Conventional lithium-ion batteries embrace graphite anodes which operate at potential as low as metallic lithium, subjected to poor rate capability and safety issues. Among possible alternatives, oxides based on titanium redox couple, such as spinel Li₄Ti₅O₁₂, have received renewed attention. Here we further expand the horizon to include a perovskite structured titanate La_0.5Li_0.5TiO₃ into this promising family of anode materials. With average potential of around 1.0 V vs. Li⁺/Li, this anode exhibits high specific capacity of 225 mA h g⁻¹ and sustains 3000 cycles involving a reversible phase transition. Without decrease the particle size from micro to nano scale, its rate performance has exceeded the nanostructured Li₄Ti₅O₁₂. Further characterizations and calculations reveal that pseudocapacitance dictates the lithium storage process and the favorable ion and electronic transport is responsible for the rate enhancement. Our findings provide fresh impetus to the identification and development of titanium-based anode materials with desired electrochemical properties.

Electrides are unique compounds where most of the electrons reside at interstitial regions of the crystal behaving as anions, which strongly determines its physical properties. Interestingly, the magnitude and distribution of interstitial electrons can be effectively modified either by modulating its chemical composition or external conditions (e.g., pressure). Most of the electrides under high pressure are nonmetallic, and superconducting electrides are very rare. Here we report that a pressure-induced stable ${\mathrm{Li}}_6\mathrm{P}$ electride, identified by first-principles swarm structure calculations, becomes a superconductor with a predicted superconducting transition temperature $T_c$ of 39.3 K, which is the highest among the already known electrides. The interstitial electrons in ${\mathrm{Li}}_6\mathrm{P}$, with dumbbell-like connected electride states, play a dominant role in the superconducting transition. Other Li-rich phosphides, ${\mathrm{Li}}_5\mathrm{P}$, ${\mathrm{Li}}_{11}{\mathrm{P}}_2$, ${\mathrm{Li}}_{15}{\mathrm{P}}_2$, and ${\mathrm{Li}}_8\mathrm{P}$, are also predicted to be superconducting electrides, but with a lower $T_c$. Superconductivity in all these compounds can be attributed to a combination of a weak electronegativity of phosphorus (P) with a strong electropositivity of lithium (Li), and opens up the interest to explore high-temperature superconductivity in similar binary compounds.

Observation of high-temperature superconductivity in compressed sulfur hydrides has generated an irresistible wave of searches for new hydrogen-containing superconductors. We herein report the prediction of high-$T_c$ superconductivity in tellurium hydrides stabilized at megabar pressures identified by first-principles calculations in combination with a swarm structure search. Although tellurium is isoelectronic to sulfur or selenium, its heavier atomic mass and weaker electronegativity makes tellurium hydrides fundamentally distinct from sulfur or selenium hydrides in stoichiometries, structures, and chemical bondings. We identify three metallic stoichiometries of ${\mathrm{H}}_4\mathrm{Te}$, ${\mathrm{H}}_5{\mathrm{Te}}_2$, and ${\mathrm{HTe}}_3$, which are not predicted or known stable structures for sulfur or selenium hydrides. The two hydrogen-rich ${\mathrm{H}}_4\mathrm{Te}$ and ${\mathrm{H}}_5{\mathrm{Te}}_2$ phases are primarily ionic and contain exotic quasimolecular ${\mathrm{H}}_2$ and linear ${\mathrm{H}}_3$ units, respectively. Their high-$T_c$ (e.g., 104 K for ${\mathrm{H}}_4\mathrm{Te}$ at 170 GPa) superconductivity originates from the strong electron-phonon couplings associated with intermediate-frequency H-derived wagging and bending modes, a superconducting mechanism which differs substantially with those in sulfur or selenium hydrides where the high-frequency H-stretching vibrations make considerable contributions.