Cylindrical Battery Electrode Assembly for Better Cylindricity
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Solution Overview
Problem
Existing cylindrical secondary batteries face issues with cylindricity and are prone to lithium plating phenomena at the outer turns of the electrode assembly, which affects their performance and efficiency.
Innovation Solution
The electrode assembly is designed with an insulating film that wraps around the assembly for at least one turn, positioning the tail end of the insulating film behind the electrode assembly's tail end, reducing the diameter difference and optimizing cylindricity by ensuring the overlapping portion of the insulating films is at a thinner region, and specific angle arrangements between connecting lines to prevent lithium plating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the insulating film is wrapped around the electrode assembly for at least one turn with the overlapping portion at the thinner region, then the diameter difference is reduced and cylindricity is improved, but the device complexity increases
Solution Approach 1:
The insulating film acts as an intermediary component that wraps around the electrode assembly, with its overlapping portion strategically positioned at the thinner region (outer turns). This mediator compensates for the natural thickness variation of the wound electrode assembly, reducing diameter difference and improving cylindricity without fundamentally changing the electrode assembly structure itself.
Solution Approach 2:
The insulating film is not uniformly distributed but specifically positioned with its overlapping portion at the thinner region of the electrode assembly (outer turns). This local quality approach targets the specific area where diameter variation occurs, providing precise correction to improve cylindricity while minimizing overall complexity.
2Shape
If the insulating film is positioned to reduce diameter difference at outer turns, then cylindricity is enhanced, but the manufacturing precision requirements increase
Solution Approach 1:
The insulating film is pre-positioned with its overlapping portion designed to align with the thinner region of the electrode assembly before final assembly. This preliminary action ensures that the diameter correction is built into the structure, reducing the need for high-precision adjustments during manufacturing and assembly processes.
Solution Approach 2:
The insulating film changes the effective diameter parameter of the electrode assembly by providing additional thickness at the outer turns where the electrode assembly is thinnest. This parameter change compensates for the natural thickness variation, improving cylindricity without requiring changes to the electrode assembly manufacturing process itself.
Data Source
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AI summary
A secondary battery (100), a pack, and an electronic apparatus are provided. The secondary battery (100) includes an electrode assembly (120) formed by a first electrode sheet (121), a first separator (141), a second electrode sheet (122), and a second separator (142) and an insulating film (300). A protruding end of a tail end (141e) of the first separator (141) and a tail end (142e) of the second separator (142) constitutes the tail end (120e) of the electrode assembly (120). A tail end (122e) of the second electrode sheet (122) extends beyond a tail end (121e) of the first electrode sheet (121). The tail end (120e) of the electrode assembly (120) extends beyond the tail end (122e) of the second electrode sheet (122). A starting end (300s) of the insulating film (300) extends beyond the tail end (120e) of the electrode assembly (120).