Semi-Solid Redox Flow Electrodes for High 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 redox flow energy storage device that incorporates semi-solid or condensed liquid ion-storing redox compositions, allowing for the use of flowable materials that can take up or release ions during operation, with specific embodiments including a mixture of liquid and solid phases, such as slurries or gels, to enhance ion storage capacity and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional liquid solvents are used in redox flow batteries, then the system maintains good flowability, but the energy density is limited due to restricted solubility of metal ion redox couples
Solution Approach 1:
The patent uses composite materials by combining solid active material particles with liquid carrier solutions to create slurry-based flow electrodes. This composite approach allows the system to achieve high energy density through increased active material concentration while maintaining flowability through the liquid carrier medium. The slurry formulation enables both solid particles to provide high capacity and liquid to ensure pumpability and flow through the electrochemical cell.
Solution Approach 2:
The patent changes the physical state parameters of the electrode materials from conventional dissolved liquid electrolytes to semi-solid slurries with controlled particle suspensions. By adjusting parameters such as particle size distribution, solids concentration, viscosity, and carrier solution composition, the system achieves high energy density while maintaining adequate flowability for continuous circulation through the electrochemical cell.
2Quantity of substance
If semi-solid or condensed liquid ion-storing compositions are used, then energy density and power density increase, but viscosity may increase potentially affecting flowability
Solution Approach 1:
The patent optimizes slurry formulation parameters including particle size distribution, solids concentration, and carrier solution composition to achieve high energy density while controlling viscosity. By carefully selecting and adjusting these parameters, the system maintains adequate flowability despite the increased solids content and energy density.
Solution Approach 2:
The patent employs porous electrode structures and flow channel designs that facilitate fluid flow even with higher viscosity slurries. The porous architecture allows the semi-solid composition to flow through the electrochemical cell effectively while maintaining high active material loading and energy density.
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 energy density and power density of the redox flow batteries, enabling higher specific energy and capacity storage compared to traditional systems, with specific energy exceeding 150 Wh/kg and total energy exceeding 50 kWh, while maintaining flowability and low viscosity.
Implementation Method 1
the positive and negative electrode reactants are soluble metal ions in liquid solution that are oxidized or reduced during the operation of the cell
Implementation Method 2
an ion-permeable membrane separating the positive and negative current collectors
Data Source
AI summary
Redox flow devices are described including a positive electrode current collector, a negative electrode current collector, and an ion-permeable membrane separating said positive and negative current collectors, positioned and arranged to define a positive electroactive zone and a negative electroactive zone; wherein at least one of said positive and negative electroactive zone comprises a flowable semi-solid composition comprising ion storage compound particles capable of taking up or releasing said ions during operation of the cell, and wherein the ion storage compound particles have a polydisperse size distribution in which the finest particles present in at least 5 vol % of the total volume, is at least a factor of 5 smaller than the largest particles present in at least 5 vol % of the total volume.