Synthesis, characterization and electrochemical study of titanium hexacyanoferrate electrode material

Titanium Hexacyanoferrate (TiHCF) was synthesized by simple co-precipitation method, and the crystal structure, water content, chemical formula and a deep structural investigation (local geometry of Ti) of as-prepared sample were done by PXRD, FT-IR, TGA, MP-AES and XAS. Electrochemical tests were performed both in glass and coin cells. From cyclic voltammetry curves, we observed redox peaks of both Fe3+/2+ and Ti4+/3+ pairs. The calculation result based on scan rate and current shows that the capacity of battery is controlled by diffusion process in aqueous electrolyte system. The as-prepared sample also shows high performance in organic electrolyte system. Compared to Li-ion batteries, the material shows high capacity for Na-ion batteries with 74 mAh/g at C/20 rate, while Li-ion batteries only have 35 mAh/g. The specific energy value we got for Na-ion coin cell is 250 Wh/kg (based on the mass of active material) and 122 Wh/kg for Li-ion coin cell. Both Li- and Na- half cells display high coulombic efficiency during cyclability test, above 95%.