Wound Secondary Battery Can Structure for Electrode Separation
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Solution Overview
Problem
Current secondary batteries face challenges in achieving high safety and performance, particularly in maintaining appropriate distances between electrodes to prevent reactant precipitation and ensuring efficient charging and discharging processes.
Innovation Solution
The secondary battery design incorporates a stacked structure with a thick and thin part in the sidewall of the battery can, where the thick part overlaps the positive electrode active material layer, maintaining electrode separation and using a tabless structure to facilitate even charging and discharging, reducing internal resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional wound structure with uniform sidewall is used, then the battery structure is simple, but the electrode distance cannot be controlled to prevent reactant precipitation
Solution Approach 1:
The battery can sidewall is designed with different thicknesses at different locations: a first sidewall thickness in a first region and a second sidewall thickness in a second region. This local variation allows the thick part to maintain electrode distance and prevent reactant precipitation while the thin part reduces overall battery volume, resolving the contradiction between safety and structure complexity.
2Reliability
If the electrode distance is increased to prevent reactant precipitation, then safety is improved, but the battery volume increases
Solution Approach 1:
Instead of uniformly increasing electrode distance throughout the battery, the invention applies a localized thick sidewall only in the first region where reactant precipitation prevention is critical. The second region maintains a thinner sidewall, thus achieving safety requirements without proportionally increasing overall battery volume.
3Productivity
If a tabless structure is used to improve charging efficiency, then charging and discharging performance is improved, but the manufacturing complexity increases
Solution Approach 1:
The electrode structure is segmented into active material layers and exposed current collector portions (tabless configuration). This segmentation allows current to be collected from multiple locations along the electrode width, improving charging efficiency by reducing current density at any single point, while the segmentation itself creates the tabless structure that facilitates this enhanced performance.
Data Source
AI summary
A secondary battery includes an electrode wound body, a first electrode current collector plate, a second electrode current collector plate, an electrolytic solution, and a battery can. The first electrode current collector plate faces a first end face of the electrode wound body. The second electrode current collector plate faces a second end face of the electrode wound body. In the electrode wound body, an outermost wind part of a second electrode is located on an outer side relative to an outermost wind part of a first electrode. A sidewall part of the battery can includes a thin part, and a thick part that protrudes toward an inner side of the battery can along a radial direction. The thick part is located to overlap, in the radial direction, an end part, of the first electrode covered part, located on a side of the first end face in the first direction.