Zigzag Electrode Assembly With Dual-Coated Separator for Bend Control
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Solution Overview
Problem
The existing zigzag-shaped electrode assemblies in lithium secondary batteries face issues with bending due to uneven bonding strengths between the separator and the positive and negative electrodes, leading to potential safety problems and increased electrical resistance.
Innovation Solution
The electrode assembly features a separator with distinct porous coating layers on both surfaces, where the first coating layer has stronger bonding with the negative electrode and the second coating layer has stronger bonding with the positive electrode, with specific particle size and composition adjustments to balance the bonding strengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If heat and pressure are increased to prevent bending of the electrode assembly, then bonding strength between separator and electrodes is improved, but permeability of the separator is degraded and electrical resistance is increased
Solution Approach 1:
The patent applies local quality by forming different porous coating layers on opposite surfaces of the separator. The first porous coating layer has a first particle size designed for strong bonding with the negative electrode, while the second porous coating layer has a second particle size optimized for bonding with the positive electrode. This localized differentiation allows each surface to provide appropriate bonding strength without requiring excessive heat and pressure, thereby preventing bending while maintaining separator permeability and electrical resistance within acceptable ranges.
2Stability of the object's composition
If bonding strength between separator and electrodes is made uniform, then bending is prevented, but productivity is reduced due to complex manufacturing process
Solution Approach 1:
The patent employs parameter changes by varying the particle size parameter in the porous coating layers formed on opposite surfaces of the separator. The first porous coating layer contains particles of a first size range, while the second porous coating layer contains particles of a second size range. This parameter differentiation enables each layer to achieve optimal bonding strength with its corresponding electrode type, ensuring uniform overall bonding performance across the separator without requiring complex multi-step manufacturing processes, thus maintaining high productivity.
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 bending and enhances safety by minimizing the difference in bonding strengths between the electrodes, maintaining high productivity and reducing electrical resistance.
Implementation Method 1
The first porous coating layer has greater bonding strength with the negative electrode than bonding strength with the positive electrode
Data Source
Figure 1~2
AI summary
The present disclosure provides an electrode assembly including a separator including a porous polymer base, a first porous coating layer formed on one surface of the porous polymer base, and a second porous coating layer formed on the other surface of the porous polymer base, the separator being bent in a zigzag shape, a negative electrode disposed between the first porous coating layers, and a positive electrode disposed between the second porous coating layers, wherein the first porous coating layer having greater bonding strength with the negative electrode than bonding strength with the positive electrode is used, to provide the electrode assembly having reduced bending because an electrode-separator bonding strength deviation on both surfaces of the separator is reduced.