Cylindrical Battery Expansion Tape for Positive End Insulation
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Solution Overview
Problem
Conventional cylindrical batteries face a risk of short circuits due to the folding of aluminum foil over the outer housing, despite the use of insulating caps, which is not addressed by existing structural designs.
Innovation Solution
A cylindrical battery design incorporating expansion tape wound around the wound core, where the expansion tape's top is level with or higher than the separator's top, expanding in three dimensions to fill gaps and separate the positive electrode end from the outer housing, accompanied by an insulating cap for double protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an insulating cap is used to protect the positive electrode end, then electrical insulation is improved, but the risk of aluminum foil folding over and contacting the outer housing remains
Solution Approach 1:
The expansion tape serves as an intermediary component between the positive electrode end and the outer housing. It actively expands to fill the gap and prevent aluminum foil from folding over and contacting the housing, providing an additional protective layer that addresses the short circuit risk that the insulating cap alone cannot prevent.
Solution Approach 2:
The expansion tape is pre-installed around the positive electrode end before final assembly. It is designed to expand automatically when exposed to moisture from the electrolyte, proactively filling the gap between the electrode and housing before any aluminum foil folding can occur, thus preventing the short circuit hazard in advance.
2Reliability
If expansion tape is added to prevent aluminum foil folding, then short circuit risk is reduced, but device complexity increases
Solution Approach 1:
The expansion tape is designed to be self-activating through automatic expansion when exposed to moisture from the electrolyte. This self-service mechanism eliminates the need for additional actuators, sensors, or control systems, adding functionality without significantly increasing device complexity. The tape autonomously fills the gap and prevents aluminum foil folding.
Solution Approach 2:
The expansion tape utilizes parameter changes in its material properties - specifically, it transitions from a compact state to an expanded state through moisture absorption. This parameter change allows the same component to serve multiple functions: initial gap filling during assembly and subsequent active prevention of aluminum foil folding, thereby improving reliability without adding structural complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design effectively prevents short circuits by ensuring the expansion tape and insulating cap cover the positive electrode end, conforming to existing structural tolerances and withstanding high temperatures, thus eliminating the risk of contact with the outer housing.
Implementation Method 1
the expansion tape expands in the directions of three dimensions, namely length, width and thickness, after coming into contact with electrolyte
Data Source
AI summary
A cylindrical battery with expansion tape including an outer housing and a wound core accommodated in the outer housing, wherein the wound core is obtained by winding and flattening a positive electrode sheet, a negative electrode sheet and a separator. The wound core includes a positive electrode end face and a negative electrode end face, and expansion tape is wound around an outer periphery of the wound core. At least at a positive electrode end of the wound core, before expansion of the expansion tape, the top of the expansion tape is level with or higher than the top of the separator.