Lithium-ion Battery Tab Positioning to Reduce Curvature Stress
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium-ion secondary batteries with film exterior materials face issues with deformation, leading to potential breakage of electrode tabs and collector foils due to curvature stress, especially when stacked layers increase, and existing solutions do not adequately address the breakage of positive-electrode-side electrode foils.
Innovation Solution
A lithium-ion secondary battery design featuring alternately stacked positive and negative electrodes with strategically positioned tabs and terminals, where the distance from the tab connection to the terminal is optimized to reduce curvature stress, and the use of insulation members to manage thickness and curvature, ensuring the battery's resistance to shock and vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the number of positive and negative electrodes stacked is increased to increase capacity per unit battery, then the capacity per unit battery is improved, but the curvature of electrode tabs increases and the possibility of tab breakage increases
Solution Approach 1:
The patent introduces a new spatial dimension by arranging electrode tabs at different positions along the stacking direction. Instead of all tabs being at the same location, tabs are distributed across multiple positions, which changes the stress distribution pattern and reduces curvature concentration at any single tab location.
Solution Approach 2:
The patent applies local quality by creating different tab configurations at different locations within the battery. Specifically, tabs in the outermost layers are positioned differently from tabs in inner layers, with each location optimized for its specific stress conditions. This local differentiation reduces the curvature stress on individual tabs while maintaining overall high capacity.
2Volume of moving object
If the distance from electrode tabs to pull-out tabs is shortened to minimize battery volume, then the battery volume is reduced, but the curvature of tabs increases and tab breakage becomes more likely
Solution Approach 1:
The patent resolves this contradiction by utilizing the stacking direction as an additional spatial dimension. Instead of shortening the tab distance in the planar direction (which would increase curvature), the design extends the tab arrangement along the stacking direction, distributing tabs across multiple layers. This maintains compact battery volume while reducing tab curvature through spatial distribution.
3Device complexity
If a film exterior material is used, then the battery structure is simplified, but the exterior material deforms and comes in contact with electrode tabs, increasing breakage risk
Solution Approach 1:
The patent applies preliminary action by pre-positioning electrode tabs at optimized locations before the exterior material is assembled. The tab positions are predetermined to account for potential exterior material deformation, ensuring that even when the exterior deforms, the tabs remain in positions with minimal curvature stress and are not subjected to harmful contact forces.
4Reliability
If the negative electrode is made larger than the positive electrode to avoid lithium deposition, then lithium deposition is prevented, but the curvature near the positive electrode end increases and stress on the negative electrode increases
Solution Approach 1:
The patent segments the negative electrode into multiple regions with different tab positions along the stacking direction. By dividing the electrode structure and positioning tabs at different locations, the stress distribution is optimized to prevent both lithium deposition and excessive curvature stress. This segmentation allows the negative electrode to be larger than the positive electrode while managing the resulting stress through strategic tab placement.
Data Source
AI summary
Provided is a battery in which collector foil is unlikely to break.In a lithium-ion secondary battery, as for a distance from a connection section between a positive electrode tab and the positive electrode terminal to a boundary section between applying and non-applying sections of positive-electrode active material in a direction perpendicular to a stacking direction, compared with a reference positive electrode having the boundary section that is located farthest to the connection section by straight-line distance, a layer of a positive electrode that is stacked in such a way as to be farthest from the reference positive electrode has a smaller distance from a boundary of the applying and non-applying sections of the positive-electrode active material to a connection section with the positive electrode tab in a direction perpendicular to a stacking direction.