The design and synthesis of NiCoO2@NiCoO2@Ni nanoflakes arrays for electrochemical energy storage

Abstract

Herein, NiCoO2 nanosheets coated on NiCoO2-flake arrays (named as NiCoO2@NiCoO2@Ni) were designed and synthesized using Ni foam as a three-dimensional substrate by combining the hydrothermal method with electrodeposition method. As compared to NiCoO2 materials obtained by only using the hydrothermal method or electrodeposition method, this as-prepared NiCoO2@NiCoO2@Ni shows advantages in morphology and electrochemical energy storage. When used as electrode materials, the obtained NiCoO2@NiCoO2@Ni arrays show remarkable electrochemical performance. The specific capacity is as high as 1029.7 C g−1 at the current density of 0.5 A g−1, which is far larger than that of pure NiCoO2 arrays prepared only using the hydrothermal method (612.7 C g−1) or electrodeposition method (316.5 C g−1). A hybrid capacitor device is assembled with the above NiCoO2@NiCoO2@Ni and graphene material for evaluating the practical application. The energy density of device is high up to 44.17 Wh kg−1 at 0.48 kW kg−1. Based on the above results, we believe that NiCoO2 arrays with unique core-shell architecture have a great potential application in the field of electrochemical energy storage.