Multilayered Architecture Assembled from Sn(HPO₄)₂ Nanosheets and Reduced Graphene Oxide As Superior Cyclability Anodes for Sodium-Ion Batteries

The two-dimensional layered material of Sn(HPO4)2 nanosheets (SNSs) with a controllable nanosheet structure and a large interlayer distance is expected to be a potential anode material for sodium ion storage. However, poor conductivity and easy agglomeration are daunting challenges to realize the practical application of the SNS as an anode material. To overcome these difficulties, a two-dimensional multilayered architecture composed of SNSs and reduced graphene oxide (rGO) is assembled by utilizing the electrostatic repulsion between the SNS and graphene oxide and by an assisting liquid nitrogen rapid freezing method. Mainly owing to the solid solution reaction mechanism of SNSs, the excellent conductivity and interfacial charge storage of rGO, and their interaction with each other, the rGO/ SNS anode exhibits improved rate capability, outstanding cycling stability of 78.6% capacity retention after 10,000 cycles at 5 A g-1, and high pseudocapacitance of a 66% capacitive contribution ratio at 0.5 mV s-1. This work is expected to promote the development of SNS-based nanomaterials for electrochemical energy storage.