Heat-Treated PBI Separator for Acid-Stable Battery Durability
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Solution Overview
Problem
Polybenzimidazole-based separators for secondary batteries shrink when immersed in acidic electrolytes, leading to reduced mechanical strength and potential breakage during charging and discharging, necessitating a solution to enhance durability and performance.
Innovation Solution
A method involving heat-treating the polybenzimidazole-based separator at 60 to 180°C to induce controlled shrinkage and subsequent cooling to room temperature, which reduces shrinkage when immersed in acidic solutions and allows for expansion, thereby improving mechanical strength and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polybenzimidazole-based separator is used in an acidic electrolyte, then the separator provides good chemical resistance and ion migration properties, but the separator shrinks and loses mechanical strength
Solution Approach 1:
The separator is pre-treated with a crosslinking agent before being installed in the battery. This preliminary chemical modification creates crosslinked structures within the polymer matrix that prevent shrinkage and maintain mechanical strength when the separator is later exposed to acidic electrolyte during battery operation.
2Ease of operation
If the separator is immersed in acidic electrolyte, then ion migration is enabled, but the separator shrinks and may break during charging and discharging
Solution Approach 1:
The chemical structure of the separator is modified by introducing crosslinked groups at controlled concentrations. This parameter change in the molecular architecture allows the separator to maintain its dimensional stability and mechanical integrity while still permitting ion migration through the porous structure during battery cycling.
3Productivity
If the separator shrinks in acidic solution, then the battery can operate, but the mechanical strength decreases leading to breakage
Solution Approach 1:
The separator is constructed as a composite material system combining polybenzimidazole polymer matrix with crosslinked structural elements. This composite structure provides both the chemical resistance needed for battery operation in acidic electrolyte and the mechanical strength to prevent breakage during charging and discharging cycles.
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 post-treatment method significantly reduces shrinkage and enhances the mechanical strength of the separator, preventing breakage and improving the overall performance and durability of secondary batteries.
Implementation Method 1
when a separator made of a polymer such as PBI is immersed in the electrolyte, the separator shrinks due to the acidity of the electrolyte
Implementation Method 2
heat-treating the polybenzimidazole-based separator at 60 to 180°C to induce controlled shrinkage
Implementation Method 3
cooling the heat-treated polybenzimidazole-based separator to room temperature, which reduces shrinkage when immersed in acidic solutions and allows for expansion
Data Source
AI summary
Disclosed is a method for post-treating a polybenzimidazole-based separator before assembling the separator to an electrode assembly, the method including: providing the polybenzimidazole-based separator; heat-treating the polybenzimidazole-based separator at 60 to 180° C.; and cooling the heat-treated polybenzimidazole-based separator to room temperature.