Non-sacrificial template synthesis of Cr2O3-C hierarchical core/shell nanospheres and their application as anode materials in lithium-ion batteries

Cr2O3-based nanospheres have been synthesized by a facile soft-template assisted method without sacrificing the template. Two types of Cr2O3 materials, the Cr2O3-C composite nanospheres (referred to as Cr2O3-C) with a novel hierarchical core/shell structure, and pure mesoporous Cr2O3 spheres (referred to as mesoporous Cr2O3) have been obtained by using a certain thermal treatment without adding more carbon precursor. The carbon coating layers in the Cr2O3-C composite distribute from the inside to the surface of the spheres continuously. Both the Cr2O3-C composite and the pure mesoporous Cr2O3 spheres are investigated with XRD, SEM, TEM, and electrochemical tests toward lithium storage. It is found that the reversible capacity for Cr2O3-C composite still retain more than 600 mA h g(-1) even after 35 cycles, showing a capacity retention of 87%, while mesoporous Cr2O3 spheres and commercial Cr2O3 can only deliver a capacity of 320 mA h g(-1) and 280 mA h g(-1), respectively. The improvements can be attributed to the superiorities both in structure and in composition.