Sulfur Dioxide Electrolyte Composition for High-Voltage Li-Ion Cells
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Solution Overview
Problem
Existing electrolyte compositions for lithium-ion cells face issues with gasification, thermal instability, and safety hazards due to high cell voltages, leading to reduced performance and service life, while sulfur dioxide-based electrolytes suffer from poor solubility of conventional lithium conducting salts and high production costs.
Innovation Solution
A liquid electrolyte composition comprising sulfur dioxide as the solvent and a conducting salt with an anionic complex of three bidentate ligands, specifically lithium triperfluoropicanolatoantimonate (LiSb(PFP)3, which is chemically stable, non-flammable, and easily recyclable, ensuring effective charge equalization and high ion conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional lithium conducting salts are used in sulfur dioxide-based electrolytes, then ion conductivity is achieved, but solubility is poor
Solution Approach 1:
The patent modifies the chemical structure of the conducting salt by introducing fluorinated alkyl groups with specific chain lengths and branching patterns. This parameter change in molecular structure enhances the salt's solubility in sulfur dioxide while maintaining its ion conductivity, directly resolving the contradiction between solubility and ion conductivity.
Solution Approach 2:
The patent creates a composite electrolyte system combining sulfur dioxide solvent with specifically designed fluorinated lithium conducting salts. This composite approach allows the unique properties of sulfur dioxide (high ion mobility) to be combined with the enhanced solubility of the fluorinated salt structure, achieving both good solubility and high ion conductivity simultaneously.
2Use of energy by moving object
If high cell voltage is applied to achieve high energy, then gasification occurs, but performance and service life are reduced
Solution Approach 1:
The patent converts the potential harm of high voltage operation (gasification) into a benefit by using fluorinated salts that are specifically designed to be stable at high voltages. The fluorinated structure acts as a protective mechanism that allows the system to operate at high energies without suffering the usual degradation, effectively turning the high voltage condition from harmful to beneficial.
Solution Approach 2:
The patent changes the chemical parameters of the conducting salt by introducing fluorinated groups, which alter the electrochemical stability window and resistance to oxidation. This parameter change enables the electrolyte to withstand high cell voltages without gasification, allowing high energy operation while maintaining service life and performance.
3Reliability
If fluorinated solvents are added to expand voltage range, then electrochemical stability is improved, but thermal defects lead to heat evolution and hazardous gas emission
Solution Approach 1:
The patent extracts the fluorinated functional groups from the solvent and transfers them to the conducting salt structure. This separation allows the electrochemical stability benefits of fluorination to be retained while eliminating the thermal instability problems associated with fluorinated solvents, thus avoiding heat evolution and hazardous gas emission.
Solution Approach 2:
The fluorinated conducting salt acts as an intermediary that provides the electrochemical stability normally associated with fluorinated solvents. The salt mediates between the need for wide voltage range operation and the need to avoid thermal defects, allowing the system to achieve high electrochemical stability without the harmful thermal effects of fluorinated solvents.
4Reliability
If organic electrolyte compositions are used, then ion mobility is achieved, but flammability and safety hazards occur
Solution Approach 1:
The patent changes the fundamental chemical parameter of the electrolyte from organic to inorganic (sulfur dioxide). This parameter change eliminates the flammability inherent in organic electrolytes while maintaining ion mobility through the unique properties of sulfur dioxide as an inorganic solvent, directly resolving the safety hazard.
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 electrolyte composition provides stable operation at various voltages, enhances safety through non-flammability, and enables cost-effective recycling, reducing production costs and environmental impact.
Implementation Method 1
The electrolyte composition contains a solvent, which ensures dissociation of the conducting salt and sufficient mobility of the lithium ions
Implementation Method 2
The current flow necessary therefor is achieved by ion transport of a conducting salt in the electrolyte composition
Implementation Method 3
sulfur dioxide as the solvent and a conducting salt with an anionic complex of three bidentate ligands
Implementation Method 4
The term 'gasification' is to be understood as meaning an electrochemical decomposition of the constituents of the electrolyte into volatile and gaseous compounds due to the use of an excessively high cell voltage
Implementation Method 5
a conducting salt with an anionic complex of three bidentate ligands, specifically lithium triperfluoropicanolatoantimonate
Data Source
AI summary
Liquid electrolyte compositions comprising a salt of the formula (I) which has an anionic complex comprising three bidentate ligands are provided. The complex comprises antimony as the central ion. Electrochemical cells comprising the liquid electrolyte composition are further provided. Salts of formula (I) are further provided.