A Postspinel Anode Enabling Sodium‐Ion Ultralong Cycling and Superfast Transport via 1D Channels

Abstract Sodium‐ion batteries are intensively investigated for large‐scale energy storage due to the favorable sodium availability. However, the anode materials have encountered numerous problems, such as insufficient cycling performance, dissatisfactory capacity, and low safety. Here, a novel post‐spinel anode material, i.e., single‐crystalline NaVSnO 4 , is presented with the confined 1D channels and the shortest diffusion path. This material delivers an ultra long cycling life (84% capacity retention after 10 000 cycles), a high discharging capacity (163 mA h g −1 ), and a safe average potential of 0.84 V. Results indicate that the post‐spinel structure is well maintained over 10 000 cycles, surprisingly, with 0.9% volume change, the Sn 4+ /Sn 2+ based redox enables two sodium ions for reversible release and uptake, and the diffusion coefficient of sodium ions is characterized by 1.26 × 10 −11 cm 2 s −1 . The findings of this study provide a new insight into design of new frameworks with polyelectronic transfers for full performance electrode materials of sodium‐ion batteries.