Non-Aqueous Electrolyte Composition for High-Temperature SEI Stability
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Solution Overview
Problem
Lithium secondary batteries face degradation issues due to transition metal ion dissolution from the positive electrode, leading to degradation of the solid electrolyte interphase (SEI) on the negative electrode, especially at high temperatures, which affects electrochemical properties and stability.
Innovation Solution
A non-aqueous electrolyte solution composition comprising an organic solvent, lithium salt, cyclic carbonate-based additive with a carbon-carbon double bond, and an azo-based initiator is used to form a durable cyclic carbonate polymer film on the negative electrode, promoting a robust SEI film through polymerization rather than ring-opening reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a nickel-rich positive electrode active material is used to increase capacity, then energy density is improved, but stability deteriorates due to transition metal ion dissolution
Solution Approach 1:
The patent introduces a cyclic carbonate-based additive containing a carbon-carbon double bond as an intermediary substance between the nickel-rich positive electrode and the negative electrode. This additive forms a protective interface layer that mediates the interaction between electrodes, preventing direct contact and ion dissolution while maintaining ionic conductivity. The additive acts as a buffer that stabilizes the electrode-electrolyte interface without compromising the high capacity of the nickel-rich material.
Solution Approach 2:
The patent modifies the chemical composition parameters of the electrolyte by incorporating a cyclic carbonate-based additive with specific molecular structure (containing carbon-carbon double bond) at optimized concentrations. This parameter change transforms the electrolyte's properties to enable formation of a more stable SEI film that can withstand the harsh conditions created by nickel-rich positive electrodes, thereby improving stability while preserving high capacity.
2Quantity of substance
If the battery is operated at high voltage to increase capacity, then energy density is improved, but electrode surface structure degradation accelerates
Solution Approach 1:
The patent applies preliminary action by having the cyclic carbonate-based additive react first during initial charging cycles to form a stable protective film on the electrode surfaces before the harmful high-voltage operation begins. This pre-formed film serves as a protective barrier that prevents subsequent degradation of the electrode surface structure during high-voltage operation, allowing the battery to operate at high voltages without rapid degradation.
3Quantity of substance
If transition metal ions are dissolved from the positive electrode, then capacity is improved, but negative electrode degradation increases due to SEI film degradation
Solution Approach 1:
The patent converts the harmful effect of transition metal ion dissolution into a beneficial outcome. The cyclic carbonate-based additive intentionally forms a modified SEI film that incorporates or neutralizes the dissolved metal ions, transforming them from harmful contaminants into stable components of the protective interface. This converted SEI film prevents further degradation of the negative electrode while allowing the beneficial capacity from nickel-rich material to be realized.
4Power
If the battery is exposed to high temperature, then power output is improved, but degradation phenomena accelerate
Solution Approach 1:
The patent creates a composite interface structure consisting of the cyclic carbonate-based additive integrated with the traditional SEI film components. This composite SEI film combines the benefits of conventional protective layers with the unique properties of the cyclic carbonate additive, particularly its thermal stability and ability to form robust polymer networks. The composite structure maintains protective functionality at high temperatures, enabling improved power output without accelerated degradation.
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 enhances the stability of the SEI film at high temperatures, reducing negative electrode degradation and improving the overall performance of lithium secondary batteries by forming an electrode-electrolyte interface with low resistance and stability.
Implementation Method 1
a non-aqueous electrolyte solution composition which is composed of an organic solvent, a lithium salt, a cyclic carbonate-based additive containing a carbon-carbon double bond, and an azo-based initiator
Implementation Method 2
forming a stable SEI film on the negative electrode
Data Source
AI summary
The present invention relates to a non-aqueous electrolyte solution composition which is composed of an organic solvent, a lithium salt, a cyclic carbonate-based additive containing a carbon-carbon double bond, and an azo-based initiator,wherein the azo-based initiator is represented by Formula 1, andthe cyclic carbonate-based additive is included in an amount of 0.01 wt % to 5 wt % based on the total non-aqueous electrolyte solution composition.In Formula 1, R1 to R4 are each independently selected from an alkyl group having 1 to 5 carbon atoms or an alkoxy group having 1 to 5 carbon atoms, and a case where all of R1 to R4 are methyl groups is excluded.