Internal Electric Field Built on Heterointerface of H2TiO3/H4Ti5O12 Hybrid Enabling Promoted Li Extraction Performance

With potentially high lithium (Li) exchange capacity and long cycle ability, Ti-based oxides of H2TiO3 and H4Ti5O12 are considered to be promising Li-ion sieve (LIS) materials applied for Li resource extraction in the liquid phase. However, the LISs usually demonstrate unsatisfactory Li exchange performance under the approximately neutral condition without the strong impetus derived from the rapid combination between OH- in the surrounding solution and H+ ionized from LIS. Herein, a hybrid of H2TiO3/H4Ti5O12 with rich phase boundaries is constructed via a facile one-step solid-state method. Owing to the different Fermi energy levels of the two phases, the electrons are transferred at the phase interface between H2TiO3 and H4Ti5O12, developing an internal electric field (IEF). The built IEF provides an extra driving force to boost the solid-phase Li+ transport, hence enhancing the Li extraction kinetics. Threrfore, the H2TiO3/H4Ti5O12 hybrid exhibits outstanding Li exchange performance of 42.43 and 20.50 mg g-1 under alkaline and neutral conditions, corresponding to the hightest Li extraction rate of 5.30 and 2.05 mg g-1 h-1 reported so far. Our work offers an innovative strategy to promote the Li exchange performance of LIS especially under neutral conditions.