Lithium Battery Electrolyte Additives for High-Temperature Stability
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Solution Overview
Problem
Lithium rechargeable batteries face instability and safety issues at high temperatures due to decomposition of electrolytes and active materials, which affects battery stability and safety, and existing solutions do not adequately address both high capacity and stability requirements.
Innovation Solution
An electrolyte composition for lithium rechargeable batteries including a non-aqueous organic solvent, lithium salt, vinylene carbonate, fluoroethylene carbonate, and a nitrile-based compound, such as adiponitrile, which enhances storage stability at high temperatures by maintaining an optimal open circuit voltage (OCV) of 4.2V or higher.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional electrolytes are used to achieve high capacity, then battery capacity is improved, but storage stability deteriorates at high temperatures due to decomposition
Solution Approach 1:
The patent applies preliminary action by adding specific additives (vinylene carbonate at 0.1-5 wt%, fluoroethylene carbonate at 0.1-5 wt%, and nitrile-based compounds at 0.1-10 wt%) to the electrolyte composition before battery assembly. These additives proactively prevent decomposition reactions by forming protective films on electrode surfaces during initial cycles, thereby maintaining storage stability at high temperatures while preserving high capacity. This pre-preventive measure addresses the contradiction by preparing the system in advance to resist thermal degradation.
Solution Approach 2:
The patent employs composite materials by creating a multi-component electrolyte system that combines conventional lithium salts (LiPF6, LiBF4) with specific carbonate solvents (EC, DEC, EMC) and functional additives (vinylene carbonate, fluoroethylene carbonate, nitrile-based compounds). This composite electrolyte composition synergistically integrates the high ionic conductivity of conventional components with the thermal stability provided by the additive package, achieving both high capacity and improved storage stability at elevated temperatures.
2Reliability
If electrolyte additives are increased to improve storage stability, then storage stability is improved, but battery capacity may be reduced
Solution Approach 1:
The patent applies parameter changes by precisely controlling the concentration ranges of electrolyte additives: vinylene carbonate (0.1-5 wt%), fluoroethylene carbonate (0.1-5 wt%), and nitrile-based compounds (0.1-10 wt%). These optimized parameter ranges ensure sufficient storage stability improvement without excessive additive content that would reduce ionic conductivity and battery capacity. The balanced composition achieves the optimal trade-off between stability enhancement and capacity preservation.
Solution Approach 2:
The patent applies local quality by concentrating the stabilizing function in specific additive components (vinylene carbonate, fluoroethylene carbonate, nitrile-based compounds) while maintaining the bulk electrolyte composition optimized for high ionic conductivity. The additives locally form protective films on electrode surfaces where decomposition occurs, providing stability enhancement precisely where needed without compromising the overall electrolyte's charge transfer efficiency and battery capacity.
3Quantity of substance
If high voltage charging is implemented to increase capacity, then battery capacity is improved, but decomposition of electrolyte and active materials increases
Solution Approach 1:
The patent applies blessing in disguise by utilizing the decomposition-prone electrolyte components (vinylene carbonate and fluoroethylene carbonate) to form protective solid electrolyte interphase (SEI) films on electrode surfaces. These films, which would otherwise be considered degradation products, actually serve as protective barriers that prevent further decomposition of the bulk electrolyte and active materials during high voltage charging. The harmful decomposition reactions are converted into beneficial protective layers, enabling high capacity charging while reducing overall decomposition.
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 significantly improves the storage stability and safety of lithium rechargeable batteries at high temperatures by maintaining a high open circuit voltage, ensuring both high capacity and stability are met, as demonstrated by the battery cells' performance after two weeks at 60°C.
Implementation Method 1
an additive including vinylene carbonate, fluoroethylene carbonate, and a nitrile-based compound represented by Formula 1... which enhances storage stability at high temperatures by maintaining an optimal open circuit voltage (OCV) of 4.2V or higher
Data Source
AI summary
An electrolyte for a rechargeable lithium battery includes a non-aqueous organic solvent; a lithium salt; and an additive including vinylene carbonate, fluoroethylene carbonate, and a nitrile-based compound represented by Formula 1:wherein n ranges from 1 to 12 and R1 and R2 are independently a halogen, a hydrogen, or an alkyl group. Further, the alkyl group can be CmH(2m+1), in which m ranges from 1 to 10. The electrolyte for a rechargeable lithium battery improves storage stability of the rechargeable lithium battery at a high temperature. And, a rechargeable lithium battery including the electrolyte has improved storage stability.