Reduced Graphene Oxide/LiI Composite Lithium Ion Battery Cathodes.

Li-iodine chemistry is of interest for electrochemical energy storage because it has been shown to provide both high power and high energy density. However, Li-iodine batteries are typically formed using Li metal and elemental iodine, which presents safety and fabrication challenges (e.g., the high vapor pressure of iodine). These disadvantages could be circumvented by using LiI as a starting cathode. Here, we present fabrication of a reduced graphene oxide (rGO)/LiI composite cathode, enabling for the first time the use of LiI as the Li-ion battery cathode. LiI was coated on rGO by infiltration of an ethanolic solution of LiI into a compressed rGO aerogel followed by drying. The free-standing rGO/LiI electrodes show stable long-term cycling and good rate performance with high specific capacity (200 mAh g-1 at 0.5 C after 100 cycles) and small hysteresis (0.056 V at 1 C). Shuttling was suppressed significantly. We speculate the improved electrochemical performance is due to strong interactions between the active materials and rGO, and the reduced ion and electron transport distances provided by the three-dimensional structured cathode.