Phase-Change Microcapsule Coating for Battery Separator Heat Shielding
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Solution Overview
Problem
Short circuits frequently occur in batteries due to excessive heating during the laser welding of current collection assemblies, causing the separator to scald and fail.
Innovation Solution
A phase-change microcapsule with a core-shell structure is applied as a coating layer on the separator and tab, containing a first phase-change component with a melting point of 37° C. to 42° C. and a second phase-change component with a melting point of 65° C. to 75° C., along with an insulative heat-conducting wall material with a melting point greater than 75° C., which absorbs heat in a stepped manner to control the separator's temperature and prevent scalding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If laser welding is used to connect current collection assembly, then electrical connection efficiency is improved, but separator temperature rises excessively causing short circuits
Solution Approach 1:
The phase-change microcapsule acts as an intermediary thermal management layer between the laser welding zone and the separator. It absorbs excess welding heat through phase change, preventing direct heat transfer to the separator while maintaining electrical connection functionality.
Solution Approach 2:
The microcapsule utilizes phase transition of phase-change material (PCM) from solid to liquid state during laser welding. This phase change absorbs large amounts of welding heat, effectively controlling the separator temperature and preventing thermal damage that would cause short circuits.
2Reliability
If phase-change material is added to control temperature, then separator protection is improved, but device structure becomes more complex
Solution Approach 1:
The phase-change material is encapsulated in a thin shell forming microcapsules that can be uniformly distributed on the separator surface. This thin-film approach provides effective thermal protection while minimizing structural complexity and maintaining separator flexibility.
Solution Approach 2:
The invention creates a composite structure combining the separator base material with phase-change microcapsules. This composite approach integrates thermal protection functionality into the existing separator structure without requiring separate complex thermal management 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 phase-change microcapsule effectively maintains the separator's temperature below the scald-causing threshold during welding, preventing internal short circuits and ensuring the stability and longevity of the battery.
Implementation Method 1
The first phase-change component changes phase and quickly absorbs heat to cushion a heating rate of the separator
Implementation Method 2
the second phase-change component is caused to change the phase to continuously absorb a large amount of heat
Implementation Method 3
an insulative heat-conducting wall material wrapped around the core... A melting point of the insulative heat-conducting wall material is greater than 75° C.
Data Source
AI summary
Provided are a phase-change microcapsule, a separator, an electrode plate, a battery, and an electrical device. The phase-change microcapsule includes: a core and an insulative heat-conducting wall material wrapped around the core. The core includes a first phase-change component and a second phase-change component. The first phase-change component is paraffin with a melting point of 37° C. to 42° C. The second phase-change component is paraffin with a melting point of 65° C. to 75° C. A melting point of the insulative heat-conducting wall material is greater than 75° C. A mass ratio between the first phase-change component and the second phase-change component is 35:(45 to 77). The phase-change microcapsule is applied to the battery in the form of a coating layer. The specified first phase-change component and second phase-change component of a specified melting point are mixed at a specified ratio in the core.