Salt batteries are emerging as a powerful and safe alternative to common lithium-ion batteries. Developed by Swiss researchers at Empa, this technology uses common salt to store energy, making it ideal for tough environments from mobile phone antennas on mountains to offshore oil rigs. Originally designed for electric cars, their unique design promises a more durable and sustainable future for energy storage, potentially even powering entire neighborhoods one day.
What Are Salt Batteries and How Do They Work?
Unlike the batteries in your phone or laptop, salt batteries operate on a different principle. They use a solid electrolyte made of a ceramic material called sodium aluminum oxide instead of a flammable liquid. This solid design is a key reason for their incredible safety and durability.
The core components are simple and abundant: common salt (sodium chloride) and nickel, held within a steel casing. To work, the battery must be heated to around 300° Celsius. At this temperature, the salt melts and allows sodium ions to travel through the ceramic electrolyte, generating an electrical current.
This high-temperature operation is what makes the battery so stable and robust. It isn’t affected by extreme cold or heat in its surrounding environment, allowing it to perform reliably where other batteries might fail.
The Key Advantages of Using Salt Batteries
The unique design of salt batteries gives them several major benefits over other energy storage technologies. Their resilience and use of common materials make them a very attractive option for specific applications.
These batteries are built to last. The solid construction means there are no liquids to leak or degrade, leading to a long, maintenance-free lifespan. This makes them perfect for remote locations where regular service is difficult or impossible.
Some of the primary benefits include:
- Inherent Safety: With a non-flammable, solid-state design, these batteries do not catch fire, even under extreme stress or high temperatures. This is a critical advantage over lithium-ion batteries.
- Long-Term Reliability: Salt batteries are known for their long life and consistent performance over many years, requiring virtually no maintenance once installed.
- Sustainable Materials: They are made from abundant and inexpensive materials like salt and nickel, avoiding the need for rare and costly metals such as cobalt and lithium.
This combination of safety, longevity, and sustainable sourcing is driving renewed interest in the technology for a wide range of uses.
A Comparison with Lithium-ion Batteries
To better understand the unique position of salt batteries, it helps to compare them directly with the more common lithium-ion technology. While lithium-ion batteries are great for portable electronics, salt batteries excel in different areas, particularly for large-scale and stationary applications.
| Feature | Salt Battery | Lithium-ion Battery |
| Safety | Non-flammable, very high | Can catch fire, requires safety systems |
| Operating Temperature | High (around 300° C) | Moderate (0° C to 45° C) |
| Core Materials | Salt, nickel, aluminum | Lithium, cobalt, manganese, nickel |
| Lifespan | Very long, maintenance-free | Shorter, degrades over time |
This table shows that the choice between battery types depends heavily on the application’s priorities. For situations where safety and long-term reliability are more important than size and weight, salt batteries are the superior choice.
Why Salt Batteries Excel in Extreme Conditions
The true strength of salt batteries shines in high-risk and demanding environments. Their ability to operate safely at high internal temperatures makes them unaffected by external temperature swings, whether in a hot desert or a cold mountain range.
This resilience is why they are already being used in safety-critical industries. For example, they are installed in mining sites where the risk of explosion is a constant concern and on offshore oil platforms where reliability is essential.
As Empa researcher Meike Heinz states, “Salt batteries do not catch fire, even at high operating temperatures, making them viable for safety-critical applications.” This inherent safety removes the need for complex and expensive cooling and fire suppression systems that are mandatory for large lithium-ion installations.
Innovating for a Greener Future
Researchers are not stopping at the current design. Empa and its partner HORIEN Salt Battery Solutions are actively working to make salt batteries even more sustainable and cost-effective. A major focus is reducing the amount of nickel used in the batteries.
Through projects like HiPerSoNick, scientists are redesigning the internal structure of the battery cells. This work aims to maintain high performance while using less nickel, which helps avoid supply chain issues and reduces the environmental impact of mining.
Furthermore, another research effort, the EU-funded SOLSTICE project, is exploring zinc as a potential replacement for nickel. Zinc is cheaper and has a lower melting point, which presents new engineering challenges. However, recent breakthroughs suggest that a stable, nickel-free salt battery is a realistic goal for the near future.
The Future of Large-Scale Energy Storage
Looking ahead, salt batteries are poised to play a significant role in stationary energy storage. As the world shifts toward renewable energy sources like solar and wind, the need for reliable, large-scale batteries to store power is growing rapidly.
Their low material cost, ease of recycling, and exceptional safety make them an ideal candidate for powering microgrids, residential areas, and industrial facilities. With continued research and scaling, salt batteries could become a cornerstone of a safe, stable, and sustainable energy grid. These efforts promise to unlock the full potential of a technology that prioritizes both safety and environmental responsibility.
Frequently Asked Questions About Salt Batteries
What are salt batteries made of?
Salt batteries are primarily made from very common and abundant materials. Their main components are table salt (sodium chloride), nickel, and a solid ceramic electrolyte made of sodium aluminum oxide, all housed in a steel container.
Are salt batteries safer than lithium-ion batteries?
Yes, they are considered much safer. Because they use a solid, non-flammable ceramic electrolyte instead of a flammable liquid, they cannot catch fire or explode, even when damaged or operating at high temperatures.
Why do salt batteries need to be hot to work?
Salt batteries must be heated to around 300° Celsius for the salt inside to melt. This molten salt allows sodium ions to flow through the ceramic electrolyte, which is how the battery generates and stores electricity.
Can salt batteries be used in electric cars?
While they were originally designed for an electric car, their high operating temperature and lower energy density compared to lithium-ion make them better suited for stationary applications today. They are ideal for large-scale storage where size and weight are less of a concern.
Are salt batteries environmentally friendly?
They are considered more environmentally friendly than many alternatives. They use abundant, less toxic materials and avoid rare metals like cobalt. They are also easier to recycle, contributing to a more sustainable energy storage cycle.
