Synthesis of the titanium phosphide telluride Ti2PTe2: A thermochemical approach

Ti2PTe2 monolayer: a promising two-dimensional anode material for sodium-ion batteries

Developing efficient anode materials with a good electrochemical performance has been a key scientific issue in the development of sodium ion batteries (SIBs). In this work, by means of density functional theory (DFT) computations, we demonstrate that two-dimensional (2D) Ti2PTe2 monolayer is a promising candidate for this application. The exfoliation of Ti2PTe2 monolayer from its experimentally known layered bulk phase is feasible due to the moderate cohesive energy. Different from many binary 2D transitions metal chalcogenides (TMCs) that are semiconducting, Ti2PTe2 monolayer is metallic with considerable electronic states at the Fermi level. Remarkably, Ti2PTe2 monolayer has a considerably high theoretical capacity of 280.72 mA h g-1, a rather small Na diffusion barrier of 0.22 eV, and a low average open circuit voltage of 0.31 eV. These results suggest that Ti2PTe2 monolayer can be utilized as a promising anode material for SIBs with high power density and fast charge/discharge rates.

Selective and low temperature transition metal intercalation in layered tellurides

Layered materials embrace rich intercalation reactions to accommodate high concentrations of foreign species within their structures, and find many applications spanning from energy storage, ion exchange to secondary batteries. Light alkali metals are generally most easily intercalated due to their light mass, high charge/volume ratio and in many cases strong reducing properties. An evolving area of materials chemistry, however, is to capture metals selectively, which is of technological and environmental significance but rather unexplored. Here we show that the layered telluride T₂PTe₂ (T=Ti, Zr) displays exclusive insertion of transition metals (for example, Cd, Zn) as opposed to alkali cations, with tetrahedral coordination preference to tellurium. Interestingly, the intercalation reactions proceed in solid state and at surprisingly low temperatures (for example, 80 °C for cadmium in Ti₂PTe₂). The current method of controlling selectivity provides opportunities in the search for new materials for various applications that used to be possible only in a liquid.

The intercalation of metal ions in layered structures has a wide variety of applications, from energy storage to environmental remediation. Here the authors report that layered telluride structures can selectively bind transition metals and this intercalation can occur in solid state at mild conditions.