Facile Preparation And Electrochemical Properties Of Novel Vanadium And Molybdenum-based Anode Materials Of Lithium Ion Battery

As an energy storage device,lithium-ion batteries break the previous carbon fuel-based energy supply method,effectively promote the reduction of carbon emissions,and provide a new way for the sustainable development of energy and are widely used in the field of consumer electronics.Nowadays,with the advent of electrification of automobiles,higher requirements are put forward for the performance of lithium-ion batteries.Graphite,as a negative electrode material for commercial lithium-ion batteries,has a low theoretical capacity,which limits the further improvement of lithium-ion battery performance.The task of finding a new type of adode materials for lithium-ion batteries to improve the electrochemical performance is imminent.In this paper,three vanadium and molybdenum-based anode materials of lithium ion batteries were synthesized through morphology control and structure optimization,and their electrochemical performance and charge-discharge reaction mechanism were discussed.The following are the specific research contents and results:1.Through the sol-gel combined annealing method,the Ni V2O6 sample was successfully prepared,and the particle size was optimized by annealing to make the particle size uniform.Based on the multi-electron reaction of nickel and vanadium,Ni V2O6 as an anode electrode material for lithium-ion batteries exhibits excellent electrochemical performance.Under the conditions of a voltage window of 0.01-3.0 V and a current density of 800 m A g^-1,the Ni V2O6electrode provides a capacity of 690 m A h g^-1 after 400 cycles and exhibits excellent cyclic stability.What’s more,the specific capacity can reach 1190 m A h g^-1at 100 m A g^-1,which is almost three times the theoretical capacity of graphite.Through ex-situ SEM and TEM tests,the morphology changes during cycling were explored,and the in-situ XRD and ex-situ XPS were used to prove the lithium storage mechanism of the conversion reaction during the charge and discharge process.2.Inspired by the first work,the nickel vanadate material has excellent electrochemical performance due to the synergistic effect of Ni and V,and is a promising anode material for lithium-ion batteries.We synthesized Ni2V2O7 material by a sol-gel method.Ni2V2O7 as a anode for lithium-ion batteries shows excellent electrochemical performance.At a current density of 700 m A g^-1,the Ni2V2O7 electrode provides a capacity of 690 m A h g^-1 after 170cycles,and the rate performance is also excellent.We focused on the structure and morphology evolution of Ni2V2O7 materials during cycling,the mechanism of charge-discharge reaction,and which were contributed to the further research work of vanadium-based anode materials.3.Molybdenum-based materials,like vanadium-based materials,have the advantage of multi-electron reactions and are promissing electrode material.Magnesium molybdate powder was synthesized by a sol-gel method,and its electrochemical performance as an anode of lithium-ion batteries was studied.It was found that its capacity decayed seriously,with a first-cycle coulombic efficiency of 34.5%,but the subsequent cyclic capacity kept growing,and reached a high and stable capacity of 1060 m A h g^-1after 600 cycles.We use XRD and ex-situ XPS tests to explore the essential reason for the increase in capacity and provide a reference for further optimization of materials.