Wound Electrode Body Shaping to Minimize Battery Case Voids
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Solution Overview
Problem
Conventional secondary batteries have inefficiencies in volume utilization due to voids formed between the flat wound electrode body and the battery case, leading to reduced packing density and energy storage capacity.
Innovation Solution
The proposed secondary battery design features a wound electrode body with elongated positive and negative electrode sheets and separators arranged around a winding axis, forming specific flat and rounded surfaces that align with the battery case's inner surfaces, minimizing voids and enhancing volume efficiency through a manufacturing process involving winding, arranging, and pressing steps to create optimized flat and rounded surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a conventional flat wound electrode body is used, then the manufacturing process is simple, but voids are formed between the electrode body and battery case leading to reduced volume efficiency
Solution Approach 1:
The patent applies curvature by rounding the corners of the flat wound electrode body to create a rounded rectangular shape. This curvature modification allows the electrode body to better conform to the rectangular battery case, eliminating voids at the corners and significantly improving volume efficiency without fundamentally changing the winding structure
Solution Approach 2:
The patent applies local quality by selectively rounding only the corner portions of the electrode body while maintaining flat surfaces on the sides. This localized modification optimizes the fit between the electrode body and battery case, ensuring maximum contact area and minimal voids while preserving the simplicity of the overall structure
2Volume of moving object
If the electrode body is pressed to flatten it, then volume efficiency improves, but the electrode sheets may deform or damage
Solution Approach 1:
The patent applies preliminary action by pre-forming the rounded rectangular shape during the winding process itself, before the electrode body is installed in the battery case. This eliminates the need for subsequent pressing operations that could damage the electrode sheets, as the optimal shape is achieved during manufacturing when the materials are more pliable
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.