Sodium Battery Electrolyte Composition for Stable SEI and Longer Cycling
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Solution Overview
Problem
Sodium secondary batteries face challenges due to the severe dissolution of solid electrolyte interfaces (SEI), leading to side reactions, electrolyte consumption, decreased chemical and electrochemical stability, shortened cycle life, and safety concerns.
Innovation Solution
The development of an electrolyte for sodium secondary batteries that includes an ester solvent and a mixture solvent comprising a fluoroether diluent, a flame retardant, and an ionic liquid, which improves interface stability, high-temperature performance, cycling performance, and storage stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrolytes are used in sodium secondary batteries, then the battery can operate, but severe dissolution of solid electrolyte interfaces occurs leading to side reactions and shortened cycle life
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by introducing fluorinated carbonates (FEC, GFEC) and sulfones (DMC, DEC) in specific ratios. This parameter optimization creates a stable SEI interface that resists dissolution, directly resolving the contradiction between interface stability and cycle life by modifying the electrolyte's chemical properties to form a protective interface layer.
Solution Approach 2:
The patent employs a composite electrolyte system combining multiple solvent types (fluorinated carbonates and sulfones) with complementary properties. FEC/GFEC provide interface stability while DMC/DEC maintain bulk electrolyte performance. This composite approach allows the electrolyte to simultaneously achieve stable solid electrolyte interface and long cycle life through synergistic effects of different components.
2Reliability
If electrolyte components are increased to improve stability, then interface stability improves, but electrolyte consumption increases due to side reactions
Solution Approach 1:
The patent applies preliminary action by using fluorinated carbonates (FEC, GFEC) to pre-form a stable protective SEI interface layer during initial cycles. This preliminary protective layer prevents subsequent side reactions between the electrolyte and electrode materials, thereby reducing ongoing electrolyte consumption while maintaining high chemical stability throughout battery operation.
3Ease of operation
If the electrolyte uses conventional solvents, then the battery shows acceptable performance, but high-temperature performance deteriorates and safety concerns arise
Solution Approach 1:
The patent modifies the electrolyte's thermal properties by incorporating fluorinated carbonates (FEC, GFEC) which have superior high-temperature stability compared to conventional solvents. The fluorinated structure raises the electrolyte's thermal decomposition temperature and improves heat resistance, enabling the battery to maintain operational performance at elevated temperatures while enhancing safety.
4Speed
If the electrolyte viscosity is reduced to improve ion transport, then rate performance improves, but side reactions increase and interface stability decreases
Solution Approach 1:
The patent optimizes viscosity parameters by combining fluorinated carbonates (FEC, GFEC) with sulfones (DMC, DEC) in specific proportions. The sulfone components (particularly DEC) have lower viscosity and higher dielectric constant, improving ion transport kinetics. Meanwhile, the fluorinated carbonate components maintain interface stability. This parameter balancing allows fast ion transport without compromising interface stability.
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 proposed electrolyte enhances the stability of the solid electrolyte interface, improves cycling and storage performance, and increases safety by reducing side reactions and maintaining low viscosity.
Implementation Method 1
The fluoroether diluent allows the electrolyte containing the ester solvent to maintain a low viscosity, avoiding or reducing side reactions between the ester solvent and the sodium secondary battery, and improving the interface stability, cycling performance, and storage stability of the battery.
Implementation Method 2
the ionic liquid can also stabilize a solid electrolyte interface (SEI) on a negative electrode side, thereby significantly improving the interface stability of the battery
Implementation Method 3
Molecules of the flame retardant interact with molecules of the ester solvent to weaken their solvation structures, thereby achieving an effect of a high-concentration electrolyte while improving the safety of the battery.
Implementation Method 4
As an important part of a secondary battery, an electrolyte plays a crucial role in rate performance, safety, cycle life, and the like of the battery.
Data Source
AI summary
This application provides an electrolyte for sodium secondary battery, a sodium secondary battery, a battery module, a battery pack, and an electric apparatus. The electrolyte for sodium secondary battery includes an ester solvent and a mixture solvent, where the mixture solvent includes one or more of a fluoroether diluent, a flame retardant, and ionic liquid. The electrolyte of this application includes the ester solvent and the mixture solvent including one or more of the fluoroether diluent, the flame retardant, and the ionic liquid, so that the interface stability of a battery can be significantly enhanced, the cycling performance and storage stability of the battery can be improved, and the safety of the battery can be improved.