Preparation Of Zinc Coordination Complexes And Their Application In Lithium Ion Batteries

Owing to its high energy density,long service life and environmental protection,Li-ion batteries have drawn much attention from researchers.With the continuous upgrading of electronic products,the performance requirements of lithium batteries are getting higher and higher,fast charging high specific energy has become a research hotspot.The promotion of electric vehicle industry,lithium battery research has also been pushed to a climax.To improve the lithium battery performance is to fundamentally change the lithium battery electrode material and electrolyte,thus finding a suitable electrode material is one of the breakthroughs.Metal-organic framework?MOF?material is a new type of complex that combines metal ions and organic ligands via coordination bonds.At present,researchers are also concerned about the electrochemical aspects.The porous structure is conducive to the de-insertion and storage of lithium.It is promising of MOF to become a superior electrode material.In this study,a simple hydrothermal synthesis method was used in one-step to prepare a MOF material,which was modified and composited,and tested as a lithium battery anode material.The specific contents are as follows:?1?zinc is the main coordination center,five kinds of metal complexes with different structures were successfully prepared by hydrothermal method.The structures,morphologies and compositions of the five different complexes were characterized by single crystal X-ray diffraction?SXRD?,powder X-ray diffraction?PXRD?,scanning electron microscopy?SEM?and energy dispersive spectroscopy?EDS?.The five kinds of materials were each made into a negative plate,assembled into a button battery and tested battery performance,respectively.In this method,a novel 4,5-ImZnLi compound containing lithium and zinc was synthesized and cycled at a current density of 50mAh/g for 100 cycles with a first discharge specific capacity of 558mAh/g.After 100 cycles The discharge capacity is 75mAh/g.?2?Modified 4,5-ImZnLi was sintered at 400?,500?,600?for 4h in air and nitrogen atmosphere,respectively.The samples with more carbon residue showed better electrochemical performance.The constant current charge and discharge process has a longer discharge platform.After the rate performance test,the material properties are relatively stable.?3?The structure of 4,5-ImZnLi was unchanged when composited with graphene by using ultrasonic and hydrothermal methods,respectively.The performance of the battery was greatly improved.The performance of the ultrasonically treated graphene composite was superior,and the current density was constant at 50mAh/g during the charge and discharge process.The first cycle displayed the capacity of 1090mAh/g,at 100 cycle the capacity can be still maintained to 140mAh/g.?4?A new complex containing three types of metal ions,Li⁺,Zn²⁺,Co²⁺was hydrothermally synthesized.The structure,morphology and composition of the complex was characterized with several testing equipments for analyses.Although a short discharge platform appeared in the battery performance test,no noticeable increase was observed in the performance.