Cylindrical Battery Cap Assembly for Thin Sealing and Capacity
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Solution Overview
Problem
Existing secondary batteries face challenges in maintaining high capacity and energy density while ensuring airtightness and durability against forces applied during cell formation, particularly with thinner cap assemblies.
Innovation Solution
A secondary battery design featuring a cap assembly with a safety plate coupled to the lower surface of the cap-up, an insulation gasket wrapping around the cap-up and safety plate, and a gap filling portion between them, which improves airtightness and maintains a relatively large capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the cap assembly is made thinner to increase cell capacity and energy density, then the cell capacity and energy density are improved, but the cap assembly becomes more easily deformed by force applied during cell forming
Solution Approach 1:
The cap assembly is segmented into multiple functional components: cap-up, safety plate, insulation gasket, and seal ring. This segmentation allows each component to be optimized independently - the cap-up can be made thinner for increased capacity while the safety plate and other components provide the necessary structural strength and deformation resistance during cell forming.
Solution Approach 2:
The cap assembly uses composite construction with different materials for different components - the cap-up is made of aluminum foil (thin and flexible), while the safety plate, insulation gasket, and seal ring are made of resin materials with varying properties. This composite approach enables the thin cap-up to provide electrical function while the resin components provide mechanical strength and deformation resistance.
2Quantity of substance
If the cap assembly is made thinner to increase cell capacity and energy density, then the cell capacity and energy density are improved, but the airtightness of the cap assembly deteriorates
Solution Approach 1:
The sealing function is segmented from the cap-up and assigned to dedicated sealing components (insulation gasket and seal ring). This allows the cap-up to be made thinner for increased capacity while the specialized sealing components ensure airtightness through their specific geometric structures and material properties.
Solution Approach 2:
The insulation gasket and seal ring act as intermediary components between the thin cap-up and the external environment. These intermediary elements provide the airtight sealing function that would be difficult to achieve with a thin cap-up alone, allowing the cap-up to be optimized for capacity while maintaining reliability.
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 proposed design enhances airtightness and secures a larger capacity for cylindrical secondary batteries by reducing the overall thickness of the cap assembly while maintaining durability against applied forces.
Implementation Method 1
the gap filling portion may be formed by melting a part of the insulation gasket. In one or more embodiments, the gap filling part may be formed by melting a part of the insulation gasket at a temperature of 250°C to 280°C.
Data Source
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AI summary
A secondary battery includes a cylindrical can, an electrode assembly in the cylindrical can together with an electrolytic solution, and a cap assembly coupled to the top of the cylindrical can, the cap assembly including a cap-up, a safety plate coupled to a lower surface of the cap-up, and an insulation gasket wrapping the cap-up and the safety plate, the insulation gasket filling a gap filling portion between the cap-up and the safety plate.