Abstract
AbstractNiO2 slabs made of edge-sharing NiO6 octahedra are the main structural parts of the positive electrode materials involved in Ni-Cd, Ni-M- and Li-LiNiO2 secondary batteries. These electrochemical systems are among the best ones for applications. The behavior of all these electrode materials can be optimized by substituting several cations for nickel.The effect of iron and cobalt substitution has been investigated in detail. The oxidation state modifications resulting from the electrochemical cycling have been characterized from magnetic, conductivity, thermoelectric-power and Mössbauer studies. The overall results show that nickel ions are oxidized to the tetravalent state before cobalt ions. More surprisingly, the oxidation of iron-nickel mixed phases shows the simultaneous presence of tetravalent iron and nickel ions in the low spin configuration. For the first time, in situ M6ssbauer measurements have been performed during the cycling of a nickel-cadmium cell.This cationic distribution results from the competition between the intrinsic redox properties of the 3d cations and the accommodation of the oxidation levels to the ligand field imposed by the prevailing cation.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
