Influence of the Specific Surface Area of Graphene Nanoplatelets on the Capacity of Lithium-Ion Batteries

In order to understand the influence of the morphological properties of graphene materials on the electrochemical performance of electrodes for lithium-ion batteries, three different graphene nanoplatelets with the increasing specific surface area (NP1: 296 m² g^-1, NP2: 470 m² g^-1, and NP3: 714 m² g^-1) were added in the electrode formulation in different ratios. Higher specific surface area graphene nanoplatelets (NP3) exhibit reversible capacity up to 505 mA h g^-1 in the first discharge cycle (29.5% higher than that of graphite). Although significant irreversible capacity is shown for NP3, still higher reversible capacity is obtained compared to that of graphite electrode. The presence of micropores in the graphene structure benefits the lithiation. C-rate capability tests also show better performance of the graphene-based electrode. In this work, we demonstrate that graphene nanoplatelets with high specific surface area (714 m² g^-1) improve the electrochemical performance of Li-ion battery electrodes. The relationship between specific surface area, the presence of defects, and porosity is discussed.