Semi-solid redox flow battery for high energy density
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Solution Overview
Problem
Conventional redox flow batteries have low energy and power density due to limitations in solubility of metal ion redox couples in liquid solvents, which can be detrimental to cell operation and are constrained by the need for high acidity, leading to corrosion and storage issues.
Innovation Solution
The use of semi-solid or condensed ion-storing liquid reactants in redox flow energy storage devices, where at least one of the electrodes includes a flowable semi-solid or condensed liquid ion-storing redox composition capable of taking up or releasing ions, enhancing energy density and power density by allowing for higher molar concentrations of redox species without the need for acidic solutions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If metal ion redox couples are used in liquid solvents, then the battery can operate with reversible redox reactions, but the energy density is limited by the solubility of metal ions
Solution Approach 1:
The patent changes the physical state parameter of the redox-active material from dissolved liquid to semi-solid slurry or gel form. This parameter change allows the system to achieve higher effective concentrations of redox species without being constrained by solubility limits, thereby increasing energy density while maintaining flow battery operation
Solution Approach 2:
The patent creates a composite system by suspending redox-active particles in a liquid carrier medium. This composite approach combines the benefits of liquid flowability with high solid-phase concentration, enabling increased energy density while maintaining pumpability and flow characteristics necessary for redox flow battery operation
2Quantity of substance
If the solubility of metal ions is increased to enhance energy density, then more redox species are available, but corrosion of cell components increases
Solution Approach 1:
The patent introduces an intermediary approach by using solid or semi-solid redox-active materials suspended in a carrier medium rather than highly concentrated dissolved metal ions. This intermediary state provides high effective concentration for energy density while avoiding the direct corrosive effects of high metal ion concentrations on cell components
Solution Approach 2:
The patent changes the chemical state parameter from dissolved ionic form to suspended particulate or gel form. This parameter change maintains high redox species concentration for energy density while reducing the corrosivity associated with high metal ion concentrations in liquid solution
3Device complexity
If static electrode media are used, then the device structure is simple, but the power density and current extraction rate are limited
Solution Approach 1:
The patent introduces dynamic flow characteristics to the electrode media, allowing the semi-solid slurry or gel to circulate through the cell. This dynamic approach enables continuous replenishment of redox species at the electrode surfaces, significantly increasing power density and current extraction rates compared to static configurations while maintaining relatively simple device structure
4Quantity of substance
If the distance for ion conduction is increased to increase capacity, then more ions can be stored, but the power requirements constrain the total capacity
Solution Approach 1:
The patent uses dynamic flow circulation to continuously transport redox species throughout the cell, enabling long conduction paths and high total capacity without the power limitations of static systems. The flowing semi-solid media ensures continuous supply of redox species to electrode surfaces regardless of device length scale
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 and power density of redox flow batteries, enabling applications such as extended driving ranges for electric vehicles and improved stationary energy storage, with specific energies exceeding 150 Wh/kg and total energies up to 300 kWh, while avoiding corrosion issues.
Implementation Method 1
an ion-permeable membrane separating the positive and negative current collectors
Implementation Method 2
a flowable semi-solid ion-storing redox composition which is capable of taking up or releasing the ions during operation of the cell
Data Source
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AI summary
The present invention provides an energy storage device comprising an electroactive zone defined at least partially by a current collector and an ion-permeable membrane, the electroactive zone configured to contain a semi-solid electrode comprising a suspension of an ion-storing solid phase material in a liquid electrolyte, the ion-storing solid phase material being capable of taking up or releasing ions without dissolving in the electrolyte.