Fabrication of Graphene‐Encapsulated Oxide Nanoparticles: Towards High‐Performance Anode Materials for Lithium Storage

Abstract

Electrochemically active metals and metal oxides such as Sn, [1] Si, [2] SnO 2 , [3] and Co 3 O 4 [4] have long been considered as anode materials for lithium ion batteries because of their high theoretical capacities. However, a large specific volume change commonly occurs in the host matrix of these metals and metal oxides during the cycling processes, thus leading to pulverization of the electrodes and rapid capacity decay. [1][2][3] To circumvent these obstacles, carbonaceous materials with high electrical conductivity and fair ductility have been widely chosen as matrices for metals and metal oxides to improve their cycle performance. In particular, graphene, which is a monolayer of carbon atoms arranged in a honeycomb network, is becoming one of the most appealing matrices because of its unique properties such as superior electrical conductivity, [5] excellent mechanical flexibility, [6] large surface area (2630 m 2 g À1 ), [7] and high thermal and chemical stability. [8] In this regard, Si/graphene, [9] SnO 2 /graphene, [10] TiO 2 /graphene, [11] and Co 3 O 4 /graphene [12] hybrids or composites, in which metals or metal oxides are distributed onto the surface of graphene or between the graphene layers, have been fabricated by restacking graphene sheets in the presence of guest nanoparticles or corresponding organometallic precursors. Compared to other carbon matrices such as graphite, [13] carbon black, [14] and carbon nanotubes, [15] graphene sheets can more effectively buffer the strain from the volume change of metals or metal oxides during the charging-discharging processes and preserve the high electrical conductivity of the overall electrode. Nevertheless, the metal and metal oxide nanoparticles are still prone to strong aggregation during the cycle processes because of nonintimate contact between graphene layers and active nanoparticles. [7][8][9][10] This leads to a decrease in capacity of most metal or metal oxide/graphene composites by 20-50 % of their first reversible capacity after 30 cycles. [9][10] One of the most promising strategies to tackle the aggregation problem of metal and metal oxides in lithium ion batteries is to confine them within individual carbon shells. [16][17][18][19] A key challenge in this strategy is the achievement of both high electrical conductivity and a low-weight fraction of thin carbon layers on the surface of metal or metal oxide nanoparticles.Herein we describe a novel strategy for the fabrication of graphene-encapsulated metal oxide (GE-MO) by coassembly between negatively charged graphene oxide and positively charged oxide nanoparticles. The process is driven by the mutual electrostatic interactions of the two species, and is followed by chemical reduction. The resulting GE-MO possesses flexible and ultrathin graphene shells that effectively enwrap the oxide nanoparticles. This unique hybrid architecture can 1) suppress the aggregation of oxide nanoparticles, 2) accommodate the volume change during the cycle processes, 3) give rise to a high oxide content i...

Preparation and properties of poly(vinylidene fluoride) nanocomposites blended with graphene oxide coated silica hybrids

“…GO is an active material, it can act as surfactant [8], covalently combined with other materials [9], etc. In recent years, graphene hybrid nano particles appeared [10][11][12], the active GO sheets can be used to modify conventional nanoparticles which were used in polymer nanocomposites. PVDF is a polar polymer with excellent chemical, mechanical and electrical properties [13][14][15].…”

Graphene and derivatives – Synthesis techniques, properties and their energy applications

“…Another major issue with LIBs at present are the chemical stability of the active material and decrease in cyclic performance. Recent research has suggested the incorporation of conductive materials such as CNT's and carbon particles to increase specific capacity [138][139][140][141]. Yoo et al [136] have reported the use of GNS in rechargeable LIB and it was also reported the increase in specific capacity of the electrode through the interaction of GNS with C60 and CNT.…”

“…Graphene-encapsulated -CO3O4 was used as an anode material to improve the performance of LIB. It was reported that the energy density of 1100 mAh/g and current density of 74 mA/g [138]. Wu et al [139] have reported that the synthesis of graphene-anchored CO3O4 as the anode material in LIBs to improve the capacity and cyclic performance and the values were noted as 935 mAh/g of energy density and 50 mA/g of current density at 30 cycles.…”

Biological Applications of Graphene and Graphene Oxide

“…For instance, the novel 2D nanostructure has been intensively implemented to explore potential applications on super-capacitor, batteries, field-effect transistors (FETs), optical sensors and so on [12,13].…”