Scalable Fabrication of Core–Shell Sb@Co(OH)₂ Nanosheet Anodes for Advanced Sodium-Ion Batteries via Magnetron Sputtering

Antimony (Sb) has captured extensive attention as a promising anode for sodium-ion batteries (SIBs) due to its high theoretical capacity and moderate sodiated potential but is held back from practical applications owing to its pulverization induced by dramatic volumetric variations during the (de)sodiation process. Herein, we report a core–shell Sb@Co(OH)2 nanosheet anode fabricated via magnetron sputtering Sb onto the mass-productive Co(OH)2 substrate anchored on stainless-steel mesh, which is scalable and suitable for flow-line production. In SIBs, the Sb@Co(OH)2 anode displays superior rate performance (383.5 mAh/g at 30 A/g), high discharge capacity, and excellent stability. Compared with the sputtered Sb film electrode, the improved performance of the core–shell Sb@Co(OH)2 nanosheet anode can be attributed to the open framework of the Co(OH)2 substrate, not only accelerating the ion and electron transfer but also serving as the buffer for alleviating the volumetric variation and the supporting scaffold for prohibiting the aggregation. More importantly, the (de)sodiation mechanism of the Sb@Co(OH)2 anode was explored by operando (in situ) X-ray diffraction, and the similar alloying–dealloying processes (Sb ↔ NaxSb ↔ Na3Sb) for the 1st, 13th, and 30th cycles illustrate the excellent stability of the electrode.