Functionalized Graphene Quantum Dot Modification of Yolk–Shell NiO Microspheres for Superior Lithium Storage

Abstract

Yolk-shell NiO microspheres are modified by two types of functionalized graphene quantum dots (denoted as NiO/GQDs) via a facile solvothermal treatment. The modification of GQDs on the surface of NiO greatly boosts the stability of the NiO/GQD electrode during long-term cycling. Specifically, the NiO with carboxyl-functionalized GQDs (NiO/GQDsCOOH) exhibits better performances than NiO with amino-functionalized GQDs (NiO/GQDsNH ). It delivers a capacity of ≈1081 mAh g (NiO contribution: ≈1182 mAh g ) after 250 cycles at 0.1 A g . In comparison, NiO/GQDsNH electrode holds ≈834 mAh g of capacity, while the bald NiO exhibits an obvious decline in capacity with ≈396 mAh g retained after cycling. Except for the yolk-shell and mesoporous merits, the superior performances of the NiO/GQD electrode are mainly ascribed to the assistance of GQDs. The GQD modification can support as a buffer alleviating the volume change, improve the electronic conductivity, and act as a reservoir for electrolytes to facilitate the transportation of Li . Moreover, the enrichment of carboxyl/amino groups on GQDs can further donate more active sites for the diffusion of Li and facilitate the electrochemical redox kinetics of the electrode, thus together leading to the superior lithium storage performance.

The Research Development of Quantum Dots in Electrochemical Energy Storage

“…Through a facile solvothermal treatment, Yin et al synthesized yolk–shell NiO microspheres are modified by two types of functionalized graphene quantum dots (denoted as NiO/GQDs). The NiO with carboxyl‐functionalized GQDs (NiO/GQDs‐COOH) delivered a capacity of ≈1081 mA h g −1 (NiO contribution: ≈1182 mA h g −1 ) after 250 cycles at 0.1 A g −1 while the NiO with amino‐functionalized GQDs (NiO/ GQDs ‐ NH 2 ) electrode held ≈834 mA h g −1 and the bald NiO exhibits an obvious decline in capacity with ≈396 mA h g −1 retained after cycling.…”

“…And, whenever QDs are used in an electrochemical device, the electrochemical signature of the QD based electrode must be shown. These excellent properties guarantee remarkable applications of QDs in a variety of fields, such as biomolecular analysis, sensors, organic photovoltaic devices, fluorescence, photochemical reagents, solar cells, light‐emitting diodes, and catalysis . Taking all of the above into consideration, it is hardly surprising that QDs have recently gained widespread applications in the areas of batteries and ECs ( Scheme ).…”

A Flexible Film toward High‐Performance Lithium Storage: Designing Nanosheet‐Assembled Hollow Single‐Hole Ni–Co–Mn–O Spheres with Oxygen Vacancy Embedded in 3D Carbon Nanotube/Graphene Network

“…Thus, the b ‐values of 0.740 and 0.699 respectively associated with the charging and discharging process disclose that the two processes coexist during the cycling of C‐NHSNCM electrode reactions. Moreover, the contribution of diffusion ( k 2 v 1/2 ) and capacitance ( k 1 v ) could be quantitatively distinguished, based on the following equations…”

NixMnyCozO Nanowire/CNT Composite Microspheres with 3D Interconnected Conductive Network Structure via Spray‐Drying Method: A High‐Capacity and Long‐Cycle‐Life Anode Material for Lithium‐Ion Batteries

“…As expected, the prepared 3DICN‐NCS demonstrates high reversible capacity beyond the theoretical capacity of NiO (718 mAh g −1 ), stable long‐term cycling performance, and ideal rate performance, which surpasses most of the NiO‐based anode materials reported in literatures . There are three main factors for the excellent electrochemical performances of 3DICN‐NCS.…”