Battery Electrode Tape Reinforcement for Uncoated Portion Cracks
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Solution Overview
Problem
Secondary battery electrodes experience cracking and reliability issues due to stress concentration at uncoated portions during charging and discharging cycles, particularly in high-capacity batteries with active materials having high expansion ratios, leading to potential short circuits and ignition risks.
Innovation Solution
A secondary battery electrode design featuring tapes with a tensile strength of at least 230 N/mm² adhered to uncoated portions of the electrode, with the option of varying tensile strengths for the first and second tapes based on the internal expansion ratio, to prevent or reduce crack formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high-capacity active material with high expansion ratio is used to increase battery capacity, then the battery capacity is improved, but stress concentration and crack formation occur at the uncoated portion during charging and discharging cycles
Solution Approach 1:
The patent applies a tape with high tensile strength specifically at the uncoated portion where stress concentration occurs, while leaving other areas unchanged. This localized reinforcement addresses the specific problem of crack formation at the tab attachment area without affecting the overall battery capacity or other performance characteristics.
Solution Approach 2:
The patent combines the substrate material with a tape material having high tensile strength to create a composite structure at the uncoated portion. This composite construction provides enhanced mechanical strength to resist stress concentration and prevent crack formation while maintaining the electrochemical performance of the original active material.
2Reliability
If the substrate's intrinsic physical properties are sufficient to prevent stress concentration, then crack prevention is achieved, but the battery capacity must be limited to low-capacity applications
Solution Approach 1:
Instead of requiring the entire substrate to have high strength properties, the patent applies a high-tensile-strength tape only at the critical uncoated portion. This allows the use of high-capacity active materials elsewhere in the battery while providing localized reinforcement where stress concentration occurs.
Solution Approach 2:
The patent creates a composite structure by combining the substrate with a high-tensile-strength tape at the uncoated portion. This composite approach enables the battery to achieve both high capacity (through high-capacity active material) and high reliability (through the reinforced uncoated portion).
3Ease of operation
If electrode tabs are welded to uncoated portions, then electrical connection is achieved, but stress concentration and potential short circuits occur during battery operation
Solution Approach 1:
The patent applies a tape with high tensile strength specifically at the uncoated portion where the electrode tab is welded. This localized reinforcement strengthens the attachment area to prevent crack formation that could lead to short circuits, while maintaining the electrical connection functionality.
Solution Approach 2:
The patent applies the high-tensile-strength tape in advance, before the battery undergoes charging and discharging cycles. This preventive measure compensates for the stress concentration that will occur during operation, preventing crack formation and potential short circuits before they can happen.
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 mitigates stress concentration, preventing cracks and enhancing the reliability and safety of secondary batteries by compensating for the substrate's physical properties without affecting other characteristics.
Implementation Method 1
a first tape adhered to a portion of the first active material layer around the electrode tab and the uncoated portion
Data Source
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.