Flat Wound Electrode Body Layout for Higher Battery Volume Efficiency
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Solution Overview
Problem
Conventional secondary batteries with flat wound electrode bodies experience void formation between the rounded ends of the electrode body and the battery case, leading to dead spaces that reduce volume efficiency.
Innovation Solution
The proposed secondary battery features a wound electrode body with elongated positive and negative electrode sheets and a separator, wound around a central axis and flattened to create specific flat surfaces that align with the inner battery case surfaces, minimizing voids and enhancing volume efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional flat wound electrode body with rounded ends is used, then the electrode body can be easily manufactured, but voids are formed between the rounded parts and the battery case, reducing volume efficiency
Solution Approach 1:
The electrode body is segmented into multiple flat surfaces (first through fourth flat surfaces) that can be independently arranged to fit the battery case geometry, reducing void spaces while maintaining manufacturing feasibility through standardized flat surface formation processes
Solution Approach 2:
The electrode body transitions from a conventional two-dimensional flat wound structure with rounded ends to a three-dimensional configuration with multiple flat surfaces extending in different directions, enabling better spatial utilization of the battery case volume
2Volume of moving object
If the wound electrode body has multiple flat surfaces arranged along the inner peripheral surfaces of the battery case, then volume efficiency is enhanced, but the manufacturing process becomes more complex
Solution Approach 1:
The flat surfaces are formed on the electrode body during the winding process itself, rather than requiring subsequent machining or shaping operations. The winding is performed in a predetermined manner that directly creates the desired multi-surface geometry, eliminating additional manufacturing steps
Solution Approach 2:
The winding parameters (speed, tension, layer arrangement) are optimized to naturally produce flat surfaces with specific orientations and dimensions that match the battery case inner peripheral surfaces, transforming the manufacturing approach from post-processing to process-integrated shaping
Data Source
AI summary
In a secondary batter, dead spaces between a wound electrode body and the inner peripheral surfaces of a rectangular battery case are made small. The secondary battery includes a wound electrode body in which a positive electrode sheet, a negative electrode sheet, and a separator interposed between the positive electrode sheet and the negative electrode sheet are superimposed and wound around a winding axis, and a rectangular battery case that houses the wound electrode body. The wound electrode body has a first flat surface, a second flat surface, a third flat surface, and a fourth flat surface positioned on the outer peripheral surfaces around the winding axis. The first flat surface and the second flat surface face each other with the winding axis interposed therebetween. The third flat surface and the fourth flat surface face each other with the winding axis interposed therebetween.