Thermal oxidation of MoS2 into defective crystalline MoO3 with enhanced Li-ion storage kinetics

Thermal oxidation in air of molybdenum disulfide (MoS 2 ) into layer structured molybdenum trioxide (α-MoO 3 ) is investigated using a combination of thermal analysis, electron microscopy , Raman, X-ray diffraction and photoelectron spectroscopy . The phase evolutions occurred during the thermal process is characterized by the surface oxidation of MoS 2 , followed by the bulk oxidation to form α-MoO 3 and the formation of Mo 17 O 47 at higher temperatures. The single-phase MoO 3 formed at optimum temperature condition is found to possess crystalline defects and considerably greater values of Li-ion storage cycling and rate performances in comparison with samples prepared at alternative temperatures and also the initial MoS 2 . This sample (P-MoO 3 -820) exhibits a charge capacity of 628 mA h g −1 after 250 cycles (100 mA g −1 ) with a Li + diffusion coefficient of 2.3 × 10 -13 cm 2 s −1 , substantially greater than that of initial MoS 2 (8.1 ×   10 −16 cm 2 s −1 ). The electrochemical performance of P-MoO 3 -820 in full-cell configuration against a commercial LiFePO 4 cathode is evaluated and a specific capacity of 100 mAh g −1 after 500 cycles is recorded. This article, for the first time, discusses the thermal oxidation in air of MoS 2 as a simple and relatively clean approach to fabricate defective crystalline MoO 3 with enhanced Li-ion storage kinetics.