Sulfur Composite Cathode Separator Lamination Design
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Solution Overview
Problem
Lithium-sulfur batteries face challenges in achieving high capacity and cost-effective manufacturing due to limitations in the sulfur-based host material composition and interfacial layers, which affect the battery's energy density and cycling stability.
Innovation Solution
The introduction of a composite cathode-separator lamination (CSL) with a sulfur-based host material, a carbonaceous coating, and a porous polymer-based interfacial layer, where the host material includes less than 6% polymeric binder and less than 40% electrically conductive carbon, and the interfacial layer is formed through molecular layer deposition or gel-forming precursors, enhancing the binding interface and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional sulfur-based host material with high polymeric binder and electrically conductive carbon content is used, then the structural integrity and conductivity are improved, but the energy density and manufacturing cost deteriorate
Solution Approach 1:
The patent applies parameter changes by reducing the polymeric binder content to less than 6% and electrically conductive carbon content to less than 40%, while adjusting the sulfur compound composition to achieve optimal performance with higher energy density
Solution Approach 2:
The patent uses composite materials by creating a multi-layer structure including a sulfur-based host material layer, a polymer-based interfacial layer, and a carbonaceous coating layer, where each layer contributes specific properties to achieve both structural integrity and high energy density
2Strength
If a thick interfacial layer is used between carbonaceous coating and host material, then the binding interface strength is improved, but the manufacturing complexity and cost increase
Solution Approach 1:
The patent employs thin films by using a polymer-based interfacial layer with thickness of less than 5 μm that provides sufficient binding interface strength while maintaining manufacturing simplicity and cost-effectiveness
Solution Approach 2:
The patent applies parameter changes by optimizing the interfacial layer thickness to less than 5 μm and controlling its porosity between 5% to 40%, achieving the right balance between binding strength and manufacturing complexity
3Ease of operation
If high porosity host material is used, then the electrolyte penetration and ion transport are improved, but the mechanical strength and sulfur containment deteriorate
Solution Approach 1:
The patent applies parameter changes by optimizing the host material porosity to less than 40%, which maintains sufficient ion transport capability while preserving mechanical strength and sulfur containment effectiveness
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
This configuration results in higher capacity lithium-sulfur battery cells with reduced manufacturing costs and improved cycling stability by increasing the electrical conductivity and trapping polysulfides, thereby preventing anode deterioration and electrolyte viscosity increases.
Implementation Method 1
The polymer-based interfacial layer can be a polymerized gel-forming precursor, wherein the gel forming precursor can be a branched acrylate. The gel forming precursor can be polymerized by a UV initiator in the presence of UV light. The gel forming precursor can be polymerized by an electron-beam initiator in the presence of an electron-beam. The gel forming precursor can be polymerized by thermal initiator in the presence of heat.
Implementation Method 2
The host material can include less than about 40% electrically conductive carbon. The electrically conductive carbon of the host material can be only graphene.
Implementation Method 3
improved cycling stability by increasing the electrical conductivity and trapping polysulfides
Data Source
AI summary
Composite cathode-separator laminations (CSL) include a current collector with sulfur-based host material applied thereto, a coated separator comprising an electrolyte membrane separator with a carbonaceous coating, and a porous, polymer-based interfacial layer (PBIL) forming a binding interface between the carbonaceous coating and the host material. The host material includes less than about 6% polymeric binder, and less than about 40% electrically conductive carbon, with the balance comprising one or more sulfur compounds. The PBIL can have a thickness of less than about 5 μm and a porosity of about 5% to about 40%. The host material can comprise less than about 40% conductive carbon (e.g., graphene) and have a porosity of less than about 40%. The carbonaceous coating (e.g., graphene) can have a thickness of about 1 μm to about 5 μm. The CSL can be disposed with an anode within an electrolyte to form a lithium-sulfur battery cell.