Tuning Transition Metal Oxide–Sulfur Interactions for Long Life Lithium Sulfur Batteries: The "Goldilocks" Principle. Issue 6 (18th December 2015)

• Record Type: Journal Article
• Authors: Liang, Xiao; Kwok, Chun Yuen; Lodi‐Marzano, Fernanda; Pang, Quan; Cuisinier, Marine; Huang, He; Hart, Connor J.; Houtarde, Diane; Kaup, Kavish; Sommer, Heino; Brezesinski, Torsten; Janek, Jürgen; Nazar, Linda F.
• Is Part Of: Advanced energy materials. Volume 6:Issue 6(2016)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2015-12-18
• Subjects: Li‐S batteries -- polythionate -- redox potential -- sulfur hosts -- transition metal oxides; Energy harvesting -- Materials -- Periodicals; Energy conversion -- Materials -- Periodicals; Energy storage -- Materials -- Periodicals; Photovoltaics -- Periodicals; Fuel cells -- Periodicals; Thermoelectric materials -- Periodicals; 621.31
• DOI: 10.1002/aenm.201501636
• Languages: English
• ISSNs: 1614-6832

Abstract

Abstract : The lithium‐sulfur battery is a compelling energy storage system because its high theoretical energy density exceeds Li‐ion batteries at much lower cost, but applications are thwarted by capacity decay caused by the polysulfide shuttle. Here, proof of concept and the critical metrics of a strategy to entrap polysulfides within the sulfur cathode by their reaction to form a surface‐bound active redox mediator are demonstrated. It is shown through a combination of surface spectroscopy and cyclic voltammetry studies that only materials with redox potentials in a targeted window react with polysulfides to form active surface‐bound polythionate species. These species are directly correlated to superior Li‐S cell performance by electrochemical studies of high surface area oxide cathodes with redox potentials below, above, and within this window. Optimized Li‐S cells yield a very low fade rate of 0.048% per cycle. The insight gained into the fundamental surface mechanism and its correlation to the stability of the electrochemical cell provides a bridge between mechanistic understanding and battery performance essential for the design of high performance Li‐S cells. Abstract : The Li‐S battery is a compelling energy storage system but capacity fade from the polysulfide shuttle is problematic. Proof of concept, and the critical metrics to entrap polysulfides via their redox reaction with a positive electrode host to form surface‐bound polythionate mediator species, are demonstrated. Positive electrodes within the "right" redox window are directly correlated to superior Li‐S cell performance.