Microporous Battery Separator Composition for Thickness Resilience
Find Innovative SolutionsGenerate Solutions
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
A microporous separator for lithium-ion batteries is developed using a polyolefin resin with a controlled proportion of high molecular weight chain segments, specifically 5 mol %-8 mol % with a weight-average molecular weight of 2 million to 5 million, and by optimizing the extrusion process parameters to enhance compression resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional polyolefin-based microporous membrane is used as separator, then excellent membrane mechanical strength and shutdown characteristics are achieved, 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 the polyolefin resin, specifically incorporating high molecular weight components (weight-average molecular weight of 2 million to 5 million) at controlled proportions (5 mol %-8 mol %). This parameter change in the resin composition enables the separator to achieve high resilience rate (≥2×10−4 m/s) and low compression deformation rate, resolving the contradiction between reliability and compositional stability.
2Reliability
If high molecular weight polyolefin chain segments are increased to improve resilience rate, then resilience speed increases, but manufacturing complexity increases
Solution Approach 1:
The patent specifies precise parameter ranges for the polyolefin resin, including weight-average molecular weight (2 million to 5 million) and quantity proportion (5 mol %-8 mol %). By controlling these parameters within defined ranges, the patent achieves high resilience speed (≥2×10−4 m/s) while maintaining manageable manufacturing complexity through standardized material specifications.
Solution Approach 2:
The patent performs preliminary selection and specification of the polyolefin resin with predetermined molecular weight characteristics before the separator manufacturing process. This preliminary action of pre-characterizing the resin material simplifies subsequent manufacturing steps and reduces overall process complexity while ensuring the desired resilience performance.
3Strength
If extrusion process parameters are optimized to improve compression resistance, then separator performance improves, but process control difficulty increases
Solution Approach 1:
The patent optimizes extrusion process parameters including temperature (150°C-260°C), screw speed (60 r/min-125 r/min), and die geometry to achieve the desired molecular weight distribution and morphology in the separator. These parameter optimizations enhance compression resistance while establishing controllable process windows that manage measurement and control difficulties.
Solution Approach 2:
The patent implements feedback control in the extrusion process by monitoring and adjusting parameters such as extruder temperature and screw speed based on the desired output characteristics. This feedback mechanism enables precise control of the separator's molecular weight distribution and physical properties, achieving high compression resistance with manageable process control.
Data Source
AI summary
The present disclosure relates to a microporous separator for lithium battery and its preparation method. Specifically, the present disclosure 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 disclosure also provides a preparation method for a highly resilient microporous separator for lithium battery.