Cylindrical Battery Insulating Plate for Lead Fold Control
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Solution Overview
Problem
Cylindrical secondary batteries face issues with short-circuiting due to variations in the folding position of the positive electrode lead with respect to the insulating plate, leading to production failures and increased costs, particularly when the lead hole size in the arc direction affects insertability.
Innovation Solution
A cylindrical non-aqueous electrolyte secondary battery design featuring an insulating plate with a lead hole having a concentric arc and chord-shaped straight portions to prevent short-circuiting by controlling the positive electrode lead's folding position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the lead hole size in the arc direction is increased to improve the insertability of the positive electrode lead, then the ease of manufacture is improved, but the risk of short-circuiting increases due to greater variation in folding position
Solution Approach 1:
The lead hole is designed with an asymmetric shape consisting of a semicircular arc portion and a straight line portion, rather than a symmetric circular shape. This asymmetric configuration creates a preferred folding direction for the positive electrode lead, guiding it away from the electrode group while maintaining a manageable hole size for easy insertion.
Solution Approach 2:
The insulating plate is pre-formed with the specific lead hole shape and the positive electrode lead is pre-positioned to extend in the radial direction before final assembly. This preliminary configuration ensures that the lead naturally folds away from the electrode group through the arc portion, preventing short-circuiting before the battery is completed.
2Reliability
If the lead hole size is reduced to decrease the folding position variation, then the reliability is improved, but the insertability of the positive electrode lead deteriorates
Solution Approach 1:
The lead hole shape transitions from a one-dimensional size constraint to a two-dimensional geometric configuration. By using a combination of arc and straight line portions, the hole maintains a compact area (controlling folding variation) while providing sufficient opening in specific directions (maintaining insertability).
Solution Approach 2:
Different portions of the lead hole have different functional qualities: the arc portion provides guidance for lead insertion and folding, while the straight line portion defines the boundary that limits folding position variation. This local differentiation of hole characteristics simultaneously achieves both insertability and reliability.
Data Source
AI summary
The secondary cell—includes an exterior can, a sealing body closing one end of the exterior can, an electrode group disposed inside the exterior can, and an insulating plate disposed between the sealing body and the electrode group. In the electrode group, a positive electrode and a negative electrode are wound in a spiral shape with a separator interposed between. The insulating plate is shaped as a disc having a lead hole penetrated by a positive electrode lead drawn out from the electrode group, and a center hole penetrating the center part of the insulating plate. The outer edge of the lead hole includes a curve part positioned along an arc that is concentric with respect to the outer circumference of the insulating plate as seen in plan view, and linear parts-positioned along a chord linking the two ends of the arc.