Ballistic‐Aggregated Carbon Nanofoam in Target‐Side of Pulsed Laser Deposition for Energy Storage Applications
Subrata Ghosh, Massimiliano Righi, Andrea Macrelli, Giorgio Divitini, Davide Orecchia, Alessandro Maffini, Francesco Goto, Gianlorenzo Bussetti, D. Dellasega, Valeria Russo, Andrea Li Bassi, Carlo S. Casari
Abstract
Abstract In pulsed laser deposition, along the traditionally exploited deposition on the front‐side of the plasma‐plume, a coating forms on the surface of the target as well. For reproducibility, this residue is usually cleaned and discarded. Here we instead investigate the target‐side coated materials and employ them as a binder‐free supercapacitor electrode. The ballistic‐aggregated, target‐side nanofoam is compact and features a larger fraction of sp 2 ‐carbon, higher nitrogen content with higher graphitic‐N and lower oxygen content with fewer COOH groups than that of diffusive‐aggregated conventional nanofoams. They are highly hydrogenated graphite‐like amorphous carbon and superhydrophilic. The resulting symmetric micro‐supercapacitor delivers higher volumetric capacitance of 522 mF/cm 3 at 100 mV/s and 104 % retention after 10000 charge‐discharge cycles over conventional nanofoam (215 mF/cm 3 and 85 % retention) with an areal capacitance of 134 μF/cm 2 at 120 Hz and ultrafast frequency response. Utilizing the normally discarded target‐side material can therefore enable high performing devices while reducing waste, cost and energy input per usable product, leading towards a greater sustainability of nanomaterials synthesis and deposition techniques.