Film Package Battery Separator Heat Resistance
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Solution Overview
Problem
Film package batteries face issues with heat-resistant safety and susceptibility to vibration and impact due to the damage of polymer film separators during the fusion-bonding process of fixing tapes, especially as energy density increases.
Innovation Solution
A film package battery design featuring a separator that does not melt or soften at temperatures above 200°C, with a heat shrinkage ratio of 3% or less, and a fixing tape attached to the battery element and inner surface of the film package for enhanced stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixing tape is thermally fused and bonded to the outer package to fix the battery element, then the battery element is secured against vibration and impact, but the separator made of polymer film is damaged by heat
Solution Approach 1:
The separator material is changed to one with high heat resistance (melting point of 200°C or higher) and controlled thermal shrinkage properties (heat shrinkage ratio of 3% or less at 100°C). This parameter change allows the separator to withstand the thermal fusion process without damage while maintaining its structural integrity and functional performance.
Solution Approach 2:
The separator is constructed as a composite material combining a heat-resistant base fabric (such as polyimide, aramid, or polyester) with a porous coating layer. This composite structure provides both the necessary mechanical strength and thermal stability to resist damage during thermal fusion while maintaining ion permeability for battery operation.
2Use of energy by moving object
If the separator is made of polymer film for flexibility and ion conductivity, then electrochemical performance is improved, but heat resistant safety deteriorates
Solution Approach 1:
The separator uses a composite structure with a heat-resistant base fabric providing thermal stability (melting point ≥200°C) and a porous coating layer maintaining ion conductivity. This composite approach allows the separator to simultaneously achieve high heat resistance and good electrochemical performance.
Solution Approach 2:
The separator incorporates a porous coating layer on the heat-resistant base fabric, which provides channels for ion transport while the underlying heat-resistant substrate maintains structural integrity at elevated temperatures. The porous structure ensures ion conductivity without compromising heat resistance.
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 solution provides a highly reliable film package battery with improved heat-resistant safety and resistance to vibration and impact, preventing damage to electrode tabs and the battery structure.
Implementation Method 1
at least at 200° C., the separator does not melt or soften
Implementation Method 2
a fixing tape fixed to a part of the battery element and fixed to an inner surface of the film package
Data Source
AI summary
A film package battery 1 has a battery element (20) having a positive electrode, a negative electrode and a separator that are stacked or wound, wherein, at least at 200° C., the separator does not melt or soften and has a heat shrinkage ratio of 3% or less; a film package (10) enclosing the battery element; and a fixing tape (70) fixed to a part of the battery element and fixed to an inner surface of the film package.