Battery Electrolyte Composition for Wide-Temperature Li-Ion Conductivity
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Solution Overview
Problem
Secondary batteries, particularly lithium-ion batteries, face performance degradation due to temperature fluctuations, with low viscosity of electrolytes at low temperatures reducing carrier ion conductivity and increasing internal resistance, making them unsuitable for cold climates and tropical regions, and requiring improved safety and stability.
Innovation Solution
A nonaqueous solvent with an ionic liquid and a low viscosity organic solvent mixture, where the ionic liquid constitutes 20-80 volume %, is used, combined with cyclic carbonates and lithium hexafluorophosphate, to maintain high lithium ion conductivity and heat resistance across a wide temperature range, enhancing safety and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the viscosity of the electrolyte is reduced at low temperatures, then carrier ion conducting performance improves, but safety and stability deteriorate
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by introducing specific ionic liquids (imida-zolium type, pyridinium type, phosphonium type, or ammonium type) with defined molecular structures and charge distribution. This composition parameter change enables the electrolyte to maintain low viscosity at low temperatures while preserving safety and stability through the inherent properties of the ionic liquid molecules
Solution Approach 2:
The patent creates a composite electrolyte system by combining ionic liquids with traditional electrolyte components (cyclic carbonates and chain carbonates). This composite approach integrates the low-temperature flow properties of ionic liquids with the safety and stability characteristics of conventional electrolytes, achieving both low viscosity and high safety simultaneously
2Adaptability or versatility
If conventional electrolytes are used, then manufacturing simplicity is maintained, but temperature range adaptability deteriorates
Solution Approach 1:
The patent modifies the electrolyte composition parameters by incorporating ionic liquids with specific molecular structures (imida-zolium, pyridinium, phosphonium, or ammonium types). These parameter changes enable the electrolyte to function across an expanded temperature range from -40°C to 60°C while maintaining manageable composition through defined concentration ranges (1-30 wt% ionic liquid content)
3Temperature
If ionic liquid concentration is increased, then low temperature viscosity decreases, but cost and complexity increase
Solution Approach 1:
The patent optimizes the ionic liquid concentration parameter within a specific range (1-30 wt%) to achieve the desired low-temperature viscosity reduction. By controlling this parameter within defined bounds and selecting from multiple ionic liquid types, the formulation achieves low-temperature performance without excessive complexity or cost
Solution Approach 2:
The patent employs ionic liquids with universal applicability across multiple battery types and temperature conditions. The selected ionic liquid types (imida-zolium, pyridinium, phosphonium, ammonium) can serve multiple functions including viscosity reduction, conductivity enhancement, and safety improvement, reducing the need for multiple specialized additives
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 provides a secondary battery with stable performance and safety across varying temperatures, enabling the use of secondary batteries in electric vehicles and electronic devices in diverse climates without the limitations of traditional batteries.
Implementation Method 1
adding an organic solvent with a low viscosity to an ionic liquid enables a nonaqueous solvent to have a low viscosity even at low temperatures
Implementation Method 2
A low viscosity can increase the conductivity of a nonaqueous solvent, improving carrier ion conductivity such as lithium ion conductivity
Implementation Method 3
a nonaqueous solvent with an ionic liquid and a low viscosity organic solvent mixture... to maintain high lithium ion conductivity and heat resistance across a wide temperature range
Data Source
AI summary
A nonaqueous solvent that can be used in a wide temperature range, has a low viscosity, has high lithium ion conductivity at low temperatures, or has high heat resistance is provided. The nonaqueous solvent containing an ionic liquid and an organic electrolyte for low-temperature use has a low viscosity even at low temperatures and has high carrier ion conductivity. As the organic electrolyte for low-temperature use, an electrolyte in which methyl ethyl carbonate accounts for greater than or equal to 30 volume % and less than or equal to 65 volume % can be used. A battery using the nonaqueous solvent as an electrolyte can be used in a wide temperature range and thus is preferable.