Electrode Stepped Coating Pattern for Winding Crack Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Secondary batteries face issues with cracks occurring due to folding of stepped portions between electrode active material layers and non-coating portions when wound around a core part, leading to instability and potential performance degradation.
Innovation Solution
The electrode assembly features a collector with alternating coating layers of electrode active material, where the second coating layer has a shorter length than the first, forming a stepped pattern that allows for stable winding without folding, and includes non-coating portions to maintain a gentle inclination angle, ensuring the electrode is securely wound around the core without cracks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the electrode is wound around the core part, then the electrode assembly is formed, but the stepped portion between the electrode active material layer and the non-coating portion folds causing cracks
Solution Approach 1:
The patent applies preliminary action by forming a stepped pattern at the distal end of the electrode before winding. The first coating layer extends beyond the second coating layer by a predetermined length (L1 ≥ L2), creating a gradual height transition. This pre-formed stepped structure prevents folding during the winding process by eliminating abrupt height changes, thereby preventing cracks while enabling successful electrode assembly formation.
2Device complexity
If the stepped portion height changes abruptly, then the electrode structure is simple, but the electrode folds when wound around the core part
Solution Approach 1:
The patent applies local quality by creating a stepped pattern only at the distal end of the electrode where the coating layers have different lengths. The first coating layer extends beyond the second coating layer by a predetermined length, forming a localized stepped structure with gradual height transition. This localized modification maintains simplicity in the overall electrode structure while providing the necessary gradual height change at the critical winding region to prevent folding and ensure stable winding.
3Ease of manufacture
If the electrode active material layer is uniformly coated, then the manufacturing process is simple, but cracks occur during winding due to folding
Solution Approach 1:
The patent applies segmentation by dividing the electrode active material coating into two distinct layers: a first coating layer and a second coating layer. The first coating layer is applied uniformly across the collector, while the second coating layer is applied only to a portion of the first coating layer, creating a stepped pattern at the distal end. This segmented coating approach maintains the simplicity of the coating process while achieving the precise stepped structure needed to prevent folding and cracks during winding.
Data Source
AI summary
The present invention relates to a secondary battery. The secondary battery comprises an electrode assembly in which an electrode and a separator are alternately stacked and wound, wherein the electrode comprises a collector, a first coating layer in which an electrode active material is applied to a surface of the collector, and a second coating layer in which the electrode active material is applied to the outside of the first coating layer, wherein an end of the second coating layer has a length less than an end of first coating layer in a winding direction of the electrode, and a stepped portion occurs between the end of the first coating layer and the end of the second coating layer in a direction outward from a winding center.