Rechargeable Battery Upper Tape Separator Shrinkage
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Solution Overview
Problem
Rechargeable batteries face electrical shorts due to shrinkage of the separator, which is not adequately held by the finishing tape, leading to contact between the positive and negative electrode plates during charging or discharging and heat exposure.
Innovation Solution
A rechargeable battery design that includes an upper tape with high heat resistance and insulating properties, coated with synthetic resin, surrounding the separator at the upper end of the electrode jelly roll to prevent shrinkage and electrical contact between the electrode plates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the separator is formed longer than the electrode plates to prevent electrical shorts, then the reliability is improved, but the separator shrinks during charging/discharging and heat exposure causing electrical shorts
Solution Approach 1:
The finishing tape is applied in advance to the electrode assembly before the separator shrinkage problem occurs. This preliminary action secures the separator at the wound end portion, preventing it from shrinking during subsequent charging/discharging cycles and heat exposure, thereby maintaining electrical isolation between electrodes throughout the battery's operational life.
Solution Approach 2:
The finishing tape acts as an intermediary element between the separator and the electrode assembly structure. It mediates the mechanical stresses and thermal expansions by securing the separator at the wound end portion, preventing direct contact between the separator and electrode plates while allowing the separator to maintain its electrical isolation function during operational changes.
2Ease of manufacture
If the finishing tape is attached only to the electrode assembly without securing the separator, then the manufacturing process is simplified, but the separator cannot be held properly leading to electrical shorts
Solution Approach 1:
The finishing tape is designed to perform dual functions: it finishes the electrode assembly winding and simultaneously secures the separator at the wound end portion. This self-service approach eliminates the need for separate separator securing steps, maintaining manufacturing simplicity while ensuring reliable separator positioning throughout battery operation.
3Use of energy by moving object
If the separator is exposed to heat from electrode tabs during charging/discharging, then the battery operates normally, but the heat causes separator shrinkage and electrical contact between electrodes
Solution Approach 1:
The finishing tape provides beforehand cushioning by securing the separator at the wound end portion before heat-induced shrinkage occurs during charging/discharging operations. This protective measure cushions the separator against thermal contraction, preventing electrical shorts while allowing normal battery operation and heat generation.
Data Source
AI summary
A rechargeable battery and its fabrication method prevents electrical shorts between the electrode plates by decreasing shrinkage of the separator, the battery includes: an electrode assembly including: a wound electrode jelly roll having a first electrode plate with a first electrode tab attached thereto, a second electrode plate with a second electrode tab attached thereto and a separator interposed between the first electrode plate and the second electrode plate, and an upper tape arranged to surround an upper end of the electrode jelly roll where the first electrode tab and second electrode tab extend outward therefrom; a case having an upper end opening arranged to receive the electrode assembly and an electrolyte; and a cap assembly arranged to seal the upper end opening of the case after the electrode assembly has been received in the case; the upper tape is attached to the upper end of the electrode jelly roll and surrounds the separator adjacent to an end of an innermost electrode plate of the first and second electrode plates.