Yolk-Double-Shell ZnPS₃/NC@C Polyhedra Engineered via Kirkendall-Effect-Driven Etching for Superior Sodium Storage

Transition metal phosphosulfides (TMPs) are compelling anode candidates for sodium-ion batteries thanks to their distinctive layered structure and outstanding electrochemical properties, yet facing significant intrinsic challenges including poor electronic conductivity and severe structural degradation. To address these issues, we demonstrate the construction of yolk-double-shell ZnPS₃/N-doped carbon@carbon (ZnPS₃/NC@C) polyhedra through a Kirkendall-effect-mediated tannic acid (TA) etching strategy using a resorcinol-formaldehyde (RF) coated ZIF-8 precursor. This rationally designed architecture confers several synergistic advantages: (i) the N-doped carbon matrix derived from ZIF-8/TA-Zn and the carbon shell from RF form a continuous conductive network, facilitating rapid charge transfer; (ii) the yolk-double-shell framework with ample internal void space effectively accommodates the volume variations, preserving structural integrity; and (iii) the outer carbon shell serves as a physical barrier against polysulfide dissolution, enhancing reaction reversibility. Benefiting from this multi-synergistic engineering, the novel ZnPS₃/NC@C anode exhibits impressive sodium storage performance, delivering a high charge/discharge capacity of 925.7/1128.9 mAh g^-1 at 0.1 A g^-1, along with a remarkable long-term cyclability with 96.9% capacity retention over 2000 cycles at 2.0 A g^-1. This work establishes a generalizable design paradigm integrating morphological manipulation with multi-component compositing for developing advanced electrode materials.