Sulfide Electrode Coating for Solid Cell Stability
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Solution Overview
Problem
Sulfide-based solid electrolytes react with polar solvents, leading to side reactions and poor dispersibility in electrode slurry, and existing methods fail to maintain ion conductivity and chemical stability during electrode fabrication.
Innovation Solution
A fabrication method involving forming a coating layer on sulfide-based solid electrolytes using a nonmetallic oxide, mixing with electrode active materials and conductive materials in a polar solvent, casting, removing the polar solvent, and then removing the coating layer through heating to secure chemical stability and ion conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a polar solvent is used to fabricate electrode slurry, then dispersibility of electrode materials is improved, but chemical stability of sulfide-based solid electrolyte deteriorates due to side reactions
Solution Approach 1:
A coating layer comprising a nonmetallic oxide is formed on the surface of the sulfide-based solid electrolyte to act as an intermediary barrier. This coating layer prevents direct contact and chemical reaction between the polar solvent and the sulfide-based solid electrolyte, while allowing the polar solvent to maintain its dispersibility function for electrode materials during slurry fabrication.
Solution Approach 2:
The coating layer is formed in advance before the electrode slurry fabrication process to preemptively protect the sulfide-based solid electrolyte from harmful side reactions with the polar solvent. This preliminary protective action enables the use of polar solvents without compromising the chemical stability of the solid electrolyte.
2Object-generated harmful factors
If a non-polar solvent is used to avoid side reactions, then chemical stability is maintained, but dispersibility of sulfide-based solid electrolyte deteriorates
Solution Approach 1:
The nonmetallic oxide coating layer serves as a mediator that enables the use of polar solvents by preventing direct interaction between the solvent and sulfide-based solid electrolyte, thereby resolving the contradiction between solvent polarity and chemical stability while maintaining dispersibility.
3Stability of the object's composition
If organic dispersant is added to improve dispersibility, then dispersibility of solid electrolyte is improved, but chemical stability deteriorates due to reaction with solid electrolyte during drying
Solution Approach 1:
The coating layer acts as a protective intermediary that eliminates the need for organic dispersants. By preventing direct contact between the sulfide-based solid electrolyte and polar solvent, the coating layer enables the use of polar solvents as dispersants without requiring additional organic dispersant additives that would react with the solid electrolyte.
4Object-generated harmful factors
If coating layer is formed to protect solid electrolyte, then chemical stability is improved, but ion conductivity deteriorates
Solution Approach 1:
The patent specifies that the nonmetallic oxide coating layer should have a boiling point of 300°C to 700°C, which allows the coating to be removed at controlled temperatures. This parameter control enables the coating to provide protection during slurry fabrication while being removable to restore ion conductivity in the final electrode product.
Solution Approach 2:
The coating layer is temporarily formed during slurry fabrication to provide protection, then removed in a subsequent step to restore ion conductivity. This periodic application and removal of the coating layer allows the system to benefit from protection during fabrication while maintaining high ion conductivity in the final product.
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 method ensures chemical stability and maintains ion conductivity of sulfide-based solid electrolytes, improving the dispersibility and stability of the electrode slurry while simplifying the process.
Implementation Method 1
forming a coating layer on a surface of the sulfide-based solid electrolyte by heating a nonmetallic oxide at 300 to 700° C.
Implementation Method 2
removing the polar solvent by heating the cast electrode slurry at 100 to 300° C.
Implementation Method 3
removing the coating layer by heating the electrode slurry from which the polar solvent is removed at 300 to 700° C.
Data Source
AI summary
A fabrication method of an electrode for an all solid cell includes: providing a sulfide-based solid electrolyte; forming a coating layer on a surface of the sulfide-based solid electrolyte by heating a nonmetallic oxide at 300 to 700° C.; forming electrode slurry by mixing an electrode active material, the sulfide-based solid electrolyte formed with the coating layer, and a conductive material with a polar solvent; casting the electrode slurry on at least one surface of an electrode current collector; removing the polar solvent by heating the cast electrode slurry at 100 to 300° C.; and removing the coating layer by heating the electrode slurry from which the polar solvent is removed at 300 to 700° C.