Polyimide-Polyolefin Separator for Capacitor Short Circuit Prevention
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Solution Overview
Problem
Capacitor devices, such as batteries and capacitors, face issues with foreign substances like metal powder entering between electrode plates, leading to short circuits due to low resistance of existing separator layers, particularly those made of resin particles, which are prone to penetration and dendrite growth.
Innovation Solution
A separator-integrated electrode plate is designed with a polyimide layer and a polyolefin particle layer, where the polyimide layer provides mechanical strength and resistance to penetration, and the polyolefin particles have a melting point of 140° C or less, allowing ion permeability while preventing metal powder and dendrite penetration, and shutting down current flow in case of overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a separator layer is made of resin particles applied and dried on an electrode plate, then the manufacturing process is simplified, but the resistance to penetration of foreign substances such as metal powder and dendrite is reduced
Solution Approach 1:
The separator layer is constructed as a composite material combining a polyimide film base layer with a polyolefin resin particle layer. The polyimide film provides mechanical strength and penetration resistance, while the polyolefin particles provide heat-responsive shutdown functionality. This composite structure resolves the contradiction by integrating both structural integrity and functional properties in a single separator layer that maintains ease of manufacture through coating processes.
Solution Approach 2:
Different regions of the separator layer have different functions: the polyimide film portion provides mechanical strength and penetration resistance, while the polyolefin resin particles provide heat-responsive shutdown capability. This local differentiation of material properties allows the separator to simultaneously achieve high penetration resistance and reliable thermal protection without compromising manufacturing simplicity.
2Reliability
If a separator layer is made of porous film to improve resistance to penetration, then the resistance to penetration of foreign substances is improved, but the mechanical strength and resistance to fracture are reduced
Solution Approach 1:
The separator layer combines a polyimide film (providing mechanical strength) with a polyolefin resin particle layer (providing penetration resistance and thermal shutdown function). This composite approach allows the system to achieve both high mechanical strength and high penetration resistance simultaneously, resolving the contradiction between these two properties.
Solution Approach 2:
The polyimide film portion of the separator provides the mechanical strength and structural integrity, while the polyolefin resin particles provide the penetration resistance and thermal response functionality. This functional differentiation allows each material to optimize its contribution without compromising the other's properties.
3Ease of operation
If the separator layer allows ion permeation, then the capacitor device can function properly, but the resistance to penetration of metal powder and dendrite is reduced
Solution Approach 1:
The dual-layer composite structure of polyimide film and polyolefin particles creates a separator that maintains ion permeability through its porous structure while the polyimide film matrix provides mechanical barriers that resist penetration by metal powder and dendrite. The combination allows both ion transport and penetration resistance to coexist.
Solution Approach 2:
The separator layer utilizes a porous structure formed by the polyolefin resin particles that allows ion permeation for proper capacitor function, while the polyimide film base layer provides a mechanically strong matrix that prevents penetration by foreign substances. The porous architecture enables ion transport without sacrificing penetration 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 effectively prevents short circuits by enhancing the resistance of the separator layer to foreign substances and ensures safe shutdown in case of abnormal heat generation, maintaining ion permeability and mechanical integrity.
Implementation Method 1
the polyolefin resin particles having a melting point of 140° C. or less... if the battery abnormally generates heat because of a short circuit between the electrodes and other reasons and hence the temperature of the separator layer (the polyolefin particle layer) rises to a high temperature of 140° C. or more, the resin particles melt and fill in current paths, thereby shutting down a flow of current
Implementation Method 2
a separator layer provided on the active material layer and configured to allow ions contained in electrolyte to permeate through the separator layer
Data Source
AI summary
A separator-integrated electrode plate includes a current collecting sheet; an active material layer provided on the current collecting sheet, and a separator layer provided on the active material layer and configured to allow ions in electrolyte to pass through. The separator layer includes a polyimide layer provided on the active material layer and made of polyimide that has been melted in a solvent and then deposited as a film, and a polyolefin particle layer provided on the polyimide layer and made of polyolefin resin particles accumulated on the polyimide layer, the polyolefin resin particles having a melting point of 140° C. or less.