Directional Regulation of Surface Chemistry of Graphene Using Carbon Dots for Sodium-Ion Battery Anodes

Abstract

In this study, we have fabricated carbon dot/reduced graphene oxide (CDs/rGO) composites using oxygen-functionalized CDs and conductive graphene oxide (GO) by a hydrothermal method and calcination at 250 °C. The CDs can manipulate the surface functional groups of the composites by consuming C–O bonds and introducing CO bonds. As sodium-ion battery anodes, CDs/rGO with a high CO group content exhibits a great reversible capacity of 308 mAh g–1 at 0.05 A g–1, which is up to 1.8 times that of rGO (173 mAh g–1). It retains a capacity of 116 mAh g–1 after 2000 cycles at 2 A g–1. When assembled into a full cell, the activated anode and NVP@C display a higher initial discharge capacity of 291 mAh ganode –1 with an average working voltage of 2.5 V. The good performance of CDs/rGO is mainly due to the synergistic effects of the CDs with abundant Na storage sites and rGO with a conductive network. The improved electrochemical properties are dominated by the capacitive Na storage mechanism. This work implies that the oxygen-functionalized CDs could serve as medium to regulate the surface chemistry of carbon materials.

Edge Graphitized Oxygen‐Rich Carbon Based on Stainless Steel‐Assisted High‐energy Ball Milling for High‐Capacity and Ultrafast Sodium Storage

“…Notably, the C=O group is unsaturated, which can store Na + through addition reaction, and contribute additional capacity to the carbon electrode. [16] As discussed in the TEM results, the stainless steel-assisted ball milling induces surface graphitization but simultaneously damages the internal structure and creates a large number of structural defects. Considering the very thin graphitic layer, it is obvious that the overall graphitization degree would become lower after ball milling.…”

“…Notably, the CO group is unsaturated, which can store Na + through addition reaction, and contribute additional capacity to the carbon electrode. [ 16 ]…”

“…These unsaturated double bonds are highly active and can react reversibly with Na through an addition reaction, thus supplying sufficient energy storage sites. [15,16] Besides, the Na storage on oxygen sites is a surface-controlled pseudo-capacitive process with fast kinetics, which is facilitated to achieve high-rate capability. In recent years, a few publications on oxygen-doped carbons have been reported.…”

Structural Design of 3D Current Collectors for Lithium Metal Anodes: A Review

“…High intrinsic carrier mobility, chemical and mechanical properties, make 2D graphene with sp 2 carbon atom layers and its derivatives promising in advanced industrial applications [46c,52] . Therefore, graphene‐based materials (such as graphene oxide, GO) with different structures and compositions have been designed and synthesized for use in Li metal anode collectors [53]…”