Pyrimidine-Based Electrolyte for Lithium Battery SEI Stability
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Solution Overview
Problem
Conventional lithium secondary batteries face issues with the stability of the solid electrolyte interface (SEI) layer at high temperatures, leading to increased inner pressure and poor conductivity at low temperatures, which affects their performance and life cycle.
Innovation Solution
A non-aqueous electrolyte solution comprising a pyrimidine-based compound, a non-fluorinated solvent, and a fluorinated solvent, with a fluorine content range of 0.1 to 50 wt%, is used to form a stable and durable SEI layer, enhancing the battery's high-temperature stability and life characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a large amount of ethylene carbonate is used in the electrolyte solution, then the battery can maintain stable structure, but the SEI layer stability at high temperature deteriorates and inner pressure increases
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by introducing fluorinated cyclic carbonate compounds with specific fluorine content (0.1-50 wt%) and pyrimidine-based compounds (0.01-5 wt%). This parameter change modifies the SEI layer formation characteristics, enabling stable SEI layers at high temperatures while maintaining battery structure stability.
Solution Approach 2:
The patent creates a composite electrolyte system by combining fluorinated cyclic carbonate (which forms stable SEI), non-fluorinated cyclic carbonate (which provides ionic conductivity), and pyrimidine-based compounds (which enhance SEI stability). This composite approach synergistically resolves the contradiction between structure stability and SEI layer stability.
2Stability of the object's composition
If ethylene carbonate is used to maintain battery structure, then structural stability is improved, but conductivity at low temperature deteriorates
Solution Approach 1:
The patent modifies the electrolyte composition by incorporating fluorinated cyclic carbonate compounds that have lower freezing points and better low-temperature fluidity compared to conventional ethylene carbonate. This parameter change maintains structural stability while improving low-temperature ionic conductivity.
Solution Approach 2:
The patent applies different functional components to different temperature conditions: fluorinated cyclic carbonate provides low-temperature conductivity, while pyrimidine-based compounds ensure high-temperature SEI stability. This local quality approach addresses temperature-dependent performance variations.
3Ease of manufacture
If conventional electrolyte composition is used, then manufacturing simplicity is maintained, but battery life cycle at high temperature deteriorates
Solution Approach 1:
The patent modifies the electrolyte composition parameters by adding specific fluorinated cyclic carbonate and pyrimidine-based compounds in defined concentrations. These parameter changes enhance high-temperature life cycle while maintaining compatibility with existing manufacturing processes.
Solution Approach 2:
The pyrimidine-based compound acts as an intermediary substance that mediates between the fluorinated cyclic carbonate and the anode surface, forming a stable SEI layer that protects against high-temperature degradation. This intermediary mechanism extends battery life without complicating manufacturing.
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 solution significantly improves the life cycle and stability of lithium secondary batteries at both room and high temperatures, minimizing capacity decrease and maintaining high-rate charging/discharging performance.
Implementation Method 1
lithium ions emitted from a cathode active material such as a lithium-metal oxide is transferred into an anode active material such as graphite and inserted between the layers of the anode active material, at which high reactive lithium reacts with the electrolyte solution and carbon present in the anode active material on the surface of the anode active material such as graphite to produce a compound such as Li 2 CO 3 , Li 2 O and LiOH
Implementation Method 2
The SEI layer functions as an ion tunnel, allowing only lithium ions to pass through. As an effect of such an ion tunnel, the SEI layer prevents the molecule of an organic solvent having large molecular weight, which is included in the electrolyte solution and transferred together with lithium ions, from being inserted between the layers of the anode active material
Implementation Method 3
The non-aqueous electrolyte solution according to one aspect of the present invention, which comprises a fluorinated solvent, a non-fluorinated solvent and a pyrimidine-based compound, is used in a lithium secondary battery to minimize the capacity decrease and provide a markedly improved life characteristics and stability even if charging/discharging cycles are repeated several hundred times at room temperature and at high temperature
Data Source
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Figure 3
AI summary
The present invention provides non-aqueous electrolyte solution for a lithium secondary battery, comprising a pyrimidine-based compound, a non-fluorinated solvent and a fluorinated solvent; and a lithium secondary battery using the same.