Complementary two-phase anode improving stability and conductivity for lithium storage performance

Metal chalcogenides with multiple lithium ions storage capability have received extensive attentions in recent years; however, their practical application is restricted by the structural instability and poor reversibility. Herein, a unique structure of N and S co-doped C/TiO2 nanofibers is reported to support SnS nanosheets for fast and ultra-stable lithium storage. The incorporation of TiO2 can notably suppress the excessive uncontrollable growth of SnS and improve the structural stability of the electrode material. The effects of the ratios between Ti and Sn and the corresponding synthesis temperatures on the structure and electrochemical properties of the electrodes have been systematically studied. The interface charge transfer behavior of SnS and TiO2 composite heterostructure was clarified by density functional theory (DFT) calculation. The electronic interaction SnS and TiO2 can effectively reduce the energy band gap and form a built-in electric field at the interface of the two phases. This is beneficial for the adsorption of lithium ion and consequently accelerate the reaction kinetics of the electrode material. After the two phases are combined, the agglomeration of SnS is effectively suppressed, and the overall conductivity of the composite is greatly improved. Furthermore, the synergistic effect induced by SnS and TiO2 enables the good stability of the electrode in both lithium-ion half-cells and full cells. This work can provide new insights toward improving the performance of alloy-type anodes.