Imide-Based Copolymer Separator for Lithium Battery Heat Resistance
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Solution Overview
Problem
Existing rechargeable lithium batteries face challenges in achieving stable performance due to limitations in heat resistance and solubility in organic solvents, which can lead to short-circuits and reduced battery stability during overheating.
Innovation Solution
A separator for rechargeable lithium batteries is developed, featuring a heat-resistant porous layer composed of an imide-based copolymer with specific repeating units and inorganic particles, which enhances heat resistance and solubility in low-boiling-point solvents, while minimizing shrinkage and internal resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a conventional separator is used, then the battery can operate, but the separator shows poor heat resistance and shrinks during overheating, causing short-circuits
Solution Approach 1:
The separator is constructed as a composite material consisting of a polyolefin base layer combined with a heat-resistant porous layer containing imide-based copolymer and inorganic particles. This composite structure provides both the functional properties of the base separator and the thermal stability of the heat-resistant layer, preventing shrinkage and short-circuits during overheating while maintaining normal battery operation.
2Stability of the object's composition
If the heat-resistant porous layer uses only organic polymer binder, then the structure is simple, but the solubility in low-boiling-point solvents is poor and stability is reduced
Solution Approach 1:
The heat-resistant porous layer uses a composite binder system combining organic polymer with inorganic particles. This composite binder provides improved solubility in low-boiling-point solvents while maintaining structural integrity and stability. The inorganic particles contribute to thermal stability and prevent the organic polymer from dissolving excessively, creating a balanced composition that resolves the solubility-stability contradiction.
3Reliability
If the separator uses high polymer content to improve stability, then the heat resistance improves, but the internal resistance increases
Solution Approach 1:
The heat-resistant porous layer is designed with controlled porosity to balance stability and resistance. The porous structure allows efficient lithium ion transport, reducing internal resistance, while the inorganic particles and imide-based copolymer provide the necessary thermal stability and heat resistance. The pore size and distribution are optimized to maintain ion conductivity without compromising the structural stability needed for overheating protection.
Data Source
AI summary
A separator for a rechargeable lithium battery and a rechargeable lithium battery, the separator including a substrate, and a heat-resistant porous layer on at least one side of the substrate, the heat-resistant porous layer including an imide-based copolymer, wherein the imide-based copolymer includes a first repeating unit represented by Chemical Formula 1 and a second repeating unit represented by Chemical Formula 2: