Asymmetric Bipolar Pulsed dc Sputtered Nanocrystalline VN Coatings for Electrode Materials in Lithium Battery

Nanocrystalline vanadium nitride (VN) coatings for electrode materials for lithium battery with various deposition parameters have been prepared using dc and asymmetric bipolar pulsed dc magnetron sputtering. The deposition parameters such as pulse frequency and the duty cycle were varied from 0 to 50 kHz and 100 to 75%, respectively. Microstructural, crystallographic and electrical characterizations were performed by FE-SEM, AFM, XRD and 4-point probe method. With an increase in pulse frequency, coating microstructure evolved from a porous columnar structure to a highly dense one. Single-phase cubic (FCC) VN coatings with different preferential orientations were obtained as a function of pulse frequency. Minimum resistivity of 108 mu Omega-cm was obtained for the coatings deposited at pulse frequency of 25 kHz.