Lithium Battery Electrolyte Additive for High-Temperature Stability
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Solution Overview
Problem
Lithium secondary batteries face issues with thickness expansion and performance degradation at high temperatures due to gas generation and electrode resistance, primarily caused by the reaction between the positive active material and electrolyte, leading to irreversible reactions and SEI film destruction.
Innovation Solution
An electrolyte for lithium secondary batteries comprising a non-aqueous organic solvent, a lithium salt, and an additive represented by specific chemical formulas, which improves high-temperature storage characteristics by controlling the additive's weight percentage and solvent composition to prevent excessive swelling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional electrolytes are used in lithium secondary batteries, then the batteries can operate at high temperatures, but thickness expansion and performance degradation occur due to gas generation and SEI film destruction
Solution Approach 1:
The patent introduces a specific additive compound (with formulas 1 or 2) as an intermediary substance in the electrolyte that mediates between the positive active material and the electrolyte solvent. This additive forms a protective interface layer that prevents direct harmful reactions between the positive electrode material and electrolyte, thereby preventing gas generation and SEI film destruction while maintaining high temperature operation capability
Solution Approach 2:
The patent modifies the electrolyte composition by incorporating specific additives with defined chemical structures (formulas 1 and 2) where R groups can be halogen, alkyl, or fluorinated alkyl groups. By changing the chemical parameters of the electrolyte components and optimizing their ratios, the electrolyte's thermal stability is improved, preventing decomposition reactions that cause thickness expansion while maintaining operational functionality at elevated temperatures
2Power
If the battery operates at high temperatures, then energy delivery is maintained, but irreversible reactions increase and cause thickness expansion
Solution Approach 1:
The patent converts the potentially harmful high-temperature conditions into a benefit by using the elevated temperature to promote the formation of a stable protective interface layer through the additive compounds. The additive molecules undergo controlled reactions at high temperature to form a robust protective film that prevents further harmful reactions, effectively converting the thermal energy that would cause damage into a protective mechanism
Solution Approach 2:
The additive compounds act as intermediary substances that intervene between the positive active material and the electrolyte solvent. At high temperatures, these intermediaries form stable protective layers that prevent direct contact and harmful reactions between the electrode material and electrolyte, thereby eliminating gas generation and thickness expansion while preserving power delivery capability
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 proposed electrolyte significantly enhances high-temperature storage characteristics and cycle-life performance by reducing thickness expansion and maintaining battery integrity, as demonstrated by cyclic voltammetry, EIS measurements, and high-temperature cycle-life characteristics.
Implementation Method 1
the reaction between the positive active material and the electrolyte, which are significantly increased at particularly high temperature
Implementation Method 2
the solid electrolyte interface (SEI) film formed on the negative active material surface
Implementation Method 3
an organic solvent in which a lithium salt is dissolved has been used
Data Source
AI summary
Provided are an electrolyte for a lithium secondary battery and a lithium secondary battery including the same wherein the electrolyte includes a non-aqueous organic solvent; a lithium salt; and an additive represented by Chemical Formula 1.