Battery Electrode Tape Layout for Crack-Resistant Uncoated Tabs
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Solution Overview
Problem
Secondary battery electrodes experience swelling and stress concentration at uncoated portions during charging and discharging cycles, leading to crack formation, particularly in high-capacity batteries with active materials of higher expansion ratios, which can result in reliability issues, short circuits, and potential ignition.
Innovation Solution
A secondary battery electrode design featuring tapes with a tensile strength of at least 230 N/mm² attached to uncoated portions of the electrode, with the option for different tensile strengths for each tape, to prevent or reduce crack formation by complementing the substrate's physical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high-capacity active materials with higher expansion ratios are used to increase battery capacity, then the battery energy storage capability is improved, but stress concentration and crack formation occur at uncoated portions during charging and discharging cycles
Solution Approach 1:
The patent applies tape to the uncoated portions of the electrode substrate before the swelling and stress concentration occur during battery operation. This preliminary protective action prevents cracks from forming when the high-capacity active materials expand during charging cycles, thus maintaining electrode integrity while enabling high capacity
Solution Approach 2:
The tape serves as an intermediary element between the substrate and the external environment, absorbing and distributing the stress generated by the expanding active material. This mediator prevents direct stress concentration at the uncoated portions, resolving the contradiction between high capacity and electrode reliability
2Device complexity
If the intrinsic physical properties of the substrate are relied upon to prevent stress concentration, then the electrode structure remains simple, but cracks form at uncoated portions when using high expansion ratio active materials
Solution Approach 1:
Instead of changing the overall substrate structure, the patent applies tape locally only at the uncoated portions where stress concentration occurs. This localized intervention maintains the simplicity of the overall electrode structure while providing targeted protection against cracks at critical areas
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The tape attachment effectively prevents or reduces crack formation in secondary battery electrodes, maintaining reliability and safety without affecting other characteristics, even with high expansion ratios.
Implementation Method 1
a first tape adhered to a portion of the first active material layer around the electrode tab and the uncoated portion; and a second tape arranged opposite the first tape and adhered to a portion of the second active material layer around the uncoated portion
Data Source
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AI summary
The secondary battery electrode includes a substrate including an uncoated portion including a first surface and a second surface, the second surface being opposite the first surface, and a coated portion on which a first active material layer and a second active material layer are coated, the second active material layer being on a surface of the substrate opposite the first active material layer. The secondary battery also includes an electrode tab coupled to the substrate, a first tape adhered to a portion of the first active material layer around the electrode tab and the uncoated portion, and a second tape opposite the first tape and adhered to a portion of the second active material layer around the uncoated portion. Further, a tensile strength of at least one of the first tape or the second tape is 230 N/mm2 or greater.