Separator Air Permeability Testing for Shutdown and Meltdown Temperature
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Solution Overview
Problem
Existing methods for determining the shut-down and melt-down temperatures of separators in lithium secondary batteries are inaccurate and require the preparation of a coin cell, which can lead to electrolyte vaporization and indirect measurement of pore blocking, making precise determination difficult.
Innovation Solution
A system using air permeability to directly measure the shut-down and melt-down temperatures of separators, comprising an air permeability-determining unit, jigs, a heating unit, a temperature sensor, and a controlling unit to calculate these temperatures based on air permeability changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If TMA instrument is used to observe separator shrinking behavior, then temperature increase can be monitored, but pore blocking cannot be determined directly and accurate shut-down temperature cannot be determined
Solution Approach 1:
The patent replaces the mechanical TMA measurement system with a pneumatic measurement system that directly measures air permeability. Instead of indirectly observing separator changes through mechanical dimension measurements, the invention uses air flow through the separator pores to directly detect pore blocking status and determine shut-down temperature accurately.
Solution Approach 2:
The patent introduces air as an intermediary substance to detect separator pore blocking. By measuring air permeability through the separator, the system can directly determine when pores are blocked without needing to observe mechanical changes or prepare complex coin cell structures.
2Measurement precision
If coin cell is prepared to determine ion conductivity, then separator performance can be tested, but the procedure becomes complex and time-consuming
Solution Approach 1:
The patent extracts the essential measurement function from the complex coin cell structure. By directly measuring air permeability through the separator alone, without needing to assemble complete coin cells with electrodes and electrolyte, the invention simplifies the test setup while maintaining measurement capability for separator performance.
Solution Approach 2:
The patent creates a simplified copy of the separator testing function that eliminates unnecessary components. Instead of testing the entire coin cell assembly, the invention directly tests the separator's pore blocking characteristics through air permeability measurement, achieving the same informational goal with reduced complexity.
3Temperature
If temperature is increased to carry out safety test, then shut-down and melt-down temperatures can be determined, but electrolyte is vaporized causing measurement interference
Solution Approach 1:
The patent replaces the expensive and problematic electrolyte with simple air as the testing medium. Air can be heated to high temperatures without vaporizing or interfering with measurements, eliminating the harmful effects of electrolyte decomposition while still allowing determination of separator thermal safety characteristics.
Solution Approach 2:
The patent changes the physical state and chemical composition of the testing medium from liquid electrolyte to gaseous air. This parameter change allows the system to withstand higher temperatures without decomposition, enabling accurate measurement of melt-down temperature without the interference of vaporized electrolyte.
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 system allows for precise and rapid determination of shut-down and melt-down temperatures without the need for a coin cell or electrolyte, providing accurate and reproducible results.
Implementation Method 1
an air permeability-determining unit 170 configured to determine the air permeability (Gurley value) of the separator
Implementation Method 2
a heating unit 140 configured to heat the first jig or the second jig
Implementation Method 3
a temperature sensor 150 configured to measure the temperature of the first jig or the second jig
Data Source
AI summary
The present disclosure relates to a system for determining the shut-down temperature and melt-down temperature of a separator. The system includes a jig having a through-hole, a heating unit, a temperature sensor, a controlling unit and an air permeability-determining unit. In this manner, it is possible to provide a novel system for determining the shut-down temperature and melt-down temperature of a separator by using the air permeability (Gurly value) of the separator.