Cylindrical Battery Negative Electrode Tab Groove Design
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Solution Overview
Problem
Cylindrical non-aqueous electrolyte secondary batteries face issues with blocked hollow parts during abnormal heat generation, preventing smooth gas discharge and potential buckling of electrode tabs due to cornered projections.
Innovation Solution
A non-facing part in the negative electrode is wound without facing the positive electrode, with a negative electrode tab joined for over 0.75 turns and featuring a groove along its width direction to prevent excessive cornering and ensure smooth gas discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the negative electrode tab is wound for more than or equal to 0.75 turns to prevent blockage of the hollow part, then gas discharge capability is improved, but the two ends of the negative electrode tab project in a cornered form causing increased diameter and potential buckling
Solution Approach 1:
The negative electrode tab is divided into two functional parts: a first negative electrode tab portion wound for more than or equal to 0.75 turns to ensure gas discharge capability, and a second negative electrode tab portion wound for less than 0.5 turns to prevent cornered projection. This segmentation allows each part to fulfill its specific function without compromising the other.
Solution Approach 2:
Different winding lengths are applied to different portions of the negative electrode tab based on their functional requirements. The first portion has extended winding (≥0.75 turns) for gas discharge, while the second portion has limited winding (<0.5 turns) to avoid projection, creating local quality differences that optimize overall performance.
2Stability of the object's composition
If the non-facing part is extended for more than or equal to two full turns to suppress deformation, then winding-start side stability is improved, but the hollow part may become blocked during abnormal heat generation
Solution Approach 1:
The negative electrode structure is segmented into a non-facing part for stability and a tab portion for gas discharge. The tab is further divided into two portions with different winding lengths, allowing the system to achieve both deformation suppression and blockage resistance simultaneously.
Solution Approach 2:
The winding length parameter is optimized differently for different parts of the negative electrode tab. By setting specific winding length ranges (≥0.75 turns for the first portion, <0.5 turns for the second portion), the invention achieves optimal balance between stability and gas discharge capability.
Data Source
Figure 1
Figure 2~3
Figure 4~5(b)
AI summary
This cylindrical nonaqueous electrolyte secondary battery includes a positive electrode (11) and a negative electrode (12). The negative electrode (12) includes: a non-facing portion (60) wound, toward a winding start side, from a facing portion (59) facing a winding inner side of a start end portion (11a) of the positive electrode (11), in a winding direction in a state in which the non-facing portion (60) does not face the positive electrode (11); and a negative electrode tab (21) joined to the non-facing portion (60). The negative electrode tab (21) includes a negative electrode facing portion (21a) facing the negative electrode (12) and a lead-out portion (21b) that is shorter in length than a portion which is of the negative electrode facing portion and has the longest length in the longitudinal direction of the negative electrode in an expanded state and is led out to the outside with respect to one end of the negative electrode in the width direction. The portion having the longest length of the negative electrode facing portion is wound around 0.75 times or more and a root portion which is the boundary of the lead-out portion with the negative electrode facing portion is wound around less than 0.5 times. At least one groove (22) extending along the width direction of the negative electrode is provided in the negative electrode facing portion.