Phenolic Resin Battery Separator for High-Temperature Shrinkage Control
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Solution Overview
Problem
Lithium secondary battery separators face challenges with heat shrinkage at high temperatures, leading to potential short circuits and safety issues, as existing solutions either increase resistance or compromise electrolyte impregnation rates.
Innovation Solution
A separator with a porous polymer resin substrate and a heat resistance layer made of resol-based phenolic resin, which hardens at high temperatures, is applied to reduce heat shrinkage while maintaining low resistance, preventing short circuits and improving safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a coating layer including inorganic material and binder is formed on polyolefin-based substrate to improve heat resistance, then high-temperature safety is improved, but the separator may still shrink at high temperature causing short circuit
Solution Approach 1:
The patent uses biaxial orientation to change the physical structure of the polyolefin substrate, creating a cross-linked molecular structure that resists thermal shrinkage. This parameter change in the substrate's molecular arrangement allows it to maintain dimensional stability at high temperatures while preserving the coating layer's heat resistance properties
Solution Approach 2:
The patent creates a composite structure by forming a coating layer containing inorganic material and binder on the biaxially oriented polyolefin substrate. This composite material combines the heat resistance of the inorganic coating with the improved thermal stability of the oriented substrate, achieving both heat resistance and shrinkage resistance
2Strength
If the separator is uniaxially or biaxially oriented to increase strength and thin the separator, then mechanical strength is improved, but the separator shrinks when temperature increases causing short circuit
Solution Approach 1:
The patent applies biaxial orientation to change the molecular structure of the polyolefin substrate, creating a cross-linked network that provides both mechanical strength and resistance to thermal shrinkage. This structural parameter change allows the separator to maintain its dimensions at high temperatures while retaining enhanced mechanical properties
3Strength
If electrode adhesion layer is formed on porous substrate with inorganic layer to increase adhesion force, then adhesion between separator and electrode is improved, but resistance of separator is increased
Solution Approach 1:
The patent applies the coating layer selectively on specific surfaces of the biaxially oriented polyolefin substrate, creating local functional zones that provide adhesion and heat resistance where needed while preserving the low resistance properties of the oriented substrate in the bulk structure
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 effectively reduces heat shrinkage to prevent short circuits and maintains low resistance, enhancing the safety and performance of lithium secondary batteries by using a resol-based phenolic resin heat resistance layer on the separator substrate.
Implementation Method 1
a heat resistance layer including a phenolic resin which is hardened when heated
Data Source
AI summary
A separator for a lithium secondary battery, the separator including a separator substrate including a porous polymer resin and a heat resistance layer on at least one side of the separator substrate. The heat resistance layer includes a phenolic resin configured to be hardened when heated. The heat shrinkage at a high temperature is improved, and it is possible to prevent short circuit between electrodes.