Morphology-controllable synthesis of 3D CoNiO2 nano-networks as a high-performance positive electrode material for supercapacitors

•A three-dimensional (3D) assembly of CoNiO2 nanowire networks was prepared.•Sodium-p-styrenesulfonate (PSS) plays a key role in forming the structure.•The as-prepared 3D CoNiO2 electrode exhibits high power and energy densities.•The proposed method is easy to provide an industrial mass production.•The method can be used to fabricate different morphologies of nanomaterials.

Here, we report a novel three-dimensional (3D) assembly of CoNiO2 nanowire networks using a facile and scalable hydrothermal method followed by an annealing process for supercapacitor applications. The X-ray diffraction (XRD) results revealed the formation of highly-crystalline CoNiO2 nano-networks. Scanning electron microscope (SEM) analysis showed the formation of a 3D interconnected network of CoNiO2 nanowires during the synthesis. In addition, a formation mechanism for 3D CoNiO2 nano-networks was proposed. Electrochemical analysis showed a typical pseudocapacitive behavior for the CoNiO2 nanowire networks. The as-prepared CoNiO2 electrode exhibited a high specific capacitance of 1462 F g−1 (45.32 F cm−2) at a current density of 1 A g−1 (31 mA cm−2) and an excellent rate capability of 1000 F g−1 (31 F cm−2) at 32 A g−1 (992 mA cm−2). Moreover, a good cycle stability was achieved at 4 A g−1 with no degradation over 800 cycles, indicating the stable 3D structure of CoNiO2 after the redox reactions. The high rate capability and the good cycle stability indicated that the as-prepared 3D CoNiO2 electrode could satisfy the needs of supercapacitors with both high power and energy densities.