ETRI cracks key commercialization hurdles for fire-safe aqueous zinc-ion batteries

South Korean researchers have overcome key commercialization barriers for next-generation aqueous zinc-ion batteries, a technology designed to eliminate fire risk at the source.

The breakthrough reduces performance degradation during rapid charging and discharging while significantly extending battery lifespan, and is expected to substantially accelerate the commercialization of next-generation batteries.

Researchers from the Electronics and Telecommunications Research Institute (ETRI) and Sungkyunkwan University announced Thursday that they had each developed core cathode and anode material technologies capable of simultaneously addressing three chronic limitations of aqueous zinc-ion batteries: power output degradation, electrode structural damage and dendrite formation.

Aqueous zinc batteries are secondary batteries that use water as the electrolyte. Unlike lithium-ion batteries, which rely on volatile liquid electrolytes, they carry no fire risk and are environmentally friendly. Because each zinc ion transfers two electrons — compared to one for lithium ions — they also theoretically offer more than twice the capacity per ion.

Repeated rapid charging and discharging, however, had caused sharp performance drops and structural damage to the electrodes.

Dendrite formation posed an additional problem: during charging, zinc deposits on the anode surface in elongated crystalline structures that shorten battery life. These dendrites can pierce the separator between the anode and cathode, triggering electrical short circuits and seriously degrading battery performance.

To address cathode performance degradation, the team moved away from the conventional approach in which only zinc ions (Zn²⁺) participate in the reaction, introducing instead a "dual-ion intercalation structure" in which potassium ions (K⁺) operate alongside zinc ions.

Zinc ions face a high energy barrier when moving through the electrode interior, slowing their migration, whereas potassium ions move comparatively freely.

By designing the electrode so that both ions react together, the researchers reduced ion-clustering bottlenecks and effectively curbed power output loss and voltage drop even under high-rate charging and discharging conditions.

Performance evaluations under high-rate charge-discharge conditions confirmed significant improvements in power retention and long-term stability.

The team also developed a zinc metal anode technology that resolves the longstanding problem of non-uniform zinc metal growth on the anode.

By controlling the direction of zinc growth into a stable configuration, the researchers fundamentally suppressed dendrite formation.

The anode technology operated stably for more than 3,000 hours of continuous charge-discharge cycling and proved effective at suppressing hydrogen gas evolution and byproduct formation.

"Through nanostructured interface design, we simultaneously controlled the initial nucleation and growth direction of zinc metal, realizing a stable, dendrite-free zinc anode," said Shin Dong-ok, an ETRI researcher. "We expect this technology to be effectively applied to next-generation aqueous secondary battery systems that demand both high energy density and long cycle life."