Three-dimensional hierarchical mesoporous flower-like TiO2@graphdiyne with superior electrochemical performances for lithium-ion batteries

Three-dimensional hierarchical flower-like TiO2@graphdiyne is prepared via a solvothermal process, and the structural properties and electrochemical performances are systematically investigated. The obtained results show that TiO2@graphdiyne delivers a high reversible capacity of 432.4 mA h g(-1) after 300 cycles at a current density of 1 A g(-1), about 3 times that (139.7 mA h g(-1)) of pristine TiO2. The high reversible capacities, excellent rate capability and cycle stability of TiO2@graphdiyne might be attributed to the hierarchical mesoporosity of graphdiyne with butadiyne linkages, which could not only provide innumerable interconnected active sites for lithium storage but also facilitate fast Li-ion diffusion. The built-in electric field derived from the difference in work function between TiO2 and graphdiyne could facilitate electron-transfer and Li-ion migration across heterojunction interfaces. Moreover, electron percolation and a local built-in electric field induced by oxygen vacancies in the TiO2 matrix could also enhance the kinetics of Li-ion insertion/deinsertion.