Room-Temperature Synthesis and Stable Na-ion Storage Performance of Two-Dimensional Mixed Lead–Bismuth Oxychloride

Two-dimensional (2D) mixed-cationic Sillén-type heterostructures have garnered widespread interest in energy conversion and storage applications. However, the current synthesis strategies to prepare them demand a high temperature, longer reaction durations, toxic chemicals, and a complex reaction setup, which hinder their large-scale applications. Herein, we unveil a new rapid room-temperature chemical precipitation route to prepare 2D-PbBiO₂Cl within ∼45 min. X-ray diffraction (XRD) and scanning electron microscopy (SEM) mechanistic studies show that its formation proceeds through topotactic ion exchange from an analogous PbBiO₂NO₃ intermediate. As an anode material in the sodium-ion battery (NIB), this 2D structure displays a stable sodium storage performance (∼240 mAh g^–1 for 450 cycles at 100 mA g^–1). Most importantly, the combined electrochemical and in operando XRD studies reveal a distinct (de)­sodiation process of the 2D-PbBiO₂Cl in comparison with the reported Na–(Pb/Bi) phase diagram, which is ascribed to the mixed chemical character of the electrochemically formed nanoscale Bi-rich (Pb/Bi) alloy. This study highlights the feasibility of room-temperature synthesis of 2D mixed-cationic Sillén-type phases and stabilization of their nanoscale alloys, which can potentially exhibit a distinct electrochemical behavior.