Nano-crosslinked mesoporous graphene for superior Na-ion storage.

Abstract

In this study, we present a straightforward method for fabricating nano-crosslinked mesoporous graphene with exceptional sodium-ion storage capabilities. The process involves the mechanochemical preparation of acidic graphene oxide (AGO) powder, followed by the thermochemical exfoliation of AGO to produce thermochemically exfoliated graphene (TEG) characterized by the layer spacing of 0.362 nm, an increased specific surface area, and a distinctive nano-crosslinked porous structure. Specifically, TEG prepared at 400 °C (TEG-400) exhibits remarkable Na-ion storage performance, showcasing an initial capacity and Coulombic efficiency of 402 mAh·g−1 (100 mA·g−1) and 86 %, respectively. Notably, TEG-400 demonstrates outstanding cyclic stability with a reversible capacity of 281 mAh·g−1 after 300 cycles at 200 mA·g−1, and 219 mAh·g−1 after 1000 cycles at 2000 mA·g−1. The superior electrochemical performance of the TEG-400 electrode can be attributed to its large specific surface area (517 m2·g−1), high pore volume (2.29 cm3·g−1), and introduced defects, providing ample active sites for the rapid storage of sodium ions through surface adsorption into the defect sites. This research offers insights for advancing the development and design of next-generation high-performance sodium-ion battery electrode materials.