Battery Packaging Material Thickness Design for Pinhole Suppression
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Solution Overview
Problem
Conventional battery packaging materials, particularly film-shaped laminates, face challenges in suppressing pinholes and cracks during molding, which can lead to electrolyte leakage and short-circuits, especially when the metal layer thickness is reduced below 30 μm, limiting their diversification, thinning, and weight reduction capabilities.
Innovation Solution
A battery packaging material comprising a sheet-shaped laminate with a base material layer, a metal layer, and a sealant layer, where the thickness of the metal layer at curved sections and between sections satisfy specific relationships (a≥b>c or a≥c>b), effectively reducing the generation of pinholes and cracks, even at very small thicknesses, and incorporating an adhesive layer for enhanced bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the thickness of the metal layer is reduced to achieve weight reduction and thinning, then the weight and thickness of the battery packaging material are reduced, but pinholes and cracks are very easily generated during molding
Solution Approach 1:
The invention applies different thickness requirements to different regions of the metal layer. Specifically, the first curved section (corner region) requires a thickness of 30 μm or more, while other sections can have reduced thickness. This local differentiation allows weight reduction in non-critical areas while maintaining pinhole suppression in critical corner regions where stress concentrates during molding.
Solution Approach 2:
The invention establishes thickness specifications for the metal layer before the molding process occurs. By pre-determining that the first curved section must have a thickness of 30 μm or more, the design proactively prevents pinhole generation during subsequent molding operations, rather than attempting to correct defects after they occur.
2Length of moving object
If the thickness of the metal layer is reduced to achieve thickness reduction, then the thickness of the battery packaging material is reduced, but pinholes and cracks are very easily generated during molding
Solution Approach 1:
The invention applies different thickness requirements to different regions of the metal layer. Specifically, the first curved section (corner region) requires a thickness of 30 μm or more, while other sections can have reduced thickness. This local differentiation allows thickness reduction in non-critical areas while maintaining pinhole suppression in critical corner regions where stress concentrates during molding.
3Reliability
If adhesive layers are added to improve moldability, then the bonding strength is improved, but the device complexity increases
Solution Approach 1:
The invention changes the thickness parameter of the metal layer in the first curved section to 30 μm or more, which fundamentally improves moldability and reduces pinhole generation. This parameter change achieves the bonding and sealing reliability needed for deep molding without requiring additional adhesive layers, thereby avoiding increased structural complexity.
Data Source
AI summary
Battery packaging material wherein a sheet-like laminated body is formed by sequentially stacking at least a base layer, metal layer, and sealant layer, the battery packaging material being equipped with substantially rectangular space that is formed to protrude from the sealant layer side toward the base layer side, and accommodates a battery element on the sealant layer side. In planar view from the base layer side view, a first and second curved sections are provided from the center portion toward the battery packaging material end parts, in a cross section in the thickness direction on a line connecting opposing corner parts protruding in a substantially rectangular shape. The thickness (a) of the metal layer at the first curved section, (c) of the metal layer at the second curved section, and (b) of the metal layer at the section located between the first and second curved sections, satisfy the following relationship a≥b>c or a≥c>b.