Synthesis Of 5 2 2 2 2 Composites And Their Applications In Lithium Ion Batteries

In this social environment, the environment pollution is more and more serious, and the natural resources exhausted. People are all searching some resources which is free and no environment pollution and cyclic to solve this extremely urgent problem. In the1980s, the researchers Nagoura etc. from Japan found that petroleum coke as anode and LiCoO2which has layered structure as cathode can make a secondary Li-ion battery which can be recurrently utilized. But LiCoO2has a lower theoretical capacity and cobalt could pollute the environment, could not reach the demand of no pollution and higher capacity. It evokes many researchers to study some cathode materials which have no pollution, higher capacity and good stabilization.Vanadium pentoxide has obtained many attentions of researchers because of its low cost, no environment pollution and higher capacity. Due to the bad electrical conductivity and easy phase change at charge and discharge, it has a worse cycle stability which hinders its further development and utilization. Many researchers coated metallic oxide and carbon outside to increase the electrical conductivity and others dopped the transition metal cations in the process of vanadium pentoxide synthesis, increasing its stability in the circulation process.In this paper, we synthesized the pure V2O5by polyol method, and in order to solve the phase change when it was charged and discharged to improve the stabilization, we chose the amorphous manganese dioxide as a buffer layer coated on the surface of V2O5, obtaining a V2O5/MnO2composite material at last. We did a series of electrochemical test, and as a result, the first discharge capacities of V2O5and V2O5@MnO2cathodes at the current density of0.05A/g were345and284mAh/g respectively, but with the cycles increasing, the capacity of pure V2O5decayed faster, after50cycles the discharge capacities decreased to131and197mAh/g, equivalently the capacity decayed4.28and1.74per cycle respectively. The performance at the current density of0.1A/g also exhibited like the phenomenon of the current density at0.05A/g, the specific capacity of V2O5decayed faster than the V2O5/MnO2composite material.In order to study the rate during the charge/discharge process, the specific discharge capacities at different discharge rates as at0.05A/g,0.1A/g,0.2A/g,0.5A/g and0.05A/g again. After these charge/discharge processes, the battery made of cathode could provide the capacity of199mAh/g amounting to the capacity retention of78%. While V2O5, only had a retention capacity of59%after the same charge/discharge process.