Tab-Less Cylindrical Battery Structure for Stable Jelly-Roll Welding
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Solution Overview
Problem
Cylindrical batteries face issues with jelly-roll movement inside the battery housing, leading to potential damage and increased manufacturing complexity and cost, along with poor current collection efficiency and thermal stability due to strip-shaped electrode tabs.
Innovation Solution
A tab-less cylindrical battery design with uncoated portions at the top and bottom of the jelly-roll electrode assembly, where current collecting plates are welded directly to these portions to improve current collection efficiency, and the use of single particle or pseudo-single particle positive electrode active materials and silicon-based negative electrode active materials to enhance thermal stability and energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a jelly-roll structure with strip-shaped electrode tabs is used, then current collection efficiency is poor and thermal stability is reduced, but the manufacturing process is simple
Solution Approach 1:
The patent extracts the problematic strip-shaped electrode tabs from the jelly-roll structure and replaces them with uncoated portions that extend directly from the wound electrodes. This extraction eliminates the weak current collection path through narrow tabs while maintaining the simplicity of the jelly-roll manufacturing process.
Solution Approach 2:
The patent transitions from one-dimensional strip-shaped tabs to two-dimensional uncoated portions that extend radially and axially from the jelly-roll core. This dimensional change increases the surface area for current collection and improves thermal contact with the current collecting plate without complicating the manufacturing process.
2Reliability
If additional components are added to prevent jelly-roll movement, then movement damage is reduced, but manufacturing complexity and cost increase
Solution Approach 1:
The patent merges the current collecting plate with the jelly-roll structure by directly coupling it to the uncoated portions that are integral parts of the wound electrodes. This integration eliminates the need for separate movement prevention components while providing both current collection and mechanical stabilization functions through a single coupled structure.
Solution Approach 2:
The uncoated portions serve multiple functions: they act as current collectors, provide mechanical anchoring to prevent jelly-roll movement, and enable thermal contact. This multi-functionality eliminates the need for additional dedicated components for each function, reducing manufacturing complexity and cost.
3Device complexity
If current is concentrated in strip-shaped electrode tabs, then the structure is simple, but resistance is large and heat generation is high
Solution Approach 1:
The patent applies local quality by creating uncoated portions with different dimensions and positions along the jelly-roll structure. The uncoated portions have larger surface areas at critical locations for current collection and thermal management, while maintaining the overall simplicity of the jelly-roll construction through selective modification of local regions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution minimizes jelly-roll movement, reduces internal resistance, prevents internal short circuits, and improves welding strength, thermal stability, and energy density, while maintaining low manufacturing complexity and cost.
Implementation Method 1
current collecting plates are welded directly to these portions to improve current collection efficiency
Implementation Method 2
use of single particle or pseudo-single particle positive electrode active materials and silicon-based negative electrode active materials to enhance thermal stability and energy density
Implementation Method 3
a separator serving as an insulator is interposed between a positive electrode and a negative electrode, and they are wound to form an electrode assembly in the form of a jelly roll
Data Source
AI summary
Discussed is a cylindrical battery having an electrode assembly in which a first electrode, a second electrode, and a separator interposed therebetween are wound. The first electrode and the second electrode include a first uncoated portion and a second uncoated portion along a winding direction, respectively. At least one of the first uncoated portion and the second uncoated portion is defined as an electrode tab by itself and includes a core-side uncoated portion, an outer circumference uncoated portion, and an intermediate uncoated portion between the core-side uncoated portion and the outer circumference uncoated portion. At least one of the core-side uncoated portion and the outer circumference uncoated portion has a smaller height than the intermediate uncoated portion in a winding axis direction. The cylindrical battery includes a battery housing, a first current collecting plate, a cap plate, a spacer, and an external terminal electrically connected to the second uncoated portion.