Ionic Liquid Catholyte for Low-Temperature Molten Salt Battery
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Solution Overview
Problem
Molten salt batteries using liquid sodium as the anode face challenges with high operating temperatures, leading to thermal management and safety issues, as well as stringent requirements for battery components.
Innovation Solution
The development of an electrolyte comprising an ionic liquid, a redox couple, and a sodium salt, specifically using 1-ethyl-3-methylimidazolium chloride (EMICl) and aluminum chloride, with a solid electrolyte that is permeable to sodium ions, allowing for a liquid cathode that operates at lower temperatures and reduces material costs while minimizing fire hazards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If molten salt batteries use liquid sodium as the anode with solid electrolyte and solid cathode, then good kinetics can be achieved, but high operating temperatures (>300°C) are required which cause thermal management and safety problems
Solution Approach 1:
The patent changes the physical state parameter of the cathode from solid to liquid, creating a liquid cathode that operates at lower temperatures (below 300°C) while maintaining good electrochemical kinetics. This parameter change in the cathode material's state of matter resolves the contradiction between achieving good kinetics and avoiding high operating temperatures.
Solution Approach 2:
The patent employs a composite electrolyte system combining solid electrolyte with liquid cathode containing ionic liquids and molten salts. This composite approach allows the solid electrolyte to provide good ionic conductivity and kinetics while the liquid cathode operates at reduced temperatures, thus resolving the thermal management issue while maintaining electrochemical performance.
2Reliability
If high operating temperatures are used to maintain good kinetics, then electrochemical performance is improved, but thermal management and safety issues worsen
Solution Approach 1:
The patent changes the operating temperature parameter from >300°C to below 300°C by introducing a liquid cathode system. This parameter change improves safety and thermal management while maintaining electrochemical performance through the liquid cathode's enhanced ionic conductivity and reduced activation energy requirements.
Solution Approach 2:
The liquid cathode acts as an intermediary between the solid electrolyte and the external circuit, enabling electrochemical reactions to proceed at lower temperatures. The ionic liquid components serve as mediators that facilitate ion transport and reduce the temperature threshold for effective electrochemical performance, thereby improving safety while maintaining reliability.
3Productivity
If liquid sodium anode is used with solid cathode, then good kinetics are achieved, but stringent requirements are imposed on battery components
Solution Approach 1:
The patent changes the cathode from solid to liquid state, which fundamentally alters the operating conditions and material requirements. The liquid cathode operates at lower temperatures and with reduced mechanical constraints, thereby relaxing the stringent requirements on battery components such as seals, containers, and structural elements while maintaining good kinetics.
Solution Approach 2:
The liquid cathode system uses readily available ionic liquids and molten salts that can be easily replenished or replaced. This approach reduces the complexity of maintaining stringent requirements on permanent structural components, as the liquid cathode can be refilled or replaced without replacing the entire battery structure, thereby simplifying the overall device requirements.
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 configuration enables high energy efficiency, low operating temperatures, and immunity to internal shorts, resulting in a battery that can deliver a significant portion of its theoretical energy density with high voltage and low fire risk.
Implementation Method 1
a solid electrolyte separating the anode current collector and the cathode current collector. The solid electrolyte is permeable to sodium ions
Implementation Method 2
The one half of the redox couple includes a metal in a first oxidation state that is oxidized or reduced to yield the metal in a second oxidation state
Data Source
AI summary
An ionic liquid catholyte includes an ionic liquid, such as 1-ethyl-3-methylimidazolium chloride (EMICl), at least one half of a redox couple, and a sodium salt. The ionic liquid catholyte is suitable for use as a liquid cathode in an electrochemical device including an anode current collector, an anode in contact with the anode current collector, a cathode current collector, a liquid cathode in contact with the cathode current collector, and a solid electrolyte separating the anode and cathode current collectors. The one half of the redox couple includes a metal in a first oxidation state that is oxidized or reduced to yield the metal in a second oxidation state, and the redox couple includes the metal in the first oxidation state and the metal in the second oxidation state. The solid electrolyte is permeable to sodium ions and is in contact with the liquid anode and the liquid cathode.