Facile synthesis and lithium storage mechanism study of directly usable tin-based metal organic framework

Abstract

• Tin-based MOFs have been successfully prepared and directly applied to Li-ion storage without annealing treatment. • The modified Sn-PA anode material has excellent electrochemical properties such as high reversible capacity and long-cycle stability. • The stable structural unit of Sn-PA and the active sites of Sn and O atoms are considered the reason for their excellent electrochemical performance. Tin-based materials have been demonstrated to be promising candidates for LIBs owing to their dramatic lithium storage properties. However, its large volume variation and poor cyclic stability severely impede practical utilization. In the present study, a novel Sn-based metal–organic framework (Sn-PA) has been one-step synthesized by a facile low-temperature aqueous solution method and has been directly used as anode materials, without subsequent annealing treatment. The simulated structure diagram and theoretically calculated revealed that in Sn-PA MOFs, Tin ions combine with four oxygen atoms from three organic ligands to form a stable and unique network structure. With a layered network structure and efficient electron transport channels, the Sn-PA electrode exhibits excellent electrochemical performance, achieves a high reversible capacity of 1530 mAh g −1 after 400 cycles at a current density of 0.5 A g −1 , and provides a highly stable capacity of 777 mAh g −1 at a high current density of 5 A g −1 . Kinetic analyses verified that the reversible synergistic effects between O atoms with high electro-negativity and Sn atoms with high capacity, as the main storage center of lithium ions, contribute to its excellent electrochemical performance.