Preparations And Electrochemical Performances Research Of Ternary Niobium (Tantalum)-based Metal Oxides

Lithium-ion batteries?LIBs?have attracted worldwide attention for the outstanding advantages such as high safety,high power density,long cycle life,fast charge/discharge properties and friendliness to the environment.Conventional graphite is a widely used anode material in the present commercial lithium-ion batteries,however,the graphite anode has disadvantages such as low theoretical capacity,poor rate performance induced by its low Li diffusion coefficient,and safety issues related to lithium deposition.Thus,explore new type anode materials,modulate the microstructure and realize their controllable preparation,which are important scientific significance and practical application value for the development of high performance LIBs.This paper selected ternary niobium?tantalum?-based metal oxides as the specific research object,prepared the nanoscale electrode materials combined with physical and chemical methods,decorated the materials using graphite with good electrical conductivity and chemical stability,synthesized composite materials and improved the electrochemical properties of materials.Obtained research as follow:1.Nanoscale CrNbO4 electrode materials were prepared using ball-milling method.The electrochemical tests showed that the discharge/charge capacities of CrNbO₄ after ball-milling maintain 132.6/131.5 mAh g^-1 after 50 cycles compared to 63.5/63 mAh g^-1 of materials without ball-milling,suggesting high energy ball-milling is an effective method to improve electrochemical behaviors of electrodes.2.Ternary niobium?tantalum?-based transition metal oxides MNO4?M=Fe and Cr,N=Nb and Ta?were successfully prepared by co-precipitation methods and their electrochemical performances were discussed and compared with preparations using high solid-state method.3.FeTaO₄/Graphite composite material was prepared by ball-milling method.FeTaO₄/Graphite can keep a capacity of 223.3 mAh g^-1 after 100 cycles while pristine FeTaO₄ remain only 60.4 mAh g^-1.This results showed the graphite can improve the electrochemical performance of the ternary tantalum-based metal oxides.4.AlNbO₄/Graphite composite material was synthesized using co-precipitation method.The discharge capacity of pristine AlNbO₄ decrease to 34.2 mAh g^-1 after 50cycles while AlNbO₄/Graphite composite material still sustain a capacity of 121.9 mAh g^-1.The improvement of electrochemical performance can be attributed to the addition of graphite,beneficial to the transmission of electronic and providing more reaction sites.