Composite Separator Coating for Electrode Stability and Cell Strength
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Solution Overview
Problem
Conventional lithium-ion battery separators suffer from poor cooperation stability between the separator and the electrode sheets, leading to mechanical weakness, electrode sheet deformation, and reduced cycle performance due to loose cell structures and electrode sheet wrinkles.
Innovation Solution
A composite separator with a porous base film coated by a base layer containing inorganic particles and non-adhesive polymers, where the non-adhesive polymers have a larger particle size than the base layer thickness, providing physical adhesion with the electrode sheet and chemical adhesion with the base film, enhancing mechanical strength and electrolyte infiltration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional separator with adhesive polymer and inorganic particles coated on polyolefin base film is used, then the separator structure is simple and manufacturing is easy, but the adhesion between the porous active layer and electrode sheet is poor, leading to reduced cooperation stability and mechanical strength
Solution Approach 1:
The patent uses a composite coating layer comprising inorganic particles, adhesive polymer, and non-adhesive polymer with specific particle size ratio (5:1 to 20:1). This composite structure combines the adhesion benefits of adhesive polymer with the mechanical interlocking benefits of large non-adhesive particles, achieving both ease of manufacture and improved cooperation stability between separator and electrode sheet
Solution Approach 2:
The patent creates local quality differentiation within the coating layer by using particles of significantly different sizes (inorganic particles 1-10 μm versus non-adhesive polymer particles 0.05-2 μm at 5:1 to 20:1 ratio). The larger inorganic particles provide anchor points for adhesion while the smaller non-adhesive particles fill gaps and enhance surface contact with the electrode sheet, achieving localized optimization of adhesion properties
2Quantity of substance
If the electrode sheet area and cell size are increased, then the battery capacity is improved, but the cooperation stability between separator and electrode sheet deteriorates, leading to increased looseness degree and reduced mechanical strength
Solution Approach 1:
The patent changes the particle size distribution parameter of the coating layer, specifically using non-adhesive polymer particles with maximum diameter 5:1 to 20:1 smaller than inorganic particles. This parameter change creates a hierarchical structure that maintains effective adhesion pressure distribution even when cell size and electrode area are scaled up, preventing increased looseness degree and maintaining mechanical strength
3Reliability
If the non-adhesive polymer particle size is increased to improve physical adhesion with electrode sheet, then the adhesion stability is improved, but the uniformity of particle distribution in the coating layer may be affected
Solution Approach 1:
The patent applies local quality by creating a hierarchical particle structure where large inorganic particles (1-10 μm) serve as anchor points distributed throughout the coating layer, while small non-adhesive polymer particles (0.05-2 μm) fill the interstices and provide uniform surface contact. This local differentiation of particle functions achieves both adhesion stability and distribution uniformity
Solution Approach 2:
The patent combines materials with vastly different particle sizes (inorganic particles 1-10 μm and non-adhesive polymer particles 0.05-2 μm at 5:1 to 20:1 ratio) into a composite coating layer. The size disparity creates a self-organizing structure where larger particles provide structural framework and smaller particles ensure uniform distribution, achieving both adhesion stability and manufacturing precision
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The composite separator improves mechanical strength and cycle performance by stabilizing the adhesion between the electrode sheet and the porous base film, reducing electrode sheet deformation and enhancing lithium ion conductivity.
Implementation Method 1
the non-adhesive polymer C provided on the base layer... capable of generating physical adhesion between the electrode sheet and the electrode sheet
Implementation Method 2
the adhesive polymer B in the base layer and the porous base film produce, i.e., a side of the base layer is physically adhered to the electrode sheet through the non-adhesive polymer C, and another side of the base layer is chemically adhered to the porous base film
Implementation Method 3
A separator, as a key safety component of a lithium-ion battery, has a rich pore structure, and is used to block the direct contact between the positive electrode sheet and the negative electrode sheet while allowing ions to pass through
Data Source
Figure 1
AI summary
Disclosed in the present disclosure is a composite separator and a preparation method and application thereof. A composite separator includes a porous base film (1) and a coating (2). The coating (2) is provided on a surface of the porous base film (1), the coating (2) includes a base layer (21) and a non-adhesive polymer C (22) provided on the base layer (21), and the base layer (21) includes inorganic particles A and an adhesive polymer B. A maximum particle size of the non-adhesive polymer C (22) is greater than a thickness of the base layer (21) and a particle size of the non-adhesive polymer C (22) is in a range of 0.3 µm to 30 µm. The adhesive polymer B includes a first component and a second component. The first component includes at least one of a vinyl polymer, a propylene-based polymer, an amide-based polymer, and an epoxy-based polymer. The second component includes a cellulose-based polymer.