Expandable Microbead Coating for Battery Thermal Runaway Interruption
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Solution Overview
Problem
Existing lithium-ion batteries face safety issues due to thermal runaway caused by abnormal conditions such as impact, overcharge, or short circuit, which leads to self-heating and enhanced internal pressure, resulting in energy release and potential explosion.
Innovation Solution
A battery electrode plate is designed with an expandable microbead having a core-shell structure, where the shell is made of melamine resin and the core comprises a foamable azo compound. This microbead is integrated into a safe conductive coating on the electrode plate, which expands and disrupts the conductive network when the battery temperature exceeds a certain threshold, preventing further energy release and thermal runaway.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the initial foaming temperature of the microbead is set higher than 100°C to avoid expansion during battery production, then the microbead maintains structural integrity during manufacturing, but the microbead cannot expand in time to prevent abnormal discharge during battery temperature rise
Solution Approach 1:
The patent adjusts the foaming temperature parameter of the microbead to an optimal range (100-150°C) that balances two conflicting requirements: being high enough to prevent premature expansion during battery production (80-100°C), but low enough to enable timely expansion during abnormal battery temperature rise. This parameter optimization resolves the contradiction between manufacturing reliability and safety response speed.
2Reliability
If the particle diameter of the expandable microbead is increased to enhance foaming capacity, then the microbead has sufficient influence on conductivity during expansion, but the thickness of the safe conductive coating must be increased, thereby decreasing battery energy density
Solution Approach 1:
The patent optimizes the particle diameter parameter of the expandable microbead to a specific range (0.2-10 μm, preferably 0.5-5 μm) that achieves the maximum foaming capacity and conductivity disruption effect without requiring excessive coating thickness. This parameter optimization ensures sufficient safety performance while maintaining high battery energy density.
Solution Approach 2:
The patent transforms the potential harm of large particle size (requiring thicker coating) into a benefit by optimizing the particle size to achieve maximum safety effect at minimal coating thickness, thereby converting the trade-off into a winning solution that simultaneously achieves high foaming capacity and high energy density.
3Reliability
If existing methods are used to prevent thermal runaway, then the battery safety is improved, but the prevention is not effective and quick enough
Solution Approach 1:
The patent incorporates expandable microbeads with predetermined foaming temperature (100-150°C) into the safe conductive coating before battery assembly. These microbeads are pre-positioned to automatically expand and disrupt conductive networks when the battery temperature reaches the abnormal range, providing preliminary protective action that is both effective and rapid without requiring external control systems.
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 use of expandable microbeads in the safe conductive coating effectively prevents thermal runaway by blocking electronic channels and stopping chemical reactions, thereby enhancing the safety performance of lithium-ion batteries.
Implementation Method 1
the core comprises a foamable azo compound... expands and disrupts the conductive network when the battery temperature exceeds a certain threshold
Implementation Method 2
the shell comprises or consists of a melamine resin... when the battery temperature exceeds a certain threshold
Data Source
AI summary
An expandable microbead having a core-shell structure, wherein the shell is made of melamine resin, and the core is mainly made of a foamable azo compound is disclosed. An electrode plate, comprising a safe conductive coating coated on a surface of a current collector is also described. The above-mentioned expandable microbead is used for the coating, thereby favorably preventing thermal runaway caused by abnormal battery temperature rise, and improving the safety performance of a lithium-ion battery.