LiFePO4 - xNy thin films were sputter-deposited on micron carbon fibers (MCFs) under a gas mixture of N-2/Ar/H-2 as electrode materials in pseudocapacitors. The MCFs were fabricated by thermal chemical vapor deposition on stainless steel substrates as current collectors. Various amounts of N-2 were introduced by controlling the flow ratios of N-2 to Ar/H-2. The LiFePO4 - xNy thin films coated on the surfaces of MCFs were observed by field emission scanning electron microscopy. The electrochemical properties of the LiFePO4 - xNy thin films were characterized using cyclic voltammetry and charge-discharge processes. The LiFePO4 - xNy thin-film electrode deposited under the optimal N-2 contents exhibited a high specific capacitance of 722 F/g at 1 A/g. Even at a current of 20 A/g, the electrode delivered a capacitance of 298 F/g. The pseudocapacitors using LiFePO4 - xNy thin-film electrodes showed no significant capacitance fading after 1000 cycles at 1 A/g. The results indicated that nitrogen doping improved the electrochemical performances of LiFePO4, demonstrating the potential of LiFePO4 - xNy as an active material in pseudocapacitors. (C) 2015 Elsevier B.V. All rights reserved.