Do the bridging oxygen bonds between active Sn nanodots and graphene improve the Li-storage properties?

Abstract

To make alloying anodes be practicability for lithium-ion batteries, graphene-incorporation has been demonstrated as one of the most effective strategies. However, successive lithiation/delithiation would usually lead to the detachment and self-aggregation of active alloying nanoparticles and graphene. Herein, an oxygen-bonds-bridging (Sn–O–C) Sn/graphene (Sn–O–G) micro/nanocomposite, in which Sn particles are in the ultrasmall scale of <3nm and embedded in graphene-based microspheres, was prepared via an in-situ co-reduction procedure. Electrochemical tests demonstrated that the Sn–O–G exhibited much improved Li-storage properties in terms of high reversible capacity (1246mAh/g at 50mA/g), superior high-rate capabilities (220mAh/g at 16A/g) and long-term cycle life (410mAh/g after 2000 cycles at 4A/g) in comparison to the Sn/graphene (Sn/G) prepared from the similar procedures just without the presence of Sn–O–C bonds. Because of the same morphology, size and microstructures of both Sn-based anodes, it is speculated that such enhanced properties of Sn–O–G should be benefited from the Sn–O–C bonds. In order to answer “Do the bridging oxygen bonds between active Sn nanodots and graphene improve the Li-storage properties?”, several ex-situ technologies were employed to track the physicochemical and electrochemical variation of Sn–O–G electrodes, revealing the reversibility of breaking/re-formation and durability of Sn–O–C bonds during the successive Li-insertion/extraction. Therefore, the answer is “YES”.