Abstract:

Lithium (Li)/sodium (Na)-sulfur (S) batteries are considered to be competitive candidates for the next-generation energy storage devices due to ultrahigh theoretical energy densities and potential low costs. However, the insulating nature of S and dissolution of intermediate polysulfides hinder the development. Here, the use of selenium (Se) or tellurium (Te) as eutectic accelerators in S cathodes can significantly improve the performances. Se and Te can not only be easily introduced into S to form uniform dispersions at the molecular level through S-Se or S-Te bonds and contribute to capacity through their inherent redox reactions, but also significantly accelerate reaction kinetics and alleviate polysulfide dissolution to achieve excellent battery performances. Even for solid-state conversion mechanisms or in all-solid-state batteries, Se or Te can enhance the electronic and ionic conductivities to result in better rate and cycling performances. Overall, Se or Te modified S cathodes possess good compatibility with both Li and Na anode materials and can exhibit excellent electrochemical performances. Therefore, the use of Se or Te as eutectic accelerators in S cathodes is a universal and effective strategy to enhance battery performances and obtain better Li/Na-S batteries.

Full-text：https://link.springer.com/article/10.1007/s41918-020-00072-5

Key words: Selenium, Tellurium, Eutectic accelerator, Sulfur battery, Kinetics