Wound Electrode Battery Structure Using Segmented Stop Tapes
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Solution Overview
Problem
In high-capacity type batteries, especially those used for in-vehicle applications, the increased size of the wound electrode body leads to longer winding stop tapes, which are prone to twisting and wrinkling. These wrinkles can cause uneven charging and discharging reactions and the deposition of metallic lithium (dendrite).
Innovation Solution
The battery design incorporates multiple winding stop tapes attached to the outer surface of the wound electrode body at intervals along the winding axis direction. This configuration helps to inhibit the occurrence of wrinkles on the winding stop tapes, even when the wound electrode body is long, thereby reducing the likelihood of uneven reactions during charging and discharging and preventing dendrite formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the wound electrode body size is increased for high-capacity battery, then the battery capacity is improved, but the winding stop tape becomes longer and is more likely to wrinkle
Solution Approach 1:
The single long winding stop tape is divided into multiple shorter winding stop tapes (first, second, and optionally third winding stop tapes) arranged in the winding axis direction. This segmentation prevents the tape from twisting and wrinkling while still providing effective winding prevention for the long electrode body in high-capacity batteries.
2Reliability
If a single long winding stop tape is used, then the winding is prevented, but the tape is likely to twist and wrinkle when pulled out
Solution Approach 1:
The winding stop function is distributed across multiple shorter tapes instead of one long tape. Each tape is attached at different positions along the winding axis, providing reliable winding prevention while maintaining tape integrity and avoiding twisting or wrinkling.
3Manufacturing precision
If the winding stop tape is wrinkled, then the step is formed and thickness is locally increased, but this leads to uneven charging and discharging reaction
Solution Approach 1:
By using multiple shorter winding stop tapes instead of one long tape, the risk of wrinkling is significantly reduced. Each short tape can be properly attached without the cumulative twisting and wrinkling that occurs with long tapes, thereby maintaining uniform electrode body thickness and ensuring reliable charging and discharging performance.
4Stability of the object's composition
If pressure is applied to the wound electrode body, then the compactness is improved, but the wrinkled portion is strongly pressed causing dendrite deposition
Solution Approach 1:
Multiple shorter winding stop tapes eliminate wrinkling that would otherwise create localized thick portions. When pressure is applied during battery assembly, the uniform surface ensured by segmented tapes prevents concentrated stress on wrinkled areas, avoiding dendrite formation while still achieving the necessary compactness.
Data Source
AI summary
A battery disclosed herein includes: an exterior body including a bottom wall and an opening facing the bottom wall; a sealing plate sealing the opening of the exterior body; and one or a plurality of wound electrode bodies, in which a band-shaped positive electrode including a positive electrode active material layer and a band-shaped negative electrode including a negative electrode active material layer are laminated via a band-shaped separator and are wound around a winding axis. A length of the positive electrode active material layer is 15 cm or more in a winding axis direction of the wound electrode body. A plurality of winding stop tapes are attached to an outer surface of the wound electrode body at intervals in the winding axis direction.