NiSb@PEO Hollow Nanospheres with Stabilized Structure for Improved Sodium Storage

Abstract Antimony has a high theoretical capacity, is widely used as an anode material for sodium‐ion batteries (SIB). However, the reversible sodiation/desodiation causes the structure collapse of the materials and then a rapid capacity fade. To solve this issue, the rationally designed NiSb@PEO (PEO, polyethylene oxide) hierarchical hollow nanospheres are successfully synthesized via the combination of hydrothermal and galvanic replacement methods. The unique hierarchical hollow nanospheres can alleviate volume expansion and mechanical stress, maintaining structural integrity during cycling. The PEO coating offers a highly conducive network and is conducive to forming stable solid electrolyte interface film on the surface of NiSb nanospheres. In addition, the nanospheres can shorten the transport pathway for the charged species. Benefiting from these structural advantages, NiSb@PEO hollow nanospheres as anodes for SIB display excellent sodium storage properties. At the current density of 100 mA g −1 , the initial charge specific capacity of the NiSb@PEO anode is 446 mAh g −1 , and the capacity retains 82.5% after 100 cycles. NiSb@PEO can maintain a reversible capacity of 284 mAh g −1 even at a high current density of 1600 mA g −1 .