A Lithium-Sulfur Battery Using Binder-Free Graphene-Coated Aluminum Current Collector

Lithium-sulfur battery of practical interest requires thin-layer support to achieve acceptable volumetric energy density. However, the typical aluminum current collector of Li-ion battery cannot be efficiently used in the Li/S system due to the insulating nature of sulfur and a reaction mechanism involving electrodeposition of dissolved polysulfides. We study the electrochemical behavior of a Li/S battery using a carbon-coated Al current collector in which the low thickness, the high electronic conductivity, and, at the same time, the host ability for the reaction products are allowed by a binder-free few-layer graphene (FLG) substrate. The FLG enables a sulfur electrode having a thickness below 100 μm, fast kinetics, low impedance, and an initial capacity of 1000 mAh g_S ^-1 with over 70% retention after 300 cycles. The Li/S cell using FLG shows volumetric and gravimetric energy densities of 300 Wh L^-1 and 500 Wh kg^-1, respectively, which are values well competing with commercially available Li-ion batteries.