Alkali Metal Sulfur Battery Electrolyte Suppressing Polysulfide Shuttle
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Solution Overview
Problem
Alkaline-sulfur batteries face challenges with polysulfide shuttle, leading to reduced Coulomb efficiency, cycle stability, and self-discharge due to the solubility of polysulfides in common electrolytes, which existing solutions like LiNO3 cannot fully address without causing side reactions and anode degradation.
Innovation Solution
An electrolyte composed of a sulfone and a fluorine-containing ether in a volume ratio of ≥1:4, along with a cathode additive for homogenized polysulfide distribution, effectively suppresses polysulfide shuttle, enhancing Coulomb efficiency, long-term stability, and cycle stability without using LiNO3.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If LiNO3 is added to suppress polysulfide shuttle, then Coulomb efficiency improves, but anode degradation occurs and cycle stability deteriorates
Solution Approach 1:
The patent removes LiNO3 from the electrolyte composition entirely, replacing it with a fluorinated ether/sulfone electrolyte system. This extraction eliminates the harmful side reactions and anode degradation caused by LiNO3 while maintaining polysulfide shuttle suppression through the unique properties of the fluorinated ether that has high solubility for polysulfides
Solution Approach 2:
The patent changes the chemical composition parameters of the electrolyte by using a specific volume ratio of fluorinated ether to sulfone (≥1:4). This parameter change creates an electrolyte environment that simultaneously suppresses polysulfide shuttle and prevents anode degradation without requiring LiNO3, thereby resolving the contradiction between Coulomb efficiency and cycle stability
2Productivity
If LiNO3 is used to improve Coulomb efficiency, then polysulfide shuttle is suppressed, but side reactions occur and active material is consumed
Solution Approach 1:
The patent extracts LiNO3 from the system and replaces it with a fluorinated ether-based electrolyte. The fluorinated ether maintains high polysulfide solubility and suppresses shuttle effects without causing the continuous consumption of active material that occurs with LiNO3, thereby eliminating the trade-off between Coulomb efficiency and active material preservation
3Ease of operation
If common electrolytes are used, then polysulfides are soluble, but polysulfide shuttle occurs and reduces battery performance
Solution Approach 1:
The patent changes the chemical parameters of the electrolyte by using fluorinated ether with specific molecular structure and properties. This parameter change results in an electrolyte that maintains high polysulfide solubility for easy operation while simultaneously suppressing polysulfide shuttle through the unique solvation effects of the fluorinated ether, thereby improving battery performance without sacrificing ease of operation
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 proposed electrolyte and cathode design achieve high Coulomb efficiency, long-term stability, and cycle stability in alkaline-sulfur batteries, with improved oxidation stability and ignition safety over a wide temperature range, and nearly 90% active material utilization.
Implementation Method 1
Fluorinated ethers (especially TTE or HFE) have been used in the past as electrolyte additives, but these are characterized by low solubility for polysulfides
Implementation Method 2
The electrolyte according to the invention contains a sulfone, which results in particularly high oxidation stability
Implementation Method 3
the electrolyte exhibits increased resistance to ignition and thus allows its use in alkaline-sulfur batteries over a wide temperature range
Data Source
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Figure 3A~3B
AI summary
According to the invention, an electrolyte is provided for an alkali-sulfur battery. An alkali-sulfur battery is also provided, which contains the electrolyte according to the invention. The electrolyte according to the invention contains a mixture of a sulfone and a fluorine-containing ether in a volume ratio of ≥ 1:4 (v:v). Through the use of said electrolyte, the shuttling of polysulfide species from the cathode to the anode can be effectively suppressed, without the use of LiNO3. Through the electrolyte in alkali-sulfur batteries, a high coulombic efficiency, long-term stability (low self-discharge) and cycle durability can be achieved even without the use of LiNO3. Coloumbic efficiency, long-term stability and cycle durability can be further improved through the use of a cathode which contains an additive for uniform distribution of polysulfide inside the cathode. In addition, uses of components of the alkali-sulfur battery according to the invention are also disclosed.