Nonaqueous Electrolyte Additives for Low-Resistance SEI Formation
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Solution Overview
Problem
Nonaqueous electrolyte solutions with existing additives have not been effective in reducing battery resistance and maintaining battery capacity in lithium-ion batteries, particularly for applications requiring long life and high performance.
Innovation Solution
A combination of specific cyclic sulfone compounds, carbonate compounds, and cyclic disulfonic acid ester compounds is used as additives in the nonaqueous electrolyte solution to form a stable solid electrolyte interface (SEI) on electrode surfaces, reducing initial resistance and resistance increase during charge/discharge cycles while maintaining discharge capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional additives are used in nonaqueous electrolyte solutions, then battery capacity is maintained to some extent, but battery resistance increases significantly during charge/discharge cycles
Solution Approach 1:
The patent combines multiple additive compounds (cyclic carboxylic acid ester with specific structural features and sulfur-containing compounds) to create a composite additive system that forms a balanced SEI film. This composite approach allows the film to simultaneously provide capacity maintenance and low resistance characteristics that single additives cannot achieve alone.
Solution Approach 2:
The patent specifies precise compositional parameters for the additive compounds, including molecular weight ranges, structural characteristics (cyclic ester groups, sulfur-containing groups), and concentration ratios. By controlling these parameters, the SEI film properties are optimized to achieve both low resistance and good capacity maintenance.
2Productivity
If higher energy density batteries are developed, then output and capacity are improved, but resistance increases and longevity decreases
Solution Approach 1:
The additive compounds act as intermediaries between the electrolyte and electrode surfaces, forming an SEI film that mediates the interaction. This intermediary layer protects the high-energy-density electrode materials from degradation while maintaining ionic conductivity, thus preserving longevity despite increased energy density.
Solution Approach 2:
The patent creates a SEI film with non-uniform local properties - regions with different compositions and structures that provide both protective functions and conductive pathways. This local quality variation allows the film to simultaneously protect against degradation and maintain low resistance for high output performance.
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 combination significantly reduces initial resistance, minimizes resistance increase, and enhances discharge capacity maintenance rate, especially in lithium-ion batteries with high Ni ratio positive electrode active materials, leading to improved battery performance and longevity.
Implementation Method 1
The additives are decomposed during an initial charge/discharge to form a film called a solid electrolyte interface (SET) on a surface of an electrode
Implementation Method 2
consumption of electricity for decomposition of a solvent and the like in the electrolyte solution is reduced
Data Source
AI summary
Disclosed is an additive for a nonaqueous electrolyte solution, containing a first compound represented by Formula (1) and a second compound which is a carbonate compound, a cyclic sulfone compound, and/or a cyclic disulfonic acid ester compound.[In Formula (1), Q represents an alkylene group or alkenylene group having 4 to 8 carbon atoms, which forms a cyclic group together with a sulfur atom of a sulfonyl group, X represents a sulfonyl group, a carbonyl group, or a phosphoryl group, R1 represents an alkyl group having 1 to 4 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, an aryl group, an alkoxy group having 1 to 4 carbon atoms, an alkenyloxy group having 2 to 6 carbon atoms, an alkynyloxy group having 2 to 6 carbon atoms, or an aryloxy group, and n represents 1 or 2.]