Controlled Synthesis of Bismuth Atomic Clusters on Porous TiO₂ Nanobiscuit with Ultrafast Sodium Storage

Abstract Bismuth (Bi) has attracted widespread attention for sodium storage due to its high electronic/ionic conductivity, suitable reaction potential, and theoretical capacity (386 mAh g −1 ). However, Bi electrodes have a relatively high volumetric expansion ratio, which constrains their high capacity and affects the battery's cycle performance. Herein, a highly dispersed Bi atomic cluster is controllably prepared anchored on a porous TiO 2 substrate through in situ segregation from Bi 4 Ti 3 O 12 (TiO 2 /Bi AC ). The highly dispersed Bi clusters can serve as an “Ionic sponge” and accommodate more Na + without causing excessive stress. Additionally, it aids in the decomposition of NaPF 6 , leading to the formation of a durable solid‐electrolyte interphase (SEI) layer rich in inorganic components. As expected, TiO 2 /Bi AC exhibits excellent sodium storage performance in terms of cycling stability (346 mAh g −1 after 1000 cycles@ 1A g −1 ) and rate capability (231 mAh g −1 @ 100 A g −1 ). The pouch cell is further assembled and exhibits a specific capacity of 1.2 Ah after 200 cycles. This discovery presents a new method for developing efficient anode materials and is essential for steering the advancement of anode materials with fast charge–discharge capabilities.