MAX‐phase Derived Tin Diselenide for 2D/2D Heterostructures with Ultralow Surface/Interface Transport Barriers toward Li‐/Na‐ions Storage

Abstract 2D tin diselenide and its derived 2D heterostructures have delivered promising potentials in various applications ranging from electronics to energy storage devices. The major challenges associated with large‐scale fabrication of SnSe 2 crystals, however, have hindered its engineering applications. Herein, a tin‐extraction synthetic method is proposed for producing large‐size SnSe 2 bulk crystals. In a typical synthesis, a Sn‐containing MAX phase (V 2 SnC) and a Se source are heat‐treated under a reducing atmosphere, by which Sn is extracted from the V 2 SnC phase as a rectified Sn source to form SnSe 2 crystals in the cold zone. After the following liquid exfoliation, the obtained 2D SnSe 2 nanosheets have a lateral size of a few centimeters and an atomic thickness. Furthermore, by coupling with 2D graphene to form 2D/2D SnSe 2 /graphene heterostructured electrodes, as validated by theoretical calculation and experimental studies, the superior Li‐/Na‐ion storage performance with ultralow surface/interface ion transport barriers are achieved for rechargeable Li‐/Na‐ion batteries. This innovative synthetic strategy opens a new avenue for the large‐scale synthesis of selenides and offers more options into the practical application of emerging 2D/2D heterostructure for electrochemical energy storage.