Electrode Assembly Separator Thickness Gradient
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Solution Overview
Problem
Pouch-type secondary batteries face issues with heat stability due to separator shrinkage around electrode tabs, leading to potential short-circuits during charge/discharge cycles.
Innovation Solution
An electrode assembly with a separator having a thickness gradient, where the side with electrode tabs is 1.1-2 times thicker than the other side, and optionally featuring a porous coating layer with inorganic particles and a binder polymer, to prevent separator shrinkage and enhance thermal safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separator is used in the electrode assembly, then it prevents short-circuit between electrodes, but it shrinks around the electrode tab due to heat generation causing short-circuit
Solution Approach 1:
The separator is designed with different thicknesses at different locations: a first thickness at the electrode tab region and a second thickness at other regions. This local quality variation allows the separator to resist heat-induced shrinkage at the critical tab area while maintaining appropriate properties elsewhere, preventing short-circuit during charge/discharge cycles
Solution Approach 2:
The separator's physical parameter (thickness) is changed spatially to address the thermal stability issue. By increasing the thickness at the electrode tab region, the separator gains enhanced resistance to thermal shrinkage in the high-temperature zone, thereby maintaining its structural integrity and preventing short-circuit
2Temperature
If the separator thickness is increased at the electrode tab side, then heat stability is improved, but manufacturing complexity increases
Solution Approach 1:
Rather than uniformly increasing separator thickness throughout, the invention applies local quality enhancement by making the separator thicker only at the electrode tab region where heat generation occurs. This targeted approach improves heat stability at the critical location while minimizing overall structural complexity and manufacturing difficulty
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 effectively prevents separator shrinkage and short-circuits, thereby improving the heat stability and thermal safety of the battery.
Implementation Method 1
current density is the highest around the electrode tab while repeating charge/discharge, and thus temperature may be increased significantly. As a result, there has been a problem in that a separator is shrunk around the electrode tab
Data Source
AI summary
The present disclosure is directed to providing an electrode assembly which improves the thermal safety of a battery by preventing shrinking of a separator adjacent to electrode tabs. The electrode assembly includes a positive electrode plate having a positive electrode tab at one end thereof, a negative electrode plate having a negative electrode tab at one end thereof, and a separator interposed between the positive electrode plate and the negative electrode plate, wherein the positive electrode plate and the negative electrode plate are stacked so that each of the tabs may be positioned in the same direction, and the separator has a gradient in thickness so that the thickness of one side having the electrode tabs are larger than that of the other side.