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Vanadium nitride (VN) thin films were prepared by reactive DC magnetron sputtering of a vanadium target using nitrogen as reactive gas. The structural, morphological, and compositional evolution of these films is described based on hysteresis diagrams plotting the sputtering power versus nitrogen flow rate. These diagrams, measured across various cathode voltages and discharge pressures, unveil three distinct deposition regimes: metallic, intermediate, and contaminated. The microstructure of the films was found to be closely linked to the deposition regime, ranging from dense and amorphous in the metallic regime to porous and crystalline in the contaminated regime, while the composition varies from vanadium-rich to near-stoichiometric VN. Sputtered VN thin films used as electrodes for microsupercapacitors were investigated by cyclic voltammetry. Results highlight that the intermediate deposition regime, characterized by high crystallinity and porosity, yields the highest capacitance values, above 900 F cm−3. Such high volumetric capacitance is attributed to the highly porous structure and large specific surface area. In addition, in these deposition conditions, films are composed of crystalline VN with a significant amount of amorphous VOx on the surface, which allow these thin film electrodes to behave both as current collectors and pseudocapacitive electrodes. This work gives detailed insights into VN thin film microstructure and composition in reactive sputtering based on hysteresis curves. It emphasizes how we could use these curves to target specific microstructure, composition, and eventually achieve functional properties. In particular, these findings have important implications for the design and optimization of microstructured electrodes for energy storage applications. [ABSTRACT FROM AUTHOR]

Vanadium nitride film made using a thin film deposition technique is a promising electrode material for micro‐supercapacitor applications owing to its high electrical conductivity and high volumetric and surface capacitance values in aqueous electrolyte. Nevertheless, the cycling stability has to be improved to deliver good capacitance during a large number of cycles. Here, it is shown that vanadium nitride films made by a magnetron sputtering deposition method exhibit remarkable cycling stability (high capacitance retention value after 150 000 cycles), ultra‐high rate capability (75% of the initial capacitance at 1.6 V s−1), while providing high surface capacitance values (≈1.4 F cm−2) and very low ageing of the VN electrodes (no loss of performance after 13 months). Additionally, new findings regarding the location of vanadium oxides species responsible for the charge storage mechanism in pseudocapacitive VN films are revealed by transmission electron microscopy electron energy‐loss spectroscopy analyses at the nanoscale. [ABSTRACT FROM AUTHOR]

Abstract: First step in the way to the fabrication of an all-solid microbattery for autonomous wireless sensor node, amorphous thin solid films of lithium phosphorus oxynitride (LiPON) were prepared by radio-frequency sputtering of a mixture target of P2O5/Li2O in ambient nitrogen atmosphere. The morphology, composition, and ionic conductivity were characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and A.C. impedance spectroscopy. With a thickness of 1.4μm, the obtained LiPON amorphous layer provided an ionic conductivity close to 6×10−7 Scm−1 at room temperature. MicroRaman UV spectroscopy study was successfully carried out for the first time on LiPON thin films to complete the characterization and bring further information on LiPON structure. [Copyright &y& Elsevier]

• Ionic implantation (As+) has been performed on pseudocapacitive VN thin films. • Structural and microstructural changes have been evidenced. • The influence of implantation energy on the electrochemical properties of the thin film electrodes has been investigated. • Areal capacitance of VN films decreases when As+ ions are implanted. • However, a better capacitance retention is clearly evidenced for implanted VN electrodes when increasing the cycling rate. • Surface phenomena are emphasized upon ion implantation as compared to sub-surface mechanisms. The influence of microstructural or structural defects is seldom investigated in pseudocapacitive electrodes. Indeed, most of the synthesized materials do present defects at every scales which contribute to the improvement of the charge storage. In this study VN thin films were deposited by reactive magnetron sputtering. The as-deposited VN films were compared with similar films implanted with arsenide cations (As+) with energies ranging from 20 keV up to 150 keV. The influence of the ionic implantation on the structure and microstructure of the pristine films was characterized by several techniques. The initial curing of the internal stress of as-deposited VN films observed for low implantation energies was lost with increasing implantation energy. Concomitantly, the electrochemical behaviors of the VN films were investigated. All the VN films show a pseudocapacitive behavior at 2 mV.s−1. At low scan rates, the as-deposited film exhibits the highest areal capacitance (45 mF.cm−2) which drastically decreases upon increasing the scan rate. Only 30% of the initial capacitance is maintained at 100 mV.s−1. Despite lower capacitances at 2 mV.s−1, As+ implanted VN films exhibit better capacitance retention in the same conditions, i.e. up to 65% of the initial capacitance is maintained at 100 mV.s−1. The contributions coming from surface and subsurface reactions have been determined which enable to propose possible origins for the changes occurring in charge storage mechanisms upon ion implantation. [ABSTRACT FROM AUTHOR]