Novel Organic Carbonate Electrolyte for Wide Temperature Stability
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Solution Overview
Problem
Current electrolytes for ultra capacitors and lithium batteries face challenges with low temperature performance, as they freeze at sub-zero temperatures and exhibit high vapor pressures at high temperatures, limiting their operational range and stability.
Innovation Solution
Development of novel symmetrical and unsymmetrical organic carbonates with a wide liquidus range of -65° C. to 171° C., combined with conductive salts like quaternary ammonium tetrafluoroborate, to create electrolyte solutions that maintain conductivity and stability across a broad temperature range, enabling high operating voltages and low vapor pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If volatile solvents like THF, methyl formate, methyl acetate, dimethyl ethylene glycol, or dimethoxy ethane are used to achieve low temperature performance down to -40°C or -50°C, then low temperature freezing point is improved, but high temperature vapor pressure increases causing stability problems above 70°C
Solution Approach 1:
The patent changes the chemical parameters of the solvent system by introducing novel organic carbonates with specific molecular structures (formula I) that have fundamentally different vapor pressure characteristics compared to conventional volatile solvents. These new carbonates maintain low-temperature fluidity while exhibiting negligible vapor pressure at high temperatures, thus resolving the contradiction between low-temperature performance and high-temperature stability.
Solution Approach 2:
The patent creates a composite electrolyte system combining novel organic carbonates (formula I) with conventional carbonates like ethylene carbonate and propylene carbonate, along with specific lithium salts. This composite approach leverages the low-temperature advantages of the new carbonates while the cyclic carbonates provide high-temperature stability and suppress vapor pressure, achieving both low-temperature fluidity and high-temperature stability simultaneously.
2Power
If propylene carbonate is used in capacitor electrolytes to achieve higher operating cell voltage, then voltage capability is improved, but solubility of tetrafluoroborate salt decreases rapidly on cooling and conductivity drops below -20°C
Solution Approach 1:
The novel organic carbonates (formula I) act as intermediary substances that mediate between the conflicting requirements of high voltage operation and low temperature conductivity. They provide a molecular environment that maintains salt solubility and ionic mobility at low temperatures while being compatible with high operating voltages, thus resolving the contradiction between voltage capability and low-temperature reliability.
3Power
If ethylene carbonate is used with cyclic organic carbonate mixtures to achieve higher operating cell voltage in ultra capacitors, then voltage performance is improved, but the electrolyte freezes before -20°C is reached
Solution Approach 1:
The patent changes the physical parameters of the electrolyte system by introducing novel organic carbonates with significantly depressed freezing points. These new carbonates have molecular structures that prevent crystallization at low temperatures while maintaining the high voltage performance characteristics needed for ultra capacitor applications, thus resolving the contradiction between voltage performance and freezing point.
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 novel electrolyte solutions provide stable operating cell voltages up to 4V and maintain conductivity from -65° C. to 171° C., ensuring reliable performance in extreme temperatures without freezing, suitable for both ultra capacitors and lithium batteries.
Implementation Method 1
the conductivity of the electrolyte will go to zero if it freezes before a desired low temperature performance is achieved
Implementation Method 2
The performance of ultra capacitor and lithium battery electrolytes at low temperature is a continuing problem since the conductivity of the electrolyte will go to zero if it freezes
Implementation Method 3
The problem is that the performance of these electrolytes at high temperatures such as >70°C causes high vapor pressures in the batteries with these volatile low boiling solvents
Data Source
AI summary
The present invention provide novel compounds and electrolyte solutions which can be used in capacitors and lithium batteries and which have a liquidus range of from about −65 to about 171 degrees C.