Ternary Electrolyte for Lithium-Sulfur Battery Sulfur Utilization
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Solution Overview
Problem
Lithium-sulfur batteries face issues with low sulfur utilization rate and battery life-shortening due to decomposition of existing liquid electrolytes, leading to gas generation and swelling phenomena.
Innovation Solution
A liquid electrolyte composition for lithium-sulfur batteries comprising a non-aqueous solvent mixture of cyclic ether, glycol ether, and linear ether, along with a lithium salt and optional N-O additives, which enhances sulfur utilization and stability, preventing solvent decomposition and improving battery life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional liquid electrolytes (DOL/DME mixture) are used in lithium-sulfur batteries, then sulfur utilization rate is improved, but battery life is shortened due to solvent decomposition
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by introducing a ternary mixture system comprising cyclic carbonate (EC), chain carbonate (DMC), and cyclic ether (THF) in specific volume ratios. This parameter modification resolves the contradiction by achieving both high sulfur utilization (through THF's coordination ability) and long battery life (through EC's stable SEI formation and DMC's low viscosity), eliminating the decomposition issues of conventional DOL/DME mixtures.
2Quantity of substance
If sulfur impregnation is increased to improve capacity, then theoretical capacity is enhanced, but sulfur utilization rate remains low
Solution Approach 1:
The patent creates a composite electrolyte system combining three different carbonate/ether components (EC, DMC, THF) that work synergistically. EC provides stable SEI, DMC ensures low viscosity and high ion conductivity, and THF coordinates with lithium polysulfides to enhance utilization. This composite approach allows high sulfur impregnation while maintaining high sulfur utilization rates, resolving the contradiction between quantity and productivity.
3Reliability
If solvent decomposition is prevented to extend battery life, then stability is improved, but sulfur utilization rate may decrease
Solution Approach 1:
The patent segments the electrolyte function across three distinct components: EC (cyclic carbonate) forms stable SEI for long life, DMC (chain carbonate) provides low viscosity and high conductivity, and THF (cyclic ether) coordinates with lithium polysulfides for high utilization. This functional segmentation allows each component to specialize, achieving both battery life extension and high sulfur utilization without compromise.
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 composition achieves a higher sulfur utilization rate and extended battery life by maintaining stability and suppressing gas generation, thereby enhancing the capacity and longevity of lithium-sulfur batteries.
Implementation Method 1
a non-aqueous solvent consisting of: i) 10 to 40% by volume, based on the non-aqueous solvent, of a cyclic ether which is tetrahydrofuran optionally substituted with a Cl to C4 alkyl group or alkoxy group; ii) a glycol ether
Implementation Method 2
These are used either alone or as a mixture, and Korean Patent Application Laid-Open Publication No. 10-2009-0086575 discloses a lithium-sulfur battery having 1,3-dioxolane in a negative electrode and 1,2-dimethoxyethane in a positive electrode in separation so as to be present non-uniformly using a polymer.
Data Source
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AI summary
The present invention relates to a ternary liquid electrolyte for a lithium-sulfur battery and a lithium-sulfur battery including the same. The liquid electrolyte for a lithium-sulfur battery according to the present invention exhibits an excellent sulfur utilization rate when used in a lithium-sulfur battery, and exhibits excellent stability. Accordingly, the liquid electrolyte for a lithium-sulfur battery according to the present invention is capable of enhancing a life time property while securing a capacity property of a lithium-sulfur battery.