Acetonitrile Electrolyte Composition for High-Temperature Li-Ion Durability
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Solution Overview
Problem
Lithium-ion batteries using acetonitrile-based electrolyte solutions exhibit inferior high-temperature durability, with issues such as peeling points between the cathode current collector and increased electrical resistance, leading to deterioration in performance.
Innovation Solution
A non-aqueous electrolyte solution containing acetonitrile with a cyclic anion-containing lithium salt, specifically within certain concentration ranges, and optionally including LiPF6 and a nitrogen-containing cyclic compound or silane-based additives, to enhance stability and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If acetonitrile-based electrolyte solution is used, then output characteristics and low-temperature characteristics are improved, but high-temperature durability deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte solution by introducing a specific cyclic carboxylate additive (formula 1) with controlled concentration ranges. This additive modifies the electrolyte's chemical properties to suppress peeling phenomena at the cathode current collector while maintaining the beneficial low-temperature performance of acetonitrile-based solutions.
Solution Approach 2:
The patent creates a composite electrolyte system by combining acetonitrile-based solvent with cyclic carboxylate additive (formula 1) and optionally other components like LiPF6. This composite formulation synergistically combines the high conductivity and low-temperature performance of acetonitrile with the high-temperature stability provided by the cyclic carboxylate, resolving the durability contradiction.
2Reliability
If acetonitrile-based electrolyte solution is used, then ion conductivity is improved, but peeling phenomena between cathode current collector occur
Solution Approach 1:
The cyclic carboxylate additive (formula 1) acts as an intermediary substance that mediates between the electrolyte solution and the cathode current collector. It forms a protective interface layer that prevents direct harmful interactions causing peeling, while still allowing ionic transport, thus maintaining conductivity while improving adhesion strength.
Solution Approach 2:
The patent modifies the interfacial parameters at the cathode current collector by introducing the cyclic carboxylate additive. This changes the chemical and physical parameters of the electrode-electrolyte interface, suppressing peeling phenomena while preserving the high ionic conductivity characteristic of acetonitrile-based electrolytes.
3Ease of operation
If acetonitrile-based electrolyte solution is used, then low-temperature characteristics are improved, but internal resistance increases at high temperature
Solution Approach 1:
The patent changes the thermal stability parameters of the electrolyte solution by adding the cyclic carboxylate additive (formula 1). This additive suppresses temperature-dependent degradation reactions and peeling phenomena that cause internal resistance increase at high temperatures, while maintaining the low-temperature operational characteristics of the acetonitrile-based system.
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 solution improves long-term high-temperature durability while maintaining excellent output and low-temperature characteristics, reducing peeling phenomena and internal resistance.
Implementation Method 1
In order to form a solid electrolyte interface (SEI) on a surface of a negative electrode to thereby suppress the reductive decomposition of the non-aqueous solvent
Implementation Method 2
suppress the reductive decomposition of the non-aqueous solvent
Implementation Method 3
it is possible to carry out reversible lithium intercalation to and lithium deintercalation from the electrode
Implementation Method 4
reversible lithium intercalation to and lithium deintercalation from the electrode
Implementation Method 5
lithium bis(trifluoromethanesulfonyl)imide represented by the formula LiN(SO2CF3)2 is dissolved in acetonitrile
Implementation Method 6
can effectively suppress a decrease in ionic conductivity in a low temperature range to obtain excellent low-temperature characteristics
Data Source
AI summary
The present invention provides a nonaqueous electrolyte solution which contains a nonaqueous solvent and a lithium salt, wherein: the nonaqueous solvent contains acetonitrile in an amount of 3% by volume to 97% by volume relative to the total amount of the nonaqueous solvent; the lithium salt contains a cyclic anion-containing lithium salt that is represented by formula (1) (wherein Rf moieties may be the same as or different from each other, and each represents a fluorine atom or a perfluoro group having 4 or less carbon atoms); and the content of the cyclic anion-containing lithium salt that is represented by formula (1) is from 0.001 to 5 in terms of the molar ratio relative to the content of the acetonitrile.