title: MoOxthin films deposited by magnetron sputtering as an anode for aqueous micro-supercapacitors.
abstract: In order to examine the potential application of non-stoichiometric molybdenum oxide as anode materials for aqueous micro-supercapacitors, conductive MoOxfilms (2 ⩽x⩽ 2.3) deposited via RF magnetron sputtering at different temperatures were systematically studied for composition, structure and electrochemical properties in an aqueous solution of Li2SO4. The MoOx(x≈ 2.3) film deposited at 150 °C exhibited a higher areal capacitance (31 mF cm-2measured at 5 mV s-1), best rate capability and excellent stability at potentials below -0.1 V versus saturated calomel electrode, compared to the films deposited at room temperature and at higher temperatures. These superior properties were attributed to the multi-valence composition and mixed-phase microstructure, i.e., the coexistence of MoO2nanocrystals and amorphous MoOx(2.3 <x⩽ 3). A mechanism combining Mo(IV) oxidation/reduction on the hydrated MoO2grain surfaces and cation intercalation/extrusion is proposed to illustrate the pseudo-capacitive process.
authors.affiliation: The State Key Laboratory for New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, People's Republic of China.
authors.forename: Can
authors.initials: C
authors.lastname: Liu
authors.affiliation: The State Key Laboratory for New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, People's Republic of China.
authors.forename: Zhengcao
authors.initials: Z
authors.lastname: Li
authors.affiliation: The State Key Laboratory for New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, People's Republic of China.
authors.forename: Zhengjun
authors.initials: Z
authors.lastname: Zhang
keywords: anode material; aqueous micro-supercapacitor; mixed-phase; molybdenum oxide; substoichiometric