Study of electrochemical hydrogen charge/discharge properties of FePO_4 for application as negative electrodes in hydrogen batteries

摘要

We report the electrochemical hydrogen charge/discharge properties of electrodes containing crystalline and amorphous FePO_4 as active material in KOH electrolyte. Crystalline and amorphous FePO_4 were synthesized by an alcohol-assisted precipitation method, and the powders obtained were characterized by X-ray diffraction. X-ray photoelectron spectroscopy is used to investigate the mechanism of hydrogen charge/discharge behavior of FePO_4. The electrochemical hydrogen charge/discharge properties of electrodes containing crystalline and amorphous FePO_4 were investigated for potential application as negative electrodes in rechargeable hydrogen batteries. In galvanostatic discharge/charge mode at 25℃, the crystalline FePO_4 showed a maximum discharge capacity of 109 mAhg~(-1), while the amorphous FePO_4 showed a maximum discharge capacity of 81.4 mA kg~(-1). The electrochemical kinetic properties, exchange current density, and proton diffusivity were calculated using linear polarization measurement and the potential-step method.