Cubic Mn-Ln (Ln La, Ce, Pr) bimetallic metal-organic frameworks for highly stable lithium storage capacity

Metal-organic frameworks (MOFs) have attracted considerable attention in the field of anodes for lithium-ion batteries (LIBs) due to their high specific surface area, tuneable pore structure, and multi-metal synergy effects. The reported MOFs as LIB anodes normally suffer from irreversible phase changes during electrochemical cycling. In this work, we report for the first time the synthesis and structural elucidation of a class of cubic Mn-Ln bimetallic MOFs C15H5Mn3N6LnO13(LnLa, Ce, Pr). Benefiting from their unique crystal structures and the introduction of rare earth elements (LnLa, Ce, Pr), they exhibit excellent thermal and electrochemical stability. Serving as anode materials for LIBs, they maintain the original crystal structures and morphologies after 400 cycles at a current density of 100 mAg−1. The capacities of Mn-Ln MOFs increase continuously, and their structures keep stable during electrochemical reaction processes. Detailed electrochemical measurements, analysis, and density functional theory calculations indicate that the increased capacity is attributed to the enhanced Li+ adsorption capability that arises from the opening of the ultra-micropores of MOFs during cycling. The charge-rich Ln elements in the pores become the main force to provide the adsorption capability. This work may enrich the understanding and development of stable MOFs for highly stable LIBs.