Lithium Sulfur Battery Anode Structure with Segmented Carbon Layers
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Solution Overview
Problem
Lithium sulfur batteries face reduced energy capacity and increased resistance due to insufficient sulfur reaction area and local aggregation of Li2S, especially at high sulfur loading and current densities, which are critical for electric vehicle batteries.
Innovation Solution
An anode structure with a sulfur anode laminated on aluminum foil and a carbon coating layer, where sulfur is dispersed between the anode and a polyester separation membrane, allowing for rolling and sufficient electrolyte replacement to enhance energy density without excess sulfur immersion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If sulfur is highly loaded in the anode to increase energy density, then the energy density increases, but the sulfur utilization rate decreases and local aggregation of Li2S occurs
Solution Approach 1:
The patent divides the anode into multiple functional layers: a sulfur-containing layer with sulfur dispersed in a carbon matrix, and a sulfur-free carbon layer. This segmentation allows sulfur to be distributed across different regions, increasing the reaction area and preventing local aggregation of Li2S while maintaining high sulfur loading for high energy density.
2Power
If the current density is increased to improve output, then the output improves, but the local aggregation of Li2S intensifies and discharge capacity decreases
Solution Approach 1:
The sulfur-free carbon layer acts as a buffer that distributes the reaction sites across the layered structure. When high current density is applied, Li2S forms in multiple locations simultaneously rather than aggregating in one spot, maintaining discharge capacity while delivering high power output.
3Reliability
If a thick carbon structure layer is used to improve cell capacity and lifespan, then electrolyte replacement is sufficient and reaction area increases, but the energy density decreases
Solution Approach 1:
The patent applies carbon material locally where needed for structural support and reaction area (in the sulfur-containing layer and as a sulfur-free carbon layer), rather than using a uniformly thick carbon structure. This localized approach provides sufficient electrolyte replacement and reaction area while minimizing the weight penalty, maintaining high energy density.
4Ease of manufacture
If rolling of the carbon structure layer is performed to increase volume energy density, then the manufacturing process is simplified, but Li2S local aggregation occurs and cell lifespan decreases
Solution Approach 1:
The layered structure with sulfur dispersed in a carbon matrix and a sulfur-free carbon layer provides inherent structural integrity that allows rolling without causing Li2S aggregation. The segmentation prevents sulfur concentration in any single location, so even when rolled, the battery maintains good cell lifespan and performance.
Data Source
AI summary
An anode structure of a lithium sulfur battery includes a sulfur anode laminated on an aluminum foil, and a carbon coating layer disposed between the sulfur anode and a carbon structure layer in which sulfur is immersed. The sulfur anode includes the sulfur, a conductor, and a binder. The carbon structure layer in which sulfur is immersed is a polyester (PE) separation membrane separated from a counter electrode. A loaded amount of sulfur within the anode structure is dispersed to the sulfur anode and the carbon structure layer in which the sulfur is immersed.