Dry-Process Sulfur-Carbon Cathode for High Sulfur Loading
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Solution Overview
Problem
Conventional lithium-sulfur secondary battery positive electrodes have limited sulfur loading due to the inclusion of conductive materials and binders in the slurry process, leading to reduced energy density and increased manufacturing time and cost.
Innovation Solution
A dry process is used to create a free-standing film positive electrode material with a high sulfur content by applying a sulfur-carbon composite to a current collector with a minimal binder layer, eliminating the need for complex slurry-based processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a slurry process is used to manufacture the positive electrode with conductive material and binder, then the electrode structure is stable and manufacturable, but the loading amount of positive electrode active material is reduced and energy density is lowered
Solution Approach 1:
The invention extracts and removes the conductive material and binder from the positive electrode structure, retaining only the sulfur-carbon composite active material. This is achieved by using a dry process where sulfur is directly coated on carbon material without requiring additional conductive additives or binding agents, thereby maximizing the active material loading amount and energy density
Solution Approach 2:
The invention changes the manufacturing parameters from a slurry-based wet process to a dry coating process. This parameter change eliminates the need for solvents, drying steps, and rolling operations, simplifying the manufacturing process while enabling higher active material content in the final electrode
2Ease of manufacture
If a slurry process with multiple steps (mixing, coating, drying, rolling) is used, then the electrode can be manufactured with good structure, but time and cost are increased
Solution Approach 1:
The invention extracts and eliminates unnecessary manufacturing steps from the conventional slurry process. By removing the mixing, coating, drying, and rolling steps and replacing them with a simple dry coating method, the manufacturing process is significantly simplified and time is reduced
Solution Approach 2:
Instead of following the conventional approach of mixing materials into a slurry and then processing through multiple steps, the invention inverts the approach by directly applying dry sulfur-carbon composite material to the electrode substrate, reversing the traditional manufacturing sequence and achieving simplicity
3Use of energy by moving object
If sulfur is used as positive electrode active material, then theoretical energy density is five times higher than conventional materials, but electrical conductivity is extremely low (5×10^-30 S/cm)
Solution Approach 1:
The invention creates a composite material structure where sulfur is coated on or integrated with conductive carbon material. This composite structure combines the high energy density of sulfur with the electrical conductivity of carbon, achieving both high capacity and adequate conductivity without requiring additional conductive additives
Solution Approach 2:
The invention applies local quality by concentrating sulfur in specific locations on the carbon material surface or within its structure, creating regions of high energy density while maintaining the overall conductive network provided by the carbon framework
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 approach results in a lithium secondary battery with improved sulfur loading, reduced non-capacity substances, and enhanced electrochemical reactivity, while simplifying the manufacturing process and reducing costs.
Implementation Method 1
the property of the sulfur formed on the surface of the sulfur-carbon composite, which is melt under pressure and aggregates with the surrounding sulfur
Implementation Method 2
the sulfur-carbon composite produced thereby is used
Data Source
AI summary
A positive electrode, a lithium secondary battery comprising the same, and a method of manufacturing the same are provided. The positive electrode comprises a positive electrode current collector; a positive electrode active material layer including a free-standing film positive electrode material manufactured by a dry process, taking advantage of strong self-cohesive force of sulfur-carbon composite under pressure condition; and a binding layer bonding the positive electrode active material layer and the positive electrode current collector.