期刊
ACS APPLIED MATERIALS & INTERFACES
卷 13, 期 11, 页码 13191-13199出版社
AMER CHEMICAL SOC
DOI: 10.1021/acsami.0c22636
关键词
graphene quantum dot; hollow porous SiO2; high-performance; local electrical field; density functional theory; anode
By tiling graphene quantum dots in hollow porous SiO2, a rapid lithium ion diffusion channel and abundant heterointerfaces are provided, resulting in enhanced anode performance.
Graphene is widely used to enhance the electrochemical performance of anodes. However, graphene tends to be vertical with the lithium-ion (Li+) diffusion direction, and a few heterointerfaces are formed between graphene and active materials by point-to-point contact. Herein, a graphene quantum dots (GDs) tiling hollow porous SiO2 (HSiO2@GDs) anode is predicted by density functional theory (DFT) and is achieved by experiments. Due to the ultrasmall size, the tiling of GDs would provide Li+ a rapid diffusion channel and abundant heterointerfaces (face-to-face contact) between the GDs and the hollow porous SiO2 (HSiO2). Moreover, owing to the higher electrostatic potential of SiO2, the large-scale local electrical field from GDs to HSiO2 is established at the heterointerfaces, which provide extra Li+ storage sites and further facilitate the Li+ transfer. To our knowledge, the HSiO2@GDs shows the highest specific capacities at various current densities (such as similar to 1100 mA h/g at 5 A/g and similar to 2250 mA h/g at 0.2 A/g) among reported silicon oxides anodes and presents excellent cycling stability (similar to 1000 mA h/g after 2000 cycles at 3 A/g). Moreover, the design idea is available to design other widely studied graphene-containing anodes such as the Si, SnO2, TiO2, and MoS2.
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