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

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 NaVSnO4, 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 Sn4+/Sn2+ based redox enables two sodium ions for reversible release and uptake, and the diffusion coefficient of sodium ions is characterized by 1.26 x 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.