TiO2-based cathode with modest oxygen vacancies and defective Ti3+ for long-life lithium-oxygen batteries

Abstract

Rational designed cathode including the surface engineering of catalyst e.g. defect creation and the precise selection of catalyst that could avoid the side reaction of carbon have been verified of great concern in achieving long-life lithium-oxygen batteries. Herein, oxygen vacancies and Ti3+ were both introduced into a tubular brush-like cathode structure, in which nano-needled TiO2 grew in situ on carbon textile (CT), and further enhancement of the catalytic performance was achieved by loading RuO2. The introduction of oxygen vacancies and Ti3+ in TiO2 could regulate the charge overpotential, and the synergistic effect between ruthenium dioxide and titanium dioxide accelerated charge transfer, and adjusted the electronic structure to achieve the surface-mediated formation mechanism of thin film lithium peroxide. Besides, TiO2 grew evenly on the surface of carbon matrix, thus restraining the carbon corrosion. Thus, CT@TiO2 and CT@TiO2-RuO2 provided low overpotentials of 0.94 V and 0.69 V and superior cycle life. Meanwhile, an ultra-long life of 317 cycles was achieved in the battery with the CT@TiO2-RuO2 cathode at a high current density of 0.3 mA cm−2.