EP-4738593-A1 - ELECTROLYTE COMPOSITE SEPARATOR, PREPARATION METHOD, AND LITHIUM BATTERY

EP4738593A1EP 4738593 A1EP4738593 A1EP 4738593A1EP-4738593-A1

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 invention, 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.

Inventors

ZHUANG, Zhi
QI, Jiapeng
SU, XIAOMING
BAO, Jinzhen
JIA, Yuanchao
CAI, YUHONG
CHENG, YUE

Assignees

Shanghai Energy New Materials Technology Co., Ltd.

Dates

Publication Date: 20260506
Application Date: 20240809

Claims (15)

An electrolyte composite separator, characterized by comprising a base film, a solid electrolyte layer arranged on at least one side of the base film, and a resin layer at least arranged on one side of the solid electrolyte layer away from the base film, wherein a peel strength between the solid electrolyte layer and the base film is greater than that between the solid electrolyte layer and the resin layer.
The electrolyte composite separator according to claim 1, wherein the peel strength between the solid electrolyte layer and the base film is 80-220 N/m.
The electrolyte composite separator according to claim 1 or 2, wherein the peel strength between the solid electrolyte layer and the resin layer is 20-50 N/m.
The electrolyte composite separator according to claim 1, wherein a thickness of the solid electrolyte layer is 1-5 µm.
The electrolyte composite separator according to claim 1, wherein a thickness of the resin layer is 0.5-3 µm.
The electrolyte composite separator according to claim 1, wherein the electrolyte composite separator comprises the resin layer, the base film, the solid electrolyte layer and the resin layer that are sequentially stacked.
The electrolyte composite separator according to claim 1, wherein one side of the base film is provided with the solid electrolyte layer, and the other side of the base film is provided with the resin layer.
The electrolyte composite separator according to claim 7, wherein a ceramic layer is arranged between the base film and the resin layer; a ceramic layer is arranged between the base film and the solid electrolyte layer, a first peel strength is present between the base film and the ceramic layer, a second peel strength is present between the ceramic layer and the solid electrolyte layer, and the peel strength between the solid electrolyte layer and the base film is a minimum value of the first peel strength and the second peel strength; or a ceramic layer is arranged between the base film and the solid electrolyte layer, a material forming the ceramic layer is selected from at least one of aluminum oxide, magnesium oxide, magnesium hydroxide, boehmite, and calcium carbonate, a first peel strength is present between the base film and the ceramic layer, a second peel strength is present between the ceramic layer and the solid electrolyte layer, and the peel strength between the solid electrolyte layer and the base film is a minimum value of the first peel strength and the second peel strength.
The electrolyte composite separator according to claim 1, wherein a material forming the solid electrolyte layer comprises an oxide solid electrolyte; or a material forming the solid electrolyte layer comprises 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.
The electrolyte composite separator according to claim 1, wherein a material forming the resin layer comprises at least one of an acrylic resin and polyvinylidene fluoride.
A preparation method for an electrolyte composite separator, characterized in that the electrolyte composite separator comprises a base film, a solid electrolyte layer arranged on at least one side of the base film, and a resin layer at least arranged on one side of the solid electrolyte layer away from the base film; and the preparation method comprises: a step for preparing the solid electrolyte layer: obtaining a first slurry containing a solid electrolyte material and a first adhesive, and coating the first slurry on at least one side of the base film to obtain the solid electrolyte layer; and a step for preparing the resin layer: obtaining a second slurry containing a thermal adhesive resin material and a second adhesive, and coating the second slurry on at least the other side of the solid electrolyte layer to obtain the resin layer, wherein the bonding strengths of the first adhesive and the second adhesive are the same, and the mass content of the first adhesive in the first slurry is higher than that of the second adhesive in the second slurry; and/or the bonding strength of the first adhesive is higher than that of the second adhesive.
The preparation method according to claim 11, wherein the first adhesive is selected from two-component polyurethane glue.
The preparation method according to claim 11, wherein the second adhesive is selected from an acrylic adhesive.
The preparation method according to claim 11, wherein in the step for preparing the resin layer, the second slurry is coated on the other side of the solid electrolyte layer in a roll coating or spray coating manner.
A lithium-ion battery, comprising the electrolyte composite separator according to any one of claims 1-10 and an electrode plate attached to the electrolyte composite separator, wherein a part of the thermal adhesive resin in the electrolyte composite separator is fused into the electrode plate.

Description

CROSS-REFERENCE This application claims priority to Chinese Patent Application No. 202311006763.2, titled "ELECTROLYTE COMPOSITE SEPARATOR AND PREPARATION METHOD THEREFOR, AND LITHIUM-ION BATTERY" and filed on August 11, 2023, all the contents of which are hereby incorporated by reference. TECHNICAL FIELD The present invention relates to the technical field of lithium-ion batteries, and in particular to an electrolyte composite separator and a preparation method therefor, and a lithium-ion battery. BACKGROUND With the increasing demand for lithium-ion batteries, consumers have made higher requirements on the performance of the lithium-ion batteries. A solid or semi-solid lithium-ion battery is expected to greatly solve the safety problem of the lithium-ion battery. In the solid or semi-solid lithium-ion battery, the problem that a solid electrolyte is difficult to fully contact with an electrode easily is likely to occur, and a solid-liquid interface between an electrode material and an electrolytic solution is partially converted to a solid-solid interface between the electrode material and the solid electrolyte, and mutual diffusion and even reaction among components may form a vacancy charge layer and the like, such that the internal resistance of the lithium-ion battery is increased, and the cycle performance of the lithium-ion battery is deteriorated. Currently, in order to solve the problem of interfacial bonding between a solid electrolyte layer and the electrode, a thermal adhesive layer may be introduced on the surface of the solid electrolyte layer. However, the introduction of the thermal adhesive layer increases the internal resistance of the lithium-ion battery. SUMMARY In view of the above-mentioned shortcomings, the present invention provides an electrolyte composite separator and a preparation method therefor, and a lithium-ion battery so as to partially or wholly solve the problem of excessive internal resistance of a lithium-ion battery including a thermal adhesive layer in the related art. The present invention is implemented as follows: in a first aspect, an example of the present invention provides an electrolyte composite separator, including a base film, a solid electrolyte layer arranged on at least one side of the base film, and a resin layer at least arranged on one side of the solid electrolyte layer away from the base film. A peel strength between the solid electrolyte layer and the base film is greater than that between the solid electrolyte layer and the resin layer. In the implementation process, the solid electrolyte layer is arranged on the base film, and the resin layer is arranged on the solid electrolyte layer, such that ionic conductivity of the electrolyte composite separator can be improved. Besides, the resin layer is arranged on the surface of the solid electrolyte layer, such that the contact between the solid electrolyte layer and an electrode is fuller and closer in the process of hot pressing. Since the peel strength between the resin layer and the solid electrolyte layer is lower, when the lithium-ion battery is prepared, the resin layer may be partially fused into an electrode material after the hot pressing, such that the electrolyte layer is in full contact with the electrode material, the resin content between contact interfaces of the electrolyte layer and the electrode material is reduced, and internal resistance of the lithium-ion battery is reduced. With reference to the first aspect, in an alternative embodiment of the present invention, the peel strength between the solid electrolyte layer and the base film is 80-220 N/m. In the implementation process, the peel strength between the solid electrolyte layer and the base film is 80-220 N/m, such that the stability of the electrolyte composite separator can be improved, and the falling probability of the solid electrolyte layer can be reduced. With reference to the first aspect, in an alternative embodiment of the present invention, the peel strength between the solid electrolyte layer and the resin layer is 20-50 N/m. In the implementation process, the peel strength between the solid electrolyte layer and the resin layer is 20-50 N/m, such that the internal resistance of the electrolyte composite separator can be reduced while the adhesion between the electrolyte composite separator and an electrode plate is ensured. With reference to the first aspect, in an alternative embodiment of the present invention, a thickness of the solid electrolyte layer is 1-5 µm. In the implementation process, the thickness of the solid electrolyte layer is 1-5 µm, such that the ionic conductivity of the electrolyte composite separator can be further improved. With reference to the first aspect, in an alternative embodiment of the present invention, a thickness of the resin layer is 0.5-3 µm. In the implementation process, the thickness of the resin layer is 0.5-3 µm, such that a transmission distance between the solid electr