Additive, electrolyte for rechargeable lithium battery, and rechargeable lithium battery including the same
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Solution Overview
Problem
Rechargeable lithium batteries face challenges in maintaining high energy density and cycle-life characteristics, particularly at high temperatures, due to resistance increases and decomposition of the electrolyte interface, which affects their performance and longevity.
Innovation Solution
An electrolyte composition for rechargeable lithium batteries is developed, including a non-aqueous organic solvent, a lithium salt, and an additive represented by Chemical Formula 1, which forms a strong solid electrolyte interface (SEI) on the negative electrode, reducing resistance and improving ion conductivity, and is used in specific weight percentages to optimize battery performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrolyte compositions are used, then the battery can operate, but resistance increases and the electrolyte interface decomposes at high temperatures, reducing cycle-life and performance
Solution Approach 1:
The patent introduces a fluorinated cyclic carbonate additive as an intermediary substance that mediates between the electrolyte and the negative electrode. This additive preferentially decomposes to form a protective SEI layer, acting as a mediator that prevents direct harmful interactions between the electrolyte and electrode at high temperatures, thereby reducing resistance increase and improving cycle-life characteristics
Solution Approach 2:
The patent modifies the chemical composition parameters of the electrolyte by incorporating fluorinated cyclic carbonate compounds with specific molecular structures (Formula 1 where R1-R6 are specific combinations of H, F, and alkyl groups). This parameter change in the electrolyte composition alters the decomposition behavior and SEI formation characteristics, enabling stable performance at high temperatures
2Use of energy by moving object
If the battery is designed for high energy density, then power capacity increases, but maintaining performance and longevity at high temperatures becomes more difficult
Solution Approach 1:
The patent creates a composite electrolyte system combining fluorinated cyclic carbonate additives with conventional cyclic carbonate solvents (EC, PC) and chain carbonates (DMC, DEC). This composite material approach leverages the high dielectric constant of cyclic carbonates for lithium salt dissolution while the fluorinated additive provides thermal stability and protective SEI formation, achieving both high energy density and high-temperature reliability
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 enhances cycle-life characteristics and high-temperature storage properties by preventing resistance increases, ensuring better battery performance and longevity.
Implementation Method 1
forms a strong solid electrolyte interface (SEI) on the negative electrode, reducing resistance and improving ion conductivity
Implementation Method 2
improving ion conductivity
Data Source
Figure 1
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AI summary
An additive represented by Chemical Formula 1, an electrolyte for a rechargeable lithium battery including the same, and a rechargeable lithium battery, wherein, in Chemical Formula 1, R1 to R6 are each independently a substituted or unsubstituted C1 to C10 alkyl group, a substituted or unsubstituted C1 to C10 alkoxy group, a substituted or unsubstituted C2 to C10 alkenyl group, a substituted or unsubstituted C3 to C10 cycloalkyl group, a substituted or unsubstituted C3 to C10 cycloalkenyl group, or a substituted or unsubstituted C6 to C20 aryl group.