Semi-Solid Redox Flow Battery Energy Density
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Solution Overview
Problem
Conventional redox flow batteries have a relatively low energy density due to the limited solubility of metal ion redox couples in liquid solvents, which restricts their power and energy storage capabilities.
Innovation Solution
The introduction of a semi-solid or condensed ion-storing liquid redox composition that can flow and participate in electrochemical reactions, enhancing energy storage by using a mixture of liquid and solid phases, such as slurries or gels, which can include ion storage compounds like metal fluorides, oxides, or intercalation compounds, to increase the solubility and energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional redox flow batteries use liquid solvents with metal ion redox couples, then the device can operate with simple fluid flow, but the energy density is limited due to restricted solubility
Solution Approach 1:
The patent changes the physical state parameter of the redox-active material from dissolved liquid phase to suspended solid phase (particles or powder). This parameter change enables much higher concentrations of redox-active material to be packed into the electrolyte, thereby significantly increasing energy density while maintaining fluid flow characteristics suitable for battery operation
Solution Approach 2:
The patent creates a composite electrolyte system combining liquid carrier fluid with suspended solid redox-active particles. This composite approach allows the system to benefit from both the fluidity of liquid solvents and the high density of solid active materials, resolving the contradiction between ease of operation and energy density
2Quantity of substance
If the concentration of redox-active material is increased to improve energy density, then more energy can be stored, but the viscosity and flow resistance increase
Solution Approach 1:
By changing the particle size parameter of the solid redox-active material to sub-micron or nanoscale dimensions, the patent reduces flow resistance and viscosity effects even at high concentrations. This allows high energy density to be achieved without excessive pumping power requirements
Solution Approach 2:
The patent employs porous electrode structures that can accommodate high concentrations of suspended particles while maintaining adequate fluid flow pathways. The porous structure increases surface area for electrochemical reactions while allowing the fluid to flow with reduced resistance, balancing energy density with acceptable pumping power
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 significantly increases the specific energy of redox flow batteries, enabling higher power and energy storage capacities, potentially supporting extended driving ranges for electric vehicles and improving stationary energy storage applications.
Implementation Method 1
liquid state redox reactions are carried out at the positive and negative electrodes
Implementation Method 2
an ion-permeable membrane separating the positive and negative electrode reactants
Data Source
AI summary
Redox flow devices are described in which at least one of the positive electrode or negative electrode-active materials is a semi-solid or is a condensed ion-storing electroactive material, and in which at least one of the electrode-active materials is transported to and from an assembly at which the electrochemical reaction occurs, producing electrical energy. The electronic conductivity of the semi-solid is increased by the addition of conductive particles to suspensions and/or via the surface modification of the solid in semi-solids (e.g., by coating the solid with a more electron conductive coating material to increase the power of the device). High energy density and high power redox flow devices are disclosed. The redox flow devices described herein can also include one or more inventive design features. In addition, inventive chemistries for use in redox flow devices are also described.