Synthesis of self-grown nanostructured NiO via pulse ionization for binderless psuedocapacitor electrode

Abstract

In air laser irradiation was carried out onto Ni sheet with ultra-short, pulsed laser for direct synthesis of NiO thin layer. The layer consisted of 3D nanostructures with excellent porosity and enhanced surface area for the fabrication of pseudo capacitive electrodes. Mainly laser parameters such as scan speed and frequency were analyzed. It was observed that at lower scan speed, excellent surface area was achievable which during microscopy, the morphology of the structure depicted a “broccoli” like structure. The oxidized layer forms because of series of events at ultra-short duration associated with laser-material interaction in ambient conditions such as energy transfer, heating, melting, evaporation, ionization, plasma formation, rapid quenching, and oxide layer formation. The obtained oxide layer consists of 3D self-standing nanostructure with the active material directly growing on the substrate without the requirement of binder. A combined contribution of pseudo capacitance due to surface rapid, redox reactions along with ion adsorption-desorption because of EDL's presence provided remarkable performance. With this fabrication approach, NiO, a battery active material demonstrated fast charge-discharge capabilities evident from galvanostatic charge-discharge test. Owing to the idea of one step direct synthesis and green fabrication process, the performance of the electrode was remarkable. An areal capacitance of 98.682 mF cm−2 and specific capacity of 59.209 mC cm−2 was achievable at a current density of 1 mA cm−2. This work promotes the idea of green synthesis of nano morphology and one step fabrication method.