Lithium - lanthanide bimetallic metal organic frameworks towards negative electrode material for lithium ion battery.

Novel lithium-lanthanide (lanthanide shortened as Ln: cerium and praseodymium) bimetallic coordination polymers of the formula C10H2LnLiO8(Ln: Ce named as CeLipmaand Pr named as PrLipma) and C10H3CeO8(named as Cepma) were prepared by a simplehydrothermal method. The 3 compounds were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), single crystal X-ray diffraction (SXRD), scanning electron microscopy (SEM), transmission electron microscope (TEM) andX-ray photoelectron spectroscopy(XPS). The results of the structural refinement show that they belong to triclinic symmetry and P-1 space group with cerium (or praseodymium) and lithium cations forming coordination bonds to oxygen atoms from different pyromellitic acid molecules and constructing into three-dimensional (3D) structures, it is interesting of the frameworks to exclude any coordination water and lattice water. As an electrode material for lithium ion batteries, CeLipma exhibits a maximum capacity of 800.5 mAh/g and a retention of 91.4% after 50 cycles at a current density of 100 mA/g. The favorable electrochemical properties of the lanthanide coordination polymers show potential application prospect in the field of electrode materials.