Expandable-graphite-derived graphene for next-generation battery chemistries

Abstract

Lithium–sulfur and lithium–air batteries offer theoretical energy densities an order of magnitude higher than that of current lithium-ion batteries and are considered as promising candidates as the next-generation battery chemistries. For an efficient use of these new battery chemistries, careful selection of suitable electrode materials/structures is critical. Graphene, a unique two-dimensional nanomaterial, with its superior electronic conductivity, mechanical strength, and flexibility has been successfully applied in battery studies. Graphene, even with imperfect layers, will be of great interest to battery industrial applications if the manufacturing cost is reduced. Herein, we demonstrate the application of low-cost graphene sponge/sheets derived from expandable graphite in both lithium–sulfur and hybrid lithium–air batteries, respectively, as a cathode conductive matrix to accommodate the soluble polysulfides and as a catalyst for the oxygen reduction reaction. High utilization of active materials and good cycling stability are realized in lithium–sulfur and hybrid lithium–air batteries by employing this low-cost material, demonstrating its promise for use in next-generation battery chemistries.