Deposition of binder-free oxygen-vacancies NiCo2O4 based films with hollow microspheres via solution precursor thermal spray for supercapacitors

Abstract

Hollow micro-/nanostructures and oxygen vacancies are highly desirable for supercapacitors due to high active surface area and outstanding electrochemical properties. In order to benefiting from the both effect, binder-free oxygen-vacancies NiCo2O4 based films with hollow microspheres were pioneering directly deposited via one kind thermal spray technology, named solution precursor thermal spray (SPTS) process. To our best knowledge, the rapid one-step SPTS route was firstly employed to synthesize and deposit NiCo2O4 films for supercapacitor applications. The CV data clearly demonstrated that the specific capacitances of more oxygen-deficient NiCo2O4 electrodes with hollow microspheres (i.e. F12) are significant higher than that of NiCo2O4 films composed by solid particles (i.e. P12) with less oxygen vacancies, exhibiting a rapid increment of about 20 times. The oxygen-vacancies NiCo2O4 film composed of hollow spheres possesses large specific capacitance of 902 F/g at the current density of 1 A/g with a good capacitance retention of 89.2% after 2500 cycles under 20 mV/s scan rate and a quite small resistance. Furthermore, this work pointed out that the Solution Precursor Thermal Spray (SPTS) route with high-interest for depositing other binder-free metal oxides based films as electrodes for other energy storage applications, benefiting from suitable surface morphologies and in-situ introduced oxygen vacancies as well.