Metal-organic framework-derived Pb2P2S6: a new conversion-alloying anode material for high-performance sodium-ion batteries.

Metal thiophosphates (MTPs) are compelling high-capacity anode candidates for sodium-ion batteries (SIBs) but are plagued by intrinsic poor conductivity and drastic volume expansion. To address these challenges, we demonstrate the application of Pb2P2S6 as a novel high-performance SIB anode by ingeniously constructing a polypyrrole (PPy)-armored porous Pb2P2S6/C composite via a facile metal-organic framework (MOF)-derived synthesis. The Pb-MOF precursor serves as a self-sacrificial template, directly transforming into Pb2P2S6 through phosphosulfurization. The synchronous carbonization effectively shortens ion diffusion paths and alleviates volume strain. Concurrently, the conformal PPy coating acts as a highly conductive and elastic armor, establishing a robust electron transport network, stabilizing the electrode-electrolyte interface, and confining the active material within the porous scaffold. This multi-functional design endows the composite with exceptional sodium storage performance, including a high reversible capacity (1372.5/1110.4 mAh g-1 at 0.1 A g-1), excellent rate capability (503.6 mAh g-1 at 5.0 A g-1), and remarkable long-term cycling stability (91.3% capacity retention after 2000 cycles at 5.0 A g-1). Systematic in-/ex-situ characterizations are conducted to elucidate the sodium storage mechanism of Pb2P2S6. This work not only introduces a promising new anode material but also establishes a versatile strategy for the structural design of advanced electrodes.