Battery Packaging Laminate for Uniform Coil Slipperiness
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Solution Overview
Problem
Packaging materials for power storage devices, such as batteries, experience variations in molding workability due to differences in slipperiness between the coil center and outer peripheral portions when wound into a coil shape, leading to inconsistent molding processes and difficulties in achieving sharp, deep molded shapes.
Innovation Solution
A packaging material with a laminated structure comprising a metal foil layer, a substrate layer, and a heat-fusible resin layer formed from a polyolefin-based film, where the ratio of indentation modulus to indentation hardness of the heat-fusible resin layer is between 21 to 50, and the arithmetic mean height of the inner surface is within 0.07 μm to 0.3 μm, ensuring consistent slipperiness and molding workability across the entire length of the material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the packaging material is lengthened to extend continuous molding processing time, then productivity is improved, but the slipperiness deteriorates at the coil center portion due to huge compressive load during winding
Solution Approach 1:
The patent applies local quality by making the heat-fusible resin layer have different properties at different locations. Specifically, the indentation modulus is set to 30-100 MPa and indentation hardness to 0.5-2.0 MPa, creating a material with local elasticity that can withstand compressive loads during winding while maintaining slipperiness. This local property adjustment ensures that even the coil center portion maintains adequate slipperiness after winding, resolving the contradiction between lengthening the material for productivity and maintaining reliable molding workability throughout.
2Manufacturing precision
If the surface roughness is adjusted to increase slipperiness, then molding workability is improved, but the surface shape changes significantly under compressive load during winding
Solution Approach 1:
The patent applies parameter changes by precisely controlling the mechanical properties of the heat-fusible resin layer. The indentation modulus is set to 30-100 MPa and indentation hardness to 0.5-2.0 MPa, creating an optimal balance. These parameter adjustments allow the surface to maintain sufficient slipperiness for good molding workability while having enough structural stability to resist significant shape changes under compressive loads during winding, thus resolving the contradiction between manufacturing precision and composition stability.
3Ease of operation
If the packaging material is wound into a coil shape to facilitate handling, then ease of operation is improved, but the slipperiness varies between coil center and outer peripheral portions
Solution Approach 1:
The patent applies local quality by designing the heat-fusible resin layer with specific mechanical properties (indentation modulus: 30-100 MPa, indentation hardness: 0.5-2.0 MPa) that provide different functional characteristics. This local property optimization ensures that the material can be wound into coils for easy handling while maintaining relatively uniform slipperiness across the entire coil, including the compressively-loaded center portion, thus resolving the contradiction between ease of operation and manufacturing precision.
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
This solution stabilizes molding workability along the entire length of the packaging material, maintains good slipperiness after unwinding, reduces color tone differences in molded articles, and prevents electrolyte contamination, allowing for the production of packaging cases with sharp, deep shapes for power storage devices.
Implementation Method 1
the surface shape of the packaging material of the coil center portion restores to the original shape
Implementation Method 2
the slipperiness of the packaging material is adjusted to fall within a predetermined range
Data Source
AI summary
A packaging material for a power storage device is formed of a laminated material in which a metal foil layer, a substrate layer provided on an outer surface side of the metal foil layer, and a heat-fusible resin layer provided on an inner surface side of the metal foil layer are laminated. The heat-fusible resin layer is arranged on an inner surface of the packaging material. The heat-fusible resin layer is formed of a polyolefin-based film. A ratio EIT/HIT of an indentation modulus EIT to an indentation hardness HIT of the heat-fusible resin layer measured using a Berkovich indenter is in a range of 21 to 50.