Flat Battery Sealing Can Design for Capacity and Strength
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Solution Overview
Problem
Conventional flat batteries face a trade-off between capacity and strength, with configurations that increase capacity often compromising sealing properties and vice versa, due to the deformation of the sealing can's circumferential wall during crimping.
Innovation Solution
A flat battery design featuring a sealing can with a single-layer circumferential wall that includes a rectilinear portion with higher Vickers hardness than the corner portion, and an upright portion with greater thickness and hardness, which suppresses deformation during crimping to maintain sealing properties, while allowing for increased capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a folded-back portion is formed in the sealing can to increase strength, then sealing properties are improved, but capacity is reduced
Solution Approach 1:
The patent applies local quality by creating a folded-back portion only at specific locations (corner portions and intermediate portions) of the sealing can's circumferential wall, rather than folding the entire wall. This localized folding provides strength enhancement exactly where needed during crimping, while preserving the overall capacity of the battery by minimizing the space occupied by the folded structure.
2Quantity of substance
If the circumferential wall is made thinner to increase capacity, then battery capacity is improved, but sealing properties deteriorate due to deformation during crimping
Solution Approach 1:
The patent applies preliminary action by pre-forming folded-back portions in the circumferential wall before the crimping process. These pre-formed folds create structural reinforcement that prevents deformation during the subsequent crimping operation. This allows the use of thinner wall materials for increased capacity while maintaining sealing reliability, as the folded portions anticipate and prevent the deformation that would otherwise occur during crimping.
Data Source
AI summary
A flat battery of the present invention is a flat battery including an exterior can and a sealing can with which an opening of the exterior can is sealed, wherein the exterior can and the sealing can include a bottom portion and a circumferential wall extending upright from an outer circumference of the bottom portion and have a cylindrical shape that is open at one end; a distal end portion of the circumferential wall of the exterior can is bent toward a central axis of the sealing can to form a curve, whereby the exterior can is fixed to the sealing can by crimping; in a cross-sectional shape of the sealing can in the direction of the central axis, the circumferential wall of the sealing can is a single layer wall without being folded back, and the circumferential wall of the sealing can includes a rectilinear portion that is connected to the bottom portion via a corner portion; and an angle θ1 formed by the bottom portion and the rectilinear portion may be greater than 90°.