Preparation of a Reduced Graphene Oxide Wrapped Lithium-Rich Cathode Material by Self-Assembly

A lithium-rich cathode material wrapped in sheets of reduced graphene oxide (RGO) and functionalized with polydiallyldimethylammonium chloride (PDDA) was prepared by self-assembly induced from the electrostatic interaction between PDDA-RGO and the Li-rich cathode material. At current densities of 1000 and 2000mAg(-1), the PDDA-RGO sheet wrapped samples demonstrated increased discharge capacities, increasing from 125 to 155mAhg(-1) and from 82 to 124mAhg(-1), respectively. The decreased resistance implied by this result was confirmed from electrochemical impedance spectroscopy results, wherein the charge-transfer resistance of the pristine sample decreased after wrapping with the PDDA-RGO sheets. The PDDA-RGO sheets served as a protective layer sand as a conductive material, which resulted in an improvement in the retention capacity from 56 to 81% after 90cycles.