Mechanochemical synthesis of amorphous and crystalline Na2P2S6- elucidation of local structural changes by X-ray total scattering and NMR.

The development of all-solid-state sodium-ion batteries as an alternative energy storage system to lithium based techniques demands for sodium conducting solid electrolytes and an understanding of the sodium conduction mechanism governed by the local structure of these glass-ceramic materials. Na2P2S6 was synthesized in an amorphous state with subsequent crystallization. The change of the local structure before and after crystallization was analyzed in detail regarding the presence of structural building blocks such as [P2S6]2-, [P2S6]4-, [P2S7]4-, and [PS4]3-. The structure of the crystalline phase differs markedly compared to the corresponding amorphous phase.