Sodium has always been an appealing candidate for next-generation batteries. It is cheaper, more sustainable to source, and far more abundant than lithium. The problem has never been availability. The problem has been performance.
Sodium batteries typically fall behind lithium systems in two areas: ionic conductivity and compatibility with high-loading cathode designs. In solid-state configurations, the challenge becomes even tougher. Solid electrolytes for sodium have struggled to move ions efficiently, and earlier designs required thin cathodes that limited energy density and made the technology impractical for real-world use.
A research group has now demonstrated a way to stabilize a high-conductivity form of sodium hydridoborate for use as a solid electrolyte. They used a thermal process that heats the material into a metastable phase and then rapidly cools it to lock in a crystal structure with significantly higher ionic mobility. The result is a material with ionic conductivity orders of magnitude higher than its precursor, pushing it into a performance range relevant for solid-state battery designs.
Just as important is the fabrication method. The process relies on a heating and quenching technique that is already widely used in materials manufacturing. That increases the likelihood that the material can be scaled without reinventing production infrastructure.
To test its practical value, the researchers paired the electrolyte with an O3-type cathode coated in a chloride-based solid electrolyte. They were able to build a thicker, higher-areal-loading cathode rather than relying on ultrathin experimental films. That matters because thicker cathodes reduce the ratio of inactive to active material, improving the energy density of the full cell rather than just the theoretical performance of its components.
This does not mean sodium batteries are ready to replace lithium across every application. Cycle life, interface stability, and overall energy density still need work, especially for mobile systems like electric vehicles where size and weight are critical. But in markets such as grid-scale energy storage, where cost and sustainability are significant drivers, sodium is becoming more viable.
The key shift is that sodium-based solid-state batteries are no longer held back by fundamental electrolyte limitations. With a scalable path to high ionic conductivity and compatibility with higher-capacity cathodes, sodium is beginning to transition from an alternative concept into a serious contender.
The race between sodium and lithium is not over, but it is no longer a one-sided contest.
Original Story: Breakthrough advances sodium-based battery design | Pritzker School of Molecular Engineering | The University of Chicago
