Recent progress in electrochemical application of Magnéli phase Ti4O7-based materials: a review

Magnéli phases TinO2n − 1 are a series of sub-stoichiometric titanium oxides with a unique crystal structure, and Ti4O7 possesses the highest electronic conductivity while being able to maintain excellent chemical inertness in various corrosive environments, which is a required property for electrode materials in electrochemical systems. Therefore, Ti4O7 has become one of the major substitutes for carbon materials such as graphite and shows superior catalytic activity for electrode reactions and electrochemical stability in diverse batteries and electrochemical degradation systems, following the trend of carbon-free electrodes and costing less than the advanced electrodes such as boron-doped diamond. It has been demonstrated that Ti4O7 has great potential in the electrochemistry fields, especially as an electrode carrier. In this paper, we review the research progress of Ti4O7 as an electrode material in fuel cells, lithium-oxygen batteries, lithium-sulfur batteries, lithium-ion batteries, wastewater treatment, etc., including advanced fabrication technology, theoretical research, and application performance. Meanwhile, the current problems and future research directions of Ti4O7 are also pointed out.