural stability of the electrolyte membrane.

[0035] In combination with the second aspect, in an optional embodiment of the present application, the second adhesive is selected from acrylic adhesive.

[0036] In the above implementation process, the acrylic adhesive has a low peel strength and can reduce the internal resistance of the lithium battery.

[0037] In combination with the second aspect, in an optional embodiment of the present application, in the step of preparing the resin layer, the second slurry is coated on the other side of the solid electrolyte layer by roller coating or spraying.

[0038] In the above implementation process, the second slurry is applied to the other side of the solid electrolyte layer by rolling or spraying, which can form a relatively loose thermal adhesive layer on the surface of the solid electrolyte layer, and can further reduce the internal resistance of the lithium battery while hardly reducing the bonding strength.

[0039] In a third aspect, an example of the present application provides a lithium battery comprising the electrolyte composite membrane provided in the first aspect and an electrode sheet attached to the electrolyte composite membrane; wherein a portion of the hot-adhesive resin in the electrolyte composite membrane is integrated into the interior of the electrode sheet.

[0040] In the above implementation process, the electrolyte composite diaphragm provided in the first aspect has a low internal resistance while having a high ionic conductivity, which can improve the electrical performance of the lithium battery. In addition, a resin layer is provided on the surface of the solid electrolyte layer of the electrolyte composite diaphragm, which can make the contact between the solid electrolyte layer and the electrode closer during the hot pressing process, reduce the transmission distance between the electrolyte and the electrode interface, and reduce the internal resistance of the lithium battery. At the same time, the peel strength between the resin layer and the solid electrolyte is small, and the resin layer can be integrated into the electrode material after hot pressing, which can further reduce the internal resistance of the lithium battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art.

[0042] FIG1 is a cross-sectional schematic diagram of a first electrolyte composite membrane provided by an example of this application;

[0043] FIG2 is a schematic diagram of the preparation process of the electrolyte composite membrane provided by the example of this application;

[0044] FIG3 is a cross-sectional schematic diagram of a second electrolyte composite membrane provided by an example of this application;

[0045] FIG4 is a cross-sectional schematic diagram of a third electrolyte composite membrane provided by an example of this application;

[0046] FIG5 is a cross-sectional schematic diagram of a fourth electrolyte composite membrane provided by an example of this application;

[0047] FIG6 is a cross-sectional schematic diagram of a fifth electrolyte composite membrane provided by an example of this application;

[0048] FIG7 is a cross-sectional schematic diagram of a sixth electrolyte composite membrane provided by an example of this application;

[0049] FIG8 is a schematic cross-sectional view of a lithium battery provided in an example of this application.

[0050] Icon: 100-lithium battery; 1-electrolyte composite diaphragm; 11-base membrane; 12-solid electrolyte layer; 13-resin layer; 14-ceramic layer; 2-positive electrode; 3-negative electrode. DETAILED DESCRIPTION

[0051] The embodiments of the present application will be described in detail below with reference to the examples, but it will be understood by those skilled in the art that the following examples are merely illustrative of the present application and should not be considered as limiting the scope of the present application. In the examples, if specific conditions are not specified, the conditions are carried out according to conventional conditions or manufacturer recommendations. The reagents or instruments used are not specified by the manufacturer and are conventional products that can be purchased commercially.

[0052] In solid-state or semi-solid-state lithium batteries, the solid-liquid interface between the electrode material and the electrolyte will partially transform into the solid-solid interface between the electrode material and the solid electrolyte, which can easily lead to problems such as insufficient contact between the solid electrolyte and the electrode. In addition, the mutual diffusion and even reaction between the components will form vacancy charge layers, resulting in increased internal resistance of the lithium battery and poor battery cycle performance.

[0053] In order to improve the interface bonding problem between the solid electrolyte layer and the electrode, a thermo-adhesive resin may be introduced onto the surface of the solid electrolyte layer, and the thermo-adhesive property of the thermo-adhesive resin may be utilized to achieve a tight bond between the solid electrolyte layer and the electrode.

[0054] However, the inappropriate introduction of adhesive resin peel strength, cohesion and thickness will increase the internal resistance of lithium batteries.

[0055] Based on this, the present application provides an electrolyte composite diaphragm and its preparation method, which can reduce the internal resistance of lithium batteries to a certain extent. To make the purpose, technical solution and advantages of the present application embodiment more clear, the technical solution in the present application embodiment will be clearly and completely described below in conjunction with the accompanying drawings.

[0056] 1 , the electrolyte composite membrane 1 provided in the example of the present application includes a base membrane 11, a solid electrolyte layer 12 arranged on at least one side of the base membrane 11, and a resin layer 13 arranged on at least one side of the solid electrolyte layer 12 facing away from the base membrane 11.

[0057] The resin layer 13 is a thermo-adhesive resin that becomes viscous when heated and has an adhesive function when heated.

[0058] 2 , the preparation method of the electrolyte composite membrane 1 provided in the example of this application includes:

[0059] S1. Preparation steps of solid electrolyte layer 12:

[0060] A first slurry containing a solid electrolyte material and a first adhesive is obtained, and the first slurry is coated on at least one side of the base film 11 to prepare the solid electrolyte layer 12 .

[0061] The present application does not limit whether the first slurry is coated on one side or both sides of the base film 11 . In one possible embodiment, please continue to refer to FIG. 1 , the first slurry can be coated on one side of the base film 11 to prepare the solid electrolyte layer 12 .

[0062] Alternatively, in another possible embodiment, referring to FIG. 3 , the first slurry may be coated on both sides of the base film 11 , and the solid electrolyte layer 12 may be coated on both sides of the base film 11 .

[0063] Furthermore, the present application does not limit the specific material of the base film 11, and relevant personnel can make corresponding choices as needed.

[0064] In some possible embodiments, the material of the base film 11 may be selected from one or more of polyethylene, polypropylene, polyvinylidene fluoride, and polyimide.

[0065] Furthermore, the present application does not limit the specific type of solid electrolyte material. In one possible embodiment, the solid electrolyte layer material includes an oxide solid electrolyte.

[0066] The oxide solid electrolyte has good structural stability and can further improve the stability of the electrolyte composite membrane 1.

[0067] Exemplarily, the oxide solid electrolyte may be selected from at least one of lithium titanium aluminum phosphate, lithium lanthanum zirconium oxide, and lithium lanthanum titanium oxide.

[0068] Alternatively, in some other possible embodiments, the solid electrolyte material may be selected from at least one of a sulfide-based solid electrolyte, LiPON, and Li3N. Alternatively, the solid electrolyte material may be selected from at least one of an organic polymer solid electrolyte, such as a PEO-based solid electrolyte, a PAN-based solid electrolyte, a PMMA-based solid electrolyte, a PVDF-based solid electrolyte, a PEO-PAN-based solid electrolyte, a PEO-PMMA-based solid electrolyte, a PEO-PVDF-based solid electrolyte, a PMMA-PVDF-based solid electrolyte, a PMMA-PAN-based solid electrolyte, a PAN-PVDF-based solid electrolyte, a PEO-PAN-PMMA-based solid electrolyte, a PEO-PVDF-PMMA-based solid electrolyte, a PEO-PAN-PVDF-based solid electrolyte, and a PAN-PMMA-PVDF-based solid electrolyte.

[0069] Furthermore, the present application does not limit the specific type of the first adhesive. In one possible embodiment, the first adhesive is selected from two-component polyurethane glue.

[0070] The two-component polyurethane glue has high bonding strength, which can improve the peeling strength between the base film 11 and the resin layer 13 and improve the stability of the electrolyte composite membrane 1.

[0071] Alternatively, in other possible embodiments, the first adhesive can be selected from one or more of styrene-butadiene rubber, water-soluble unsaturated resin SR-1B, sodium alginate, polyurethane, polyacrylic acid, polyethyl acrylate, polymethacrylic acid, sodium polyacrylate, sodium polycarboxymethyl cellulose, acrylamide, polyvinyl alcohol and carboxymethyl chitosan.

[0072] Furthermore, the first slurry may also include a dispersant to improve the distribution uniformity of the solid electrolyte coating.

[0073] This application does not limit the specific type of dispersant, and relevant personnel can make corresponding choices as needed.

[0074] In some possible embodiments, the dispersant may be selected from one or more of deionized water, methanol, ethanol, or propanol.

[0075] Furthermore, the first slurry may further include a thickener to adjust the viscosity of the first slurry and improve coating uniformity.

[0076] This application does not limit the specific type of thickener, and relevant personnel can make corresponding selections as needed.

[0077] In some possible embodiments, the thickener may be selected from at least one of carboxymethyl cellulose and polyether-modified silicone polymers.

[0078] Furthermore, the first slurry may further include a leveling agent. The present application does not limit the specific type of the leveling agent. In some possible embodiments, the leveling agent may be selected from one or more of polysiloxane leveling agents, polyester leveling agents, polyurethane leveling agents, and polyacrylate leveling agents.

[0079] Furthermore, the present application does not limit the content of the first adhesive in the first slurry, and relevant personnel can adjust the content of the first adhesive as needed. For example, the peel strength between the base film 11 and the solid electrolyte layer 12 can be adjusted by adjusting the content of the first adhesive.

[0080] Furthermore, this application does not limit the specific coating method, and relevant personnel can make corresponding choices as needed.

[0081] In a possible embodiment, the first slurry may be applied to the surface of the base film 11 by roller coating. The roller coating method can improve the stability of the coating structure of the solid electrolyte layer 12.

[0082] Alternatively, in some other possible embodiments, the first slurry may be applied to the surface of the base film 11 by spraying, blade coating, or slit coating.

[0083] Furthermore, the present application does not limit the thickness of the solid electrolyte layer 12 after coating, and relevant personnel can make corresponding selections as needed.

[0084] In some possible embodiments, the thickness of the solid electrolyte layer 12 may be 1-5 μm.

[0085] For example, the thickness of the solid electrolyte layer 12 may be in the range of one or any two of 1 μm, 2 μm, 3 μm, 4 μm and 5 μm.

[0086] In a possible embodiment, referring to FIG. 4 , a ceramic slurry may be coated on one side of the base film 11 to form a ceramic layer 14 , and then a first slurry may be coated on the ceramic layer 14 to form a solid electrolyte layer 12 .

[0087] The material forming the ceramic layer 14 may be selected from at least one of aluminum oxide, magnesium oxide, magnesium hydroxide, boehmite, and calcium carbonate.

[0088] Exemplarily, the material forming the ceramic layer 14 is selected from alumina.

[0089] In order not to affect the peeling strength between the base film 11 and the solid electrolyte layer 12 , in a possible embodiment, the adhesive in the ceramic slurry may have the same content or type as the first adhesive.

[0090] Furthermore, referring to FIG. 5 , ceramic slurry may be coated on both sides of the base film 11 to form ceramic layers 14 on both sides of the base film 11 .

[0091] Further, please continue to refer to FIG2 , the preparation method of the electrolyte composite membrane 1 provided in the example of this application also includes:

[0092] S2, preparation steps of resin layer 13:

[0093] A second slurry containing a thermo-adhesive resin material and a second adhesive is obtained, and the second slurry is applied to at least the other side of the solid electrolyte layer 12 to prepare the resin layer 13 .

[0094] The specific type of the non-thermal adhesive resin material of this application can be selected by relevant personnel according to their needs.

[0095] In some possible embodiments, the material of the resin layer includes at least one of acrylic resin and polyvinylidene fluoride.

[0096] Furthermore, a low molecular weight copolymer type polyvinylidene fluoride can be selected to maintain a higher hot adhesive strength while reducing the amount added.

[0097] Furthermore, the present application does not limit the specific type of the second adhesive. In one possible embodiment, the second adhesive is selected from acrylic adhesives.

[0098] Furthermore, the second slurry may further include a dispersant to improve the distribution uniformity of the hot-adhesive resin coating.

[0099] The present application does not limit the specific type of the dispersant. In some possible embodiments, the dispersant may be selected from one or more of deionized water, methanol, ethanol, or propanol.

[0100] Furthermore, the second slurry may further include a thickener to adjust the viscosity of the second slurry and improve coating uniformity.

[0101] The present application does not limit the specific type of the thickener. In some possible embodiments, the thickener may be selected from at least one of carboxymethyl cellulose and polyether-modified silicone polymer.

[0102] Furthermore, the present application does not limit the content of the second adhesive in the second slurry, and relevant personnel can adjust the content of the second adhesive as needed.

[0103] For example, the peel strength between the base film 11 and the solid electrolyte layer 12 can be adjusted by adjusting the content of the second adhesive. Alternatively, a second adhesive with lower bonding strength can be used to reduce the peel strength between the base film 11 and the solid electrolyte layer 12.

[0104] This application does not limit whether the types of the first adhesive and the second adhesive are the same, and relevant personnel can make corresponding adjustments as needed.

[0105] In one possible embodiment, the first adhesive and the second adhesive are selected from the same adhesive. To improve the peel strength between the base film 11 and the solid electrolyte layer 12, the adhesive content in the first slurry can be increased. To reduce the peel strength between the solid electrolyte layer 12 and the resin layer 13, the adhesive content in the second slurry can be reduced.

[0106] Alternatively, in another possible embodiment, the first adhesive and the second adhesive may be adhesives having different adhesive strengths. To improve the peel strength between the base film 11 and the solid electrolyte layer 12, an adhesive with higher adhesive strength may be used as the first adhesive. To reduce the peel strength between the solid electrolyte layer 12 and the resin layer 13, an adhesive with lower adhesive strength may be used as the second adhesive.

[0107] Furthermore, the present application does not limit the specific coating method of the resin layer 13, and relevant personnel can make corresponding choices according to needs.

[0108] In a possible embodiment, the second slurry may be applied to the surface of the corresponding film layer by spraying, thereby forming a loose resin layer 13 .

[0109] Alternatively, in some other possible embodiments, the second slurry may be applied to the surface of the corresponding film layer by roller coating, blade coating, or slit coating.

[0110] For example, the second slurry may be applied to the surface of the solid electrolyte layer 12 by spraying.

[0111] For example, the second slurry may be applied to the surface of the base film 11 by spraying.

[0112] For example, the second slurry may be applied to the surface of the ceramic layer 14 by spraying.

[0113] In one possible embodiment, please continue to refer to Figure 3, the first slurry can be coated on both sides of the base film 11 to form two solid electrolyte layers 12, and then the second slurry is coated on the surface of each solid electrolyte layer 12 to form two resin layers 13.

[0114] In one possible embodiment, referring to FIG. 4 , a ceramic slurry may be applied to one side of base film 11 to form ceramic layer 14. A first slurry may then be applied to the surface of ceramic layer 14 to form solid electrolyte layer 12. A second slurry may then be sprayed onto the surface of solid electrolyte layer 12 to form resin layer 13. Furthermore, a second slurry may be applied to the other side of base film 11 to form resin layer 13.

[0115] In a possible embodiment, a ceramic slurry may be coated on one side of the base film 11 to form a ceramic layer 14 , and then a second slurry may be coated on the ceramic layer 14 to form the resin layer 13 .

[0116] For example, referring to FIG5 , a ceramic slurry can be applied to both sides of the base film 11 to form ceramic layers 14 on both sides of the base film 11. A first slurry is then applied to the surface of the ceramic layer 14 on one side to form a solid electrolyte layer 12. A second slurry is then sprayed onto the surface of the solid electrolyte layer 12 to form a resin layer 13. A second slurry is then applied to the surface of the ceramic layer 14 on the other side to form a resin layer 13.

[0117] For example, referring to FIG6 , a ceramic slurry can be applied to both sides of the base film 11 to form ceramic layers 14 on both sides of the base film 11. A first slurry is then applied to the surfaces of the ceramic layers 14 on both sides to form solid electrolyte layers 12. A second slurry is then sprayed onto the surface of each solid electrolyte layer 12 to form a resin layer 13.

[0118] In one possible embodiment, referring to FIG. 7 , a first slurry may be applied to one side of the base film 11 to form a solid electrolyte layer 12 , and then a second slurry may be applied to the other side of the base film 11 and the side of the solid electrolyte layer 12 away from the base film 11 to form a resin layer 13 .

[0119] Furthermore, the present application does not limit the thickness of the resin layer 13, and relevant personnel can make corresponding choices as needed.

[0120] In some possible embodiments, the thickness of the resin layer 13 may be 0.5-3 μm.

[0121] For example, the thickness of the solid electrolyte layer 12 may be in a range between one or any two of 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm and 3 μm.

[0122] Furthermore, the present application does not limit the thickness of the ceramic layer 14 , and relevant personnel can make corresponding choices as needed.

[0123] In some possible embodiments, the thickness of the ceramic layer 14 may be in a range between one or any two of 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm and 5 μm.

[0124] The example of the present application also provides a lithium battery 100, comprising an electrolyte composite membrane 1, and an electrode sheet attached to the electrolyte composite membrane 1; wherein part of the hot-adhesive resin in the electrolyte composite membrane 1 is melted into the interior of the electrode sheet.

[0125] This application does not limit the specific type of the lithium battery 100, and relevant personnel can make corresponding adjustments as needed.

[0126] In one possible embodiment, referring to FIG8 , a lithium battery 100 includes a positive electrode 2, a negative electrode 3, and an electrolyte composite separator 1 disposed between the positive electrode 2 and the negative electrode 3. Part of the thermo-adhesive resin in the resin layer 13 in the electrolyte composite separator 1 is melted into the interior of the electrode.

[0127] The electrolyte composite membrane 1 of the present application is further described in detail below with reference to the examples.

[0128] Example 1

[0129] Example 1 provides an electrolyte composite membrane 1. The structure of the electrolyte composite membrane 1 is shown in FIG1 , and includes a base membrane 11, a solid electrolyte layer 12, and a resin layer 13 stacked in sequence. The preparation method thereof is as follows:

[0130] (1) Raw material preparation

[0131] Lithium aluminum titanium phosphate, water, two-component polyurethane glue, thickener (CMC1500), dispersant (sodium acrylate) and leveling agent (polyether siloxane) were mixed in a mass ratio of 40:50:5:1:0.02:0.003 to prepare a first slurry.

[0132] A second slurry was prepared by mixing water, low molecular weight copolymer PVDF, acrylic adhesive, thickener (CMC1500) and dispersant (sodium acrylate) in a mass ratio of 80:5:1:1:0.02.

[0133] The base film 11 is selected from ND9 produced by Shanghai Enjie, which is a wet-process base film of about 9 μm.

[0134] (2) Coating

[0135] The first slurry is coated on one side of the base film 11 by roller coating to a coating thickness of about 3 μm, and then dried to obtain the solid electrolyte layer 12 .

[0136] The second slurry is applied on the solid electrolyte layer 12 by spraying, with a coating thickness of about 2 μm, and dried to obtain the resin layer 13 .

[0137] Example 2

[0138] Example 2 provides an electrolyte composite membrane 1. The structure of the electrolyte composite membrane 1 is shown in FIG3 , and includes a resin layer 13 , a solid electrolyte layer 12 , a base membrane 11 , a solid electrolyte layer 12 and a resin layer 13 stacked in sequence.

[0139] The difference between its preparation method and Example 1 is that in step (2), the first slurry is applied to both sides of the base film 11 by roller coating, the coating thickness on both sides is about 3 μm, and then dried to obtain the solid electrolyte layer 12 located on both sides of the base film 11.

[0140] Then, the second slurry is coated on each solid electrolyte layer 12 by spraying, with each coating layer having a thickness of about 2 μm, and dried to obtain the resin layer 13 .

[0141] Example 3

[0142] Example 3 provides an electrolyte composite membrane 1. The structure of the electrolyte composite membrane 1 is shown in FIG4 , and includes a resin layer 13, a base membrane 11, a ceramic layer 14, a solid electrolyte layer 12, and a resin layer 13 stacked in sequence. The base membrane 11 is a wet-coated membrane having a thickness of approximately 5 to 22 μm.

[0143] The difference between its preparation method and Example 1 is:

[0144] Step (1) also includes preparing a third slurry: aluminum oxide, water, two-component polyurethane glue, thickener (CMC1500), dispersant (sodium acrylate) and leveling agent (polyether siloxane) are mixed in a mass ratio of 40:45:5:1:0.02:0.003 to prepare the third slurry.

[0145] In step (2), the third slurry is applied to one side of the base film 11 by roller coating, with a coating thickness of about 3 μm, and dried to obtain a ceramic layer 14 located on one side of the base film 11.

[0146] Subsequently, the first slurry is coated on the ceramic layer 14 by roller coating to a coating thickness of about 3 μm, and dried to obtain the solid electrolyte layer 12 on the ceramic layer 14 .

[0147] Finally, the second slurry is sprayed on the solid electrolyte layer 12 and the other side of the base film 11, with a coating thickness of about 2 μm. After drying, the resin layer 13 located on the solid electrolyte layer 12 and the base film 11 is obtained.

[0148] Example 4

[0149] Example 4 provides an electrolyte composite membrane 1, which differs from Example 1 in that: in step (1), the content of the second adhesive in the second slurry is higher, and the second slurry is prepared by mixing water, low molecular weight copolymer PVDF, acrylic adhesive, thickener (CMC1500) and dispersant (sodium acrylate) according to a mass ratio of 80:5:3:1:0.02.

[0150] Example 5

[0151] Example 5 provides an electrolyte composite membrane 1, which differs from Example 1 in that:

[0152] In step (2), the second slurry is applied to the solid electrolyte layer 12 by spraying, with a coating thickness of about 5 μm, and dried to obtain the resin layer 13 .

[0153] Comparative Example 1

[0154] Comparative Example 1 provides an electrolyte composite membrane 1, which differs from Example 3 in that:

[0155] In step (1), water, low molecular weight copolymer PVDF, two-component polyurethane glue, thickener (CMC1500) and dispersant (sodium acrylate) are mixed in a mass ratio of 80:5:1:1:0.02 to prepare a second slurry.

[0156] Test Case

[0157] Each film layer prepared in Examples 1-3 and Comparative Example 1 was tested for film thickness, air permeability, peel strength, internal resistance, and ionic conductivity. The test results are shown in Table 1. In Example 3 and the Comparative Example, the peel strength between the base film and the aluminum oxide was the first peel strength, the peel strength between the aluminum oxide and the solid electrolyte layer was the second peel strength, and the peel strength between the base film and the solid electrolyte layer was the minimum of the first and second peel strengths. In Example 3, the first peel strength between the base film and the aluminum oxide was 200 N / m, the second peel strength between the aluminum oxide and the solid electrolyte layer was 200 N / m, and the peel strength between the base film and the solid electrolyte layer was 200 N / m.

[0158] Table 1

[0159] Analysis of results: It can be seen from Example 3 and Comparative Example 1 that by adjusting the type of adhesive so that the adhesion of the first adhesive is higher than that of the second adhesive, the peel strength between the resin layer 13 and the solid electrolyte layer 12 can be made smaller than the peel strength between the solid electrolyte layer 12 and the base membrane 11, so that the electrolyte composite membrane 1 has lower permeability, lower membrane internal resistance and higher ionic conductivity.

[0160] Combining Examples 1 and 2, it can be seen that the ionic conductivity of the diaphragm changes significantly before and after the preparation of the resin layer 13, indicating that the preparation method provided in the example of this application can further improve the ionic conductivity by preparing the resin layer 13 on the surface of the solid electrolyte layer 12.

[0161] From Examples 1 and 4, it can be seen that, relative to the content of the first adhesive, the content of the second adhesive can be reduced so that the peel strength between the resin layer 13 and the solid electrolyte layer 12 is less than the peel strength between the solid electrolyte layer 12 and the base membrane 11, thereby making the electrolyte composite membrane 1 have lower permeability, lower membrane internal resistance and higher ionic conductivity.

[0162] It can be seen from the combination of Example 1 and Example 5 that, by using the preparation method provided in the examples of this application, a resin layer 13 with a thickness of 0.5-3 μm is prepared on the surface of the solid electrolyte layer 12 , which can further reduce the internal resistance.

[0163] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. An electrolyte composite membrane, wherein: It includes a base film, a solid electrolyte layer arranged on at least one side of the base film, and a resin layer arranged on at least one side of the solid electrolyte layer away from the base film; wherein the peeling strength between the solid electrolyte layer and the base film is greater than the peeling strength between the solid electrolyte layer and the resin layer.

2. The electrolyte composite membrane according to claim 1, wherein: The peel strength between the solid electrolyte layer and the base film is 80-220 N / m.

3. The electrolyte composite membrane according to claim 1 or 2, wherein: The peel strength between the solid electrolyte layer and the resin layer is 20-50 N / m.

4. The electrolyte composite membrane according to claim 1, wherein: The thickness of the solid electrolyte layer is 1-5 μm.

5. The electrolyte composite membrane according to claim 1, wherein: The thickness of the resin layer is 0.5-3 μm.

6. The electrolyte composite membrane according to claim 1, wherein: The electrolyte composite separator includes the resin layer, the base film, the solid electrolyte layer and the resin layer which are stacked in sequence.

7. The electrolyte composite membrane according to claim 1, wherein: The solid electrolyte layer is disposed on one side of the base film, and the resin layer is disposed on the other side of the base film.

8. The electrolyte composite membrane according to claim 7, wherein: A ceramic layer is provided between the base film and the resin layer; Alternatively, a ceramic layer is provided between the base film and the solid electrolyte layer, the base film and the ceramic layer have a first peel strength, the ceramic layer and the resin layer have a second peel strength, and the peel strength between the solid electrolyte layer and the base film is the minimum value of the first peel strength and the second peel strength; Alternatively, a ceramic layer is provided between the base film and the solid electrolyte layer, the material forming the ceramic layer is selected from at least one of aluminum oxide, magnesium oxide, magnesium hydroxide, boehmite or calcium carbonate, and there is a first peel strength between the base film and the ceramic layer, there is a second peel strength between the ceramic layer and the resin layer, and the peel strength between the solid electrolyte layer and the base film is the minimum of the first peel strength and the second peel strength.

9. The electrolyte composite membrane according to claim 1, wherein: The material forming the solid electrolyte layer includes an oxide solid electrolyte; Alternatively, the material forming the solid electrolyte layer includes an oxide solid electrolyte, and the oxide solid electrolyte is selected from at least one of lithium aluminum titanium phosphate, lithium lanthanum zirconium oxide, and lithium lanthanum titanium oxide.

10. The electrolyte composite membrane according to claim 1, wherein: The material forming the resin layer includes at least one of acrylic resin and polyvinylidene fluoride.

11. A method for preparing an electrolyte composite membrane, wherein: The electrolyte composite diaphragm comprises a base film, a solid electrolyte layer disposed on at least one side of the base film, and a resin layer disposed on at least one side of the solid electrolyte layer away from the base film; The preparation method comprises: The solid electrolyte layer is prepared by obtaining a first slurry containing a solid electrolyte material and a first adhesive, and applying the first slurry to at least one side of the base film to prepare the solid electrolyte layer; The preparation step of the resin layer is as follows: obtaining a second slurry containing a hot viscous resin material and a second adhesive, and mixing the second slurry at least coating on the other side of the solid electrolyte layer to obtain the resin layer; The bonding strengths of the first adhesive and the second adhesive are the same, the mass content of the first adhesive in the first slurry is higher than the mass content of the second adhesive in the second slurry; and / or the bonding strength of the first adhesive is higher than the bonding strength of the second adhesive.

12. The preparation method according to claim 11, wherein The first adhesive is selected from two-component polyurethane glue.

13. The preparation method according to claim 11, wherein The second adhesive is selected from acrylic adhesives.

14. The preparation method according to claim 11, wherein: In the step of preparing the resin layer, the second slurry is coated on the other side of the solid electrolyte layer by roller coating or spraying.

15. A lithium battery, wherein: It comprises the electrolyte composite diaphragm according to any one of claims 1 to 10 and an electrode sheet attached to the electrolyte composite diaphragm; wherein part of the hot adhesive resin in the electrolyte composite diaphragm is integrated into the interior of the electrode sheet.

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