CoPSe: A New Ternary Anode Material for Stable and High‐Rate Sodium/Potassium‐Ion Batteries

Abstract The exploration of ideal electrode materials overcoming the critical problems of large electrode volume changes and sluggish redox kinetics induced by large ionic radius of Na + /K + ions is highly desirable for sodium/potassium‐ion batteries (SIBs/PIBs) toward large‐scale applications. The present work demonstrates that single‐phase ternary cobalt phosphoselenide (CoPSe) in the form of nanoparticles embedded in a layered metal–organic framework (MOF)‐derived N‐doped carbon matrix (CoPSe/NC) represents an ultrastable and high‐rate anode material for SIBs/PIBs. The CoPSe/NC is fabricated by using the MOF as both a template and precursor, coupled with in situ synchronous phosphorization/selenization reactions. The CoPSe anode holds a set of intrinsic merits such as lower mechanical stress, enhanced reaction kinetics, as well as higher theoretical capacity and lower discharge voltage relative to its counterpart of CoSe 2 , and suppressed shuttle effect with higher intrinsic electrical conductivity relative to CoPS. The involved mechanisms are evidenced by substantial characterizations and density functional theory (DFT) calculations. Consequently, the CoPSe/NC anode shows an outstanding long‐cycle stability and rate performance for SIBs and PIBs. Moreover, the CoPSe/NC‐based Na‐ion full cell can achieve a higher energy density of 274 Wh kg −1 , surpassing that based on CoSe 2 /NC and most state‐of‐the‐art Na‐ion full cells based on P‐, Se‐, or S‐containing binary/ternary anodes to date.