Molten Sodium Cell with Ion Conductive Membrane
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Solution Overview
Problem
Conventional molten sodium-based rechargeable batteries operate at high temperatures, leading to thermal management issues, safety concerns, and high operational costs due to the need for expensive components resistant to these temperatures, and inefficiencies in energy usage.
Innovation Solution
A molten sodium secondary cell design utilizing a sodium ion conductive electrolyte membrane that operates between 100° C and 170° C, featuring a sodium metal negative electrode and a positive electrode compartment with a liquid positive electrode solution, allowing for efficient sodium ion transport and reduced thermal requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional high temperature operation (>270°C) is used with sodium β′′-alumina ceramic electrolyte separator, then Faradaic efficiency approaches 100%, but thermal management problems and safety issues arise
Solution Approach 1:
The patent changes the operating temperature parameter from conventional high temperatures (>270°C) to a lower temperature range (100-170°C). This is achieved by using a sodium ion conductive electrolyte membrane that maintains high ionic conductivity at lower temperatures, thereby reducing thermal management requirements and safety risks while preserving acceptable Faradaic efficiency
Solution Approach 2:
The patent employs a composite electrolyte system consisting of a sodium ion conductive electrolyte membrane combined with specific electrode materials (such as sulfur cathode and sodium anode). This composite structure enables the cell to operate at lower temperatures while maintaining high Faradaic efficiency through optimized material interactions and ion transport pathways
2Reliability
If high operating temperatures (>270°C) are used, then sufficient ionic conductivity is achieved, but energy consumption increases and components require high temperature resistance
Solution Approach 1:
The patent changes the temperature operating parameter to 100-170°C, which significantly reduces the energy required to heat and maintain the cell compared to conventional >270°C operation. The sodium ion conductive electrolyte membrane is specifically selected to provide adequate ionic conductivity at this lower temperature range, thereby reducing overall energy consumption
3Reliability
If conventional sodium β′′-alumina ceramic electrolyte separator is used, then high Faradaic efficiency is achieved, but expensive high temperature resistant components are required
Solution Approach 1:
The patent changes the operating temperature parameter to 100-170°C, which allows the use of less expensive electrolyte membranes and electrode materials that do not require high temperature resistance. This temperature reduction directly lowers component costs while maintaining acceptable Faradaic efficiency through optimized material selection and cell design
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 cell achieves efficient operation at lower temperatures, reducing energy consumption, enhancing safety, and minimizing thermal management challenges while maintaining high specific energy density, thus offering a more cost-effective and environmentally friendly alternative.
Implementation Method 1
a sodium ion conductive electrolyte membrane that separates the negative electrode from the positive electrode solution
Implementation Method 2
During discharge, electrochemical reduction occurs at the cell's positive electrode, while electrochemical oxidation occurs at the cell's negative electrode
Implementation Method 3
During discharge, electrochemical reduction occurs at the cell's positive electrode, while electrochemical oxidation occurs at the cell's negative electrode
Data Source
AI summary
The present invention provides a molten sodium secondary cell. In some cases, the secondary cell includes a sodium metal negative electrode, a positive electrode compartment that includes a positive electrode disposed in a liquid positive electrode solution, and a sodium ion conductive electrolyte membrane that separates the negative electrode from the positive electrode solution. In such cases, the electrolyte membrane can comprise any suitable material, including, without limitation, a NaSICON membrane. Furthermore, in such cases, the liquid positive electrode solution can comprise any suitable positive electrode solution, including, but not limited to, an aqueous sodium hydroxide solution. Generally, when the cell functions, the sodium negative electrode is molten and in contact with the electrolyte membrane. Additionally, the cell is functional at an operating temperature between about 100° C. and about 170° C. Indeed, in some instances, the molten sodium secondary cell is functional between about 110° C. and about 130° C.