Fluorinated Electrolyte Additive for Low-Resistance SEI and Gas Suppression
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Solution Overview
Problem
Existing lithium-ion batteries face reduced capacity over time due to initial resistance and gas generation issues, despite the use of additives like derivatives of vinylene carbonate, which also degrade and affect performance.
Innovation Solution
A nonaqueous electrolyte solution containing specific compounds represented by Formula (1a) or (1b), which form a stable solid electrolyte interface (SEI) to reduce initial resistance and suppress gas generation, improving cycle characteristics and battery performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If derivatives of vinylene carbonate are used as additives to form SEI, then cycle characteristics are improved, but gas generation increases and battery performance deteriorates
Solution Approach 1:
The patent changes the chemical structure parameters of the additive by introducing fluorine atoms at specific positions (using compounds with formulas (1) and (2) where R1-R6 are specific combinations of H, F, and alkyl groups). This structural modification allows the additive to form SEI with reduced gas generation while maintaining good cycle characteristics, thus resolving the contradiction between cycle life improvement and gas suppression.
Solution Approach 2:
The patent uses composite electrolyte formulations combining the fluorinated cyclic carbonate additives with other electrolyte components (cyclic carbonates, chain carbonates, lithium salts) to achieve synergistic effects. The composite approach allows forming a stable SEI layer that prevents gas generation while maintaining excellent cycle characteristics, addressing both aspects of the contradiction.
2Reliability
If conventional additives are added to electrolyte solution to form SEI, then capacity reduction over time is suppressed, but initial resistance increases
Solution Approach 1:
The patent modifies the chemical parameters of the additive molecules by introducing fluorine substitution at specific positions in the cyclic carbonate structure. This parameter change enables the formation of an SEI layer with different properties - one that provides good capacity retention over cycles while having lower resistance characteristics, thus resolving the contradiction between capacity retention and initial resistance.
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 additive significantly reduces initial resistance and enhances long-term cycle characteristics while minimizing gas generation, leading to improved battery performance and stability.
Implementation Method 1
The additives are decomposed during a first charge/discharge to form a film called a solid electrolyte interface (SEI) on a surface of an electrode
Implementation Method 2
the lithium ions can be transferred between electrodes through the SEI
Data Source
AI summary
Disclosed is an additive for nonaqueous electrolyte solutions, including a compound represented by Formula (1a) or (1b).In Formulae (1a) and (1b), Z represents a monovalent group represented by Formula (2a), (2b), or (2c).