Square Battery Convex Features for Shape Precision
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Solution Overview
Problem
Reduced thickness in metal can secondary batteries leads to variations in internal pressure, causing shape deformations and degrading the precision of the outer shape, necessitating large dimensional tolerances in battery pack and module design.
Innovation Solution
Incorporating convex portions on the surfaces of the outer can and lid of the battery, allowing for precise evaluation of the battery's outer shape through distances between these features, enhancing shape precision and error evaluation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the metal can thickness is reduced to decrease weight and improve mounting density, then weight reduction and mounting density improvement are achieved, but variations in internal pressure cause shape deformations and outer shape precision degradation
Solution Approach 1:
The patent introduces convex portions with specific geometric parameters (protrusion height h1, base width w1, spacing d1) on the metal can surface. These parameterized features serve as dimensional references that maintain measurement precision despite the thin-walled structure's susceptibility to pressure-induced deformations. The convex portions transform the measurement reference from the degradable can surface to the stable protrusion features.
2Area of stationary object
If the metal can thickness is reduced to improve mounting density, then mounting density is improved, but outer shape precision degrades due to shape deformations
Solution Approach 1:
The patent defines specific parameter ranges for the convex portions (protrusion height h1: 0.1-5mm, base width w1: 2-20mm, spacing d1: 3-30mm) that optimize the balance between maintaining outer shape precision and achieving high mounting density. These parameterized features enable precise dimensional measurement while the thin-walled design maintains high packing efficiency.
3Measurement precision
If convex portions are added to the outer can and lid surfaces for shape evaluation, then outer shape evaluation precision is improved, but device complexity increases
Solution Approach 1:
The patent applies the convex portion features only at specific locations on the outer can and lid surfaces where dimensional reference is needed, rather than uniformly across the entire battery structure. This localized application provides measurement precision at critical points while minimizing the overall structural complexity and material usage.
Solution Approach 2:
The convex portions are designed with curved or rounded features (protrusions with height h1 and base width w1) that are easier to manufacture with standard metal forming processes compared to sharp edges or complex geometries. The curved surfaces of the convex portions provide stable dimensional references that are tolerant to minor manufacturing variations.
Data Source
AI summary
A square secondary battery of an embodiment includes an outer can formed in a shape of a bottomed cylinder having a cross-sectional shape of a substantially quadrangular shape, the outer can having an opening, a power generation element contained in the outer can, and a lid having a positive electrode terminal and a negative electrode terminal, the lid covering the opening of the outer can. Two or more convex portions exist on each of one or more surfaces of a side surface of an outer surface of the outer can, a bottom surface of the outer surface of the outer can, and a surface having the positive electrode terminal and the negative electrode terminal of an outer surface of the lid.