NiCo2O4 doubled-shelled nanocages with enhanced lithium storage properties

Abstract

NiCo2O4 double-shelled nanocages were prepared through a metal–organic-framework-engaged strategy that relied on the unique reaction of zeolitic imidazolate framework-67 with Ni(NO3)2 and H2O. The microstructure and phase composition of NiCo2O4 double-shelled nanocages were characterized systematically. It was found that NiCo2O4 double-shelled nanocages were composed of nanocrystalline, showing cage-in-cage hollow polyhedron structure with large specific surface area of 193.76 m2 g−1 and abundant mesopores. As anodic materials for lithium-ion batteries, NiCo2O4 double-shelled nanocages demonstrated remarkable lithium storage properties with high discharge capacity, stable cycling performance and excellent rate capability, surpassing NiCo2O4 single-shelled nanocages. At 0.1C, the average discharge capacity over 100 cycles was 1132 mAh g−1. After 100 cycles, a reversible capacity as high as 1138 mAh g−1 was still delivered and coulombic efficiency was 98.2%. The discharge capacity at 2C reached 811.3 mAh g−1. The enhanced Li-storage performance should be attributed to their nanocrystalline, mesopores and double-shelled hollow nanocage structure.