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Functionalized Graphene Quantum Dot Modification of Yolk–Shell NiO Microspheres for Superior Lithium Storage
Author(s) -
Yin Xiaojie,
Chen Hengqiao,
Zhi Chuanwei,
Sun Weiwei,
Lv LiPing,
Wang Yong
Publication year - 2018
Publication title -
small
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.785
H-Index - 236
eISSN - 1613-6829
pISSN - 1613-6810
DOI - 10.1002/smll.201800589
Subject(s) - non blocking i/o , quantum dot , materials science , electrode , graphene , chemical engineering , lithium (medication) , surface modification , mesoporous material , nanotechnology , electrochemistry , chemistry , catalysis , organic chemistry , medicine , endocrinology , engineering
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/GQDsCOOH) exhibits better performances than NiO with amino‐functionalized GQDs (NiO/GQDsNH 2 ). It delivers a capacity of ≈1081 mAh g −1 (NiO contribution: ≈1182 mAh g −1 ) after 250 cycles at 0.1 A g −1 . In comparison, NiO/GQDsNH 2 electrode holds ≈834 mAh g −1 of capacity, while the bald NiO exhibits an obvious decline in capacity with ≈396 mAh g −1 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.