In the realm of energy storage, salt batteries are emerging as a promising alternative to the ubiquitous lithium-ion battery. Originally designed for electric cars, these batteries now find applications in powering mobile phone antennas and, perhaps one day, entire neighborhoods. Empa, a Swiss research institution, in collaboration with HORIEN Salt Battery Solutions, is pioneering advancements in this technology, aiming to harness its longevity and safety potential for wider use.
A History Rooted in Innovation and Safety
The story of salt batteries began with an ambitious idea: to power the Mercedes-Benz A-Class with an electric energy source. However, the project shifted to a combustion engine, changing the vehicle’s weight distribution, which eventually caused it to tip during the infamous elk test. The original plan had called for a salt battery, which operates differently from conventional batteries by using a solid electrolyte of sodium aluminum oxide. This material allows for enhanced safety and durability but poses unique design challenges.
Fast forward to today, and salt batteries are valued for their resilience in extreme conditions. Unlike lithium-ion batteries, which rely on a flammable liquid electrolyte, salt batteries incorporate a ceramic ion conductor, making them suitable for volatile environments such as mining sites and offshore oil platforms. “Salt batteries do not catch fire, even at high operating temperatures, making them viable for safety-critical applications,” says Empa’s Meike Heinz.
Advantages of Salt Batteries in High-Risk Environments
The partnership between Empa and HORIEN began in 2016 with the goal of enhancing the performance of these batteries through Innosuisse-funded projects. The advantages of salt batteries are particularly evident in high-risk environments where safety concerns limit the use of lithium-ion technology.
Some key benefits include:
- High-temperature operation: Salt batteries run at around 300° Celsius, ensuring they remain stable in fluctuating temperatures.
- Long life and reliability: With a solid design and resistance to environmental changes, salt batteries offer maintenance-free performance over extended periods.
- Cost-effective materials: Composed mainly of common salt and nickel, salt batteries sidestep the demand for rare metals such as cobalt and lithium.
While high-temperature operation requires these batteries to be pre-heated, they offset this with low maintenance needs and an ability to perform reliably in remote locations, from mountaintop antennas to deep-sea oil platforms. The materials used are also easier to recycle, paving the way for a more sustainable solution in energy storage.
Redesigning the Salt Battery for a Greener Tomorrow
Empa’s research does not stop at the current advantages; instead, it seeks to refine the technology for even more sustainable applications. A recent collaboration between Empa and HORIEN focuses on reducing the nickel content of salt batteries, a necessary move given the increased environmental and economic concerns surrounding nickel extraction.
Through the HiPerSoNick project, funded by the Swiss Federal Office of Energy, scientists are exploring cell modifications that could one day lead to nickel-free designs. This involves meticulous coordination of cell composition and structure to maintain efficiency. “We’ve made strides in reducing the nickel component, which could help avoid critical material shortages,” Heinz explains.
Furthermore, the EU-funded SOLSTICE project, in place until mid-2025, is investigating the potential of zinc as an alternative to nickel. Zinc’s lower melting point presents a new challenge, but recent breakthroughs indicate this might be feasible with proper stabilization of the battery’s internal structure.
Future Prospects for Large-Scale Salt Battery Deployment
Looking ahead, salt batteries could become a game-changer for stationary energy storage, especially for applications requiring reliability and low maintenance. With further scaling, these batteries may one day power entire residential areas. The low cost of raw materials and ease of recycling make them especially attractive in markets focused on long-term sustainability.
The research is still ongoing, with Empa and HORIEN planning follow-up projects to further refine and scale these batteries. Should these efforts succeed, salt batteries could represent a key shift in how energy is stored and distributed, particularly in regions or industries that prioritize both safety and environmental impact.
