Enhancing Reversible Reactions via Phase Engineering on Bi-Crystal GeS2 Nanosheets for Superior Sodium-Ion Storage

Phase engineering for synchronously realizing the demand of electrochemical reactions and structural stability has attracted the great enthusiasm of researchers to obtain high capacity and tolerance for Na+ insertion, especially the construction of uniform heterostructures by regulating the crystal structure in the same phase. Herein, ultrathin GeS2 nanoflakes composed of a mixture of orthorhombic and monoclinic crystal structures have been constructed by employing an in situ Ge-MOF sulfidation method. Benefiting from the combined effect of the accelerated reaction kinetics derived from the self-assembly of heterostructures, and the enhanced reaction reversibility originating from the excellent homogeneity of heterointerfaces and a stable intermediate phase interface, the GS-OM electrode materials show outstanding rate properties (371.9 mA h g–1 at 30 A g–1) and Na+ uptake/removal durability (603.9 mA h g–1 at 10 A g–1 over 1000 cycles) and even deliver an excellent practicability (104.01 mA h g–1 at 1 A g–1 over 300 cycles for full cells). Of note, this constructed phase engineering is expected to provide powerful guidance and effective insight for designing better sodium ion battery anodes with not only superior electrochemical reaction reversibility but also improved structure perdurability.