Planar Sodium Battery Venting Design
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Solution Overview
Problem
Tubular design-based sodium-beta batteries face limitations in power and energy densities, charge density, and safety due to thick cathodes, volumetric changes, and pressure issues during charge/discharge cycles.
Innovation Solution
A molten sodium battery design incorporating metallic interconnect frames with vent holes and β″ alumina solid electrolyte plates, allowing for gaseous communication and pressure relief, with a cathode composition of transition metals and sodium chloride, and a secondary electrolyte, enabling higher sodium content and improved power density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a tubular design with thick cathode is used, then structural integrity is improved, but power and energy densities are reduced
Solution Approach 1:
The battery is divided into multiple planar cells stacked together, with each cell having thin cathode layers. This segmentation allows for better ion transport and higher power density while maintaining structural integrity through the stacked configuration and interconnect frames.
Solution Approach 2:
The design transitions from a tubular (3D cylindrical) geometry to a planar stacked (layered) geometry. This dimensional change enables thinner cathode layers with larger surface area, improving power density while the vertical stacking maintains overall structural strength.
2Stability of the object's composition
If a tubular design with thick electrolyte is used, then mechanical stability is improved, but high power characteristics are limited
Solution Approach 1:
The electrolyte is segmented into thin planar layers between stacked cells, reducing ion transport distance and enabling high power characteristics while maintaining mechanical stability through the distributed stacked structure.
3Ease of manufacture
If sodium is provided as salt on cathode side and separated during charge/discharge, then manufacturing simplicity is improved, but charge density is reduced
Solution Approach 1:
Sodium metal is pre-loaded onto the anode side during assembly, eliminating the need for salt decomposition and separation during operation. This preliminary action enables higher charge density while simplifying the charge/discharge process.
4Reliability
If vent holes are incorporated for pressure relief, then safety is improved, but device complexity increases
Solution Approach 1:
The interconnect frames serve multiple functions: providing structural support, enabling electrical connection between cells, and incorporating vent holes for pressure relief. This multi-functionality improves safety without significantly increasing device complexity.
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 design enhances power and energy densities, prevents electrolyte damage from pressure buildup, and allows for more efficient sodium utilization, resulting in higher performance and reliability compared to traditional tubular designs.
Implementation Method 1
β''—Al2O3 exhibits a higher sodium ionic conductivity (typically 0.2 ̃0.4 S cm−1 at 300° C.) and is the preferred phase for sodium battery electrolyte applications
Implementation Method 2
the vapor pressure of molten sodium metal and other gases can create a differential pressure within the cell
Data Source
AI summary
A method of making a molten sodium battery is disclosed. A first metallic interconnect frame having a first interconnect vent hole is provided. A second metallic interconnect frame having a second interconnect vent hole is also provided. An electrolyte plate having a cathode vent hole and an anode vent hole is interposed between the metallic interconnect frames. The metallic interconnect frames and the electrolyte plate are sealed thereby forming gaseous communication between an anode chamber through the anode vent hole and gaseous communication between a cathode chamber through the cathode vent hole.