Flowable Metal Sulfide Electrodes with Percolating Networks
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Solution Overview
Problem
Conventional redox flow batteries have relatively low energy densities due to their design, which limits their ability to efficiently store and release energy, particularly in the precipitation regimes where higher capacities and densities are needed.
Innovation Solution
The development of an energy storage device with a flowable electrode comprising a sulfur or metal sulfide electroactive material suspended or dissolved in a fluid, combined with a percolating electronically conductive network, allowing for increased charge transfer area and reduced charge transfer resistance, enabling reversible cycling through precipitation regimes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional redox flow battery design is used, then the device structure is simple and scalable, but the energy density is low
Solution Approach 1:
The patent employs porous conductive particles (such as carbon nanotubes, graphene, or porous metal oxides) that form a three-dimensional percolating network within the flowable electrode. This porous structure dramatically increases the charge transfer area available for electrochemical reactions while maintaining the fluidity and flowability of the electrode material, thereby achieving high energy density without sacrificing device simplicity
Solution Approach 2:
The patent creates a composite flowable electrode material consisting of electroactive material particles (such as metal sulfides or polysulfides) combined with conductive particles forming a percolating network. This composite structure enables both high electrical conductivity and high electroactive material loading, resolving the contradiction between simple device structure and high energy density
2Ease of operation
If conventional flow battery electrodes are used, then the electrode material is fluid and easy to circulate, but the charge transfer area is limited
Solution Approach 1:
The patent transitions from two-dimensional charge transfer at planar electrode surfaces to three-dimensional charge transfer throughout the bulk volume of the flowable electrode. The percolating network of conductive particles creates conductive pathways in three dimensions, allowing electrochemical reactions to occur throughout the entire electrode volume rather than just at the surface, thereby dramatically increasing charge transfer area while maintaining fluidity
Solution Approach 2:
The porous structure of the conductive particles creates an extensive internal surface area network that remains suspended in the fluid medium. This porous network provides numerous sites for charge transfer while the overall material maintains its flowable character, enabling both high charge transfer area and easy circulation
3Ease of operation
If conventional flow battery electrodes are used, then the electrode can be circulated, but the charge transfer resistance is high
Solution Approach 1:
The patent forms a composite where conductive particles (such as carbon nanotubes, graphene, or conductive metal particles) create a percolating network throughout the flowable electrode. This composite structure provides continuous conductive pathways that reduce charge transfer resistance, while the overall material remains fluid and circulable. The conductive network acts as an embedded current collector within the flowing electrode material
4Quantity of substance
If sulfur or metal sulfide electroactive material is used, then the specific capacity increases, but the material insolubility in fluid causes poor electrochemical activity
Solution Approach 1:
The patent introduces conductive particles as an intermediary between the insoluble sulfur or metal sulfide electroactive material and the fluid electrolyte. These conductive particles provide surfaces for electrochemical reactions to occur and facilitate electron transfer, enabling high-capacity materials like sulfur and metal sulfides to exhibit good electrochemical activity despite their inherent insolubility in the fluid medium
Solution Approach 2:
The patent creates a composite structure where insoluble high-capacity electroactive materials (sulfur, metal sulfides) are combined with conductive particles and suspended in fluid. This composite approach allows the insoluble materials to maintain their high specific capacity while the conductive network enables efficient charge transfer, and the fluid suspension ensures good circulation and contact with electrolyte
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 approach results in higher energy densities and specific capacities, potentially five times greater than conventional flow batteries, by facilitating charge transfer throughout the electrode volume and utilizing both solution and precipitation regimes effectively.
Implementation Method 1
A battery stores electrochemical energy by separating an ion source and an ion sink at differing ion electrochemical potentials. A difference in electrochemical potential produces a voltage difference between the positive and negative electrodes; this voltage difference will produce an electric current if the electrodes are connected by a conductive element.
Implementation Method 2
electronically conductive particles suspended in the fluid, the electronically conductive particles forming a percolating conductive network
Implementation Method 3
at least positive and negative electrode compartments separated by an ionically conductive membrane
Data Source
AI summary
The present invention generally relates to energy storage devices, and to metal sulfide energy storage devices in particular. Some aspects of the invention relate to energy storage devices comprising at least one flowable electrode, wherein the flowable electrode comprises an electroactive metal sulfide material suspended and/or dissolved in a carrier fluid. In some embodiments, the flowable electrode further comprises a plurality of electronically conductive particles suspended and/or dissolved in the carrier fluid, wherein the electronically conductive particles form a percolating conductive network. An energy storage device comprising a flowable electrode comprising a metal sulfide electroactive material and a percolating conductive network may advantageously exhibit, upon reversible cycling, higher energy densities and specific capacities than conventional energy storage devices.