Segmented Electrochemical Cell Eliminating Graphite Felt
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Solution Overview
Problem
Existing electrochemical cells using molten alkali metals and sulfur require large amounts of graphite felt for operation, which limits their capacity and efficiency, and are prone to uncontrolled reactions due to solid electrolyte fractures.
Innovation Solution
The electrochemical cell design incorporates a cathode space divided into segments with electrically conductive outer walls that act as electrodes, eliminating the need for graphite felt and incorporating a chemical barrier layer to prevent uncontrolled reactions, with a solid electrolyte and porous electrode configuration for improved mass transfer and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If large amounts of graphite felt are used in existing electrochemical cells, then the cells can operate with molten alkali metals and sulfur, but the capacity and efficiency are limited
Solution Approach 1:
The patent removes graphite felt entirely from the electrochemical cell design. Instead of using graphite felt as a current collector and electrode structure, the invention employs the cathode container wall itself as the current collector and uses a liquid cathode material in contact with the solid electrolyte membrane, eliminating the need for graphite felt and thereby increasing storage capacity and efficiency
Solution Approach 2:
The cathode container wall serves multiple functions simultaneously: it acts as the current collector, provides structural containment for the cathode material, and facilitates electrical contact. This multi-functionality replaces the traditional separate graphite felt component, reducing material quantity while maintaining or improving performance
2Reliability
If the solid electrolyte is used to separate anode and cathode spaces, then ion transport is enabled, but fracture of the ceramic can lead to uncontrolled reactions
Solution Approach 1:
The patent introduces a liquid cathode material as an intermediary layer between the solid electrolyte membrane and the sulfur cathode material. This liquid layer acts as a buffer that prevents direct contact between sodium ions and sulfur in case of solid electrolyte fracture, thereby preventing uncontrolled reactions while maintaining reliable ion transport through the intact solid electrolyte
Solution Approach 2:
The design anticipates potential solid electrolyte fracture by pre-positioning a liquid cathode material layer that can absorb and neutralize the harmful effects of such failures. This cushioning layer is in place before any fracture occurs, ready to prevent uncontrolled reactions between anode and cathode materials
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 design enhances the storage capacity and efficiency of the electrochemical cell by reducing the amount of graphite felt required and minimizing the risk of uncontrolled reactions, allowing for safer and more effective energy storage.
Implementation Method 1
a solid electrolyte membrane (3) separating an anode space (57) from a cathode space (65), where the solid electrolyte membrane (3) has a first side (3a) facing the anode space (57) and a second side (3b) facing the cathode space (65)
Implementation Method 2
a liquid cathode material (66) arranged on the second side (3b) of the solid electrolyte membrane (3), wherein the liquid cathode material (66) is in ionic contact with the second side (3b) of the solid electrolyte membrane (3) and is able to absorb sodium ions (Na+) from the anode space (57) through the solid electrolyte membrane (3)
Implementation Method 3
a reaction of the alkali metal with the cathodic reaction participant occurs at the cathode. This is, for example when using sodium as alkali metal and sulfur as cathodic reaction participant, the reaction of sodium and sulfur to form sodium polysulfide
Implementation Method 4
To charge the battery, the sodium polysulfide is dissociated again into sodium and sulfur at the electrode by introduction of electric energy
Data Source
AI summary
A device for storing electrical energy is disclosed. The device includes an electrochemical cell having a cathode chamber for holding a liquid cathode material and an anode chamber for holding a liquid anode material. The cathode and anode chambers are separated by a solid electrolyte, wherein the solid electrolyte is surrounded by a planar construction having openings, through which the cathode material can flow. The planar construction is made of an electrically conductive material. The cathode chamber includes at least one segment, wherein each segment has a jacket composed of an electrically conductive material and the jacket is fastened to the planar construction having openings in a fluid-tight and electrically conductive manner and wherein each segment is filled with a porous felt or a porous material different from porous felt. A method for assembling and starting up the device and a method for operating the device is also disclosed.