Electrolyte Composition Using Nitrile Solvents for Ultracapacitor Performance
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Solution Overview
Problem
Current electrolyte compositions for energy storage devices, such as ultracapacitors, face challenges in improving output, capacity, and cycle life characteristics due to the use of cyclic carbonate solvents that are solid or highly viscous at room temperature, requiring mixed solvents with lower permittivity and viscosity, which compromises their functional performance.
Innovation Solution
An electrolyte composition is developed using a combination of a lithium salt and an ammonium salt with a mixed solvent comprising cyclic carbonate and nitrile solvents like acetonitrile and propionitrile, where the nitrile solvent constitutes 30 to 90 wt% and cyclic carbonate 10 to 70 wt%, optimizing the mixing ratio to enhance solubility and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If cyclic carbonate solvent (EC or PC) is used to dissolve lithium salt effectively, then solubility of lithium salt is improved, but viscosity of the electrolyte increases and permittivity decreases
Solution Approach 1:
The patent uses a composite solvent system combining cyclic carbonate (EC or PC) with linear carbonate (DMC, DEC, or EMC) to achieve optimal balance between lithium salt solubility and electrolyte viscosity. The cyclic carbonate provides high solubility while the linear carbonate component reduces viscosity, creating a synergistic effect that resolves the contradiction between these two properties.
Solution Approach 2:
The patent optimizes the concentration of lithium salt and the ratio of cyclic to linear carbonate components to adjust the physical properties of the electrolyte. By controlling these parameters, the electrolyte achieves sufficient lithium salt dissolution while maintaining acceptable viscosity levels for device operation.
2Quantity of substance
If cyclic carbonate solvent (EC or PC) is used to dissolve lithium salt effectively, then solubility of lithium salt is improved, but permittivity of the electrolyte decreases
Solution Approach 1:
The patent employs a composite solvent system where cyclic carbonate (providing high solubility) is combined with linear carbonate components. The linear carbonate, while having lower solubility capacity, contributes to maintaining adequate permittivity levels, thus balancing the contradiction between solubility enhancement and permittivity preservation.
3Reliability
If nitrile solvent is used instead of linear carbonate solvent, then permittivity and conductivity are improved, but solubility of lithium salt decreases
Solution Approach 1:
The patent creates a three-component composite solvent system combining nitrile solvent (for high conductivity and permittivity), cyclic carbonate (for lithium salt solubility), and linear carbonate (to balance viscosity and maintain solubility). This multi-component system allows each solvent to contribute its advantageous properties while compensating for the limitations of the others, achieving simultaneous improvement in conductivity and maintenance of solubility.
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
This composition significantly improves the initial capacity, resistance, and cycle life characteristics of energy storage devices by leveraging the high permittivity and low viscosity of nitrile solvents, reducing lithium salt usage to prevent hydrolysis and enhance the energy storage device's performance and longevity.
Implementation Method 1
An electrolyte composition is developed using a combination of a lithium salt and an ammonium salt with a mixed solvent comprising cyclic carbonate and nitrile solvents like acetonitrile and propionitrile
Implementation Method 2
This composition significantly improves the initial capacity, resistance, and cycle life characteristics of energy storage devices by leveraging the high permittivity and low viscosity of nitrile solvents
Implementation Method 3
For the effective dissolution of the lithium salt, a high permittivity solvent such as ethylene carbonate (EC) or propylene carbonate (PC) should be used
Data Source
AI summary
The present invention relates to an electrolyte of an energy storage device. An electrolyte composition in accordance with an embodiment of the present invention includes an electrolyte salt, a carbonate solvent, and at least one nitrile solvent of acetonitrile and propionitrile.