Heat-Treated PBI Battery Separator for Acidic Electrolyte Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Polybenzimidazole-based separators for secondary batteries shrink when immersed in acidic electrolytes, leading to a decrease in 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 followed by cooling to room temperature to induce controlled shrinkage and prevent further shrinkage when immersed in acidic solutions, thereby improving mechanical strength and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polybenzimidazole-based separator is used in an aqueous secondary battery with acidic liquid electrolyte, then the separator provides good chemical resistance and ion migration properties, but the separator shrinks when immersed in the electrolyte, resulting in decreased mechanical strength and potential breakage
Solution Approach 1:
The patent applies preliminary heat treatment to the polybenzimidazole-based separator before battery assembly. This pre-treatment causes the separator to shrink in advance under controlled conditions, so that when the separator is later immersed in the acidic electrolyte, it does not undergo additional shrinkage that would compromise its mechanical strength. The preliminary action of heat treatment pre-adjusts the separator's dimensional stability.
Solution Approach 2:
The patent changes the physical parameter of the separator by subjecting it to heat treatment at specific temperatures (typically 60-180°C). This parameter change modifies the separator's internal structure and dimensional characteristics, causing it to reach a stable state before battery operation. The heat treatment parameter transformation converts the separator from a shrink-prone state to a dimensionally stable state.
2Strength
If the separator is heat-treated at high temperature to reduce shrinkage, then the mechanical strength is improved, but the processing complexity increases
Solution Approach 1:
The patent optimizes the heat treatment parameters within a specific temperature range (60-180°C) and time duration to achieve the desired shrinkage reduction. By carefully selecting and controlling these parameters, the patent accomplishes the strength improvement goal while avoiding excessive processing complexity. The parameter optimization ensures that the treatment is neither too mild to be ineffective nor too extreme to be impractical.
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 prevents breakage of the separator, enhancing the durability and performance of secondary batteries by allowing slight expansion when immersed in acidic electrolytes, thus improving the battery's lifespan and efficiency.
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 followed by cooling to room temperature to induce controlled shrinkage
Data Source
Figure 1
Figure 2A
Figure 2B
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.