阅读说明：本技术 锂电池复合隔膜及其制备方法 (Lithium battery composite diaphragm and preparation method thereof ) 是由 韩笑 陈明功 于 2019-08-19 设计创作，主要内容包括：本发明公开了锂电池复合隔膜,包括基膜所述基膜两侧涂覆有网状陶瓷涂层和涂胶层,所述涂胶层位于所述网状陶瓷涂层的两端；其制备的方法步骤如下：S1：在基膜两侧均匀涂覆一层陶瓷层,并通过控制涂覆点使其在基膜表面形成网状结构；S2：将S1中涂覆后的基膜的陶瓷层的两端均匀涂覆涂胶层。本发明的隔膜中间网状陶瓷涂层可以提供更多的锂离子通道,同时可以存储更多的电解液,从而降低电池内阻,提升电池循环寿命；隔膜两侧PVDF涂胶层在与正负极片粘接时,可以减少电池在除气过程中电解液的损失量,从而提升电池循环性能；采用本发明的复合隔膜的电池相对于采用普通隔膜的电池,在电池安全性和电池倍率性能上得到较大的提升。(The invention discloses a lithium battery composite diaphragm which comprises a base film, wherein two sides of the base film are coated with a reticular ceramic coating and rubber coating layers, and the rubber coating layers are positioned at two ends of the reticular ceramic coating; the preparation method comprises the following steps: s1: uniformly coating a ceramic layer on two sides of the base film, and forming a net structure on the surface of the base film by controlling coating points; s2: and uniformly coating glue coats on the two ends of the ceramic layer of the base film coated in the step S1. The reticular ceramic coating in the middle of the diaphragm can provide more lithium ion channels and can store more electrolyte, so that the internal resistance of the battery is reduced, and the cycle life of the battery is prolonged; when the PVDF glue-coated layers on the two sides of the diaphragm are bonded with the positive and negative pole pieces, the loss of electrolyte in the degassing process of the battery can be reduced, so that the cycle performance of the battery is improved; compared with the battery adopting the common diaphragm, the battery adopting the composite diaphragm of the invention has the advantages that the battery safety and the battery multiplying power performance are greatly improved.)

1. The lithium battery composite diaphragm is characterized by comprising a base film, wherein two sides of the base film are coated with a reticular ceramic coating and a rubber coating, and the rubber coating is positioned at two ends of the reticular ceramic coating.

2. The lithium battery composite separator according to claim 1, wherein the width of the mesh-shaped ceramic layer accounts for 80-90% of the width of the base film, and the glue coating layers at both ends of the mesh-shaped ceramic layer are symmetrically distributed.

3. The lithium battery composite separator according to claim 1, wherein the base film is one or more of polyethylene, polypropylene or non-woven fabric, and the thickness of the base film is 6-25 μm.

4. The lithium battery composite separator according to claim 1, wherein the reticulated ceramic coating is one or more of alumina, boron carbide, silica, silicon nitride, and boron nitride, and the reticulated ceramic coating has a thickness of 0.5-4 μm.

5. The lithium battery composite separator according to claim 1, wherein the glue coating layer is a PVDF coating layer, and the thickness of the PVDF layer is 0.5-2 μm.

6. A method for preparing a lithium battery composite separator as claimed in any one of claims 1 to 5, wherein: the method comprises the following steps:

s1: uniformly coating a ceramic layer on two sides of the base film, and forming a net structure on the surface of the base film by controlling coating points;

s2: and uniformly coating glue coats on the two ends of the ceramic layer of the base film coated in the step S1.

7. The method for preparing a composite separator for a lithium battery as claimed in claim 6, wherein the ceramic layer in S1 is applied by dot coating, and the coating dots are dots with a diameter of 0.1-2 μm.

8. The method for preparing the lithium battery composite separator according to claim 6, wherein the glue coating in the step S2 is performed by a spray coating method.

Technical Field

The invention relates to the technical field of lithium batteries, in particular to a lithium battery composite diaphragm and a preparation method thereof.

Background

The conventional commonly used lithium ion battery diaphragm structure is mainly a Polyethylene (PE), polypropylene (PP) single-layer microporous membrane or a polypropylene/polyethylene/polypropylene (PP/PE/PP) three-layer diaphragm, the polyethylene or polypropylene diaphragm material has poor air permeability and lyophilic property, and the material has poor thermal stability, and when the temperature reaches a certain value, the diaphragm is fused, so that the positive electrode and the negative electrode are in direct contact, the internal short circuit of the battery is generated, and finally the battery fails.

Disclosure of Invention

Based on the technical problems in the background art, the invention provides the lithium battery composite diaphragm and the preparation method thereof, and the liquid absorption capacity, the high temperature resistance and the puncture resistance of the composite diaphragm are improved.

The invention provides a lithium battery composite diaphragm which comprises a base film, wherein two sides of the base film are coated with a reticular ceramic coating and rubber coating layers, and the rubber coating layers are positioned at two ends of the reticular ceramic coating.

Preferably, the width of the reticular ceramic layer accounts for 80-90% of the width of the base film, and the glue coating layers at the two ends of the reticular ceramic layer are symmetrically distributed.

Preferably, the base film is one or more of polyethylene, polypropylene or non-woven fabrics, and the thickness of the base film is 6-25 μm.

Preferably, the reticular ceramic coating is one or more of alumina, boron carbide, silicon dioxide, silicon nitride and boron nitride, and the thickness of the reticular ceramic coating is 0.5-4 μm.

Preferably, the rubber coating layer is a PVDF coating layer, and the thickness of the PVDF layer is 0.5-2 μm.

The preparation method of the lithium battery composite diaphragm provided by the invention comprises the following steps:

s1: uniformly coating a ceramic layer on two sides of the base film, and forming a net structure on the surface of the base film by controlling coating points;

s2: and uniformly coating glue coats on the two ends of the ceramic layer of the base film coated in the step S1.

Preferably, the ceramic layer in S1 is applied by a dot coating method, and the coating dots are dots with a diameter of 0.1-2 μm.

Preferably, the glue coating in S2 is performed by a spray coating method.

Compared with the prior art, the invention has the beneficial technical effects that:

(1) the reticular ceramic coating in the middle of the diaphragm can provide more lithium ion channels and can store more electrolyte, so that the internal resistance of the battery is reduced, and the cycle life of the battery is prolonged;

(2) when the PVDF glue-coated layers on the two sides of the diaphragm are bonded with the positive and negative pole pieces, the loss of electrolyte in the degassing process of the battery can be reduced, so that the cycle performance of the battery is improved;

(3) compared with the battery adopting the common diaphragm, the battery adopting the composite diaphragm of the invention has the advantages that the battery safety and the battery multiplying power performance are greatly improved.

Drawings

Fig. 1 is a schematic structural diagram of a lithium battery composite separator according to the present invention;

fig. 2 is a result of a needle test of a battery proposed by the present invention using the separator prepared in example 1;

fig. 3 is a result of a needle-punching test of a battery proposed by the present invention using the separator prepared in comparative example 2.

In the figure: 1-basal membrane, 2-reticular ceramic coating and 3-gluing layer.

Detailed Description

The present invention will be further illustrated with reference to the following specific examples.