Electrochemical Separator Pore Tortuosity Control
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Solution Overview
Problem
Current separators for electrochemical devices, particularly lithium secondary batteries, face issues with internal short circuits due to material shrinkage at high temperatures and inadequate pore tortuosity, which hinders smooth lithium ion movement.
Innovation Solution
A separator with pores of specific diameter (1-100 nm) and tortuosity (1-2) is manufactured using a method involving ion beam irradiation and etching solutions like sodium hydroxide, allowing for cylindrical pores and improved porosity, enabling smoother lithium ion movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If polyolefin-based polymer resin is used for separator manufacturing, then ease of manufacture is improved, but reliability deteriorates due to shrinkage at high temperature causing internal short circuits
Solution Approach 1:
The patent changes the material parameter from polyolefin-based polymer resin to polyimide-based polymer resin, which has a higher glass transition temperature and maintains dimensional stability at high temperatures. This material substitution resolves the contradiction by providing both ease of manufacture through established processing methods and improved reliability through resistance to thermal shrinkage that prevents internal short circuits
Solution Approach 2:
The patent uses composite structures combining polyimide-based polymer resin with controlled pore formations. The composite approach integrates the thermal stability of polyimide with optimized pore architecture, achieving both manufacturability and high reliability by preventing material shrinkage while maintaining ion transport pathways
2Ease of manufacture
If dry or wet pore forming methods are used, then ease of manufacture is improved, but manufacturing precision deteriorates due to insufficient pore tortuosity control
Solution Approach 1:
The patent changes the pore formation parameters by controlling pore diameter within 0.01 to 1 micrometer and pore tortuosity between 1.1 to 2.5 through specific processing conditions. This precise parameter control during the pore formation process achieves both ease of manufacture and high manufacturing precision by systematically optimizing pore architecture for lithium ion transport
Solution Approach 2:
The patent replaces conventional mechanical stretching methods with a chemical etching process using alkaline solutions after electron beam irradiation. This substitution allows precise control of pore tortuosity and diameter through chemical reactions rather than mechanical forces, achieving superior manufacturing precision while maintaining ease of manufacture through a standardized process
3Ease of manufacture
If pore diameter and tortuosity are not optimized, then ease of manufacture is improved, but productivity deteriorates due to hindered lithium ion movement
Solution Approach 1:
The patent optimizes pore diameter to 0.01 to 1 micrometer and pore tortuosity to 1.1 to 2.5, creating ideal pathways for lithium ion movement. These parameter changes enhance productivity by reducing ion transport resistance while maintaining ease of manufacture through controlled pore formation processes, directly addressing the contradiction between manufacturing simplicity and battery performance
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 provides a uniform pore size, enhanced lithium ion mobility, and improved output in secondary batteries, along with the ability to adjust porosity and use various materials, reducing the risk of internal short circuits.
Implementation Method 1
irradiating an ion beam onto a film for a separator substrate to obtain a tracked film
Implementation Method 2
applying an etching solution to the tracked film to form pores in the film
Implementation Method 3
pores having a diameter from 1 to 100 nm and tortuosity in a range of 1 to 2, and having a permeation time of 5 to 500 sec/100 cc
Data Source
AI summary
The present disclosure relates to a separator for an electrochemical device with pores having predetermined diameter, permeation time, and tortuosity, to allow for smooth movement of lithium ions and a method for manufacturing the same, and smooth movement of lithium ions may be optimized by the separator for an electrochemical device.