Orchestrating stress dispersion and shrinkage confinement via interfacial covalent stitching for high-rate and durable potassium storage.

Potassium-ion batteries (PIBs) are attractive for resources and suitable potential, but are limited by the large K+ radius causing sluggish kinetics and severe volume expansion. Bi2S3 offers high theoretical capacity, suitable potassium storage potential, and a one-dimensional (1D) nanorod morphology, making it a promising PIB anode despite its poor conductivity and severe volume changes. Conventional single strategies such as carbon coating or nanostructuring alone are insufficient to address these inherent issues. In this work, a covalently-confined Bi/Bi2S3 core-shell nanorod composite encapsulated in nitrogen-doped carbon (Bi/Bi2S3@NC) with Bi-O-C bonding is constructed. The 1D morphology of Bi/Bi2S3 effectively shortens the K+ diffusion path. The N-doped carbon shell acts as a conductive physical buffer layer, synergizing with the Bi-O-C interface to enable stress dispersion and shrinkage confinement for structural integrity. Benefiting from the multi-structural synergistic optimization, the Bi/Bi2S3@NC anode delivers a capacity of 230.0 mAh g-1 at 50 A g-1, and maintains a capacity of 183.9 mAh g-1 after 1900 cycles at 5 A g-1. Furthermore, the full cell achieves an energy density of 129.86 Wh kg-1 at 772.5 W kg-1, outperforming similar reported works. This work presents an efficient route toward developing bismuth-based anodes of superior performance.