Combined Experimental and Computational Studies of a Na2Ni1−xCuxFe(CN)6 Cathode with Tunable Potential for Aqueous Rechargeable Sodium-Ion Batteries

• Published in: Chemistry : a European journal 2015-10, Vol.21 (44), p.15686-15691
• Main Authors: Hung, Tai-Feng, Chou, Hung-Lung, Yeh, Yu-Wen, Chang, Wen-Sheng, Yang, Chang-Chung
• Format: Article
• Language: English
• Subjects: batteries; charge analysis; Chemistry; co-precipitation; density functional calculations; sodium
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.201501485

Herein, potential‐tunable Na2Ni1−xCuxFe(CN)6 nanoparticles with three‐dimensional frameworks and large interstitial spaces were synthesized as alternative cathode materials for aqueous sodium‐ion batteries by controlling the molar ratio of NiII to CuII at ambient temperature. The influence of the value of x on the crystalline structure, lattice parameters, electrochemical properties, and charge transfer of the resultant compound was explored by using powder X‐ray diffractometry, density functional theory, cyclic voltammetry, galvanostatic charge–discharge techniques, and Bader charge analysis. Of the various formulations investigated, that with x=0.25 delivered the highest reversible capacity, superior rate capability, and outstanding cycling performance. These attributes are ascribed to its unique face‐centered cubic structure for facile sodium‐ion insertion/extraction and the strong interactions between Cu and N atoms, which promote structural stability. Such potential! Potential‐tunable Na2Ni1−xCuxFe(CN)6 nanoparticles with three‐dimensional frameworks and large interstitial spaces were successfully synthesized as an alternative cathode for aqueous rechargeable sodium‐ion batteries by controlling the molar ratio of NiII to CuII. The resulting compound with x=0.25 delivered the highest reversible capacity, superior rate capability, and outstanding cycling stability (see figure).