Tabless Battery Wound Electrode Structure for Low-Resistance Welding
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Solution Overview
Problem
Conventional battery technology faces issues with high internal resistance during high-rate discharge due to dense welding points and insufficient space in the central portion of the electrode assembly, leading to inefficient current collection and assembly challenges.
Innovation Solution
The battery design incorporates bends in positive and negative electrode foils with asymmetric grooves and overlapping extensions to improve current collection, using a spiral structure with asymmetric bending shapes and grooves to enhance contact with current-collecting plates, and includes insulating layers to prevent short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If welding points are made denser toward the center to collect current from the whole wound foil ends, then current collection is improved, but the internal resistance increases and welding reliability decreases
Solution Approach 1:
The electrode foil is divided into multiple segments along its length, with welding points distributed at different positions rather than concentrated at the center. This segmentation allows current to be collected from multiple locations, reducing the density of welding points at any single location while maintaining overall current collection efficiency.
Solution Approach 2:
The welding point distribution is changed from a one-dimensional concentration at the center to a two-dimensional distribution along the length of the electrode foil. This dimensional change spreads the welding points out, reducing local density while maintaining total current collection capability.
2Shape
If the foil is folded from the outer periphery toward the central portion, then the electrode assembly is formed, but the central space is blocked and assembly becomes difficult
Solution Approach 1:
The electrode foil is pre-formed with bends and extensions at specific locations before assembly. These preliminary structural features guide the folding process and ensure that the foil extensions emerge at appropriate positions without blocking the central space, making the assembly process easier.
Solution Approach 2:
Instead of folding the foil in a conventional manner that blocks the center, the foil is folded with bends that direct the extensions outward or to the sides, inverting the conventional folding pattern to avoid central space obstruction.
3Shape
If conventional winding is used to form the electrode assembly, then the spiral structure is created, but insufficient space remains in the central portion for welding and assembly
Solution Approach 1:
The foil extensions with bends are nested within the spiral structure in such a way that they utilize the available space efficiently. The bends allow the extensions to follow the spiral path while maintaining emergence at the ends, maximizing space utilization without blocking the center.
Solution Approach 2:
The foil extensions incorporate curved bends rather than sharp angles, allowing them to navigate the spiral structure more efficiently and emerge at the ends without requiring excessive central space. The curvature enables smoother space utilization within the spiral configuration.
Data Source
AI summary
An electrode wound body includes positive and negative electrodes, and a separator between the positive and negative electrodes. The positive electrode includes a positive foil extension extending from a positive electrode foil. The negative electrode includes a negative foil extension extending from a negative electrode foil. The positive electrode, the negative electrode, and the separator are wound to define a spiral including a through hole with a central axis extending through the through hole. The positive and negative foil extensions extend from opposite ends of the electrode wound body. Portions of the positive foil extension include bends that bend towards the central axis so that the portions of the positive foil extension overlap to define a first surface. Portions of the negative foil extension include bends that bend towards the central axis so that the portions of the negative foil extension overlap to define a second surface.