Jelly-Roll Electrode Structure to Prevent Core Cracking
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Solution Overview
Problem
Lithium batteries face challenges in achieving high energy density and miniaturization due to cracking issues in the core portion of electrodes during the winding process, particularly in jelly-roll type structures.
Innovation Solution
The electrode structure incorporates uncoated portions between 0 L and 50 L, preventing crack formation while maintaining high energy density by excluding uncoated regions between 50 L and 100 L, thereby enhancing the electrode's durability and capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If electrode active material layers are applied across the entire electrode surface to increase energy density, then the energy density of the battery is improved, but crack formation occurs in the core portion during winding due to high curvature
Solution Approach 1:
The patent applies different configurations of active material layers to different regions of the electrode. Specifically, the first and second active material layers are positioned at outer regions (first and second regions) while the third active material layer is positioned at the inner core region (third region). This local differentiation allows the electrode to maintain high energy density at regions where they can be applied without causing cracks, while avoiding the high-curvature core region where cracks would form, thus resolving the contradiction between energy density and reliability.
2Reliability
If uncoated portions are added to prevent crack formation, then crack resistance is improved, but the energy density of the electrode structure is reduced
Solution Approach 1:
The patent segments the electrode surface into multiple distinct regions (first region, second region, and third region) with different active material layer configurations. By dividing the electrode into these segments, the design can place uncoated portions only where necessary (at the high-curvature core region) while maintaining active material coverage at regions where it contributes to energy density without causing cracks, thus balancing crack resistance and energy density.
Solution Approach 2:
The patent applies different configurations of active material layers to different regions of the electrode. Specifically, the first and second active material layers are positioned at outer regions (first and second regions) while the third active material layer is positioned at the inner core region (third region). This local differentiation allows the electrode to maintain high energy density at regions where they can be applied without causing cracks, while avoiding the high-curvature core region where cracks would form, thus resolving the contradiction between energy density and reliability.
Data Source
AI summary
An electrode structure (e.g., a jelly-roll type or kind electrode structure) and a secondary battery including the same are provided. The electrode structure includes a cathode including a cathode active material layer, an anode including an anode active material layer, and a separator between the cathode and the anode. The electrode structure includes a coated portion in which the cathode or anode active material layer is arranged, and an uncoated portion that excludes (e.g., is free of) the cathode active material layer and the anode active material layer. Two ends of the electrode structure include a portion inside that is defined as 0 L and a portion outside that is defined as 100 L, each based on a longitudinal direction, and the uncoated portion is between 0 L and 50 L in the electrode structure.