Highly Robust Sn-Based MAX Anodes Constructed via Ti₆C Octahedral Outer Immobilization and A-Layer Fe Inner Anchoring...

Tin (Sn)-based anodes offer notable potential for lithium-ion batteries (LIBs) due to their high theoretical capacity and abundance. However, incomplete lithium insertion and severe volume expansion cause capacity degradation and electrode pulverization, limiting the practical application. To overcome these challenges, we utlize the unique MAX phase structure to stabilize the Sn in the A-layer between Ti₆C octahedra while using Fe as inner anchors in the same layer to strongly enhance the Ti-Sn bonding. Based on this design, the highly robust Sn-based anode materials - layered Ti₂Sn_{1- x}Fe_xC solid-solution MAX phases with refined grains - are synthesized via a feasible atmosphere sintering followed by ball milling method. The effects of different Fe contents (x = 0, 0.10, 0.20, 0.33) on structural stability and lithium storage capacity are also clarified. Among them, the Ti₂Sn_0.67Fe_0.33C electrode exhibits a high specific capacity of 480 mAh g^-1 at 0.05 A g^-1 and maintains a specific capacity of 210 mAh g^-1 after 2000 cycles at 1 A g^-1 with an average coulombic efficiency of 99.55%, outperforming most of previously reported MAX anode materials. This study presents new material design strategies that help overcome the intrinsic limitations of Sn-based anodes, while simultaneously expanding the MAX-phase family.