Electrochemical and structural characterization of silver hafnium sulfide cathodes

Cubic Ag4Hf3S8 treated with n-butyl lithium was found to function as the cathode in a lithium cell. The structure model of cubic lithiated Ag4Hf3S8 was reconstructed on the basis of Rietveld analysis of XRD data. Its space group was assumed to be identical with that of the source, P4332. It was clarified that XRD profiles of lithiated phase can be well explained by the presence of a rigid framework structure of Hf3S8 not broken by lithium. Comparative studies on electrochemical lithium insertion into Ag4Hf3S8 were carried out in non-aqueous organic solvents. The electrochemical behavior and structural change of Ag4Hf3S8 cathode were investigated. Effect of electrolytes on discharge behavior was examined for solutions, such as (1) 1 M LiI, (2) 1 M LiClO4 and (3) 1 M LiPF6 in propylene carbonate (PC). The initial cell voltage was found to differ with the electrolyte used: 2.4 V for case (1), 2.4 V for case (2) and 3.0 V for case (3).