Sulfide Composite Electrolyte for Stable Semi-Solid Battery Interfaces
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Solution Overview
Problem
Sulfide-based solid electrolytes in batteries face issues with ionic conductivity deterioration due to interface resistance with other solid particles, chemical side reactions with liquid electrolytes, low lithium ion yield, flame retardancy loss, and unstable high-voltage oxidation stability, limiting their practical application in batteries.
Innovation Solution
A solid-liquid composite electrolyte is developed, comprising a sulfide-based solid electrolyte and a liquid electrolyte with a fluorinated organic solvent that dissolves a salt, along with additives, diluents, or polymers, to reduce side reactions, maintain high ionic conductivity, and enhance heat resistance and flame retardancy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a liquid electrolyte is added to sulfide-based solid electrolyte to improve ionic conductivity, then ionic conductivity is improved, but chemical side reactions occur at the interface and flame retardancy is lost
Solution Approach 1:
A solid electrolyte interface (SEI) layer is formed between the liquid electrolyte and sulfide-based solid electrolyte to act as an intermediary. This SEI layer prevents direct chemical side reactions while allowing ionic conductivity to pass through, and maintains flame retardancy by preventing the liquid electrolyte from directly contacting and reacting with the solid electrolyte
Solution Approach 2:
The invention creates a composite electrolyte system combining liquid electrolyte and sulfide-based solid electrolyte in a layered structure. The liquid electrolyte provides high ionic conductivity while the solid electrolyte maintains flame retardancy, and their interface is controlled to minimize harmful chemical reactions
2Reliability
If sulfide-based solid electrolyte is used to ensure safety and high ionic conductivity, then safety and ionic conductivity are improved, but interface resistance with solid particles causes deterioration of ionic conductivity performance
Solution Approach 1:
The liquid electrolyte acts as an intermediary layer between the sulfide-based solid electrolyte and other solid particles (electrode materials). This liquid layer reduces interface resistance by providing a conductive pathway that bridges the solid-solid interfaces, thereby maintaining high ionic conductivity performance without compromising safety
3Reliability
If conventional liquid electrolyte is combined with sulfide-based solid electrolyte to improve ion movement, then ion movement is improved, but high-voltage oxidation stability deteriorates resulting in unstable interface
Solution Approach 1:
The invention changes the composition parameters of the liquid electrolyte by selecting specific solvents and additives with high oxidation stability. This allows the liquid electrolyte to maintain good ion movement properties while achieving the required high-voltage oxidation stability for stable interface with positive electrode
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 composite electrolyte achieves improved ionic conductivity retention, oxidation stability, and flame retardancy, enabling nearly full utilization of positive electrode capacity and enhancing the reliability and cycle-life characteristics of batteries.
Implementation Method 1
a liquid electrolyte includes a salt and fluorinated organic solvent that dissolves the salt
Data Source
AI summary
Disclosed are a solid-liquid composite electrolyte, and a semi-solid secondary battery including the same, the solid-liquid composite electrolyte including a sulfide-based solid electrolyte and a liquid electrolyte, wherein the liquid electrolyte includes a salt and a fluorinated organic solvent that dissolves the salt, and the solid-liquid composite electrolyte further comprises at least one of an additive, a diluent, and a polymer.