Battery Separator Depressed Regions for Electrolyte Permeation
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Solution Overview
Problem
Existing secondary batteries face challenges in allowing electrolyte solution permeation into the electrode assembly while maintaining the strength of the separator, particularly due to expansion of negative electrode active materials, which can lead to electrolyte solution discharge during charging and impaired electric discharge characteristics.
Innovation Solution
A secondary battery design featuring a separator with depressed portions, specifically a larger cross-sectional area and occupancy area in the first regions compared to the second region, facilitating electrolyte solution flow and permeation into the electrode assembly while ensuring the separator's strength, particularly through a wound type electrode assembly configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the separator is made stronger to ensure structural integrity, then the separator strength is improved, but the permeation of electrolyte solution into the electrode assembly deteriorates
Solution Approach 1:
The separator is designed with non-uniform thickness, featuring a first region with smaller thickness and a second region with larger thickness. This local quality variation allows the first region to provide better permeation pathways for electrolyte solution while the second region maintains structural strength and integrity of the separator.
Solution Approach 2:
The invention transitions from considering only the planar dimensions of the separator to incorporating the thickness dimension as a variable parameter. By controlling thickness distribution across different regions, the design achieves simultaneous optimization of permeation (requiring thinner regions) and strength (requiring thicker regions).
2Quantity of substance
If negative electrode active material expands during charging, then battery capacity is improved, but space for electrolyte solution permeation deteriorates
Solution Approach 1:
The separator is pre-designed with regions of smaller thickness before battery assembly, creating advance pathways that accommodate the expansion of negative electrode active material during charging. This preliminary structural preparation ensures that electrolyte solution can still permeate effectively even when the electrode material expands.
Solution Approach 2:
Specific regions of the separator are designed with different thickness characteristics to locally accommodate expansion of negative electrode active material. The first region with smaller thickness provides buffer space and permeation pathways, while other regions maintain their structure.
3Strength
If the separator thickness is increased uniformly, then the separator strength is improved, but the electric discharge characteristics deteriorate due to impaired electrolyte distribution
Solution Approach 1:
The separator employs non-uniform thickness distribution with first regions of smaller thickness and second regions of larger thickness. This local differentiation ensures that regions requiring better electrolyte access have thinner barriers, while other regions provide structural support, thereby maintaining both strength and electric discharge characteristics.
Solution Approach 2:
The separator is functionally segmented into different regions with distinct thickness characteristics. The first region with smaller thickness is optimized for electrolyte permeation and electrode contact, while the second region with larger thickness provides overall structural integrity, achieving both goals through spatial segmentation.
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 enhances electrolyte solution permeation and retention, maintaining consistent electric discharge characteristics and slowing battery capacity decline over charging and discharging cycles, while ensuring the separator's strength and preventing uneven electrolyte distribution.
Implementation Method 1
a depressed portion is provided in a surface of the separator, the depressed portion being situated at least in the first region and allowing the electrolyte solution to flow into the depressed portion
Data Source
AI summary
A separator includes first regions, which include a first end portion and a second end portion opposite to each other in a first direction orthogonal to a thickness direction, and a second region, which is sandwiched between the first regions in the first direction and includes a central portion of the separator. A depressed portion, which is situated at least in the first region and allows an electrolyte solution to flow into the depressed portion, is provided in a surface of the separator. In a view in the first direction, a cross sectional area of the depressed portion in the first region of the separator is larger than a cross sectional area of the depressed portion in the second region of the separator.