Cross-linked Binder Separator for Lithium Battery Thermal Stability
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Solution Overview
Problem
Lithium secondary battery separators face challenges in maintaining stability and heat resistance, particularly during overheating, which can lead to short-circuits and reduced battery performance.
Innovation Solution
A separator for lithium secondary batteries is developed, featuring a substrate with a heat-resistant porous layer formed using a cross-linked binder with a specific cross-linking structure, enhancing electrolyte solution wettability and thermal stability, and optionally including a filler to prevent thermal shrinkage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separator is formed by coating a binder and ceramic particle on a porous substrate, then the separator provides basic insulation and ion transfer function, but the separator fails to secure stability due to shrinkage during overheating
Solution Approach 1:
The patent changes the chemical and physical parameters of the binder by introducing a cross-linking structure with specific functional groups (carboxyl, hydroxy, amino, isocyanate, cyanate, or thiol groups) that form thermally stable networks. This cross-linked structure prevents the binder from softening and causing substrate shrinkage at elevated temperatures, thereby maintaining dimensional stability and reliability under thermal stress
Solution Approach 2:
The patent creates a composite binder system combining organic binder polymers with inorganic ceramic particles and cross-linking agents. This composite structure leverages the thermal stability of ceramic particles and the cross-linked network to resist shrinkage, while the porous substrate provides the necessary ion transfer pathways, achieving both stability and functionality
2Reliability
If the separator uses a cross-linked binder with specific functional groups, then heat resistance and electrolyte solution wettability are improved, but the manufacturing complexity increases
Solution Approach 1:
The patent modifies the binder's chemical parameters by incorporating cross-linking functional groups that enhance heat resistance and improve electrolyte wettability. These parameter changes are achieved through selecting binder polymers with specific functional groups that can form cross-linked structures, thereby improving reliability without fundamentally changing the coating process
Solution Approach 2:
The patent uses cross-linking agents as intermediaries that facilitate the formation of thermally stable networks within the binder matrix. These agents act as mediators between the binder polymer chains, creating a cross-linked structure that improves heat resistance and wettability while maintaining a relatively simple manufacturing process through conventional coating and curing steps
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 improved separator achieves better heat resistance and electrolyte solution wettability, leading to enhanced cell performance, including rate capability and stability, thereby preventing short-circuits and ensuring safer battery operation during overheating.
Implementation Method 1
the cross-linked binder has a cross-linking structure formed from a compound represented by Chemical Formula 2
Implementation Method 2
a heat-resistance porous layer disposed on at least one surface of the substrate... to prevent thermal shrinkage
Implementation Method 3
the separator... includes micropores through which lithium ions are transferred
Implementation Method 4
The separator plays a role of electrically insulating the positive and negative electrodes
Data Source
AI summary
Provided are a separator for a lithium secondary battery including a substrate and a heat-resistance porous layer disposed on at least one surface of the substrate and including a cross-linked binder, wherein the cross-linked binder has a cross-linking structure of a compound represented by Chemical Formula 2, and a lithium secondary battery including the same.