Titanium Activation in Prussian Blue Based Electrodes for Na-ion Batteries: A Synthesis and Electrochemical Study

Min Li,Marco Giorgetti,Stefano Passerini,Angelo Mullaliu

doi:10.3390/batteries7010005

Abstract

Sodium titanium hexacyanoferrate (TiHCF, Na0.86Ti0.73[Fe(CN)6]·3H2O) is synthesized by a simple co-precipitation method in this study. Its crystal structure, chemical composition, and geometric/electronic structural information are investigated by X-ray powder diffraction (XRPD), microwave plasma-atomic emission spectroscopy (MP-AES), and X-ray absorption spectroscopy (XAS). The electroactivity of TiHCF as a host for Li-ion and Na-ion batteries is studied in organic electrolytes. The results demonstrate that TiHCF is a good positive electrode material for both Li-ion and Na-ion batteries. Surprisingly, however, the material shows better electrochemical performance as a Na-ion host, offering a capacity of 74 mAh g−1 at C/20 and a 94.5% retention after 50 cycles. This is due to the activation of Ti towards the redox reaction, making TiHCF a good candidate electrode material for Na-ion batteries.

Highlights

Activation in Prussian Blue BasedAfter the first report of Vernon D
Neff [1] in 1978 reporting the electrochemical activity of Prussian blue (PB; with the generic formula Ax Fe[Fe(CN)6 ], where A stands for an alkali metal), PB and Prussian blue analogs (PBAs; Ax M[M0 (CN)6 ], M and M0 = transition metals) have been widely studied in electrochromism [2,3], electrocatalysis [4,5], potentiometric and amperometric sensors [6,7], and more recently, as electrode materials in electrochemical energy storage systems [8,9,10,11,12,13,14,15]
titanium hexacyanoferrate (TiHCF) was synthesized by a simple co-precipitation method and tested in both Na and Li cells employing organic carbonate-based electrolytes

Summary

Introduction

Activation in Prussian Blue BasedAfter the first report of Vernon D. M0 sites are sixfold coordinated, with the former to the nitrogen atoms of the CN ligands, and the latter octahedrally coordinated to the carbon atoms of the cyanides Overall, this peculiar structure with 3D framework, contains large ionic channels and interstices, as well as abundant redox-active sites, and is characterized by strong structural stability [16,17]. This peculiar structure with 3D framework, contains large ionic channels and interstices, as well as abundant redox-active sites, and is characterized by strong structural stability [16,17] Benefiting from these structural features, PBAs have been intensively investigated as a new alternative and low-cost host material that can accommodate monovalent alkali cations such as Li+ , Na+ , and K+ ions [8,9,10], and divalent and trivalent cations including Mg2+ , Zn2+ , Ca2+ , and Al3+ [11,12,13,14,15]

Methods

Results

Conclusion