Study Identifies Surface Oxidation, Not Moisture, as Primary Cause of Prussian Blue Battery Failure

A research team at Pohang University of Science and Technology (POSTECH) in South Korea has discovered that surface oxidation of Prussian blue during dehydration processing—not residual moisture, as previously believed—is the primary cause of its performance degradation when used as a cathode material in sodium-ion batteries. Led by Professor Changshin Jo from the Departments of Battery Engineering and Chemical Engineering, with doctoral student Seunghye Jang, the team published their findings in the journal *Advanced Materials*. Based on this discovery, the researchers developed an improved dehydration process to suppress surface oxidation and extend battery lifespan. Prussian blue is considered a promising cathode material for sodium-ion batteries due to its low cost, high energy storage capacity, and iron-based composition. Sodium-ion batteries, in turn, have attracted significant attention for electric vehicles and energy storage systems owing to the abundance and low cost of sodium resources.