Construction of MoO₂ Quantum Dot–Graphene and MoS₂ Nanoparticle–Graphene Nanoarchitectures toward Ultrahigh Lithium Storage Capability

Abstract

Herein, MoO quantum dots (QDs; <5 nm) are synthesized through a one-step solvothermal process. MoO QD-bonded graphene sheets (MoO-QDs@RGO) are facilely produced and can be further converted through sulfidation into MoS nanoparticle-bonded graphene sheets (MoS-NPs@RGO). The novel MoO-QDs@RGO electrodes demonstrate exceptionally attractive lithium storage capability (e.g., 1257 mA h g at 100 mA g, being close to the highest values ever reported for a MoO-based lithium ion battery electrode), rate capability, and cycle stability. Moreover, the MoS-NPs@RGO delivered a superior capacity (1497 mA h g at 100 mA g) with outstanding rate retention and cycling stability. The superior lithium storage capabilities are ascribed to the synergetic effects of the high-surface-area graphene sheets, the well-dispersed MoS nanoparticles, and their strong bonding with each other, which effectively prevents aggregation of MoS while the composite architecture allows fast transport of electrons and ions.

Review of the Synthetic Techniques and Applications of the Quantum Dots/Graphene Composites

“…Yu et al 94 produced ZnS QDs-GR nanocomposites via a facile solvothermal method, their work would be a value to design the procedure of metal sul¯de decorated GR with further excellent properties. In 2017, Wang et al 95 synthesized MoO 2 QDs/GR through a novel facile and scalable solvothermal method. The MoO 2 QDs/GR electrodes exhibit remarkably superior lithium storage capability, outstanding cycling stability and rate retention.…”

CoO Quantum Dots Anchored on Reduced Graphene Oxide Aerogels for Lithium-Ion Storage

“…Studies have shown that smaller-sized nanoparticles in the metal oxide/rGO composites have shorter ion/electron transport channels, lesser stress changes during electrochemical cycling, and a larger reaction active area, which are beneficial to improve the rate capability and cycling stability. ,,,, Quantum dots (QDs) with a diameter of 2–20 nm have unique physical and chemical properties . Wang et al . reported that MoO 2 QDs@RGO demonstrated a lithium storage capability of 1257 mA h g –1 at 0.1 A g –1 .…”

“…9,11,16,19,25 Quantum dots (QDs) with a diameter of 2−20 nm have unique physical and chemical properties. 12 Wang et al 26 reported that MoO 2 QDs@RGO demonstrated a lithium storage capability of 1257 mA h g −1 at 0.1 A g −1 . Yang et al 27 synthesized that carbon-coated ZnO QDs exhibited a specific charge capacity of 1200 mA h g −1 at 0.075 A g −1 and a rate capability of 400 mA h g −1 at 3.75 A g −1 .…”

Compact-Nanobox Engineering of Transition Metal Oxides with Enhanced Initial Coulombic Efficiency for Lithium-Ion Battery Anodes

“…34,39 Second, the nanosized CoO grains enable complete lithiation/delithiation is kinetically possible with curtate lithium-ion diffusion paths in grain interior and between neighbouring grains. 36,40 This in turn prevents generation of inactive lithium. Third, the resulting nanoscaled cobalt metal grains accompanied by the lower transformation active energy can promote the reversibility of the conversion reaction.…”

“…These gaps not only provide fast lithium-ion transfer channels but also retard the electrolyte permeation inside the CNB. The confined electrode–electrolyte contact area is in favor of limiting most SEI formation to the outer surface instead of individual nanograins. , Second, the nanosized CoO grains enable complete lithiation/delithiation is kinetically possible with curtate lithium-ion diffusion paths in grain interior and between neighbouring grains. , This in turn prevents generation of inactive lithium. Third, the resulting nanoscaled cobalt metal grains accompanied by the lower transformation active energy can promote the reversibility of the conversion reaction. , As a consequence of the mechanism, the CoO-CNB electrode can upgrade ICE to a high value of 82.2%, which is among the highest values in TMO anodes reported.…”