Alkali‐Ion Intercalation Driven 2D‐to‐1D Transformation of CdPS ₃ for Superior Sodium Storage

ABSTRACT Metal thiophosphites (MPS ₃ ) hold great promise as anode materials for sodium‐ion batteries (SIBs) owing to their unique layered structure and high specific capacity. However, conventional top‐down exfoliation methods struggle to reduce the lateral dimensions of MPS ₃ , limiting the exposure of active edge sites and hindering ion transport kinetics. Herein, we demonstrate a novel synthesis strategy that leverages alkali‐ion intercalation to drive a 2D‐to‐1D morphological transformation of CdPS ₃ , markedly enhancing sodium storage performance. This is achieved through a two‐step alkali‐ion intercalation/exchange process, where K ⁺ intercalation first shears CdPS ₃ nanosheets into K _{2 x} Cd _{1– x} PS ₃ nanolaths, followed by Na ⁺ exchange to yield the final Na _{2 x} Cd _{1– x} PS ₃ product. The 2D‐to‐1D morphological transformation endows the Na _{2 x} Cd _{1– x} PS ₃ material with a synergistic combination of advantages: an 81.5% expansion in interlayer spacing (from 0.65 nm to 1.18 nm) that facilitates rapid ion diffusion, a high‐aspect‐ratio 1D morphology that offers abundant active edge sites and efficient electron pathways, and the introduction of Cd vacancies that boost electronic conductivity. Consequently, the fabricated Na _{2 x} Cd _{1– x} PS ₃ anode delivers superior specific capacity, rate capability, and cycling stability. This work demonstrates alkali‐ion intercalation as a powerful tool for the precise morphological engineering of layered materials, offering a generalized paradigm for designing high‐performance electrode materials.