Synthesis of layered SnO_X nanostructure composite carbon hybrid nanofiber mats by blow-spinning for high performance pseodocapacitors

Tin oxide (SnO_X) nanomaterials have received attention as electrode materials due to their large theoretical capacitance, but their use remains limited due to cumbersome processing and limited electrical conductivity. In this work, SnO_X nanoparticles, nanowires and nanorods embedded in a layered composite carbon hybrid nanofiber mat are prepared via blow-spinning followed by pre-oxidation and a high-temperature calcination self-assembly process in argon using stannous chloride and polyacrylonitrile as raw materials. As a result, a dual network conductive structure consisting of an upper SnOx nanostructure and underlying hybrid carbon nanofibers is created. The nanostructure morphology is controlled by reaction time through a transformation from nanoparticle to nanowire and lastly to nanorod and the potential formation and growth mechanism is discussed in detail. It is found that pre-oxidation introduces oxygen in the polyacrylonitrile that upon calcination into carbon nanofibers is released as oxygen containing gaseous substances that fuel transformation and oxidation of stannous chlorides and oxides into the self-assembled stannic oxide nanostructures in an approach applicable to other metal oxide structures. The SnO₂ nanowire carbon hybrid nanofibers mat (SnO₂–NW@CNFMs) exhibits the highest specific capacitance of 420.1 F g ^{− 1} at a scan rate of 5 mV s ^{− 1} and good cyclic stability of 92.5% capacitance retention after 3000 cycles at 1 A g ^{− 1} which exceeds the performance in earlier reported studies of tin oxide nanomaterials. The high electrochemical properties combined with the novel preparation procedure presented in this study promote SnO₂–NW@CNFMs as a good choice for electrodes in electronic appliances and electric vehicles.