Cyclic Dinitrile Electrolyte Additives for Lithium Battery Stability
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Solution Overview
Problem
Secondary lithium batteries face issues with increased internal resistance, gas evolution, and transition metal ion dissolution over their lifespan, which affect their performance and longevity, necessitating additives that improve these aspects without compromising other properties.
Innovation Solution
Incorporating cyclic dinitrile compounds of specific structures into the electrolyte compositions of lithium batteries, which reduce gas evolution and transition metal dissolution, while maintaining or enhancing energy density and operating voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrolyte compositions are used in secondary lithium batteries, then the batteries can operate with basic performance, but the internal resistance increases over time, gas evolves, and transition metal ions dissolve from electrode materials
Solution Approach 1:
Cyclic dinitrile compounds act as intermediary substances in the electrolyte composition, mediating between the electrode materials and the electrolyte solvent. These compounds preferentially react with transition metal ions and decompose to form protective layers that prevent harmful interactions, thereby reducing gas evolution and metal ion dissolution while maintaining stable battery performance.
Solution Approach 2:
The cyclic dinitrile compounds function as sacrificial additives that are consumed during initial battery cycles to form stable protective films on electrode surfaces. These short-living compounds decompose preferentially to create lasting protective layers, sacrificing themselves to prevent long-term degradation of the battery system.
2Duration of action of moving object
If battery operation time is extended, then energy storage capacity increases, but internal resistance increases and performance degrades
Solution Approach 1:
The cyclic dinitrile compounds perform preliminary protective actions during initial battery operation, forming stable surface films on electrode materials before significant degradation can occur. This preliminary film formation prevents subsequent increases in internal resistance and maintains low energy losses throughout the battery's operational life.
Solution Approach 2:
The additive compounds provide beforehand cushioning by creating protective interfaces between electrode materials and the electrolyte environment. These pre-formed protective layers cushion against harmful effects such as metal ion dissolution and gas evolution that would otherwise accelerate during extended operation.
3Object-generated harmful factors
If additives are added to electrolyte compositions to improve performance, then gas evolution and metal dissolution are reduced, but the complexity of the electrolyte formulation increases
Solution Approach 1:
The invention modifies the chemical composition parameters of the electrolyte by incorporating cyclic dinitrile compounds with specific molecular structures. These parameter changes introduce new chemical functionalities that target transition metal ion interactions, enabling effective suppression of metal dissolution through controlled chemical reactions rather than complex physical barriers.
Data Source
AI summary
The present invention relates to electrolyte compositions containing cyclic dinitrile compounds of formula (I) wherein X1, X2, R1, and R2 are defined as described below and to their use in electrochemical cells.