Cylindrical Secondary Battery Layout to Limit Flattening Diameter
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Solution Overview
Problem
Existing secondary batteries face challenges in maintaining a smaller maximum outer diameter without reducing capacity, which can lead to damage of the separator and decreased charging and discharging cyclability.
Innovation Solution
The secondary battery design features a circular columnar battery can with a distinct radial direction for the outer diameter of the battery can and outer package tube, ensuring they differ from each other, thereby reducing flattening and suppressing the increase in maximum outer diameter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the battery can and outer package tube are designed with aligned maximum outer diameter directions, then the manufacturing process is simplified, but the flattening increases and maximum outer diameter increases
Solution Approach 1:
The patent applies asymmetry by deliberately misaligning the maximum outer diameter directions of the battery can and outer package tube. The battery can's maximum outer diameter is in a first radial direction, while the outer package tube's maximum outer diameter is in a second radial direction that differs from the first. This asymmetric angular arrangement reduces flattening and suppresses increase in maximum outer diameter during charging and discharging cycles.
2Reliability
If the battery device uses a wound elliptical shape, then the charging and discharging cyclability characteristic is improved, but the maximum outer diameter increases
Solution Approach 1:
The patent resolves this contradiction by introducing asymmetric angular positioning between the battery can and outer package tube. The maximum outer diameter directions are arranged at different radial angles, which reduces flattening effects and suppresses the increase in maximum outer diameter while maintaining the structural benefits of the wound elliptical electrode configuration for improved cyclability.
3Device complexity
If the maximum outer diameter directions are aligned, then the structural simplicity is maintained, but the separator damage risk increases due to increased flattening
Solution Approach 1:
The patent addresses this contradiction by implementing asymmetric angular positioning where the maximum outer diameter directions of the battery can and outer package tube differ. This asymmetric arrangement reduces flattening of the battery structure, thereby lowering the risk of separator damage and improving reliability while adding controlled geometric complexity to the overall structure.
Data Source
AI summary
A secondary battery is provided and includes an electrode wound body, a battery can, and an outer package tube. The electrode wound body includes a positive electrode and a negative electrode that are stacked on each other with a separator interposed between the positive electrode and the negative electrode and are wound around a central axis. The battery can has a circular columnar outer shape in which a height direction corresponds to a direction along the central axis, and contains the electrode wound body. The outer package tube covers an outer peripheral surface of the battery can. Here, a first radial direction in which an outer diameter of the battery can is maximum and a second radial direction in which an outer diameter of the outer package tube is maximum differ from each other.