Metallic lithium could be a good electrode material for lithium-ion batteries in theory. However, combined with flammable, liquid electrolytes, it is a safety hazard. All-solid-state lithium-ion batteries could improve the safety and energy density, but they have their own issues: There is a lack of suitable solid-state electrolytes, and the interface between the electrode and the solid electrolyte can hamper performance.

Serena A. Corr, Edmund J. Cussen, University of Sheffield, UK, and colleagues have synthesized new lithium-rich double perovskites of the type Li_1.5La_1.5MO₆ (M  =  W,Te) as the first examples of a new class of lithium electrode materials. The team synthesized the compounds via a microwave-assisted solid-state approach. They prepared Li_1.5La_1.5WO₆, Li_1.5La_1.5TeO₆, and Li_1.5La_1.5W_0.5Te_0.5O₆ from La₂O₃, WO₃ and/or TeO₂, and LiOH·H₂O, which were ball-milled, pressed into pellets, and then heated in a microwave several times.

The team found that the tungsten compound allowed for reversible lithium-ion intercalation, making it a suitable anode material. The tellurium material, in contrast, could be used as a solid-state electrolyte with high electrochemical stability and a low activation barrier. These effects are due to the respective cations: W⁶⁺ is redox-active during lithium insertion, while Te⁶⁺ provides a high redox stability. According to the researchers, changing the microstructure and chemical composition of the compounds could allow for further optimization of their properties for use in all-solid-state batteries.

• Li_1.5La_1.5MO₆ (M = W⁶⁺, Te⁶⁺) as a new series of lithium-rich double perovskites for all-solid-state lithium-ion batteries,
  Marco Amores, Hany El-Shinawi, Innes McClelland, Stephen R. Yeandel, Peter J. Baker, Ronald I. Smith, Helen Y. Playford, Pooja Goddard, Serena A. Corr, Edmund J. Cussen,
  Nat. Commun. 2020.
  https://doi.org/10.1038/s41467-020-19815-5