Boosting Electrochemical Properties of Na0.67Fe0.5Mn0.5O2 via Mg Doping for Superior Sodium-Ion Storage

Abstract Layered transition-metal oxide NaxTMO2 (TM = Ni, Fe, Mn, etc.) for cathodes in sodium-ion batteries (SIBs) has gained significant research focus owing to its outstanding features, including low cost, ease of synthesis, and environmental benignity. However, it still suffers from poor structural stability, sluggish Na+ diffusion, and unsatisfactory cycling performance. To address these challenges, herein, we present an Mg doping strategy at different sites for P2–phase Na0.67Fe0.5Mn0.5O2 with superior sodium-ion storage. The Mg doping on the Fe-site can significantly diminish the Jahn–Teller effect, hence enhancing structural integrity and boosting the electrochemical performance: the Na0.67Mg0.05Fe0.45Mn0.5O2 cathode shows excellent charge-transfer kinetics along with a splendid Na+-ion diffusion coefficient (DNa+) of 2.53 × 10–10 cm2 s–1; it achieves a splendid discharge capacity of 188.3 mAh g–1 with boosted cycling capability and rate performance. The present study affords a fabulous strategy for manipulating high-performance cathodic materials for SIB applications.