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

Abstract

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.