Alkali Polysulfide Flow Battery Separator Design
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Solution Overview
Problem
Flow batteries and lithium sulfide batteries face challenges with energy density and polysulfide shuttle issues, which affect their cycling efficiency and charge/discharge performance.
Innovation Solution
An ion-selective separator composition with an alkali metal ion conducting film, a carbon layer, and an alkali metal ion conductor layer is used to separate the anode and cathode, along with an alkali-metal polysulfide catholyte and an electrolyte flushing system to enhance energy density and inhibit polysulfide shuttle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If lithium polysulfide systems are used to improve charge carrying capacity, then power density is substantially improved, but the highly lithiated species become highly insoluble
Solution Approach 1:
A carbon-coated separator is introduced as an intermediary component between the anode and catholyte. The carbon coating on the separator surface acts as a mediator that prevents direct contact and insoluble species accumulation, enabling the use of highly lithiated polysulfide species (Li2S2, Li2S) in the catholyte to achieve high power density while maintaining system stability through the intermediate carbon layer
2Quantity of substance
If polysulfide species are used to increase charge capacity, then energy storage capacity is improved, but polysulfide shuttle occurs contaminating the lithium anode or anolyte
Solution Approach 1:
The carbon-coated separator serves as a physical intermediary barrier that blocks polysulfide species from crossing over to the anode side. The carbon coating on the separator surface prevents polysulfide shuttle while maintaining ion conductivity, thus preserving charge capacity without the harmful contamination effect
Solution Approach 2:
A thin carbon coating layer is applied to the separator surface. This thin film structure is sufficient to block polysulfide species transport while maintaining flexibility and ion conductivity. The carbon layer acts as a selective barrier that prevents polysulfide contamination without compromising the charge capacity provided by polysulfide species
3Quantity of substance
If conventional flow battery systems are used, then large scale energy storage is achieved, but energy density and cycling issues occur
Solution Approach 1:
The carbon-coated separator acts as a stable intermediary component that enables reliable cycling in large-scale flow battery systems. By preventing polysulfide shuttle and insoluble species accumulation, the carbon-coated separator maintains consistent performance over multiple cycles while preserving the large-scale energy storage capability of flow battery systems
Solution Approach 2:
The invention changes the surface properties of the separator by applying a carbon coating. This parameter change in the separator surface characteristics improves wettability, prevents polysulfide adhesion, and enhances ion conductivity, thereby improving cycling performance while maintaining large-scale energy storage capacity
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 improves energy density and cycle efficiency while preventing polysulfide shuttle, leading to enhanced charge/discharge performance in a cost-effective manner.
Implementation Method 1
an alkali metal ion conducting separator film for separating the anode and the cathode
Implementation Method 2
the electrolyte flows through an electrochemical cell from an electrolyte reservoir and is charged or discharged at an electrode
Data Source
AI summary
An alkali polysulphide flow battery, components, systems and compositions for use with an alkali polysulphide flow battery and a method of manufacturing and operating a flow battery system are provided. An ion-selective separator composition for a battery having an anode and an alkali metal sulfide or polysulfide cathode is provided. The separator composition includes an alkali metal ion conducting separator film for separating the anode and the cathode, a carbon layer disposed to a cathode side of the film and an alkali metal ion conductor layer disposed to an anode side of the carbon layer.