Plasma modulated MOF-derived TiO2/C for enhanced lithium storage

Abstract

• The combined strategy consisting of nano/micro-structure by MOFs and defect engineering was reported. • Energetic ion bombardment effectively increases the chemical reaction area of TiO 2 /C. • The plasma-treated sample exhibits a highly reversible capacity and rate capability. • DFT calculations and GITT tests together prove the improvement of electrical and ion conductivity. The poor conductivity of oxides such as TiO 2 is the big challenge that severely restricts their applications in the energy storage field. The rational design of their electronic structure and nano/micro structure is an effective approach to solve this problem. In this study, a combined strategy of MOF-derived nano/micro structure and defect engineering by plasma fabrication is adopted to produce a highly defective TiO 2 /C nanocomposite, which exhibits extraordinary electrochemical performance, a highly reversible capacity of 316.9 mAh·g −1 at 0.5 A·g −1 , and a superior high-rate capability of 186.1 mAh·g −1 at 10 A·g −1 . The improvement can be ascribed by the increased specific surface area of TiO 2 /C by the energetic ion bombardment in plasma that provided more active sites. More importantly, the introduction of oxygen vacancies, Ti 3+ ion and lattice distortion can improve the intrinsic conductivities, which is also verified by density functional theory calculations as well as the resistivity and GITT measurements. It is believed that the combined strategy of MOF-derived structure and plasma fabrication can be extended to other electrode materials and have great prospects in the energy industries.