One-Sided Embossed Copper Tab for Battery Anti-Folding
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Solution Overview
Problem
Ultra-thin copper foil tabs used in batteries are prone to folding and warpage due to residual internal stress and external forces, leading to short circuits and product quality issues, with existing reinforcing rib devices either enhancing strength but risking fracture or failing to adequately address folding.
Innovation Solution
A tab made from copper foil with a surface having large compressive stress (S surface) and a surface with small compressive stress (M surface), where only the M surface is provided with an indentation or reinforcing rib, and the processing directions are controlled to ensure the M surface faces outward or inward during coating, rolling, slitting, and die cutting to counteract residual stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a tab reinforcing rib device is adopted to emboss the two surfaces of the tab, then the strength of the tab is enhanced and folding and warpage are improved, but tab fracturing occurs
Solution Approach 1:
The patent applies local quality by providing the reinforcing rib structure only on one surface of the copper foil tab rather than both surfaces. This localized approach strengthens the tab at critical areas while avoiding excessive stress concentration that would cause fracturing. The one-sided embossing creates asymmetric stress distribution that effectively prevents folding without inducing the fractures seen in two-sided embossing.
Solution Approach 2:
The patent employs asymmetry by embossing only one surface of the copper foil tab. This asymmetric treatment creates a reinforcing rib structure that counteracts the internal stress and folding tendencies of the ultra-thin copper foil without the harmful effects of symmetric two-sided embossing. The asymmetric design allows the tab to maintain strength while avoiding the fracturing issue.
2Reliability
If embossing is performed asynchronously on the two surfaces of the tab, then tab folding is reduced, but tab fracturing occurs
Solution Approach 1:
The patent applies the taking out principle by extracting the embossing operation from one surface only, rather than performing it on both surfaces. This selective removal of the embossing operation from one surface prevents the stress concentration and fracturing that occurs with two-sided embossing, while still achieving the desired effect of reducing tab folding through the reinforcing rib structure on the single embossed surface.
3Reliability
If conventional tab reinforcing methods are used, then some folding is reduced, but productivity decreases due to rewinding requirements
Solution Approach 1:
The patent applies preliminary action by performing the embossing operation during the initial coating or rolling process, rather than as a separate subsequent step. This integrated approach allows the reinforcing rib structure to be formed while the copper foil is still in a more pliable state, eliminating the need for rewinding operations and thereby maintaining high productivity while still achieving effective folding reduction.
Data Source
AI summary
A tab, a preparation method thereof, and a battery including the tab are disclosed. The tab is a copper foil material, a surface of the copper foil material having a large compressive stress is an S surface, a surface having a small compressive stress is an M surface, and only the M surface is provided with an indentation or a reinforcing rib. In the preparation method of the tab of the disclosure, the S surface/M surface of the copper foil material are identified, and it is ensured that a feed direction is oriented so that the M surface faces outward (or inward), and winding/unwinding directions of each process and a mounting direction of an embossing device are reasonably fixed, so as to ensure that a tab emboss pattern of a product is pressed on the M surface of the copper foil material rather than the S surface or both surfaces.