The two-dimensional to three-dimensional transition structures of ZnCo2O4 for the application of lithium-ion batteries

We prepare the transition structure of ZnCo2O4 via transformation from two-dimensional (2D) nanosheets to three-dimensional (3D) microspheres with the solvothermal method. ZnCo2O4 nanocrystallites were produced from the reaction of zinc acetate and cobalt nitrate in the non-aqueous methanol solution. The oriented attachment of ZnCo2O4 nanocrystallites results in the formation of the 2D wrinkled-paper-like structure of ZnCo2O4. The 2D ZnCo2O4 nanosheet agglomerate spontaneously because there is no appropriate surfactant, and they have weak electrical double layers in the precursor solution. As the stacking of 2D ZnCo2O4 nanosheets increased, the aggregate of ZnCo2O4 nanosheet was transformed into the 3D ZnCo2O4 microspheres. The transition structure of the ZnCo2O4 was composed of the interconnected ZnCo2O4 nanoparticles, which results in a porous structure to accommodate the volume expansion of ZnCo2O4 structure during the charge process. The transition structure of exhibits a remarkably high specific capacity and improved cycle performance. At a current density of 100 mA g(-1), the transition structure of ZnCo2O4 exhibited excellent initial discharge specific capacity of 2094 mA h g(-1). The discharge capacity maintain at 1296.91 mA h g(-1) after 200 cycles. Even as current density reached to 2000 mA g(-1), the average specific capacity still showed 606.88 mA hg(-1). (C) 2017 Elsevier B.V. All rights reserved.