Designed synthesis of nitrogen-rich carbon wrapped Sn nanoparticles hybrid anode via in-situ growth of crystalline ZIF-8 on a binary metal oxide

Abstract

We have established a novel and solvent-free synthesis of superior performance Sn/C anode derived from binary metal oxides which initiated the outward growth of ZIF-8 approach. The obtained anode has highly dispersed Sn nanoparticles wrapped in nitrogen-rich carbon with a 3D continuous conductive framework and a high Sn content of 82.3wt% Binary metal oxide (ZnSnO3) is chosen together with imidazole to direct ZIF-8 growing around tin oxides according to the theory of hard and soft acids and bases. This ensures an encapsulation of tin oxides with high dispersion into ZIF-8. Subsequent pyrolysis allows the outward growth of ZIF-8 convert into a continuous and nitrogen-rich (5.3wt%) carbon network with good conductivity. Meanwhile, tin oxides are reduced to Sn nanoparticles by carbothermal reduction and the reduced zinc consequently evaporates to create open pores which contribute to fast transportation of lithium-ions and electrons. Consequently, the Sn/C anode presents an initial discharge capacity of 1321mAhg−1 with superior coulombic efficiency of 80.1% at 0.2Ag−1. Reversible capacities of 901mAhg−1 at 0.2Ag−1 and 690mAhg−1 at 1Ag−1 are reserved after 150 cycles. Importantly, this designed synthesis suggests a new approach to produce other materials such as MnO/C anode exhibiting good performance.