Reduced graphene oxide supported quasi-two-dimensional ZnCo2O4 nanosheets for lithium ion batteries with high electrochemical stability

Abstract

In this work, quasi-two-dimensional spinel ZnCo2O4 (ZCO) nanosheets comprising ZCO nanoparticles of different grain size were prepared via a facile solvothermal method and followed by post-treatment. It shows that the ZCO with a small grain size can be obtained by a fast cooling post-treatment. To enhance the conductivity of ZCO, uniform and compact ZCO nanosheets were in situ grown on reduced graphene oxide (rGO), which was employed as the template. When used as an anode for lithium ion batteries (LIBs), rGO@ZCO has a highly reversible capacity of 1107.2 mAh · g−1 at 100 mA · g−1 after 100 cycles, which is the highest among all ZCO samples. Moreover, when the current density is from 50 to 500 mA · g−1, the capacity of rGO@ZCO decreased from 1046.5 to 527.6 mAh · g−1, implying superior rate ability. The electrochemical analysis, together with calculations demonstrates that the unique structure is beneficial to promote charge transport and adapt the volume change in the charge–discharge process, resulting in expected LIB performance.