Building safer batteries
Associate Professor Palani Balaya develops sodium- and lithium-ion battery technologies, raising their performance and safety for an increasingly electrified world.
As electrification spreads from motorcycles, cars and trailers to neighbourhood microgrids, the energy density of the batteries is becoming increasingly higher, and as a result, they are getting increasingly heavier and riskier. While battery capacity is a crucial differentiator, safety, cost and supply resilience are also unmistakable ingredients in formulating efficient, highperformance batteries.
Lithium-ion batteries remain the dominating workhorse, but its flammable liquids and tight supply chains leave gaps for other chemistries to fill. At the Department of Mechanical Engineering at the College of Design and Engineering, National University of Singapore, Associate Professor Palani Balaya and his team explore those options,
Issue 07 | Dec 2025
pushing ceramic- and polymer-based alternatives that let sodium, an earth-abundant element, carry the charge.
Turning grain boundaries into express lanes
To make sodium-based batteries a viable alternative, one major hurdle must be addressed: ensuring ions can move quickly through solid materials. In solid-state batteries, which replace flammable liquids with non-combustible solids, the junctions between microscopic crystals, called grain boundaries, often slow ion movement, favouring the growth of tiny metallic tendrils known as dendrites, which shorten battery life.
Assoc Prof Balaya’s team found a way to turn those vulnerable junctions into ionconducting pathways. Detailed in their paper published in the Journal of Materials Chemistry A, they introduced small amounts of two elements into a ceramic material commonly used as solid electrolytes, which altered both its crystal structure and the chemistry along the grain boundaries. This dual adjustment created smoother channels for sodium ions to flow and prevented the formation of dendrites that can cause micro short-circuits. If not mitigated, such short circuits can trigger a dangerous chain reaction known as thermal runaway.
“We created a safer, more stable ceramic electrolyte that could sustain efficient ion transport over many cycles.”
“We created a safer, more stable ceramic electrolyte that could sustain efficient ion transport over many cycles,” says Assoc Prof Balaya. “When used in a prototype solid-state sodium battery, the material enabled decent storage capacity and stability, showing that solid ceramics can rival conventional liquid-based systems in performance, without the fire risk.”
To improve flexibility and interface contact between the solid layers, the researchers also blended the ceramic particles into a polymer to create a hybrid ceramicpolymer electrolyte. This combination retained high storage performance at 60°C while adding the pliability needed for practical manufacturing. Taken together, the researchers’ work enables durable, non-flammable sodium batteries suited for large-scale storage systems where safety and cost matter as much as capacity.