Preparation And Electrochemical Performance Of Metal Oxide/Carbon Composite Anode Materials From MOFs Precursors For Lithium-ion Batteries

Metal-organic frameworks(MOFs)are crystalline materials consisting of metallic ions or metallic clusters and organic ligands.As porous materials with high specific surface aera,MOFs have great potential application in energy storage.In this study we firstly prepared Mn-MOF and Ti-MOF through solvethermal method,then we obtained MnO/C and Li4Ti5O12/C composites after high-temperature calcination from Mn-MOF precursor and lithium-doped Ti-MOF precursor.The morphology and structural feature of MnO/C and LiaTi5O12/C,as well as the electrochemical performance as anode materials for lithium-ion batteries(LIBs)were investigated in detail.The MnO/C composite material with regular three-dimentional rhombus morphology and the specific surface aera of 313 m2 g-1 was prepared from Mn-MOF by carbonizing 2 hours at 800 ? in N2 atomsphere.The MnO particles uniformly distributed in carbon matrix which could avoid the aggregation of MnO particles and shorten the transmission path of ion and electron.MnO/C composites demonstrate a high rate performance and reversible capacity as anode materials for LIBs.The specific capacities are 884 and 648 mA h g-1 after 150 and 500 cycles at 50 and 500 mA g-1,respectively.The Li4Ti5O12/C composite material(LTO/C-900)with regular morphology was obtained from lithium-doped Ti-MOF by calcining 10 hours at 900 ? in N2 atomsphere.The Li4Ti5O12/C composites possess three-dimentional cylinder morphology,and the LTO particles were dispered uniformly in carbon matrix.The electrochemical tests indicate that synthesized LTO/C-900 has high reversible capacity,rate performance and excellent cycling stability.The specific capacity of LTO/C-900 is 277 mA h g-1 after 700 cycles at 500 mA g-1,and 181?150 mA h g-1 after 1000 cycles at 1000 and 2000 mA g-1,respectively.The method from Mn-MOF to MnO/C composite material in this study is a typical approach from MOFs to metallic oxides/carbon composites.This synthesis strategy could reduce the particle size of metallic oxides and make metallic oxides dispered in carbon matrix uniformly,in comparison to the traditional methods.The process from lithium-doped Ti-MOF to Li4Ti5O12/C composite material is firstly reported in the current studies.The Li4Ti5O12/C composites from this in-situ synthesis method possess outstanding electrochemical performance,meanwhile the Li4Ti5O12 particles and carbon distribute uniformly.This synthesis strategy could also provide an extension of synthesizing cathodes for LIBs,such as LiMn2O4 and LiCoO2.