Wound Battery Cell Tape Layout to Prevent Wrinkles and Dendrites
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Solution Overview
Problem
In high-capacity batteries, the winding stop tape used to prevent loosening of the wound electrode body can become twisted and wrinkled, leading to uneven charging and discharging reactions and the deposition of metallic lithium dendrite, especially when the electrode body size increases.
Innovation Solution
The use of multiple winding stop tapes attached at intervals along the outer surface of the wound electrode body, with a configuration that includes a positive electrode tab group and a negative electrode tab group eccentrically disposed on the sealing plate, and a proportion of the total length of the winding stop tapes between 20% and 70%, to inhibit wrinkles and ensure even reactions during charging and discharging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single long winding stop tape is used to prevent loosening of the wound electrode body, then the winding loosening is prevented, but the tape becomes twisted and wrinkled leading to uneven charging and discharging reactions
Solution Approach 1:
The single long winding stop tape is divided into multiple shorter tapes attached at intervals along the wound electrode body. This segmentation prevents the tapes from twisting and wrinkling while still providing comprehensive prevention of winding loosening, thereby maintaining reliability while improving manufacturing precision and preventing dendrite formation
2Quantity of substance
If the size of the wound electrode body is increased to achieve high capacity, then the battery capacity increases, but the winding stop tape becomes longer and more prone to wrinkles
Solution Approach 1:
By dividing the winding stop tape into multiple segments attached at intervals, the patent enables the use of longer wound electrode bodies (higher capacity) without the winding stop tape becoming wrinkled. Each segment remains short and smooth while collectively covering the entire length of the high-capacity electrode body
3Stability of the object's composition
If the winding stop tape is attached continuously to prevent loosening, then the winding is secured, but wrinkles occur causing local thickness increase and uneven reactions
Solution Approach 1:
The continuous winding stop tape is replaced with multiple discrete tapes attached at intervals. This segmentation maintains the fixation stability of the wound electrode body while eliminating the wrinkles that cause local thickness increases, thereby preventing dendrite formation and uneven charging/discharging reactions
Solution Approach 2:
Instead of applying the winding stop tape continuously (excessive action), the patent uses multiple tapes at intervals (partial action). This provides sufficient fixation to prevent loosening while avoiding the harmful effects of continuous tape coverage, such as wrinkles and dendrite formation
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.