Sulfide Composite Electrolyte Balancing Conductivity and Side Reactions
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Solution Overview
Problem
Sulfide-based solid electrolytes 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 in conventional solid-liquid composite electrolytes.
Innovation Solution
A solid-liquid composite electrolyte is developed using a sulfide-based solid electrolyte combined with a liquid electrolyte containing a salt with a kosmotropic anion like OTf− or FSI− and an organic solvent, maintaining high ionic conductivity, oxidation stability, and flame retardancy by controlling the interaction between the salt and solvent, with a concentration of 2.5 m to 20 m.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a liquid electrolyte is added to sulfide-based solid electrolyte to prepare solid-liquid composite electrolyte, then ionic conductivity is improved, but chemical side reactions occur at the interface between liquid electrolyte and sulfide-based solid electrolyte
Solution Approach 1:
The patent introduces a solid electrolyte interface (SEI) layer as an intermediary between the liquid electrolyte and sulfide-based solid electrolyte. This SEI layer acts as a protective barrier that prevents direct chemical contact and side reactions between the liquid electrolyte and sulfide-based solid electrolyte, while still allowing lithium ion transport to maintain high ionic conductivity.
Solution Approach 2:
The patent creates a composite electrolyte structure combining liquid electrolyte and sulfide-based solid electrolyte in a controlled manner. By forming a solid-liquid composite electrolyte with specific compositions and interfaces, the system achieves both high ionic conductivity from the liquid component and chemical stability from the solid component, resolving the contradiction between conductivity improvement and side reaction prevention.
2Reliability
If conventional solid-liquid composite electrolyte is used, then ionic conductivity is improved, but flame retardancy is lost due to introduction of flammable liquid electrolyte
Solution Approach 1:
The patent modifies the concentration and composition parameters of the liquid electrolyte component in the composite electrolyte. By controlling the amount of liquid electrolyte and selecting specific salts and solvents with appropriate parameters, the system achieves sufficient ionic conductivity while minimizing the flammable content, thereby maintaining flame retardancy properties.
Solution Approach 2:
The patent creates different regions with different properties within the composite electrolyte. The liquid electrolyte is localized in specific areas or interfaces where it provides ionic conductivity, while the sulfide-based solid electrolyte forms the bulk structure that provides flame retardancy. This spatial differentiation of functions allows the system to achieve both high ionic conductivity and flame retardancy simultaneously.
3Reliability
If sulfide-based solid electrolyte is used, then high ionic conductivity is achieved, but interface resistance is generated with other solid particles such as positive electrode active material
Solution Approach 1:
The patent introduces a liquid electrolyte layer as an intermediary between the sulfide-based solid electrolyte and other solid particles (such as positive electrode active material). This liquid electrolyte layer acts as a mediator that facilitates lithium ion transport across the interface, reducing interface resistance while maintaining the high ionic conductivity of the sulfide-based solid electrolyte.
Solution Approach 2:
The patent modifies the interface properties by controlling the composition and concentration of the liquid electrolyte at the interface between solid electrolyte and electrode materials. By optimizing these parameters, the system achieves reduced interface resistance while preserving the high bulk ionic conductivity of the sulfide-based solid electrolyte.
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 reduces side reactions, maintains high ionic conductivity, ensures oxidation stability and heat resistance, and enhances the reliability and cycle-life characteristics of batteries, making it suitable for practical applications.
Implementation Method 1
maintaining high ionic conductivity
Implementation Method 2
a liquid electrolyte includes a salt and an organic solvent, an anion in the salt is OTf−, FSI−, or a combination thereof
Implementation Method 3
reducing side reactions between a sulfide-based solid electrolyte and a liquid electrolyte
Implementation Method 4
ensures oxidation stability, heat resistance, and flame retardancy
Implementation Method 5
heat resistance
Data Source
AI summary
Disclosed are includes a solid-liquid composite electrolyte, and a composite electrolyte film, and a semi-solid rechargeable 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 an organic solvent, an anion in the salt is OTf−, FSI−, or a combination thereof, and a concentration of the liquid electrolyte is about 2.5 m to about 20 m.