Microporous Lithium Battery Separator for Thickness Resilience
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Solution Overview
Problem
Existing microporous separators for lithium-ion batteries lack high resilience rates and low compression deformation rates in the thickness direction, which is crucial for ensuring safety and performance under impact.
Innovation Solution
The development of a microporous separator with a controlled proportion of high molecular weight chain segments in polyolefin resin, combined with optimized extrusion process parameters, to achieve a high resilience rate and low compression deformation rate in the thickness direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional polyolefin resin is used for separator manufacturing, then the separator achieves basic mechanical strength and shutdown characteristics, but the resilience rate in thickness direction is insufficient and compression deformation rate is high
Solution Approach 1:
The patent changes the molecular weight distribution parameters of polyolefin resin, specifically controlling the proportion of high molecular weight components ( Mw > 10^6) to 5-20 mol% and very high molecular weight components ( Mw > 10^7) to 0.1-5 mol%. This parameter optimization resolves the contradiction by achieving both high resilience rate (≥20%) and low compression deformation rate (≤30%) simultaneously
Solution Approach 2:
The patent creates a composite molecular structure within the polyolefin resin by combining different molecular weight segments. The synergistic effect of low, medium, and high molecular weight components forms a composite material system that provides both mechanical strength and excellent resilience properties, resolving the contradiction between durability and deformability
2Reliability
If the separator is designed to withstand impact in thickness direction, then safety performance improves, but the separator material requires specific molecular structure control that complicates manufacturing
Solution Approach 1:
The patent optimizes specific parameters of polyolefin resin including melt index (0.01-10 g/10min) and molecular weight distribution (Mw/Mn ratio of 2-10), which are controllable through standard polymerization processes. These parameter specifications enable manufacturers to produce safe separators using existing equipment and processes, avoiding excessive complexity while ensuring impact resistance
3Speed
If high molecular weight chain segments are increased to improve resilience, then the resilience speed increases, but the manufacturing precision requirements increase
Solution Approach 1:
The patent defines specific ranges for molecular weight distribution parameters that balance resilience performance with manufacturing feasibility. By specifying Mw > 10^6 at 5-20 mol% and Mw > 10^7 at 0.1-5 mol%, the patent achieves high resilience speed (≥2 × 10^-4 µm/s) while maintaining controllable manufacturing precision through standard polymerization techniques
Data Source
AI summary
The present invention relates to a microporous separator for lithium battery and its preparation method. Specifically, the present invention provides a microporous separator for lithium battery including a polyolefin resin, having excellent resilience performance and compression resistance performance in its thickness direction; the present invention also provides a preparation method for a highly resilient microporous separator for lithium battery.