Application Of Metal Organic Framework Materials Based On 1,4-benzenedicarboxvlic Acid Ligands In Lithium-ion Batteries

With the development of emerging technologies,rechargeable lithium-ion batteries have been used in more areas.However,the performance of lithium batteries couldn’t meet our demands and expectations.Herein,it has been the research hotspot to develop the high-performance lithium-ion batteries in the world,especially the development of new non-carbon anode materials with high energy density.Recently the great breakthroughts have been made in the application of metal organic frameworks(MOFs)for lithium batteries.We selected the 1,4-benzenedicarboxylic acid as ligands to synthesize different MOFs.It’s very easy and convenient to compound MOFs by using 1,4-benzenedicarboxylic acid with carboxyl groups as nucleation sites.In this work,we have accomplished following works:Firstly,Co-BDC MOF,the neotype anode electrode material for lithium ion batteries was prepared by solvothermal method using 1,4-benzenedicarboxylic acid(H2BDC)and cobalt nitrate hexahydrate(Co(NO3)2·6H2O).And a high reversible specific capacity of 1090 and 611 mAh·g-1 has been achieved at a current density of 200 and 1000 mA·g-1,respectively.At the same time,the mechanism of charge and discharge of the material was explored briefly.It was found that the cobalt maintainedat Co2+ under different charge states by ex-situ X-ray photoelectron spectroscopy(XPS)and infrared spectroscopy(IR)during charge/discharge process.It can be seen that Li+ maybe insert directly into the organic part rather than react with cobalt ions.Second,Mn-BDC MOF was synthesized by solvothermal reaction using 1,4-benzenedicarboxylic acid(H2BDC)and manganese(Ⅱ)chloride(MnCl2).We also removed the coordination solvent N-N-dimethylformamide(DMF)by thermal treatment at 200℃ and Mn-BDC@200 was obtained.And the activated Mn-BDC@200 electrode can maintain a reversible specific capacity of 974 mAh·g-1 after 100 cycles at a current density of 100 mA·g-1.Comparing with Mn-BDC MOF without heat treatment,it was found that the coordination solvent molecule(DMF)in Mn-BDC MOF has an adverse effect on electrochemical performance.Third,Fe(Zn)-BDC was synthesized by using FeCl3·6H2O,1,4-benzenedicarboxylic acid(H2BDC)via a solvothermal method.Zinc nitrate(Zn(NO3)2·6HO)as the morphological orientation agent was added into the reaction vessel at the same time.The Fe(Zn)-BDC@300 was obtained by thermal treatmentat 300℃ to remove the water molecules.Comparing with Fe-BDC@300 without zinc nitrate added,Fe(Zn)-BDC@300 showed a better morphology with consistent rod shape.Fe(Zn)-BDC@300 was tested at a current density of 100 mA·g-1 for 120 cycles,and the reversible specific capacity could obtain 863.4 mAh·g-1,which exhibited more excellent electrochemical performance than Fe-BDC@300 with a disorderly morphology.