Porous Amorphous Silicon Hollow Nanoboxes Coated with Reduced Graphene Oxide as Stable Anodes for Sodium-Ion Batteries

Abstract

Amorphous silicon (a-Si), due to its satisfactory theoretical capacity, moderate discharge potential, and abundant reserves, is treated as one of the most prospective materials for the anode of sodium-ion batteries (SIBs). However, the slow Na + diffusion kinetics, poor electrical conductivity, and rupture-prone structures of a-Si restrict its further development. In this work, a composite (a-Si@rGO) consisting of porous amorphous silicon hollow nanoboxes (a-Si HNBs) and reduced graphene oxide (rGO) is prepared. The a-Si HNBs are synthesized through “sodiothermic reduction” of silica hollow nanoboxes at a relatively low temperature, and the rGO is covered on the surface of the a-Si HNBs by electrostatic interaction. The as-synthesized composite anode applying in SIBs exhibits a high initial discharge capacity of 681.6 mAh g –1 at 100 mA g –1 , great stability over 2000 cycles at 800 mA g –1 , and superior rate performance (261.2, 176.8, 130.3, 98.4, and 73.3 mAh g –1 at 100, 400, 800, 1500, and 3000 mA g –1 , respectively). The excellent electrochemical properties are ascribed to synergistic action of the porous hollow nanostructure of a-Si and the rGO coating. This research not only offers an innovative synthetic means for the development of a-Si in various fields but also provides a practicable idea for the design of other alloy-type anodes.

Recent advancements in 3D porous graphene-based electrode materials for electrochemical energy storage applications

“…The composite was prepared by sodiothermic reduction of hollow silica nanoboxes (SiO 2 HNB) and then coated with rGO by electrostatic interaction. The optimal a-Si/rGO composite exhibits an initial capacitive discharge of 681.6 mAh g -1 at an applied current density of 100 mA g -1 and capacitive stability (142.1 mAh g -1 ) for more than 2000 cycles at 800 mA g -1 , with a reported specific surface area of around 199 m 2 g -1 (refer Table 2) [78]. Graphene inhibition improved surface and electrical properties, and porous a-Si enhanced the sodium diffusion mechanism at the electrode/electrolyte interface for better battery performance.…”

Sputtered Silicon-Coated Graphite Electrodes as High Cycling Stability and Improved Kinetics Anodes for Lithium Ion Batteries

“…It can be seen that the curves are comparable in shape, with intense peaks and low polarization of voltage, demonstrating the highly reversible Si@G-1 μm electrode. The charge storage has been represented by the existing relationship between the scan rate ( v ) and current ( i ) based on the power law formula: i = a v b = k 1 v + k 2 v 1 / 2 …”