One-step synthesis of Co-doped Zn2SnO4-graphene-carbon nanocomposites with improved lithium storage performances

摘要

Co-doped Zn2SnO4-graphene-carbon nanocomposites have been prepared for the first time through a convenient one-step hydrothermal method. The size of Co-doped Zn2SnO4 nanoparticles is about 3-5 nm and they are well dispersed on graphene nanosheets and carbon layer. L-Ascorbic acid is introduced to serve as a reductant for GO and carbon sources. The doping of Co can enhance the crystalline degree of Zn2SnO4 nanoparticles. When evaluated as anode materials for lithium ion batteries, the Co-ZTO-G-C nanocomposites exhibited a significantly higher reversible capacity of 699 mA h g(-1) after 50 cycles at 100 mA g(-1) and an improved cycling stability of 461 mA h g(-1) after 200 cycles at 500 mA g(-1) compared with Co-ZTO-G and ZTO-G-C nanocomposites. Moreover, even at a high current density of 1000 mA g(-1), the reversible capacity of 418 mA h g(-1) still remained. The improved electrochemical performance can be attributed to the synergy of the graphene substrate, the protective carbon layer, the uniform ultrafine Zn2SnO4 nanoparticles and Co doping. Therefore, Co-ZTO-G-C nanocomposites show great prospect as anodes for lithium-ion batteries.