Kinetics process of Tb(Ⅲ)/Tb couple at liquid Zn electrode and thermodynamic properties of Tb-Zn alloys formation

Electrochemical properties of rare-earth elements in the LiCl-KCl eutectic are important for the pyrometallurgical recycling process of spent nuclear fuels. In this work, the electrochemical properties of Tb(Ⅲ)/Tb(0) couple were studied by the cyclic voltammetry(CV) at a liquid Zn pool electrode. The results showed that this electrochemical reaction is quasi-reversible with mixed reversible diffusion control and the charge transfer control. The diffusion coefficient of Tb(Ⅲ) was determined to be in the order of ~10.5 cm2 s.1. Moreover, kinetic parameters, such as the standard rate constants(ks) and charge transfer coefficient(α) for the electroreduction of Tb(Ⅲ) to Tb(0) at the liquid Zn electrode, were calculated by the Nicholson method at 873 K. Additionally, it was found that Tb-Zn intermetallic compounds were easily to be formed in the measurements. Hence, the reduction process of Tb(Ⅲ)/Tb(0) couple on the Zn-coated Mo electrode was also studied to obtain more information of the Tb-Zn intermetallic compounds. Electrochemical signals stemming from various intermetallic compounds associated with TbZn12, Tb2Zn17, Tb13Zn58, Tb3Zn11, TbZn3, TbZn2 and TbZn, were observed. The thermodynamic data were thereafter estimated by applying the emf method at 823–923 K. The standard formation Gibbs energies and the standard equilibrium constant of each Tb-Zn intermetallic compounds were also calculated. Finally, enthalpies and entropies of formation and the apparent standard potentials of various Tb-Zn intermetallic compounds were also obtained.

A promising energy storage system:rechargeable Ni-Zn battery

The sharp depletion of fossil fuel resources and its associated increasingly deteriorated environmental pollution are vital challenging energy issues, which are one of the most crucial research hot spots in the twenty-first century.Rechargeable Ni–Zn batteries（RNZBs）, delivering high power density in aqueous electrolytes with stable cycle performance, are expected to be promising candidates to alleviate the current energy and environmental problems,and play an important role in green power sources. Many efforts have been focused on the investigations and improvements of RNZBs in recent decades, and it is necessary to summarize and review the achievements and challenges in this advancing field. In this paper, we review various batteries, compare and highlight the advantages of RNZBs, and introduce the recent advances in the development of electrode materials and electrolytes of RNZBs,especially the applications of novel nanostructured materials for the active electrodes. Some prospective investigation trends of RNZBs are also proposed and discussed.