Lead Foil Surface Roughness for Bipolar Battery Breakage Resistance
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Solution Overview
Problem
Lead foil in bipolar lead acid storage batteries experiences growth deformation over time, leading to breakage, which increases internal resistance and poses a significant problem in battery performance.
Innovation Solution
The lead foil is processed to have a maximum valley depth of 4 μm or less on at least one surface, ensuring uniform thickness and reducing the likelihood of breakage due to growth deformation, with preferred compositions including Sn, Ca, Ag, Cu, and Bi to enhance adhesion and corrosion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lead foil is used for electrodes in bipolar lead acid storage batteries, then the battery can function properly with positive and negative electrodes, but the lead foil experiences growth deformation over time leading to breakage
Solution Approach 1:
The patent applies parameter changes by controlling the surface roughness of the lead foil, specifically setting the maximum valley depth Rv to 15 μm or less. This parameter control prevents excessive deformation during battery operation, maintaining both the reliability of battery function and the strength of the lead foil against breakage.
2Strength
If the lead foil surface is smooth, then the maximum valley depth is reduced preventing breakage, but the adhesion between lead foil and active material may be reduced
Solution Approach 1:
The patent optimizes the surface roughness parameter to a specific range (maximum valley depth Rv of 15 μm or less) that balances two competing requirements: it is smooth enough to prevent breakage from excessive deformation, yet maintains sufficient adhesion strength for the active material. This precise parameter control resolves the contradiction between strength and adhesion.
Data Source
AI summary
A lead foil and a bipolar lead acid storage battery capable of preventing breakage of the lead foil due to growth deformation are described. The lead foil is for a current collector in a bipolar lead acid storage battery, in which at least one of a front surface or a back face has a maximum valley depth Rv of 4 μm or less in a profile curve acquired, orthogonally to a rolling direction, by surface roughness measurement with a stylus.