Etched Ion-Track Battery Separator for Polysulfide Shuttle Suppression
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Solution Overview
Problem
Lithium-sulfur batteries face challenges due to the polysulfide redox shuttle phenomenon, which leads to self-discharge and deterioration of performance, and similar issues affect other batteries operating by cationic ion circulation, such as sodium, potassium, and calcium batteries, resulting in reduced coulombic efficiency and stability.
Innovation Solution
A porous polymer etched ion-track membrane is used as a separator with specific nanochannel dimensions and geometry to allow cationic ion flux while preventing redox species migration, specifically designed for lithium-sulfur, lithium-air, lithium-ion, and sodium-ion batteries, enhancing mechanical strength and chemical resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a porous separator is used to allow ion diffusion, then ionic conductivity is improved, but mechanical strength deteriorates
Solution Approach 1:
The patent employs a porous polymer membrane with controlled porosity (20-80%) to achieve optimal balance between ion diffusion and mechanical strength. The porous structure allows sufficient electrolyte penetration and ion transport while the polymer matrix maintains structural integrity. The pore size is specifically controlled (0.01-10 micrometers) to prevent active material passage while permitting ion flow.
2Use of energy by moving object
If the separator porosity is increased to improve ion transport, then ionic conductivity is improved, but chemical resistance deteriorates
Solution Approach 1:
The patent optimizes key parameters including porosity (20-80%), pore size (0.01-10 micrometers), and membrane thickness (5-50 micrometers) to achieve the desired balance between ion transport and chemical stability. These parameter ranges are specifically selected to maintain chemical resistance while enabling sufficient ionic conductivity.
3Weight of moving object
If a thin separator is used to reduce battery weight, then weight is reduced, but mechanical strength deteriorates
Solution Approach 1:
The patent utilizes a thin polymer membrane (5-50 micrometers thick) that provides sufficient mechanical strength through its material properties and optimized porous structure. The thin film design reduces battery weight while the controlled porosity and polymer composition ensure adequate mechanical integrity and chemical resistance.
4Reliability
If the nanochannel opening tip diameter is reduced to prevent redox species migration, then polysulfide shuttle is suppressed, but manufacturing precision requirements increase
Solution Approach 1:
The patent specifies a nanochannel opening tip diameter range of 10-200 nanometers, with a preferred range of 20-100 nanometers. This parameter optimization effectively suppresses polysulfide shuttle while remaining achievable with current ion-track etching technology. The conical nanochannel geometry further enhances polysulfide blocking capability.
Solution Approach 2:
The patent employs asymmetric conical nanochannel geometry with smaller opening tip diameters (10-200 nm) compared to the overall channel dimensions. This asymmetric structure provides superior polysulfide blocking at the electrode interface while maintaining adequate ion transport through the larger channel body, and is particularly effective when the frontside opening tips face the positive electrode.
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 suppresses the polysulfide shuttle, improving coulombic efficiency and cycle stability, making it a cost-effective and scalable solution for enhancing battery performance across various cationic ion batteries.
Implementation Method 1
an appropriate porous structure, in order to make possible the diffusion of the anions and cations of the electrolyte
Implementation Method 2
an appropriate mechanical strength, in order to withstand the stresses due to the variations in volume of the active materials during the charging and discharging cycles
Implementation Method 3
a sufficient chemical resistance, in order to ensure that it holds over time since it is immersed in a highly corrosive solution (i.e. electrolyte)
Data Source
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.