Anchoring Atomic Phosphorus in a Mixed Occupancy Cu─S Framework for Ultra‐Stable and High‐Rate Sodium Storage

ABSTRACT Phosphorus (P) possesses an ultrahigh theoretical capacity of 2596 mAh g −1 , making it the most promising anode material for sodium‐ion batteries. However, Na + storage in P anodes encounters considerable technical challenges, such as low conductivity, substantial volume expansion, and poor reaction kinetics. Herein, a novel strategy was proposed that embedding P into a conductive and rigid Cu─S framework to fabricate a novel anode CuPS 2 with Cu and P atoms in occupancy at the same lattice site with a 50% probability each, achieving ultra‐stable and high‐rate Na + storage. In situ and ex situ analyses reveal the multi‐step reversible reaction processes during the charging (formation of CuPS 2 ) and discharging (precipitation of molecular‐level dispersed NaP in the ionic/electronic‐conductive (Na 3+ x )CuS 2 matrix) processes. The rigid and conductive (Na 3+ x )CuS 2 matrix maintains the phase consistency and structural stability of the anode, suppresses the migration and aggregation of intermediate products during Na + storage process, and improves the reaction kinetics of Na + storage. Consequently, the rationally designed CuPS 2 anode with Cu and P mixed occupancy achieves a high capacity of 583.8 mAh g −1 at 0.2 A g −1 and an ultra‐stable and high‐rate Na + storage capability (370 mAh g −1 at 5 A g −1 after 11 000 cycles with 90% capacity retention).