PEO-Carbon Composite Separator Layer for Polysulfide Shuttle Control
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Solution Overview
Problem
Lithium-sulfur batteries face capacity reduction and shortened lifespan due to the leaching and shuttle phenomenon of lithium polysulfide, which current technologies have not effectively addressed.
Innovation Solution
A functional separator is developed with a polyethylene oxide (PEO)-conductive carbon composite layer chemically bonded on its surface, enhancing the battery's capacity and lifetime by reducing lithium polysulfide through efficient ion transport and polysulfide adsorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional separator is used in lithium-sulfur batteries, then the battery structure is simple and easy to manufacture, but the lithium polysulfide leaching and shuttle phenomenon occurs, causing capacity reduction and shortened lifetime
Solution Approach 1:
The patent applies composite materials by combining polyethylene oxide (PEO) with conductive carbon materials to form a PEO-conductive carbon composite coating layer on the separator surface. This composite structure provides both the polysulfide adsorption capability of PEO and the electrical conductivity of carbon materials, effectively addressing the lithium polysulfide shuttle phenomenon while maintaining a relatively simple overall separator structure that can be manufactured by coating conventional separators.
2Reliability
If the separator surface is modified to adsorb lithium polysulfide, then the polysulfide shuttle phenomenon is reduced, but the ion transport efficiency may be affected
Solution Approach 1:
The patent applies local quality by creating a functional coating layer with specific properties on the separator surface while maintaining the bulk separator's original structure. The PEO-conductive carbon composite coating provides localized polysulfide adsorption capability at the separator surface, while the porous structure and ion-conductive properties of the coating allow lithium ion transport to proceed efficiently through the separator bulk, thus resolving the contradiction between adsorption and ion transport.
Solution Approach 2:
The patent utilizes porous materials by employing a porous PEO-conductive carbon composite coating structure that allows ion transport. The porous structure provides pathways for lithium ion diffusion while the high surface area of the porous material enhances polysulfide adsorption capacity, effectively balancing both requirements.
3Reliability
If a coating layer is added to the separator to reduce lithium polysulfide, then the battery capacity and lifetime are improved, but the manufacturing process becomes more complex
Solution Approach 1:
The patent applies preliminary action by pre-synthesizing the PEO-conductive carbon composite material before coating it onto the separator. This approach allows the complex composite material to be prepared in advance under controlled conditions, simplifying the actual separator manufacturing process to a coating step rather than requiring complex in-situ synthesis during separator production.
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 PEO-conductive carbon composite layer effectively reduces lithium polysulfide, improving the battery's discharging capacity and extending its lifespan by enhancing ion migration and polysulfide management.
Implementation Method 1
an electrically conductive carbon capable of reducing lithium polysulfide
Implementation Method 2
polyethylene oxide for maximum efficiency are chemically bonded
Implementation Method 3
enhancing ion migration
Data Source
AI summary
A functional separator capable of improving the capacity and lifetime of a battery by coating a material capable of reducing lithium polysulfide on the surface of the separator, a method for manufacturing the same, and a lithium secondary battery including the same. The functional separator includes a base separator and a polyethylene oxide-conductive carbon composite layer present on the surface of the base separator.