Thermodynamics of Sodium–Lead Alloys for Negative Electrodes from First-Principles

Damien K. J. Lee, Zeyu Deng, Gopalakrishnan Sai Gautam, and Pieremanuele Canepa

Abstract:

Metals, such as tin, antimony, and lead (Pb) have garnered renewed attention for their potential use as alloyant-negative electrode materials in sodium (Na)-ion batteries (NIBs). Despite Pb’s toxicity and its high molecular weight, lead is one of the most commonly recycled metals, positioning Pb as a promising candidate for a cost-effective, high-capacity anode material. Understanding the miscibility of Na into Pb is crucial for the development of high-energy density negative electrode materials for NIBs. Using a first-principles multiscale approach, we analyze the thermodynamic properties and estimate the Na-alloying voltage of the Na–Pb system by constructing the compositional phase diagram. In the Na–Pb system, we elucidate the phase boundaries of important phases, such as Pb-rich face-centered cubic and β-NaPb3, thereby improving our understanding of the phase diagram of the Na–Pb alloy. Due to the strong ordering tendencies of the Na–Pb intermetallics (such as NaPb, Na5Pb2, and Na15Pb4), we do not observe any solid-solution behavior at intermediate and high Na concentrations.