Wound Battery Foil Extensions for Low-Resistance Current Collection
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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 surfaces to enhance current collection, using a spiral structure with asymmetric bends and grooves to improve contact with current-collecting plates, and includes insulating layers to prevent short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If welding points are made dense toward the center to collect current from the whole wound foil ends, then current collection efficiency is improved, but the central space is blocked and assembly becomes impossible
Solution Approach 1:
The current collection function is segmented from the central region to the end regions of the electrode assembly. The welding points are distributed at the ends rather than concentrated at the center, allowing the central space to remain open for assembly while maintaining current collection efficiency through strategic placement at the terminus of the wound structure.
Solution Approach 2:
The welding point distribution transitions from a radial concentration toward the center to an axial concentration at the ends of the wound assembly. This dimensional shift in welding point placement allows current collection without blocking the central space, resolving the spatial conflict between electrical function and mechanical assembly.
2Power
If high-rate discharge is achieved by flowing large current, then power output is improved, but internal resistance increases causing performance degradation
Solution Approach 1:
The current collection is segmented into multiple parallel paths through distributed welding points at the ends of the electrode assembly. This segmentation reduces the current density at any single point and lowers overall internal resistance, enabling high-rate discharge without performance degradation.
Solution Approach 2:
The electrode foil extensions are pre-formed with bends and grooves before assembly to create optimal current collection geometry. This preliminary shaping ensures efficient current distribution from the outset, reducing internal resistance before high-rate discharge operations begin.
3Shape
If foil is folded from the outer periphery toward the central portion, then electrode assembly is formed, but the central space is blocked and welding becomes impossible
Solution Approach 1:
Instead of folding the foil toward the center and then attempting to weld at the center, the welding is performed at the opposite end - the outer ends of the folded structure. This inversion of the welding location allows the folding process to proceed as normal while eliminating the central space blocking problem.
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.