Composite Separator Porous Film for Heat Shrinkage and Puncture Resistance
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Solution Overview
Problem
Existing battery separators with aramid fiber layers exhibit high heat shrinkage rates and low puncture strength, leading to increased risks of short circuits and micro short circuits, which can cause thermal runaway in batteries.
Innovation Solution
A composite separator is developed, featuring a base separator coated with a porous film that includes a first material region with a polymer content of 30% or more and a rupture temperature greater than 260°C, and second and third material regions with high content of inorganic particles, reducing heat shrinkage and improving puncture resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an organic polymer adhesive coating (such as aramid fiber) is applied to improve interface bonding and overall strength, then interface bonding is improved, but heat shrinkage rate increases to 6% or higher at 130°C
Solution Approach 1:
The patent changes the material composition parameters by using 30-80 wt% aramid fiber combined with 20-70 wt% inorganic particles (such as alumina, silica, or boehmite) in the coating layer. This parameter adjustment reduces the heat shrinkage rate to 3% or lower at 130°C while maintaining interface bonding strength, as the inorganic particles provide thermal stability and restrict polymer chain motion at high temperatures.
Solution Approach 2:
The patent creates a composite coating material by combining organic polymer (aramid fiber) with inorganic particles. This composite structure leverages the high bonding strength of the polymer while the inorganic particles provide thermal stability and low heat shrinkage characteristics, achieving both improved interface bonding and reduced heat shrinkage simultaneously.
Data Source
AI summary
A composite separator includes a base separator and a film covering a surface of the base separator, where the film is a porous film. The film includes a first material region, a second material region, and a third material region, and the second material region and the third material region are respectively disposed on two sides of the first material region, and both are connected to the first material region. A material of the first material region includes a polymer. Both a material of the second material region and a material of the third material region include inorganic particles, where a mass percentage of the inorganic particles in the second material region is 90% or more, and/or a mass percentage of the inorganic particles in the third material region is 90% or more.