Mesoporous NiCo2O4 nanosheets with enhance sodium ion storage properties

• NiCo2O4 nanosheets with different microstructures were controllably synthesized.
• Ultrathin NiCo2O4 nanosheets possess a mesoporous structure and large surface area.
• Ultrathin NiCo2O4 nanosheets exhibit a high reversible capacity of 690.4 mA h g−1.

Two kinds of the NiCo2O4 nanosheets constructed by interconnected nanoparticles with different microstructures, including ultrathin NiCo2O4 nanosheets (NiCo2O4-UNSs) and common NiCo2O4 nanosheets (NiCo2O4-NSs), were controllably synthesized by a facile method. The structure and morphology of the NiCo2O4 nanosheets were analyzed and characterized by XRD, SEM and TEM. NiCo2O4-UNSs possess a large surface area (119 m2 g−1) and narrow pore distribution (around 5 nm). Subsequently, the Na-ion storage properties of such NiCo2O4 nanosheets were investigated by sodium half-cells. The ultrathin NiCo2O4 nanosheets (NiCo2O4-NSs) exhibit much improved performance than that of NiCo2O4-NSs with a high reversible capacity of 690.4 mA h g−1 at 100 mAg−1 and 141.8 mA h g−1 at the current density of 1000 mA g−1 in the voltage window of 0.01–2.5 V. Furthermore, a reversible capacity of about 203.7 mA h g−1 can be remained after 50 cycles at 200 mAg−1.