Phosphine Electrolyte for Lithium Battery High-Temperature Stability
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Solution Overview
Problem
Rechargeable lithium batteries face challenges in maintaining cycle-life and storage stability at high temperatures, and experiencing increased thickness due to electrolyte degradation.
Innovation Solution
An electrolyte composition for rechargeable lithium batteries, including a lithium salt, a phosphine compound with a trialkylsilyl group, and an organic solvent, along with a fluorine-containing carbonate compound, which enhances lithium ion mobility and prevents capacity loss and thickness increase at high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrolyte compositions are used, then the battery can operate at high temperature, but the cycle-life decreases and storage stability deteriorates
Solution Approach 1:
The patent modifies the chemical composition parameters of the electrolyte by introducing a phosphine compound with specific trialkylsilyl groups (Formula 1) alongside conventional lithium salts and organic solvents. This compositional parameter change enables the electrolyte to maintain stability at high temperatures while preserving cycle-life and storage characteristics.
Solution Approach 2:
The patent creates a composite electrolyte system combining multiple components: lithium salt, organic solvent, and the novel phosphine compound with trialkylsilyl groups. This composite material approach synergistically combines the properties of each component to achieve both high-temperature operation and improved reliability in terms of cycle-life and storage stability.
2Temperature
If conventional electrolyte compositions are used, then the battery can function at high temperature, but the thickness increases due to electrolyte degradation
Solution Approach 1:
The patent changes the chemical parameters of the electrolyte composition by incorporating the phosphine compound (Formula 1) with specific trialkylsilyl groups. This parameter modification prevents electrolyte degradation at high temperatures, thereby preventing the increase in battery thickness that would otherwise occur.
Solution Approach 2:
The patent converts the potential harmful effect of high-temperature electrolyte degradation into a beneficial outcome. By using the phosphine compound-stabilized electrolyte, the degradation that would normally cause thickness increase is prevented, turning the high-temperature challenge into an opportunity to demonstrate improved dimensional stability.
3Reliability
If the electrolyte composition is optimized for room temperature performance, then cycle-life improves, but storage stability at high temperature deteriorates
Solution Approach 1:
The patent makes the electrolyte composition universally effective across different temperature conditions. The phosphine compound with trialkylsilyl groups performs multiple functions: it maintains cycle-life at room temperature and simultaneously provides storage stability at high temperature, eliminating the need to choose between optimized room-temperature or high-temperature performance.
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 composition improves cycle-life and capacity retention at room temperature while reducing battery thickness and maintaining over 80% capacity at high temperatures, effectively addressing the degradation issues.
Implementation Method 1
a phosphine compound having at least one trialkylsilyl group... which enhances lithium ion mobility
Implementation Method 2
prevents capacity loss and thickness increase at high temperatures
Implementation Method 3
a positive electrode including a positive active material capable of intercalating/deintercalating lithium ions and a negative electrode including a negative active material capable of intercalating/deintercalating lithium ions
Data Source
AI summary
Disclosed is an electrolyte for a rechargeable lithium battery that includes a lithium salt, a phosphine compound having at least one trialkylsilyl group and organic solvent, and a rechargeable lithium battery including the electrolyte. The phosphine compound may be tris(trialkylsilyl)phosphine wherein the alkyl groups are the same or different and are each independently selected from C1 to C6 alkyl.