Li+ intercalcation pseudocapacitance in Sn-based metal-organic framework for high capacity and ultra-stable Li ion storage

Tin (Sn)-based materials are potential alternatives to the commercial graphite anode for next-generation Li-ion batteries (LIBs) due to their high theoretical capacity. However, the poor cyclic stability, originating from the large volumetric changes during charge/discharge process, hinder their practical utilization. Herein, we have successfully prepared a Sn-based metal-organic framework (MOF, Sn-PMA), and explored as potential anode materials in LIBs. Benefiting from its layered structure and efficient electron transport channels, Sn-PMA electrodes deliver a high initial capacity of 1567 mAh g−1, at 100 mA g−1, and maintained a reversible capacity of 707 mAh g−1, at 800 mA g−1, after 400 cycles. Furthermore, the detailed post-electrochemical structural, morphological and compositional analysis is carried out to unveil the structural changes and Li-ion storage mechanism of electrodes. Ex-situ XRD and XPS results revealed that, in Sn-PMA electrode, O atom, coordinated to the Sn atom, exhibited higher electronegativity, served as major Li-ion storage site and rendered excellent cyclic stability due to a stable structure. Kinetic analyses reveal that the excellent performance of the Sn-PMA is typical attributed to the pseudocapacitive contribution induced by the special porous structure.