Battery Separator with Porous Layer for Adhesion and Shutdown
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Solution Overview
Problem
Current battery separators lack sufficient heat shrinkage resistance and adhesion to electrodes while maintaining shutdown properties, leading to potential short circuits and poor battery performance.
Innovation Solution
A battery separator comprising a microporous polyolefin membrane with a modifying porous layer containing a fluorine resin and inorganic or cross-linked polymer particles, which provides improved heat resistance and adhesion without increasing the shutdown temperature, achieved through a specific membrane-forming process and lamination technique.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a modifying porous layer is laminated on a microporous polyolefin membrane to improve adhesion to electrode material, then adhesion to electrode is improved, but the shutdown properties deteriorate due to resin component infiltration into pores
Solution Approach 1:
The patent uses a microporous polyolefin membrane with controlled porosity (30-80%) and pore size (0.01-1 μm) as the base layer. The porous structure allows ion permeability while the specific pore characteristics prevent excessive resin infiltration, maintaining shutdown properties even after laminating a modifying porous layer for improved electrode adhesion.
Solution Approach 2:
The patent creates a composite structure by laminating a modifying porous layer containing functional resins (such as polyvinylidene fluoride, polyacrylonitrile, or carboxymethyl cellulose) onto a microporous polyolefin membrane. This composite structure provides both improved adhesion to electrode material and maintained shutdown properties through the synergistic combination of layers.
2Temperature
If the microporous polyolefin membrane structure is optimized for shutdown properties, then shutdown temperature is reduced, but heat shrinkage resistance in the temperature range from shutdown start to shutdown temperature deteriorates
Solution Approach 1:
The patent optimizes specific parameters of the microporous polyolefin membrane including porosity (30-80%), pore size (0.01-1 μm), and thickness (5-50 μm) to achieve a balance between shutdown temperature (135°C or lower) and heat shrinkage resistance. The membrane exhibits shrinkage rate of 20% or less at 130°C, maintaining dimensional stability while achieving low shutdown temperature through controlled pore closure characteristics.
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 solution offers a battery separator with high physical stability, rapid air resistance change, excellent heat shrinkage resistance, and strong adhesion to electrodes, ensuring safe and efficient battery operation.
Implementation Method 1
the property of closing pores upon heat generation in batteries to stop battery reaction (shutdown properties)
Implementation Method 2
a modifying porous layer containing a resin for providing or improving adhesion to electrode material
Implementation Method 3
excellent heat shrinkage resistance in a temperature range from a shutdown start temperature to a shutdown temperature
Data Source
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AI summary
A battery separator which comprises a polyolefin microporous film and a modifying porous layer laminated on at least one surface thereof, wherein the polyolefin microporous film comprises a polyethylene-based resin and exhibits (a) a shutdown temperature of 135ºC or lower, (b) an air permeation resistance change of 1×104 sec/100cc/ºC or more, and (c) a crosswise shrinkage factor at 130 ºC of 20% or less. Thus, a battery separator which exhibits high physical property stability until the initiation of shutdown, a high air permeation resistance change after the initiation of shutdown, excellent thermal shrinkage resistance in a temperature range from shutdown initiation temperature to shutdown temperature, a low shutdown temperature, and excellent adhesion to an electrode is provided.