Pouch Battery Cup Geometry for Higher Cell Volume and Flat Edges
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Solution Overview
Problem
Pouch-type secondary batteries face limitations in increasing energy density relative to volume and achieving an elegant outer appearance, leading to reduced marketability due to constraints in moldability and curvature radius of the cup part, resulting in a small volume ratio of the electrode assembly and a protruding edge phenomenon.
Innovation Solution
The design includes a pouch-type battery case with a cup part that has a difference in width with the electrode assembly of 2.5 mm or less, featuring rounded punch edges and a curvature radius corresponding to 1/20 to 1/6 of the cup part's depth, along with a moisture barrier layer made of an AA8021 aluminum alloy with a thickness of 50 μm to 80 μm and grain size of 10 μm to 13 μm, enhancing moldability and reducing the edge high phenomenon.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the moisture barrier layer uses aluminum alloy with large crystal grain size and thin thickness, then the manufacturing cost is reduced, but the moldability is deteriorated
Solution Approach 1:
The patent changes the material parameters by using aluminum alloy with small crystal grain size (10-20 μm) and increased thickness (50-80 μm) to improve moldability. This parameter change allows the pouch film to be deeply molded while maintaining structural integrity and preventing edge high phenomenon.
2Volume of stationary object
If the cup part is molded deeply, then the volume of the electrode assembly is increased, but the curvature radius and clearance of the edge cannot be improved
Solution Approach 1:
By changing the material parameters (small crystal grain size and increased thickness), the patent enables deep molding while maintaining small curvature radius and clearance at the edges. The improved moldability allows the cup part to be formed with both deep volume and sharp edge geometry.
Solution Approach 2:
The patent uses a composite pouch film structure with multiple layers including the aluminum alloy moisture barrier layer (50-80 μm thick with small grain size), sealant layers, and surface protection layers. This composite structure provides both the necessary mechanical strength for deep molding and the surface properties for achieving small curvature radius at edges.
3Quantity of substance
If the volume ratio of the electrode assembly to the cup part is small, then the manufacturing is simplified, but the energy density relative to volume is reduced
Solution Approach 1:
The patent increases the volume ratio by improving moldability through material parameter changes. The aluminum alloy with small crystal grain size and increased thickness enables the cup part to be molded more deeply, increasing the electrode assembly volume and thus the volume ratio, which directly improves energy density.
4Ease of manufacture
If the edge high phenomenon occurs, then the manufacturing process is simpler, but the height increases and energy density is reduced
Solution Approach 1:
The patent prevents edge high phenomenon by using aluminum alloy with small crystal grain size (10-20 μm) and increased thickness (50-80 μm). These parameter changes provide sufficient mechanical strength and moldability to maintain sharp edges and prevent protrusion during deep molding, achieving both simple manufacturing and elegant appearance.
Data Source
AI summary
A pouch-type secondary battery according to an embodiment of the present invention for achieving the above object includes: an electrode assembly in which electrodes and separators are stacked; and a pouch-type battery case comprising a cup part configured to accommodate the electrode assembly therein, wherein a difference in width of the cap part and the electrode assembly is 2.5 mm or less.