Lithium-Sulfur Battery Electrolyte Composition for Polysulfide Leaching
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Solution Overview
Problem
The leaching of lithium polysulfide in lithium-sulfur batteries leads to reduced capacity and cycle life characteristics due to the high solubility of lithium polysulfide in ether-based electrolytes, causing shuttle phenomena and electrode passivation, which existing methods have not adequately addressed.
Innovation Solution
An electrolyte for lithium-sulfur batteries comprising a non-aqueous organic solvent mixture of a benzene-based compound and 1,3-dioxolane, with a specific volume ratio, to suppress lithium polysulfide leaching and enhance conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the content of electrolyte is reduced to minimize lithium polysulfide leaching, then the shuttle phenomenon is suppressed, but the viscosity increases rapidly during charging/discharging, causing overvoltage and performance degradation
Solution Approach 1:
The patent optimizes the electrolyte composition parameters by selecting specific solvent types (cyclic carbonate, chain carbonate, cyclic carboxylate) and their ratios, along with appropriate lithium salt concentration (0.5-2.0 M). This compositional parameter optimization allows the electrolyte to maintain low viscosity and high ionic conductivity even at reduced electrolyte content, preventing overvoltage while suppressing lithium polysulfide leaching.
2Reliability
If carbon nanotube aggregates or porous graphene structures are used to block lithium polysulfide leaching, then the leaching is suppressed, but the manufacturing complexity increases and commercial applicability is reduced
Solution Approach 1:
The patent introduces an intermediary substance - a specifically composed electrolyte solvent system - that acts as a mediator between the positive electrode and negative electrode. This electrolyte composition controls lithium polysulfide solubility and transport, suppressing leaching and shuttle phenomena without requiring complex electrode structures like carbon nanotube aggregates or porous graphene, thereby maintaining manufacturing simplicity.
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 electrolyte maximizes positive electrode capacity and ensures stable cycle life characteristics by inhibiting lithium polysulfide leaching, reducing sulfur loss and electrode passivation.
Implementation Method 1
an ether-based compound with high solubility in lithium polysulfide is mainly used as a solvent for the electrolyte
Implementation Method 2
lithium metal releases electrons at the negative electrode, and is oxidized to the form of lithium cations
Implementation Method 3
sulfur accepts electrons at the positive electrode and is reduced to the form of sulfur anions
Implementation Method 4
due to the leaching of lithium polysulfide from the positive electrode and its shuttle phenomenon
Data Source
Figure 1(a)~1(f)
Figure 2
Figure 3
AI summary
The present invention relates to an electrolyte for a lithium-sulfur battery and a lithium-sulfur battery comprising the same, and more specifically, the electrolyte comprises a first solvent comprising a benzene-based compound and a second solvent comprising 1,3-dioxolane as a non-aqueous organic solvent, thereby suppressing the leaching of lithium polysulfide and thus enabling high capacity and long cycle life of the lithium-sulfur battery.