Cellulose Separator Viscosity Control for Electrochemical Element Durability
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Solution Overview
Problem
Conventional separators for electrochemical elements face challenges in maintaining uniform electrolyte retention and durability under high temperature conditions, leading to reduced service life and increased heat generation, as they struggle to control ionic impurities and lyophilic properties effectively.
Innovation Solution
A cellulose-based separator with a limiting viscosity between 150 to 500 ml/g, containing regenerated solvent-spun fibers, is used to enhance the affinity and retention of the electrolytic solution, while maintaining low ionic impurities and resistance, thereby extending the service life and reducing heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional separators are used, then basic separation function is achieved, but uniform electrolyte retention and durability under high temperature conditions deteriorate
Solution Approach 1:
The patent applies parameter changes by controlling the limiting viscosity of cellulose fibers within a specific range (150-500 ml/g) to optimize the separator's performance. This parameter control enables the separator to maintain both uniform electrolyte retention and high temperature durability, resolving the contradiction between reliability and composition stability.
Solution Approach 2:
The patent uses composite materials by combining cellulose-based fibers with specific limiting viscosity characteristics. This composite approach allows the separator to achieve both uniform electrolyte retention and improved durability under high temperature conditions, addressing the technical contradiction.
2Quantity of substance
If separator retains more electrolytic solution, then liquid-retaining property improves, but ionic impurities increase
Solution Approach 1:
The patent controls the limiting viscosity parameter of cellulose fibers to achieve optimal balance between electrolytic solution retention and ionic impurity content. By maintaining viscosity within 150-500 ml/g, the separator retains sufficient electrolyte while minimizing ionic impurities, thus improving reliability.
3Reliability
If separator density increases, then short circuit resistance improves, but ion permeability decreases
Solution Approach 1:
The patent optimizes the density and limiting viscosity parameters of the cellulose fiber separator to achieve a balance between short circuit resistance and ion permeability. The controlled viscosity range (150-500 ml/g) allows the separator to maintain appropriate density for short circuit resistance while preserving sufficient ion permeability for electrochemical element operation.
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 proposed separator effectively suppresses capacitance and voltage decreases under high temperature conditions, reduces heat generation, and extends the service life of electrochemical elements by improving the lyophilic and liquid-retaining properties while maintaining durability.
Implementation Method 1
the separator retains an electrolytic solution
Implementation Method 2
improving the lyophilic and liquid-retaining properties
Data Source
AI summary
Provided is a separator for an electrochemical element suitable for extending the service life of an electrochemical element under high temperature conditions. This separator for an electrochemical element is disposed between a pair of electrodes and is for separating the two electrodes from each other and retaining an electrolytic solution, wherein the separator contains a cellulose-based fiber, and the limiting viscosity of the separator as measured by the measurement method specified in JIS P 8215 is in a range of 150-500 ml/g.