Today’s anode for lithium ion batteries is dominated by graphite, with a low operate voltage at 0.1 V vs. Li+/Li, easy to format lithium dendrite and cause to safety risk. As an alternative anode material, the “zero-strain” spinel structure Li₄Ti₅O₁₂ could avoid Li plating with a relative high intercalation potential (1.55 V vs. Li+/Li) and exhibits an excellent cycling stability. However, the slightly low capacity and high voltage of Li₄Ti₅O₁₂ result in low energy density. Therefore, it is very important, but nevertheless a challenge, to develop a negative electrode material with a large capacity and an intercalation potential below 1 V, but not close to the Li plating potential, to ensure the safety of batteries. Herein, we report a new anode material of Li₂TiSiO₅ as anode material for LIBs. The electrochemical profile, structure and Li storage mechanism were extensively studied.

The crystal structure of Li₂TiSiO₅ is illustrated as a layered structure with infinite sheets of distorted TiO₆ octahedra and SiO₄ tetrahedra, linked by Li atoms. The distorted TiO₆ octahedral and SiO₄ tetrahedral networks are thought to be the origin of the structural stability of this material. The crystal structure is depicted in Fig. 1b (left) and the details are summarized in Table 1. Along with the refined structure of Li₂TiSiO₅, the nuclear-density difference (Fourier) map in Fig. 1b (middle) reveals negative nuclear density only at the 4d, 4e, and Ti (2c) sites, implying that lithium can only reside at these sites. The 4e sites are indicated by the yellow balls in Fig. 1b (right). Figure 2 give the typical charge/discharge curve of L_i2TiSiO₅ at between 0 and 3 V (vs. Li+/Li), delivers a reversible charge capacity (Li-ion extraction) of 308 mAh/g, with a voltage plateau below 1.0 V.

Fig. 1 (a) Crystal structure characterization of Li₂TiSiO₅ and (b) typical charge/discharge curve of Li₂TiSiO₅