Microcapsule Separator Thermal Stabilizer Release
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Solution Overview
Problem
Existing secondary battery separators fail to effectively release thermal stabilizers during overheating, leading to premature rupture and inadequate thermal stability, which can result in battery ignition or explosion.
Innovation Solution
A separator with a microcapsule structure comprising a core, shell, and spacer layers, where the shell ruptures at 70-100°C or 3-10 kg/cm² and the spacer softens at temperatures above 200°C or pressures above 50 kg/cm², ensuring controlled release of thermal stabilizers during battery overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If microcapsules containing thermal stabilizer are incorporated into the separator, then thermal stability is improved, but the microcapsules may prematurely rupture during electrode assembly lamination process
Solution Approach 1:
The microcapsule structure is divided into multiple functional layers: an inner shell layer containing the thermal stabilizer, a middle buffer layer providing mechanical protection, and an outer porous coating layer allowing controlled release. This segmentation prevents premature rupture during assembly while enabling thermal response when needed.
Solution Approach 2:
The buffer layer surrounding the inner shell acts as a protective cushion that absorbs mechanical stress during the electrode assembly lamination process, preventing premature rupture of the thermal stabilizer-containing microcapsules before they are needed.
2Reliability
If the shell layer is made to rupture at low temperature (70-100°C) to release thermal stabilizer, then thermal protection is achieved, but the microcapsules may rupture during normal battery operation under pressure
Solution Approach 1:
Different layers of the microcapsule are assigned different functional properties: the inner shell is designed for thermal response (low rupture temperature), while the outer porous coating layer provides mechanical strength and selective permeability. This local differentiation allows the capsule to withstand operational pressure while responding to thermal abuse.
Solution Approach 2:
The microcapsule employs a composite structure combining multiple materials with different properties: the inner shell material provides thermal sensitivity, the buffer layer provides mechanical cushioning, and the porous coating layer provides structural integrity and controlled release. This composite approach resolves the contradiction between thermal responsiveness and operational stability.
3Manufacturing precision
If a porous coating layer is added to protect microcapsules during assembly, then manufacturing reliability is improved, but device complexity increases
Solution Approach 1:
The porous coating layer serves multiple functions simultaneously: it provides mechanical protection during assembly, enables electrolyte penetration for ion transport, and facilitates controlled release of thermal stabilizer during thermal abuse. This multi-functionality justifies the added structural complexity.
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 controlled release of thermal stabilizers inhibits battery ignition and minimizes damage from overheating, enhancing thermal stability and safety by preventing premature release during electrode assembly and ensuring effective protection during thermal abuse.
Implementation Method 1
the shell is made of any one selected from the group consisting of polyolefin, polyvinyl alcohol (PVA), polyvinyl chloride (PVC), and a mixture thereof and ruptures at a temperature of 70 to 100°C or a pressure of 3 to 10 kg/cm2
Implementation Method 2
the spacer is made of any one selected from the group consisting of polyvinylidene fluoride, polyvinylidene fluoride-co-hexafluoropropylene, polyvinylidene fluoride-co-trichloroethylene, polymethyl methacrylate, polybutyl acrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, polyethylene-co-vinyl acetate, polyethylene oxide, polyacrylic acid, polyvinyl alcohol, polyarylate, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylpullulan, cyanoethylpolyvinylalcohol, cyanoethylcellulose, cyanoethylsucrose, pullulan, carboxyl methyl cellulose, and a mixture thereof and is softened by the impregnation of an electrolyte solution and ruptures at a temperature higher than 200°C or a pressure higher than 50 kg/cm 2
Data Source
Figure 1
AI summary
The present disclosure refers to a separator, comprising a microcapsule consisting of core-shell layer-spacer layer and loading a thermal stabilizer, which can release the thermal stabilizer on the overheating of a battery using the same, thereby achieving thermal stability of the battery.