Australian engineers have achieved a breakthrough in water-based flow battery technology, potentially revolutionizing home energy storage. A next-generation design overcomes the limitations of earlier flow batteries, offering a safer, cheaper, and more efficient alternative to lithium-ion systems for storing rooftop solar energy. Let’s dive into the details of this exciting development.
Flow Batteries: The Next Big Thing in Energy Storage?
Flow batteries have been around for decades, traditionally utilized for large-scale energy storage due to their size and slow charging speeds. Unlike lithium-ion batteries that store energy in solid materials, flow batteries store energy in liquid electrolytes. This offers several advantages:
- Safety: Water-based flow batteries are non-flammable and non-toxic, making them safer than lithium-ion batteries, which pose a fire risk.
- Cost-Effectiveness: Flow batteries can be manufactured using abundant and inexpensive materials, potentially leading to lower costs than lithium-ion systems.
- Scalability: The energy storage capacity of a flow battery is determined by the size of its electrolyte tanks, allowing for easy customization and scaling.
- Long Lifespan: Redox flow batteries can withstand numerous charge and discharge cycles without significant degradation, making them ideal for renewable energy storage.
However, previous flow battery designs have been too bulky and slow for residential use. The new water-based battery developed by researchers at Monash University overcomes these limitations, making it a promising candidate for home energy storage.
Monash University’s Breakthrough: A Game Changer
The key to Monash University’s breakthrough lies in a newly engineered membrane that allows for faster charging speeds. This innovation addresses a major drawback of earlier flow battery designs, making them suitable for capturing rooftop solar energy in real-time.
The Ultra-Ion-Selective SPEEK-SX Membrane
The study highlights an ultra-ion-selective SPEEK-SX membrane, enabling 600 cycles at 160 mA cm-2 with only 0.00935% per cycle capacity decay. This outperforms the industry-standard Nafion-212 membrane and offers a fluorine-free alternative.
Outperforming the Industry Standard
According to Wanqiao Liang, a PhD candidate at the Department of Materials Science and Engineering at Monash University and the study’s lead author, the new membrane design is at the heart of the team’s breakthrough.
“The key was improving ion selectivity; letting the good ions through quickly while keeping unwanted ones out,” says Liang. “Our new membrane achieves this balance, allowing fast, stable operation even at high current densities.”
In testing, the technology outperformed the industry-standard membrane in both speed and stability, running 600 high-current cycles with virtually no capacity loss.
Aims for Rooftop Solar and Home Use
The engineers state that their next-generation flow battery is expected to be much cheaper than current $10,000 lithium-ion systems and opens the door to compact, high-performance battery systems for homes.
“This is the kind of battery you’d want in your garage,” Liang said. “It’s non-toxic, non-flammable, and made from abundant materials, all while keeping up with solar power on a sunny day.”
Publishing the Results
The team’s findings have been published in a paper titled “Flow Battery with Remarkably Stable Performance at High Current Density,” in the journal Angewandte Chemie.
How Does It Work?
The Monash team’s flow battery design incorporates a nonfluorinated separator with concurrent rejection and conductivity. Unlike lithium-ion batteries, which rely on solid materials, flow batteries store energy in liquid form, offering safer and more sustainable operation.
Redox Flow Batteries Explained
Redox flow batteries store energy in liquid solutions called electrolytes, which contain chemical compounds that can change from an oxidized to a reduced state and vice versa. During operation, two types of electrolytes are pumped from separate tanks through a central electrochemical cell. In this cell, the electrolytes interact through an ion exchange membrane, generating electricity that can be used or stored.
The Membrane’s Role
The membrane plays a crucial role in the battery’s performance by selectively allowing ions to pass through while blocking unwanted substances. This improves the battery’s efficiency, stability, and lifespan. The new membrane developed by the Monash team achieves this balance, allowing for fast and stable operation even at high current densities.
Benefits of the New Water Flow Battery
The new water flow battery offers several potential benefits for residential energy storage:
- Improved Safety: The water-based electrolyte is non-flammable and non-toxic, reducing the risk of fire and environmental damage.
- Lower Cost: The battery is made from abundant and inexpensive materials, potentially making it more affordable than lithium-ion systems.
- Faster Charging: The new membrane design enables faster charging speeds, making it suitable for capturing rooftop solar energy in real-time.
- Longer Lifespan: The battery can withstand numerous charge and discharge cycles without significant degradation, ensuring a long service life.
- Scalability: The battery’s storage capacity can be easily scaled by increasing the size of the electrolyte tanks.
Real-World Testing and Future Prospects
The Monash University engineering team is currently 3D printing prototype systems and testing them under real-world conditions. If the prototypes continue to perform as expected, the battery could be commercially available in a few years.
Monash’s Microgrid
Monash University has already demonstrated its commitment to renewable energy with the installation of a 1 MWh redT energy (now known as Invinity energy) storage system in 2018. This system is a core part of the microgrid at its Clayton, Victoria campus and plays a central role in the University’s goal to become 100% energy self-sufficient and achieve Net Zero emissions by 2030.
The Competition
While Monash University’s design stands out for its combination of safety, low cost, and high-speed performance, other companies are also developing flow batteries for residential and commercial use. However, few systems worldwide have achieved the same balance of these critical factors.
AQUABATTERY
AQUABATTERY, developed in the Netherlands, is another novel flow battery that uses an acid-base reaction based on reversible water dissociation. It stores electricity in the form of chemical energy in acid, base, and saltwater solutions. Pumps circulate these fluids through a power stack with electrodes separated by membranes. The membranes allow ion exchange between electrolytes to generate electricity. This design is also customizable and suitable for long-duration applications and utility-scale deployment.
Potential Applications
The new water flow battery has the potential to revolutionize home energy storage and accelerate the transition to a cleaner energy future. It could also be used in other applications, such as:
- Grid-scale energy storage: Flow batteries can be used to store large amounts of energy from renewable sources, such as solar and wind power, helping to stabilize the grid.
- Microgrids: Flow batteries can be used to create self-sufficient microgrids that provide reliable power to communities and businesses.
- Electric vehicle charging stations: Flow batteries can be used to store energy for electric vehicle charging stations, reducing the strain on the grid.
- Desalination: Redox flow desalination (RFD) is an innovative technique that combines water desalination and energy storage in one system. It circulates saline solutions and redox agents through electrochemical cells. Ion exchange membranes allow for selective ion transfer, extracting salt from seawater and producing fresh water. In addition to producing potable water, the RFD process allows excess renewable energy to be stored in the redox molecules, which can then be released when needed, functioning like a battery.
Challenges and Opportunities
While the new water flow battery technology is promising, there are also challenges to overcome before it can be widely adopted. These challenges include:
- Energy Density: Flow batteries typically have lower energy density than lithium-ion batteries, meaning they require larger tanks to store the same amount of energy.
- Cost Reduction: While flow batteries have the potential to be cheaper than lithium-ion batteries, further cost reductions are needed to make them competitive in the market.
- Commercialization: More companies need to invest in the development and commercialization of flow battery technology to accelerate its adoption.
Despite these challenges, the opportunities for flow batteries are vast. As the world transitions to a cleaner energy future, energy storage will become increasingly important. Flow batteries offer a safe, cost-effective, and scalable solution for storing renewable energy, making them a key technology for the future.
