Synthesis, Structure, and Properties of NaP7, a Phosphorus-rich Polyphosphide

NaP7 is a phosphorus‐rich polyphosphide featuring a helical polyphosphide substructure. It can be prepared from the elements as well as via short way transport using CuI as mineralizer additive. As a potential intermediate compound during the reaction of phosphorus with sodium in sodium ion batteries, we investigated the structural and physical properties of this polyphosphide in detail. X‐ray single crystal and powder data were collected and the structure was re‐determined. Thermal properties were measured and the electronic structure was calculated using DFT methods. NaP7 is a semiconductor featuring a bandgap in the visible light region.