A Fast‐Charging and Ultra‐Stable Sodium‐Ion Battery Anode Enabled by N‐Doped Bi/BiOCl in a Carbon Framework

Abstract Owing to the abundant reserves and low cost, sodium‐ion batteries (SIBs) have garnered unprecedented attention. However, their widespread adoption is hindered by the scarcity of alternative anodes with fast‐charging capability and high stability. To overcome this challenge, a fast‐charging SIB anode, N‐doped Bi/BiOCl embedded in a carbon framework (Bi/BiOCl@NC) with a fast Na + transport channel and ultra‐high structural stability, is developed. During cycling in ether electrolyte, Bi/BiOCl@NC undergoes a remarkable transformation into a 3D porous skeleton, which significantly reduces the Na + transport pathway and accommodates volume changes. By employing density functional theory calculations to simulate the storage behavior of Na + in the structure, Bi/BiOCl@NC is theoretically characterized to have a low Na + transport barrier (0.056 eV) and outstanding electronic conductivity. Such unique characteristics induce Bi/BiOCl@NC anode to have an ultra‐high Na + storage capacity of 410 mAh·g −1 at 20 A·g −1 and exhibit outstanding cycling stability with over 2300 cycles at 10 A·g −1 . This study provides a rational scenario for the fast‐charging anode design and will enlighten more advanced research to promote the exploitation of SIBs.