Etched Ion-Track Battery Separator for Polysulfide Shuttle Suppression
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Solution Overview
Problem
Lithium-sulfur batteries and other cationic ion batteries face challenges due to the polysulfide redox shuttle phenomenon, leading to self-discharge and performance deterioration, with existing solutions being either costly or limited in effectiveness.
Innovation Solution
A porous polymer etched ion-track membrane is used as a separator, featuring nanochannels with controlled dimensions and geometry, which allows cationic ion flux while suppressing polysulfides, enhancing coulombic efficiency and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional porous separator is used, then ion transport is enabled, but polysulfide shuttle phenomenon occurs leading to self-discharge and performance deterioration
Solution Approach 1:
The patent employs a porous polymer etched ion-track membrane with precisely controlled nanochannels (10-200 nm diameter) as the separator. The porous structure enables cationic ion transport while the specific nanoscale pore dimensions physically block polysulfide molecules, resolving the contradiction between enabling ion flow and preventing polysulfide shuttle phenomenon
Solution Approach 2:
The separator features asymmetric nanochannel geometry with different opening diameters at each surface, creating local quality variations. The narrower openings at one surface provide enhanced polysulfide blocking while maintaining adequate ion transport pathways, allowing the separator to simultaneously achieve selective transport and structural stability
2Reliability
If existing solutions to suppress polysulfide shuttle are implemented, then battery performance is improved, but manufacturing cost increases or effectiveness is limited
Solution Approach 1:
The patent achieves superior polysulfide blocking by precisely controlling the nanochannel diameter parameter (10-200 nm range) through ion-track etching process variables such as ion fluence, etching time, and chemical composition. This parameter optimization enables effective polysulfide suppression using conventional polymer materials, avoiding the need for expensive alternative solutions while maintaining high coulombic efficiency
Solution Approach 2:
The invention uses commercially available polymer films (polyethylene terephthalate, polycarbonate, polyethylene, polypropylene, polyimide, polytetrafluoroethylene, or polyvinylidene fluoride) as the base material for the separator. These inexpensive, readily available materials are transformed into high-performance separators through the ion-track etching process, providing a cost-effective solution compared to specialized expensive materials
3Object-generated harmful factors
If the separator pores are made smaller to block polysulfides, then polysulfide shuttle is reduced, but ion flux may be restricted
Solution Approach 1:
The patent applies partial action by creating nanochannels with diameters (10-200 nm) that are sufficiently small to block polysulfide molecules yet large enough to maintain adequate ion transport. The asymmetric pore geometry with different opening diameters at each surface optimizes this balance, providing enhanced polysulfide rejection at the critical interface while preserving ion flux through the membrane bulk
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 membrane effectively reduces the polysulfide shuttle, improving the cycling stability and coulombic efficiency of lithium-sulfur batteries and other cationic ion batteries, offering a cost-effective and scalable solution.
Implementation Method 1
the membrane comprises a plurality of nanochannels, the majority in number of said nanochannels is continuous and has an opening tip at the frontside and an opening tip at the backside of said membrane
Implementation Method 2
which allows cationic ion flux while suppressing polysulfides
Implementation Method 3
an appropriate porous structure, in order to make possible the diffusion of the anions and cations of the electrolyte
Data Source
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Figure 5~5(b)
AI summary
The present invention relates to the use of a porous polymer etched ion-track membrane as separator for batteries comprising a positive electrode, a negative electrode and a liquid electrolyte comprising at least one salt of a cationic ion in solution in a solvent, and to batteries comprising such a membrane as porous separator.