Battery Separator Membrane Composition for Lower Shutdown Temperature
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Solution Overview
Problem
High molecular weight polyethylene membranes used in batteries have inherently higher shutdown temperatures, which can compromise safety and functionality, as reducing these temperatures without affecting physical properties is challenging.
Innovation Solution
A polymer composition incorporating high density polyethylene particles and a shutdown reducing additive, such as low density polyethylene or metallocene linear low density polyethylene, is formulated to lower the shutdown temperature of microporous membranes, allowing for safer battery operation without compromising mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high molecular weight polyethylene is used to maintain physical properties, then strength and abrasion resistance are improved, but shutdown temperature increases
Solution Approach 1:
The patent combines high density polyethylene (HDPE) particles with a shutdown reducing additive (such as low density polyethylene or metallocene linear low density polyethylene) to create a composite polymer composition. This composite structure allows the HDPE to provide mechanical strength while the additive lowers the shutdown temperature, resolving the contradiction between maintaining physical properties and reducing shutdown temperature.
Solution Approach 2:
The patent modifies the thermal parameters of the polyethylene membrane by incorporating a shutdown reducing additive that specifically targets the shutdown temperature. The additive changes the thermal behavior of the composite material, allowing it to shut down at a lower temperature while the HDPE matrix maintains the necessary mechanical properties.
2Reliability
If shutdown temperature is reduced to improve safety, then battery safety is improved, but physical properties are compromised
Solution Approach 1:
The patent uses a composite material system where HDPE particles provide the mechanical strength and structural integrity, while the shutdown reducing additive (such as LLDPE or metallocene LLDPE) provides the lowered shutdown temperature for safety. This composite approach allows both requirements to be met simultaneously without compromising either safety or physical properties.
Solution Approach 2:
The patent applies different functional properties to different components of the composite: the HDPE particles are responsible for mechanical strength and structural properties, while the shutdown reducing additive is specifically responsible for thermal shutdown behavior. This local differentiation of function allows the material to achieve both safety and mechanical performance.
Data Source
AI summary
A polymer composition for producing gel extruded articles is described. The polymer composition contains polyethylene particles combined with a plasticizer and one or more shutdown reducing additives. The shutdown reducing additives decrease the shutdown temperature of polymer articles made from the polymer composition. In one embodiment, the polymer composition is used to form a porous membrane for use of a battery separator.