Cyclic Sulfonyl Additive for Stable SEI in Li-Ion Batteries
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Solution Overview
Problem
Current additives for nonaqueous electrolyte solutions in lithium-ion batteries, such as derivatives of vinylene carbonate, do not adequately improve battery characteristics and can generate gases like carbon dioxide, leading to reduced performance, especially at high temperatures or over long charge/discharge cycles.
Innovation Solution
A compound represented by the formula (1), where Q is an optionally substituted alkenylene group forming a cyclic group with a sulfur atom, X is a sulfonyl, phosphoryl, or carbonyl group, and R1 represents various substituents, is used as an additive to form a stable solid electrolyte interface, improving initial resistance, discharge capacity retention, and suppressing gas generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If derivatives of vinylene carbonate are used as additives, then battery characteristics are improved, but gas generation increases leading to reduced performance
Solution Approach 1:
The patent modifies the chemical structure of vinylene carbonate derivatives by introducing specific substituents (R1 groups) and adjusting molecular parameters to reduce gas-generating decomposition reactions while maintaining SEI-forming capability. This involves changing the chemical composition parameters of the additive to achieve both improved reliability and reduced harmful gas generation.
Solution Approach 2:
The patent employs composite electrolyte formulations combining modified vinylene carbonate derivatives with other electrolyte components and additives to achieve synergistic effects. The composite approach allows the additive to form effective SEI layers while suppressing gas generation through complementary interactions with other electrolyte constituents.
2Duration of action of moving object
If charge/discharge cycles are repeated at high temperature, then battery operation continues, but gas generation becomes remarkable reducing performance
Solution Approach 1:
The modified vinylene carbonate derivative additive proactively forms a stable and robust SEI layer during initial cycles that prevents subsequent gas-generating decomposition reactions. This protective SEI layer acts as a barrier that cushions against high-temperature degradation and repeated cycling stresses, suppressing gas generation throughout the battery's operational life.
Solution Approach 2:
The additive is designed to be consumed during initial cycles to form the protective SEI layer, sacrificing itself to prevent long-term gas generation. The additive performs its function during the first few cycles and is depleted, but this short-lived consumption prevents ongoing harmful gas evolution during extended operation and high-temperature cycling.
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 additive enhances battery characteristics by forming a stable solid electrolyte interface, improving cycle characteristics and internal resistance, while reducing gas generation and maintaining performance over time, especially at elevated temperatures.
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
Data Source
AI summary
Disclosed is an additive for nonaqueous electrolyte solutions, which includes a compound represented by the following formula (1):in the formula (1), Q represents an optionally substituted alkenylene group having 4 to 7 carbon atoms and forming a cyclic group together with the sulfur atom of the sulfonyl group, X represents a sulfonyl group, a phosphoryl group, or a carbonyl group, R1 represents an optionally substituted alkyl group having 1 to 4 carbon atoms or the like, and n represents 1 or 2.