Study of the electrochemical properties of Fe3O4/C-Bi composites prepared by spray drying and their use in cylindrical sealed nickel iron batteries

In this paper, Fe3O4/C-Bi composites with carbon coating and bismuth added were pre-pared by step-by-step precipitation, spray carbon coating drying and high temperature treatment. The composite materials are spherical particles, which are composed of pri-mary nanoparticles coated with carbon, and the thickness of the carbon coating layer is 2 nm. Electrochemical test results show that the synergistic effect of Bi and C can effec-tively inhibit hydrogen evolution and passivation of iron electrodes. The Fe3O4/C-Bi composite materials have excellent electrochemical properties, among which the Fe3O4/C-Bi(5%) electrode has the best performance. At a current density of 300 mA g-1, the discharge capacitance is close to 700.0 mAh g-1, the coulombic efficiency is as high as 95.2%, and the rate performance is also excellent. At a current density of 2400 mA g-1, the discharge capacity reaches 500.0 mAh g-1. AA600 cylindrical iron nickel batteries prepared with an Fe3O4/C-Bi(5%) composite as the active material for iron negative electrodes realized sealing for the first time.(c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.