Non-Aqueous Battery Separator Layout for Electrolyte Distribution
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Solution Overview
Problem
Non-aqueous electrolyte secondary batteries with positive and negative electrode tabs on the sealing plate side experience degradation in cycling performance over long-term use due to electrolyte solution distribution issues.
Innovation Solution
A non-aqueous electrolyte secondary battery design where the separator has distinct air permeability regions, with a thicker first region closer to the sealing plate and a thinner second region closer to the bottom, ensuring the electrolyte solution is adequately distributed, and a restraining pressure is applied to enhance electrode assembly stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the positive electrode tab and negative electrode tab are positioned on the sealing plate side, then the battery structure is simplified and electrode assembly arrangement is improved, but the cycling performance degrades after long-term use due to electrolyte solution shortage
Solution Approach 1:
The separator is designed with different air permeability in different regions: the first region (0.3L from sealing plate side) has higher air permeability (T1) than the second region (0.3L from bottom side) with air permeability (T2), satisfying T2/T1 ≥ 1.05. This local quality differentiation ensures adequate electrolyte solution distribution to the electrode tabs on the sealing plate side while maintaining overall separator functionality.
2Ease of manufacture
If the separator has uniform thickness, then manufacturing is simplified, but electrolyte solution distribution becomes inadequate at the sealing plate side leading to performance degradation
Solution Approach 1:
The separator employs varying thickness across different regions: the first region near the sealing plate is thicker than the second region near the bottom. This thickness variation, combined with differentiated air permeability, ensures proper electrolyte distribution without requiring complex manufacturing processes, as it can be achieved through conventional separator formation techniques.
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 electrolyte solution shortage at the sealing plate side, maintaining excellent long-term endurance and cycling performance even after extended use.
Implementation Method 1
T1 which represents an air permeability of a first region of the separator that extends for a distance of 0.3L from an end of the separator close to the sealing plate toward the bottom part, and T2 which represents an air permeability of a second region of the separator that extends for a distance of 0.3L from an end of the separator close to the bottom part toward the sealing plate
Data Source
Figure 1~2
Figure 3
AI summary
A non-aqueous electrolyte secondary battery comprises an electrode assembly having a positive electrode, a negative electrode, and a separator, as well as an electrolyte solution and a battery case. The battery case has an exterior package and a sealing plate. The positive electrode has a positive electrode tab at an end of the electrode assembly, and the negative electrode has a negative electrode tab at an end of the electrode assembly. The electrode assembly is accommodated inside the battery case in such a manner that the end having the positive electrode tab and the end having the negative electrode tab face the sealing plate. T1 and T2 have the meanings as defined in the claims and the description, and satisfy a relationship of the following expression (I). 1.05≤T2/T1≤1.4