Sodium Insertion into Fe[Fe(CN) ₆ ] Framework Prepared by Microwave‐Assisted Co‐Precipitation

Prussian blue analogues (PBAs) are interesting materials for Na electrochemical insertion, owing to their ease of synthesis, rigid open framework and large interstitial space. In this work, iron hexacyanoferrate nanoparticles, FeIII[FeIII(CN)6], also known as Berlin green (BG), where both Fe centers in the Fe(III) configuration, have been synthesized by an easy microwave assisted co-precipitation method, with average particle size around 44 nm. The BG nanoparticles exhibited a 120 mAh g−1 specific capacity retention 84.8 % over 100 cycles at 20 mA current up 80 10 C rate. initial charge discharge processes were fully investigated ex-situ X-ray absorption spectroscopy (XAS). XAS results reveal that there is some irreversibility Fe−C Fe−N bond lengths change during first charge/discharge cycle. This effect was attributed electrode activation processes, partly explained observed fading.