Development and Evaluation of Sn Foil Anode for Sodium‐Ion Batteries

Metal foil electrodes are simple to prepare and have a high active material loading, making them well suited for the fabrication of inexpensive high‐energy‐density batteries. Herein, Sn metal foil is used as a binder‐ and conductive additive‐free anode for sodium‐ion batteries, achieving a high reversible specific capacity of 692 mAh g−1 and coulombic efficiency of 99% after 100 cycles at a rate of 0.1 C. During the first discharge process, the anode undergoes area expansion. It then splits into multiple parts during the first‐charge process. Upon cycling, the separated parts reconnect and form a single piece with a porous and robust coral structure owing to the self‐healing nature of the anode. A full cell with a Sn foil anode and Na3V2(PO4)3 cathode shows a stable cycle life of 100 mAh g−1 for 300 cycles. Thus, the cracking or pulverization of the Sn anode is not the principal origin of poor cycling properties. The adopted strategy will promote the development and commercialization of high‐capacity metal foil anodes that undergo volume changes during charge/discharge cycling. Binder‐ and conducting agent‐ free Sn foil is studied as anode for sodium‐ion batteries. The excellent electrochemical performance (high areal loading and superior cyclability) is obtained with aid of self‐healing properties. In addition, full cell with Na3V2(PO4)3 cathode delivers excellent rate and cycling performance. This strategy is expected to facilitate the development of high‐capacity anodes for high‐energy‐density sodium‐ion batteries.