Isotope Effects in a Li−S Battery: A New Concept.

Lithium‐sulfur battery represents an innovative technology for the next generation electrochemical energy storage, and insight into the fundamentals about its electrochemistry is a key to improved battery storage performance. With years of striving efforts, the interpretation of Li−S reaction mechanism has been extended down to a molecular level. Based on our recent work, we propose to re‐examine the Li−S electrochemistry at a (sub)atomic level. Both Li anode and S cathode are made up of mixtures of stable isotopes. Provided with almost the same nucleus structure yet different neutron numbers (and atomic mass), these isotopes could affect the thermodynamic and kinetic parameters of a chemical reaction, and energy storage capability of a Li−S battery. At the cathode, 34S forms stronger S−S bonds and shows higher tendency to react with Li than 32S, so that it helps to improve cathode reaction kinetics. High‐order polysulfide anions based on 34S show more sluggish migration in the ether electrolyte than the 32S‐based counterparts, which accounts for improved cycling stability of battery. Based on the electrochemical isotope effects of S, a conceptual technology for separating isotopes from natural chalcogen elements was introduced and shows a higher separation factor than the conventional methods. [ABSTRACT FROM AUTHOR]