Cyclic Sulfone Additive for Low Resistance SEI
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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 a specific cyclic sulfone compound with at least one carbonate compound, cyclic sulfone compound, or cyclic disulfonic acid ester compound is used as an additive in the nonaqueous electrolyte solution to form a stable solid electrolyte interface (SEI) on the electrode surface, reducing initial resistance and maintaining discharge capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing additives are used in nonaqueous electrolyte solutions, then battery capacity is maintained, but battery resistance is not sufficiently reduced
Solution Approach 1:
The patent combines multiple additives (cyclic carboxylic acid compound, cyclic sulfate compound, and chain carbonate compound) to form a composite additive system. This composite approach creates a synergistic effect where the combination of different compounds produces a more effective SEI layer than individual additives alone, simultaneously reducing resistance and maintaining capacity.
Solution Approach 2:
The patent specifies precise compositional parameters for the additive mixture, including the ratio of cyclic carboxylic acid compound to cyclic sulfate compound (0.1-10 mass ratio) and the concentration of chain carbonate compound (0.01-5 mass%). By optimizing these parameters, the SEI layer properties are tuned to achieve both low resistance and good capacity maintenance.
2Power
If conventional additives are added to improve battery performance, then discharge characteristics are enhanced, but initial resistance remains high
Solution Approach 1:
The additives perform preliminary action during the initial charge/discharge cycles to form a stable SEI layer on the electrode surface before normal operation begins. This pre-formed SEI layer reduces initial resistance and enables better discharge characteristics from the start, rather than requiring extended conditioning periods.
Solution Approach 2:
The cyclic carboxylic acid compound and cyclic sulfate compound act as intermediary substances that facilitate the formation of a stable interface between the electrode and electrolyte. This intermediary SEI layer mediates the interaction between lithium ions and the electrode, reducing resistance while maintaining good discharge characteristics.
3Object-affected harmful factors
If battery resistance is reduced through additive use, then power characteristics improve, but capacity maintenance during cycling deteriorates
Solution Approach 1:
The additive combination creates a locally optimized SEI layer with specific properties at the electrode-electrolyte interface. The cyclic carboxylic acid compound provides low-resistance characteristics while the cyclic sulfate compound contributes to stability, creating a localized region with both low resistance and high cycling stability.
Solution Approach 2:
The synergistic combination of additives ensures continuous beneficial action throughout the battery's operational life. The SEI layer formed by this combination maintains its protective and conductive properties consistently across multiple charge/discharge cycles, preventing capacity fade while keeping resistance low.
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 battery resistance and improves capacity maintenance during cycle tests, especially when used with lithium-containing composite oxides as positive electrode active materials, enhancing the performance and longevity of lithium-ion batteries.
Implementation Method 1
The additives are decomposed during an initial 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 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 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.]