Porous-Coated Battery Separator for Low-Shrinkage Electrode Adhesion
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Solution Overview
Problem
Conventional polyolefin-based separators for electrochemical devices exhibit high heat shrinkage and poor adhesive properties, leading to short-circuits between electrodes, and existing binder resins like PVDF-based materials limit adhesive performance.
Innovation Solution
A separator with a porous coating layer containing a blend of inorganic particles and a binder resin composition comprising ethylenic and acrylic binder resins with different glass transition temperatures, along with a vinylic polymer, to enhance adhesion and reduce shrinkage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polyolefin-based microporous film is used as a separator, then it provides basic separation function, but it shows severe heat shrinkage at 100°C or higher causing short-circuit between electrodes
Solution Approach 1:
The patent applies composite materials by combining polyolefin base material with PVDF-HFP copolymer coating layer, and further composite with inorganic particles (alumina, silica) to create a separator that maintains structural stability at high temperatures while providing ion conductivity, thereby resolving the heat shrinkage issue
2Strength
If a PVDF-based binder resin is used in the porous coating layer, then it provides binding function, but it limits adhesive property to the electrode
Solution Approach 1:
The patent changes the chemical composition parameters of the binder resin by using PVDF-HFP copolymer with specific fluorine content (3-15 mol%) and combining with inorganic particles, which transforms the adhesive properties to achieve strong electrode attachment while maintaining electrochemical compatibility
3Ease of operation
If the separator structure is optimized for high adhesion, then assembly can be performed under mild conditions, but manufacturing complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-forming the porous coating layer with PVDF-HFP copolymer and inorganic particles on the separator substrate before electrode assembly, which enables subsequent mild assembly conditions while the coating layer structure is already optimized for adhesion and ion conductivity
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 new separator design achieves high adhesion to electrodes, allowing for efficient assembly under mild conditions, reduces defects, and improves battery output characteristics by minimizing interfacial resistance and enhancing electrolyte affinity.
Implementation Method 1
the first binder resin is an ethylenic polymer resin comprising a polar group having a glass transition temperature (Tg) of 30° C. to 60° C., and the second binder resin is an acrylic binder resin having a glass transition temperature (Tg) of 80° C. to 120° C.
Implementation Method 2
the porous coating layer includes inorganic particles and a binder resin at a weight ratio of about 50:50-99:1
Data Source
AI summary
A separator for an electrochemical device provided with a porous coating layer including multiple types of binder resins, and a method for manufacturing the same. The separator has high adhesion between an electrode and the separator, even when any separate adhesive layer is not disposed on the surface of the separator. In addition, the separator has higher adhesion to an electrode, as compared to a separator using a fluorinated binder resin, such as polyvinylidene fluoride, used conventionally in the art. In addition, since the separator has no separate adhesive layer, it is possible to provide low interfacial resistance between the separator and an electrode. Further, the separator has high affinity to an electrolyte, as compared to a semi-crystalline polymer, such as a fluorinated binder resin, and thus improves the output characteristics of a battery.