Chinese scientists create a high-voltage sodium-sulfur battery that may rival lithium batteries.

This innovative design, currently undergoing laboratory testing, incorporates affordable materials: sulfur, sodium, aluminum, and a chlorine-based electrolyte. Early trials have shown that the battery achieves energy densities exceeding 2,000 watt-hours per kilogram, a figure that significantly outperforms existing sodium-ion batteries and competes closely with high-performance lithium batteries.

Sulfur has often been viewed as the “white whale” of battery technology due to its theoretical ability to store a large amount of energy. However, traditional lithium-sulfur batteries face the issue of sulfur generating unwanted chemical byproducts, which can lead to performance degradation and reduce the overall lifespan of the battery. This groundbreaking approach changes the dynamic by allowing sulfur to donate electrons instead of merely accepting them.

The mechanism involves the use of a pure sulfur cathode paired with a simple aluminum foil anode. The electrolyte, a mixture of aluminum chloride, sodium salts, and chlorine, facilitates the process. During the battery’s discharge cycle, sulfur atoms at the cathode release electrons and interact with chlorine to form sulfur chlorides. Sodium ions then capture these electrons, depositing themselves onto the aluminum foil.

This chemical process mitigates the typical degradation issues seen in sulfur batteries. A porous carbon layer helps retain the reactive materials, while a glass fiber separator prevents short-circuits-all of which contribute to a stable and reversible reaction.

The durability of the battery is impressive, with test cells enduring 1,400 charge-discharge cycles before showing significant capacity loss. Additionally, after being inactive for more than a year, the battery retained 95 percent of its original charge. This durability is a significant advantage for long-term energy storage applications, where batteries may not be used regularly.

What stands out even further is the estimated cost of production. The researchers project that this new battery could be produced for around $5 per kilowatt-hour based on the prices of raw materials. This cost is significantly less than many current sodium batteries and much more economical than lithium-ion batteries. If mass production of this technology is feasible, it could dramatically reduce the costs associated with storing renewable energy on the power grid.

However, there are challenges to consider. The corrosive nature of the chlorine-rich electrolyte presents safety concerns, and the performance figures reported stem from laboratory experiments involving the active material’s weight rather than fully packaged commercial cells. Transitioning from a laboratory setting to manufacturing will involve considerable engineering efforts.

This research serves as a powerful reminder of the possibilities that can arise from exploring unconventional chemistry when conventional materials like lithium become prohibitively expensive or scarce.