Rechargeable Battery Pouch with Step Portion for Edge Durability
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Solution Overview
Problem
The durability of pouch-type rechargeable batteries is compromised due to thin edges formed during the elongation process, leading to instability and potential safety issues under external impacts, especially in larger battery designs where the thickness decrease rate exceeds 50% at the edge, making it difficult to ensure the safety and stability of the electrode assembly.
Innovation Solution
The pouch design incorporates a case with a side portion featuring a step portion and slanted surfaces, where the thickness of the edge where the side and bottom surfaces meet is greater than 50% of the sealing portion, and the angles between slanted surfaces and a vertical line range from 0.5° to 45°, ensuring a more even elongation rate and reduced thickness decrease, thereby enhancing durability and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the laminate sheet is elongated to form the pouch, then the pouch can be formed into various shapes, but the edge portion becomes thinner and durability is compromised
Solution Approach 1:
The side portion is divided into multiple segments (first side portion, second side portion, third side portion) with different thickness characteristics. The first side portion maintains greater thickness while the second and third portions are elongated, segmenting the structural requirements to preserve strength where needed while achieving shape flexibility where required
Solution Approach 2:
Different portions of the pouch are given different thickness qualities according to their functional requirements. The edge portion where the side and bottom surfaces meet is designed with greater thickness (more than 50% of sealing portion thickness) to ensure durability, while other portions can be thinner to reduce weight and material usage
2Weight of moving object
If the laminate sheet is thin to reduce weight, then the pouch weight is reduced, but it is difficult to ensure durability and safety
Solution Approach 1:
The pouch structure implements local quality by varying the thickness distribution: the edge portion has greater thickness for durability while other areas can be thinner for weight reduction. This allows the pouch to be lightweight overall while maintaining safety and durability at critical locations
Solution Approach 2:
The pouch uses a laminate sheet with a multi-layer composite structure including a metal film layer and polymer coating layers. This composite material provides both weight reduction benefits and structural strength, allowing thin overall thickness while maintaining durability at critical edge portions
3Reliability
If the edge thickness is increased to ensure durability, then safety is improved, but laminate sheet consumption increases
Solution Approach 1:
The design applies local quality by concentrating the increased thickness only where structurally necessary (edge portion where side and bottom surfaces meet) rather than uniformly throughout the entire pouch. This localized thickening ensures safety and durability while minimizing additional laminate sheet consumption
Solution Approach 2:
The side portion is segmented into multiple sections with different thickness characteristics. Only the first side portion (edge portion) has greater thickness, while the second and third side portions have reduced thickness. This segmentation ensures safety at critical locations while reducing overall material consumption
Data Source
AI summary
A pouch for a rechargeable battery having stability by ensuring durability, a manufacturing method thereof, and a rechargeable battery including the same. The pouch includes a case having an opening and including a bottom surface portion, a side portion located along a periphery of the bottom surface portion and including at least one step portion, and a sealing portion located along a periphery of the side portion, and a cover configured to cover the opening of the case.