Battery Cell Tab Assembly for Thinner Lead-Tab Welding
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Solution Overview
Problem
Conventional lithium-sulfur and lithium-metal batteries face issues with thick electrode tabs that hinder proper connection to lead tabs, leading to sealing defects and short circuits due to the lithium metal's tendency to spread during welding, making it difficult to insert the electrode assembly into the cell case.
Innovation Solution
The battery cell design includes a stacked electrode tab assembly with varying thicknesses, where shorter electrode tabs are used to form a connection part that does not overlap the lead tab, allowing for improved connection quality and easier insertion into the case, while minimizing interference with other components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If electrode tabs are formed by extending lithium metal to create a negative electrode, then the battery can achieve high energy density, but the electrode tab becomes relatively thicker causing difficulty in insertion and connection
Solution Approach 1:
The electrode tab is divided into multiple individual tabs that are stacked and welded together to form an electrode tab assembly. This segmentation allows each individual tab to be thinner while achieving the required current collection area through the stacked configuration, resolving the contradiction between energy density and tab thickness.
Solution Approach 2:
Instead of increasing tab thickness in one dimension to achieve required current collection area, the solution transitions to stacking multiple thinner tabs in the vertical dimension. This dimensional change allows the assembly to achieve equivalent or greater current collection capability while maintaining individual tab thinness for easier insertion and connection.
2Reliability
If thick electrode tabs are welded to lead tabs, then electrical connection is established, but the lithium metal spreads during welding causing sealing destruction and short circuits
Solution Approach 1:
Dividing the current collection function across multiple thinner tabs reduces the amount of lithium metal present at any single welding interface. This segmentation minimizes the spreading effect during welding while maintaining reliable electrical connection through the stacked assembly configuration.
Solution Approach 2:
Each individual tab in the stack has localized welding points to the lead tab, concentrating the welding action at specific locations rather than across a large thick tab surface. This local quality approach ensures reliable electrical connection at each weld point while preventing excessive lithium spreading that would occur with a single thick tab.
3Area of stationary object
If multiple electrode tabs are stacked to form a bundle, then current collection area is increased, but the bundle thickness increases making insertion into cell case difficult
Solution Approach 1:
The current collection function is segmented across multiple individual tabs of optimized thickness. Each tab contributes to the total current collection area while maintaining a thickness that allows the stacked assembly to fit within the cell case dimensions, resolving the contradiction between area and thickness.
Solution Approach 2:
The solution transitions from increasing current collection area by thickening individual tabs to stacking multiple thinner tabs vertically. This dimensional reconfiguration achieves the required current collection area while keeping the bundle thickness within acceptable limits for cell case insertion.
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
This design reduces the thickness of the electrode tab bundle, enhances connection quality to the lead tab, and prevents the lithium metal from spreading during welding, thereby improving the sealing and electrical integrity of the battery cell.
Implementation Method 1
a first connection part formed by welding at least some of the plurality of electrode tabs to each other, and a second connection part extended from the first connection part and welded to the lead tab
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
Provided is a battery cell comprising: an electrode tab assembly in which a plurality of electrode tabs extending from a plurality of electrode plates to one side are stacked; a case in which the plurality of electrode plates are accommodated; and a lead tab electrically connected to the electrode tab assembly and having at least a portion exposed to the outside of the case. The electrode tab assembly includes: a first connection part formed by welding and coupling at least some of the plurality of electrode tabs to each other, and a second connection part extending from the first connection part and welded and coupled to the lead tab, wherein the number of electrode tabs constituting the second connection part is smaller than the number of electrode tabs constituting the first connection part.