The Zintl–Klemm Concept in the Amorphous State: A Case Study of Na–P Battery Anodes

Abstract The Zintl–Klemm concept has long been used to explain and predict the bonding, and thereby the structures, of crystalline solid‐state materials. We apply this concept to the amorphous state, examining as an example the diverse disordered Na–P phases that can form in sodium‐ion battery anodes. Using first‐principles computations combined with state‐of‐the‐art machine‐learning methods, we provide atomic‐scale insights into the structures and energetics of amorphous Na–P phases. We showcase the applicability of the Zintl–Klemm rules in the amorphous state and discuss implications for future work.