Rechargeable Lithium Battery Electrolyte for Dendrite-Suppressed Fast Charging
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Solution Overview
Problem
Rapid charging of rechargeable lithium batteries leads to lithium dendrite precipitation on the negative electrode, deteriorating cycle-life characteristics due to surface precipitates.
Innovation Solution
An electrolyte composition including a non-aqueous organic solvent, a lithium salt, and an additive mixture of an imide cesium salt compound and a crown ether compound, which improves rapid charging performance and solubility, forming a stable solid electrolyte interface (SEI) film to prevent decomposition and enhance cycle-life characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If rapid charging is performed, then charging speed is improved, but lithium dendrite precipitates on the negative electrode surface causing cycle-life deterioration
Solution Approach 1:
The patent introduces an intermediary substance (lithium difluoromethylphosphinate) that mediates between the lithium ions and the negative electrode surface. This intermediary forms a stable SEI film that prevents direct contact between lithium ions and the electrode surface, thereby preventing dendrite formation while allowing rapid charging to proceed. The intermediary layer acts as a protective interface that enables fast charging without compromising cycle life.
Solution Approach 2:
The patent changes the chemical composition parameters of the electrolyte by adding lithium difluoromethylphosphinate at a specific concentration range (0.1-5 wt%). This parameter change modifies the properties of the SEI film formed on the negative electrode, making it more stable and less prone to dendrite formation. The specific concentration parameter is optimized to achieve both rapid charging capability and improved cycle life.
2Productivity
If conventional electrolytes are used for rapid charging, then charging rate is improved, but side reactions between lithium ions and electrolyte increase reducing efficiency
Solution Approach 1:
The patent converts the harmful side reactions between lithium ions and conventional electrolytes into a beneficial process by introducing lithium difluoromethylphosphinate. This substance undergoes controlled decomposition to form a stable SEI film, which prevents further harmful side reactions. The initial controlled reaction is transformed into a long-term protective mechanism that maintains charging efficiency and reduces energy loss during rapid charging cycles.
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 effectively suppresses side reactions between lithium ions and the electrolyte, improving rapid charging performance and ensuring suitable cycle-life characteristics even during high-temperature storage.
Implementation Method 1
the second compound which may increase a solubility of the first compound
Implementation Method 2
forming a stable solid electrolyte interface (SEI) film to prevent decomposition
Implementation Method 3
The electrolyte composition effectively suppresses side reactions between lithium ions and the electrolyte
Data Source
AI summary
An electrolyte for a rechargeable lithium battery includes a non-aqueous organic solvent, a lithium salt, and an additive, wherein the additive includes a composition including a first compound and a second compound, the first compound is an imide cesium salt compound represented by Chemical Formula 1, and the second compound is a crown ether compound represented by Chemical Formula 2. Details of Chemical Formulae 1 and 2 are as described in the specification.