Aqueous Electrolyte Composition for Low-Temperature Energy Storage
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Solution Overview
Problem
Existing aqueous electrolytes for energy storage devices, such as lithium ion batteries and supercapacitors, suffer from freezing issues at low temperatures, leading to performance deterioration, and the use of additives like ethylene glycol results in increased viscosity and decreased ion conductivity.
Innovation Solution
An aqueous electrolyte composed of water and lithium trifluoromethanesulfonate at specific concentrations (4.5 to 10 mol/L) without additives, ensuring high ion conductivity and preventing freezing even at -30 °C, thereby maintaining high performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If aqueous electrolyte is used to improve stability and output, then stability and output are improved, but freezing occurs at temperature below 0°C causing performance deterioration
Solution Approach 1:
The patent changes the chemical composition parameters of the aqueous electrolyte by using specific lithium salts (lithium trifluoromethanesulfonate, lithium tetrafluoroborate, or lithium hexafluorophosphate) at optimized concentrations (0.5-10 mol/L). This compositional parameter change enables the electrolyte to maintain liquid state and functional performance at temperatures as low as -30°C or lower, resolving the freezing temperature limitation of conventional aqueous electrolytes while preserving their high stability and output characteristics.
2Temperature
If additives like ethylene glycol are used to prevent freezing, then freezing is prevented, but viscosity increases and ion conductivity decreases
Solution Approach 1:
The patent extracts and eliminates the need for traditional freezing point depression additives like ethylene glycol from the electrolyte system. Instead, it achieves freezing prevention through the inherent properties of specific lithium salts dissolved in water at optimized concentrations. This extraction of harmful additives resolves the contradiction by preventing freezing through a cleaner approach that does not compromise ion conductivity or increase viscosity, thereby maintaining high reliability.
Solution Approach 2:
The patent employs simple, readily available lithium salt compounds (lithium trifluoromethanesulfonate, lithium tetrafluoroborate, or lithium hexafluorophosphate) as the freezing prevention mechanism. These salts are chemically stable, inexpensive, and effectively prevent freezing without the side effects of complex additives. The electrolyte system uses these straightforward chemical components to achieve reliable low-temperature operation without compromising performance.
3Quantity of substance
If non-aqueous electrolyte is used to achieve high energy density, then energy density is improved, but combustibility increases and stability decreases
Solution Approach 1:
The patent creates a composite electrolyte system by combining lithium salts (lithium trifluoromethanesulfonate, lithium tetrafluoroborate, or lithium hexafluorophosphate) with water in specific concentrations (0.5-10 mol/L). This composite aqueous electrolyte achieves a balance between safety and performance, providing high stability inherent to aqueous systems while the optimized salt concentration ensures sufficient ion conductivity and energy density for practical applications. The composite approach resolves the contradiction by demonstrating that aqueous electrolytes can meet energy density requirements without the combustibility risks of organic solvents.
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 electrolyte achieves ion conductivity of 55 mS/cm or more at room temperature and 6 mS/cm or more at -30 °C, allowing for stable and efficient energy storage device operation across a wide temperature range without the drawbacks of additives.
Implementation Method 1
an aqueous electrolyte that uses specific lithium salts only, and thus can prevent freezing and realize high performance even at a very low temperatures
Implementation Method 2
The electrolyte achieves ion conductivity of 55 mS/cm or more at room temperature and 6 mS/cm or more at -30 °C
Data Source
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AI summary
The present invention relates to an aqueous electrolyte capable of improving low temperature performance. More specifically, the present invention provides an aqueous electrolyte that is an aqueous solution including lithium trifluoromethanesulfonate at a predetermined concentration range without separate additives, and thus can prevent freezing and realize high performance even at a very low temperature of about -30 °C or less, and an energy storage device including the same.