Dual-Phase Battery Separator for Pore-Closing Thermal Shutdown
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Solution Overview
Problem
Existing secondary battery separators fail to effectively halt abnormal temperature rises, compromising battery reliability.
Innovation Solution
A separator with a porous base film comprising a matrix phase and a filler phase, where the matrix phase has a higher melting peak temperature than the filler phase, allowing the filler phase to melt first and close pores to terminate electrochemical reactions during high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing separators are used, then the battery can operate normally, but the separator fails to halt abnormal temperature situations when temperature rises
Solution Approach 1:
The separator is constructed as a composite material containing both a matrix phase and a filler phase with different thermal properties. The matrix phase provides structural support while the filler phase (with lower melting point) provides thermal shutdown functionality. This composite structure enables the separator to maintain both mechanical integrity and thermal protection capabilities, resolving the contradiction between normal operation and abnormal temperature halt.
Solution Approach 2:
The invention changes the thermal parameters of the separator by incorporating a filler phase with a specific melting point range (80-180°C) that is lower than the matrix phase melting point (160-350°C). This parameter differentiation enables the filler phase to melt and close pores at abnormal temperatures, achieving thermal shutdown while the matrix phase maintains structural support at higher temperatures.
2Reliability
If the filler phase melts first to close pores, then thermal shutdown is achieved, but the structural strength may be compromised
Solution Approach 1:
The composite structure combines a filler phase (10-40 wt%) responsible for pore-closing with a matrix phase providing structural framework. The matrix phase content (60-90 wt%) ensures sufficient structural strength while the filler phase enables thermal shutdown. This composition balance resolves the contradiction between pore-closing performance and structural strength.
Solution Approach 2:
The separator's functionality is segmented into two distinct phases: the filler phase handles the pore-closing function at lower temperatures, while the matrix phase maintains structural integrity at higher temperatures. This functional segmentation allows each phase to specialize in one aspect, resolving the contradiction between thermal shutdown and structural strength.
3Stability of the object's composition
If the matrix phase has higher melting point for thermal stability, then structural integrity is maintained, but the filler phase must melt first to achieve shutdown
Solution Approach 1:
The invention deliberately creates a parameter gradient in melting points between the two phases. The filler phase melting point (80-180°C) is set lower than the matrix phase melting point (160-350°C), ensuring a specific melting sequence. This parameter differentiation enables timely shutdown via filler phase while maintaining thermal stability through matrix phase, resolving the contradiction between timely shutdown and thermal stability.
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 separator ensures timely thermal shutdown, preventing further temperature rise and enhancing battery reliability by balancing strength and pore-closing performance.
Implementation Method 1
the filler phase melts first due to poorer thermal stability, thereby closing the pores of the separator in a timely manner
Implementation Method 2
both a melting peak of the matrix phase and a melting peak of the filler phase are included
Data Source
AI summary
The present application relates to the technical field of secondary batteries and specifically provides a separator and a preparation method therefor, a secondary battery and an electric device. The separator includes a porous base film, where the porous base film includes a matrix phase and a filler phase distributed in the matrix phase; in a differential scanning calorimeter test curve of the porous base film, both a melting peak of the matrix phase and a melting peak of the filler phase are included, and a temperature of the melting peak of the matrix phase is higher than a temperature of the melting peak of the filler phase.