Battery Outer Casing Insulation via Composite Layering
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Solution Overview
Problem
The insulation performance of existing outer casing materials for lithium secondary batteries is insufficient, particularly for in-vehicle applications where size constraints and high current demands require enhanced insulation properties.
Innovation Solution
A laminated outer casing material comprising a heat-resistant resin film, a metal foil layer, and a thermoplastic resin film with a specific melt flow rate and thickness range, along with adhesive layers, to provide improved insulation and hermetic sealing capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional outer casing material with resin layer, aluminum foil, and resin layer is used, then hermetic sealing properties are improved, but insulation performance is insufficient
Solution Approach 1:
The patent uses a composite structure consisting of a heat-resistant resin film layer, a metal foil layer, and a thermoplastic resin film layer. This multi-layer composite material combines the hermetic sealing properties of the resin layers with the insulation performance of the metal foil and heat-resistant resin, thereby resolving the contradiction between hermetic sealing and insulation performance.
Solution Approach 2:
The heat-resistant resin film layer acts as an intermediary between the metal foil layer and the thermoplastic resin film layer. It provides thermal stability and prevents direct contact between the thermoplastic resin and the metal foil during heat sealing, thereby maintaining insulation performance while enabling hermetic sealing through the thermoplastic layer.
2Object-affected harmful factors
If the thickness of the inner layer is increased to improve insulation, then insulation performance is improved, but weight and size increase
Solution Approach 1:
The patent employs a composite structure where a thin thermoplastic resin film layer (0.1-200 μm) is combined with a heat-resistant resin film layer and a metal foil layer. This composite design provides excellent insulation performance without requiring a thick single layer, thereby avoiding excessive weight increase while maintaining effective insulation.
Solution Approach 2:
The patent optimizes the thickness parameter of the thermoplastic resin film layer to be within 0.1-200 μm, and controls the melt flow rate within 1-10. These parameter optimizations enable the inner layer to provide sufficient insulation performance at minimal thickness, thus preventing weight increase while achieving the desired insulation effect.
3Ease of manufacture
If the melt flow rate of the inner layer is increased to improve heat-sealing properties, then heat-sealing properties are improved, but insulation performance deteriorates
Solution Approach 1:
The patent precisely controls the melt flow rate parameter of the thermoplastic resin film layer to be within 1-10, and optimizes the thickness to 0.1-200 μm. This parameter optimization enables the resin to achieve adequate heat-sealing properties without excessive flow that would reduce insulation performance, thereby resolving the contradiction between heat-sealing and insulation.
Solution Approach 2:
The heat-resistant resin film layer serves as a mediator that allows the thermoplastic resin layer to have good heat-sealing properties while preventing the resin from directly contacting the metal foil. This mediation enables the thermoplastic layer to be optimized for heat-sealing (with melt flow rate 1-10) without compromising the overall insulation performance of the composite structure.
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 achieves excellent insulation properties and hermetic sealing, suppressing internal short-circuits and maintaining high insulation resistance values, even under varying thickness and heat-sealing conditions, thus enhancing the performance and safety of lithium secondary batteries.
Implementation Method 1
heat-sealing properties are given to the resin layer of the inner layer. By inserting a cell into such a packaging container and heat-sealing the inner layers
Implementation Method 2
excellent insulation performance is required for an outer casing material thereof... maintaining high insulation resistance values
Implementation Method 3
an outer layer which includes a heat-resistant resin film... maintaining high insulation resistance values, even under varying thickness and heat-sealing conditions
Data Source
AI summary
An outer casing material for a battery is provided which is constituted by laminating an outer layer that includes a heat-resistant resin film, a metal foil layer, and an inner layer that includes a thermoplastic resin film, wherein a melt flow rate of the inner layer is in a range of greater than or equal to 1 and less than 10.