Organic Sulfur Cathode Material for Lithium-Ion Batteries
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Solution Overview
Problem
The development of high-capacity cathodes for lithium-ion secondary batteries lags behind anodes, and elemental sulfur, despite its high theoretical capacity, is not effectively utilized due to its low conductivity and the dissolution of lithium polysulfide in organic electrolytes, leading to capacity reduction.
Innovation Solution
A method involving the use of a sulfur-containing starting material in a liquid form, combined with linear or branched alcohols, carboxylic acids, or aldehydes, subjected to heat treatment in an inert atmosphere to produce an organic sulfur material with enhanced conductivity and trapped sulfur, preventing dissolution into the electrolyte.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If elemental sulfur is used as a high-capacity electrode material, then the theoretical capacity is high (about 1670 mAh/g), but the conductivity is low
Solution Approach 1:
The patent creates a composite material where sulfur is encapsulated within a carbonaceous matrix derived from liquid organic starting materials. This composite structure provides both the high capacity of sulfur and the conductivity of carbon, resolving the contradiction between capacity and conductivity.
Solution Approach 2:
The carbonaceous material is formed locally around sulfur particles through heat treatment of liquid organic starting materials. This localized carbon formation ensures that each sulfur region has its own conductive pathway, maintaining high conductivity while preserving the high capacity of sulfur.
2Quantity of substance
If sulfur is used in battery systems with organic electrolyte, then high capacity is achieved, but lithium polysulfide dissolves into the electrolyte solution causing capacity reduction
Solution Approach 1:
Sulfur is nested within the carbonaceous matrix structure, with the carbon material forming a protective shell around the sulfur core. This nested configuration physically confines lithium polysulfide within the carbon matrix, preventing its dissolution into the electrolyte solution while maintaining the high capacity of sulfur.
Solution Approach 2:
The carbonaceous matrix acts as a flexible shell that encapsulates sulfur and accommodates volume changes during charge-discharge cycles. This shell structure prevents lithium polysulfide from escaping into the electrolyte, thereby maintaining capacity retention while preserving the high capacity of the sulfur core.
3Ease of manufacture
If solid organic materials are used as starting materials for producing sulfur-carbon composites, then the reaction proceeds slowly due to slow diffusion in solid materials
Solution Approach 1:
The patent changes the physical state parameter of the organic starting material from solid to liquid form. This parameter change dramatically increases the diffusion rate of reactants, allowing the carbonization reaction to proceed efficiently and rapidly, thus improving reaction efficiency while reducing reaction time.
Solution Approach 2:
By using liquid organic starting materials, the patent enables fluid-phase reaction dynamics that facilitate rapid mixing and diffusion. The liquid state allows for homogeneous distribution of sulfur and organic material, ensuring efficient reaction progression and reducing manufacturing time compared to solid-state reactions.
4Productivity
If high temperature is applied to liquefy or vaporize solid material for efficient reaction, then reaction efficiency improves, but manufacturing costs and process complexity increase
Solution Approach 1:
The patent changes the temperature parameter from high (required for solid liquefaction) to moderate (sufficient for liquid carbonization). By starting with liquid organic materials, the process achieves efficient reaction at lower temperatures, reducing energy consumption and simplifying the manufacturing process while maintaining high productivity.
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 resulting organic sulfur material exhibits high charge-discharge characteristics and excellent cycle stability, suitable for use as a cathode active material in both non-aqueous and all-solid-state lithium-ion batteries, with improved capacity retention.
Implementation Method 1
subjecting a solution containing a sulfur-containing starting material and a liquid organic starting material to heat treatment in an inert atmosphere
Implementation Method 2
the liquid organic substance that has undergone carbonization and thus has conductivity is efficiently bonded to sulfur
Data Source
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AI summary
The present invention provides an organic sulfur material comprising carbon, hydrogen, and sulfur as constituent elements, and having peaks in the vicinity of 480 cm-1, 1250 cm-1, 1440 cm-1, and 1900 cm-1 in a Raman spectrum detected by Raman spectroscopy. The peak in the vicinity of 1440 cm-1 is the most intense peak. This organic sulfur material, which is produced by using a liquid organic starting material, achieves high capacity. This organic sulfur material preferably does not have peaks in the vicinity of 846 cm-1 or 1066 cm-1.