Organic molecule confinement reaction for preparation of the Sn nanoparticles@graphene anode materials in Lithium-ion battery.

ABSTRACT

Sn@Graphene composites as anode materials in Lithium-ion batteries have attracted intensive interest due to the inherent high capacity. On the other side, the high atomic ratio (Li4.4Sn) induces the pulverization of the electrode with cycling. Thus, suppressing pulverization by designing the structure of the materials is an essential key for improving cyclability. Applying the nanotechnologies such as electrospinning, soft/hard nano template strategy, surface modification, multi-step chemical vapor deposition (CVD), and so on has demonstrated the huge advantage on this aspect. These strategies are generally used for homogeneous dispersing Sn nanomaterials in graphene matrix or constructing the voids in the inner of the materials to obtain the mechanical buffer effect. Unfortunately, these processes induce huge energy consumption and complicated operation. To solve the issue, new nanotechnology for the composites by the bottom-up strategy (Organic Molecule Confinement Reaction (OMCR)) was shown in this report. A 3D organic nanoframes was synthesized as a graphene precursor by low energy nano emulsification and photopolymerization. SnO2 nanoparticles@3D organic nanoframes as the composites precursor were in-situ formed in the hydrothermal reaction. After the redox process by the calcination, the Sn nanoparticles with nanovoids (~100 nm, uniform size) were homogeneously dispersed in a Two-Dimensional Laminar Matrix of graphene nanosheets (2DLMG) by the in-situ patterning and confinement effect from the 3D organic nanoframes. The pulverization and crack of the composites were effectively suppressed, which was proved by the electrochemical testing. The Sn nanoparticles@2DLMG not delivered just the high cyclability during 200 cycles, but also firstly achieved a high specific capacity (539 mAh g-1) at the low loading Sn (19.58 wt%).