Interference of the Reference Electrodes' Leakage on the Aging of Copper Hexacyanoferrate for Aqueous Zn-Ion Batteries

Global warming necessitates sustainable energy storage systems like aqueous Zn-ion batteries. Copper hexacyanoferrate (CuHCF) is a cost-effective, easily synthesized cathode material. Generally, a three-electrode setup containing a reference electrode (e.g., Ag/AgCl or SCE) is used to study the active material. Herein, it is shown that the presence of the reference electrode can interfere with the aging and cycle life of the active material through ions leaked from the reference's solution. Potassium leakage reduces CuHCF lifespan at high levels but slightly improves it at low levels, while sodium leakage shows weaker effects overall. Sodium-based reference solutions yield more reliable results, whereas potassium contamination risks misleading measurements.