Variable-Porosity Separator for Battery Dry Region Prevention
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Solution Overview
Problem
Energy storage devices experience ion transport obstruction and inconsistent kinetics due to uneven electrolyte distribution 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 to dry regions and balancing ion transport across the cell.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separator with uniform porosity 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 region (closer to the tab) has a first porosity, while the second region (farther from the tab) has a second porosity. This local quality variation 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 uniform manufacturing and localized performance requirements.
Solution Approach 2:
The separator is divided into multiple regions with distinct porosity characteristics. The first region and second region are separately defined and manufactured with different pore-forming ratios, creating a segmented structure that addresses the specific ion transport needs of different cell positions, thus improving reliability without requiring complete structural redesign.
2Speed
If the porosity is increased to improve ion transport, then ion transport speed increases, but electrolyte retention decreases
Solution Approach 1:
Different regions of the separator are assigned different porosity values to balance ion transport speed and electrolyte retention locally. The first region has optimized porosity for sufficient ion transport to the upper cell area, while the second region has adjusted porosity to maintain electrolyte retention, thereby resolving the contradiction between speed and quantity at different locations.
3Ease of manufacture
If a single pore-forming ratio is used, then the manufacturing process is simple, but dry regions form at the upper part of the cell
Solution Approach 1:
The separator uses different pore-forming ratios in different regions to achieve uniform electrolyte distribution. The first region uses a first pore-forming ratio to prevent dry region formation at the upper cell part, while the second region uses a second pore-forming ratio to maintain overall electrolyte balance, thus improving reliability while maintaining reasonable manufacturing simplicity.
Solution Approach 2:
The manufacturing process is segmented into separate mixing and extrusion steps for different pore-forming ratios. This allows the production of a multi-region separator with tailored porosity characteristics, addressing the electrolyte distribution problem without requiring overly complex manufacturing procedures.
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 retention and ion transport consistency, improving the electrical performance and cycle life of energy storage devices by maintaining stable electrochemical reactions and reducing internal resistance.
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
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.