Variable-Porosity Separator for Battery Dry Region Replenishment
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Solution Overview
Problem
Energy storage devices experience ion transport obstruction and inconsistent kinetics due to electrolyte depletion and dry regions forming at the upper part of the cell, leading to reduced electrical performance over time.
Innovation Solution
A separator with varying porosities is manufactured by mixing base materials and pore-forming agents at different ratios, extruding, and connecting sheets to create portions with distinct porosities, ensuring timely electrolyte replenishment and balanced ion transport.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a uniform porosity separator is used, then the manufacturing process is simple, but ion transport obstruction occurs at the upper part of the cell after long-term operation
Solution Approach 1:
The separator is designed with different porosity values in different regions: the first portion (closer to the tab) has a first porosity, while the second portion (farther from the tab) has a second porosity. This local variation in porosity ensures that the upper part of the cell receives sufficient ion transport capacity to prevent ion obstruction, while the lower part maintains appropriate ion flow, thereby resolving the contradiction between reliability and structural complexity.
2Speed
If the porosity is increased to enhance ion transport, then ion transport speed improves, but the mechanical strength of the separator decreases
Solution Approach 1:
Different regions of the separator have different porosity values optimized for their specific functions. The first portion with higher porosity (first pore-forming ratio) enhances ion transport speed in the upper cell region where ion obstruction occurs, while the second portion with lower porosity (second pore-forming ratio) maintains greater mechanical strength. This localized optimization resolves the contradiction between ion transport speed and separator strength.
3Reliability
If a single porosity separator is manufactured, then the manufacturing process is simple and fast, but it cannot address electrolyte depletion at the upper part of the cell
Solution Approach 1:
The separator manufacturing process is segmented into multiple stages: preparing different mixtures with different pore-forming ratios, extruding different portions separately, and then connecting them. This segmentation allows each portion to be optimized for its specific function (electrolyte replenishment in the upper region), thereby improving reliability while accepting increased manufacturing complexity as a necessary trade-off.
Solution Approach 2:
The pore-forming ratio parameter is changed across different portions of the separator. The first mixture has a first pore-forming ratio, while the second mixture has a second pore-forming ratio. This parameter variation enables the separator to address electrolyte depletion in the upper cell region by providing enhanced porosity where needed, resolving the contradiction between reliability and manufacturing efficiency.
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 enhances electrolyte replenishment to dry regions, balances ion transport, reduces internal resistance, and improves the cycle performance and electrical performance of energy storage devices.
Implementation Method 1
The pore-forming agent is removed from the first extruded sheet and the second extruded sheet, so that the first extruded sheet has a first porosity and the second extruded sheet has a second porosity less than the first porosity
Data Source
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AI summary
A separator, a method for manufacturing the separator, an energy storage device, and an electricity-consumption apparatus are provided. The separator has a portion with a first porosity and a portion with a second porosity arranged in a width direction of the separator. The second porosity is less than the first porosity. The first portion is disposed closer to the tab of the energy storage device than the second portion.