Secondary Battery Electrode Layout for Stable Collector Welding
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Solution Overview
Problem
The existing secondary battery designs face challenges in achieving stable welding and flatness of the collector body exposure parts, leading to unstable welding and potential buckling issues, which affect the internal resistance and performance during high-rate discharging.
Innovation Solution
The battery design stabilizes the bending point of the negative electrode active material uncovered parts by using a structured configuration with insulating layers, ensuring proper overlap and flatness, thereby reducing gaps and improving weld quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the collector body exposure part is bent to be welded, then the battery can be assembled, but the welding becomes unstable and flatness cannot be ensured due to buckling
Solution Approach 1:
The insulating layer is formed on the collector body exposure part before bending and welding operations. This preliminary coating prevents buckling during bending by providing a protective layer that maintains structural integrity, ensuring the surface remains sufficiently flat for stable welding without requiring post-bending corrections
2Power
If high-rate discharging is implemented to achieve high output power, then power delivery improves, but internal resistance increases causing instability
Solution Approach 1:
A resin coating is applied to the collector body exposure part to prevent oxidation and maintain low contact resistance. This protective layer ensures stable electrical connection during high-rate discharging by preventing degradation of the collector body surface, thereby maintaining reliability while enabling high power output
Data Source
AI summary
A secondary battery suppresses an occurrence of a welding defect as much as possible. A negative electrode includes, at a first major surface of a negative electrode foil having a band shape, a first negative electrode active material covered part covered with a negative electrode active material layer, a first negative electrode active material uncovered part extending in a longitudinal direction of the negative electrode foil, and a first insulating layer provided between the first negative electrode active material covered part and the first negative electrode active material uncovered part. The negative electrode further includes, at a second major surface which is another major surface of the negative electrode foil, a second negative electrode active material covered part covered with a negative electrode active material layer, a second negative electrode active material uncovered part extending in the longitudinal direction of the negative electrode foil, and a second insulating layer provided between the second negative electrode active material covered part and the second negative electrode active material uncovered part. When at least a negative electrode side of an electrode wound body is viewed in a section taken along a plane including a central axis, the first major surface faces toward the central axis of the electrode wound body, and furthermore, the first insulating layer is smaller in length than the second insulating layer.