Microporous Battery Separator Materials for High-Temperature Ionic Flow
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Solution Overview
Problem
Current Lithium-ion battery separators fail to maintain functionality and prevent contact between the anode and cathode at elevated temperatures, leading to shutdown at high temperatures, which limits the battery's operational duration and efficiency.
Innovation Solution
Development of high melt temperature microporous battery separators with a glass transition temperature of at least 250°C, utilizing polymers like Polybenzimidazole (PBI) or blends, which are soluble in moderately volatile solvents, ensuring dimensional and structural integrity to prevent contact and allow ionic flow at temperatures up to 250°C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional polyolefin separators are used, then manufacturing cost and ease of manufacture are improved, but the separator fails to maintain structural integrity and prevent contact at elevated temperatures above 100°C
Solution Approach 1:
The patent changes the fundamental thermal parameter of the separator material by transitioning from polyolefin (melting point ~160°C) to aramid polymer (glass transition temperature >300°C). This parameter change enables the separator to maintain dimensional stability and structural integrity at temperatures exceeding 100°C, directly resolving the contradiction between reliability at high temperature and the temperature limit of conventional materials.
Solution Approach 2:
The invention employs composite material construction by combining aramid polymer fibers with appropriate binders and potentially other functional materials to create a separator that achieves both high-temperature stability and the required microporous structure for ionic conductivity. This composite approach allows the separator to simultaneously satisfy mechanical strength requirements at elevated temperatures and the functional requirements for battery operation.
2Stability of the object's composition
If the separator melt temperature is increased to prevent contact at high temperature, then thermal stability is improved, but ionic transfer capability deteriorates due to shutdown at lower temperatures
Solution Approach 1:
The patent changes the thermal transition mechanism from melting (polyolefin) to glass transition (aramid), which occurs at significantly higher temperatures. This parameter change allows the separator to maintain its microporous structure and ionic transfer capability at temperatures where conventional separators would melt and collapse, thereby simultaneously achieving dimensional stability and sustained ionic conductivity at elevated temperatures.
Solution Approach 2:
The invention utilizes a microporous aramid fiber structure that maintains pore openness and ionic conductivity at high temperatures through the polymer's inherent thermal stability. The porous architecture is preserved because aramid polymers do not undergo melting transitions like polyolefins, ensuring continuous ion transport pathways remain open even when the battery operates at temperatures that would cause conventional separators to shut down.
3Reliability
If high glass transition temperature polymers like PBI are used, then high temperature structural integrity is improved, but manufacturing complexity increases due to solvent requirements
Solution Approach 1:
The patent addresses manufacturing complexity by changing the processing parameters of the aramid polymer, specifically selecting solvents and processing conditions that enable fabrication despite the polymer's high glass transition temperature. This parameter optimization allows the high-performance material to be manufactured using adapted conventional techniques rather than requiring entirely new manufacturing approaches.
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 high melt temperature separators effectively maintain physical structure and ionic transfer capabilities at elevated temperatures, preventing shutdown and ensuring partial or full battery function for extended periods, even at temperatures exceeding 200°C.
Implementation Method 1
a glass transition temperature of at least 250°C, utilizing polymers like Polybenzimidazole (PBI) or blends
Implementation Method 2
continue to provide a substantial level of battery function (ionic transfer, discharge) when the battery is maintained at elevated temperatures
Data Source
AI summary
Disclosed or provided are non-shutdown high melt temperature or ultra high melt temperature microporous battery separators, high melt temperature separators, battery separators, membranes, composites, and the like that preferably prevent contact between the anode and cathode when the battery is maintained at elevated temperatures for a period of time and preferably continue to provide a substantial level of battery function (ionic transfer, discharge) when the battery is maintained at elevated temperatures for a period of time, methods of making, testing and/or using such separators, membranes, composites, and the like, and/or batteries, high temperature batteries, and/or Lithium-ion rechargeable batteries including one or more such separators, membranes, composites, and the like.