Thermochromic Battery Separator Coating for Thermal Runaway Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Commercial secondary batteries suffer from poor thermal resistance, leading to increased safety risks due to thermal shrinkage and potential short circuits during high internal temperatures, which existing separators fail to adequately address.
Innovation Solution
A separator with a thermochromic coating containing materials like azobenzene, barium stearate, and inorganic metal salts that change color with temperature changes, allowing early detection of thermal runaway and preventing explosions by processing the battery in time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional separator is used, then the battery can operate normally, but the thermal resistance is poor and thermal shrinkage occurs during high internal temperatures leading to short circuits
Solution Approach 1:
The separator is constructed as a composite material combining a polyolefin base film with a coating layer containing inorganic particles (such as aluminum oxide, aluminum hydroxide, magnesium hydroxide) and binder resin. This composite structure provides both the mechanical integrity of the base film and the thermal stability of the inorganic-containing coating, preventing thermal shrinkage while maintaining normal battery operation.
Solution Approach 2:
The invention modifies the thermal properties of the separator by changing the composition and content parameters of inorganic particles in the coating layer. By controlling the inorganic particle content (5-90 mass%), binder resin content (5-40 mass%), and coating thickness (1-20 μm), the separator achieves optimal thermal resistance and dimensional stability at high temperatures without compromising other performance parameters.
2Reliability
If the separator structure is modified to improve thermal resistance, then thermal runaway detection is enhanced, but the manufacturing complexity increases
Solution Approach 1:
The invention incorporates thermochromic materials into the coating layer that undergo color changes at specific temperature thresholds (e.g., turning red at 100°C, black at 150°C). This provides visual indication of thermal runaway conditions, enhancing safety monitoring while maintaining a relatively simple single-layer coating structure that does not significantly increase manufacturing complexity.
Solution Approach 2:
The coating layer acts as an intermediary between the base film and the external environment, providing thermal stabilization and detection functions. The inorganic particles in the coating serve as thermal mediators that absorb and dissipate heat, while thermochromic materials mediate temperature information through color changes, allowing the separator to perform multiple functions without requiring complex multi-layer structures.
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 thermochromic coating enables accurate monitoring of thermal runaway, reducing the risk of explosions and improving battery reliability by allowing timely intervention, while maintaining good air permeability and cycle performance.
Implementation Method 1
the coating includes a thermochromic material. A color of the thermochromic material may change with a change of an internal temperature of a battery
Data Source
Figure 1~2
Figure 3~6
AI summary
The present application provides a separator, a secondary battery including a separator, and a power consuming apparatus. The separator includes a first base film and a coating. The coating is located on a surface of the first base film, and the coating includes a thermochromic material.