LiMn₂O₄Surface-modified By V₂O₅for Enhanced Lithium Ion Battery Performance

Now, although LiCoO₂is used as the main anode in lithium ion batteries, it’s notapplied in those large ones due to its low availability of capacity and high cost. As aresult, LiMn₂O₄has caused the attention of scientists and researchers. It has been theunique3-D channel-structure anode material because it’s one kind of abundant resourcethat is cheap, environmentally friendly and safe. The material, however, has its owndefects. LiMn₂O₄can be substaintially reduced in the circulating process and themelting of Mn，etc. To overcome the above-mentioned defects, strengthen the material’sreversible capacity and prolong its circulating span, researchers have done some workfor improvement in the way of making, mixing, and surface modifying. Therefore, thisthesis mainly delves into the improvement of electrochemistry function by modifyingthe surface of LiMn₂O₄.LiMn₂O₄which acted as a good lithium ion battery anode materials is prepared bythe sol–gel method at room temperature. It is found that all the XRD diffraction peaksof the LiMn₂O₄in conformity with the standard spectrum TEM images of the pristinesample showed that the particle mainly forms irregular shape and the particle size ofLiMn₂O₄arranged from150to400nm. The acetyl acetone vanadium VO（C5H7O2）2issoaked on the surface of LiMn₂O₄material and then is burned at500℃in air for heattreatment two hours. XPS, EDS and XRD research results show that the vanadium donot intercalate the skeleton structure of LiMn₂O₄during the heat treatment, butVO（C5H7O2）2has completely transformed into V₂O₅and wraps in the surface ofLiMn₂O₄material to result in forming V₂O₅coated layers. V₂O₅coated LiMn₂O₄exhibited a more reduced of the resistance than that of the bare LiMn₂O₄, whichilluminated by the EIS spectra. Therefore, electronic conductivity of LiMn₂O₄will beappropriately increased after surface modification by V₂O₅coated. It is indicated thatthe V₂O₅-coated LiMn₂O₄exhibits the better rate performance and a excellent cycle lifeat room temperature or elevated temperature. Specially, the modification materials also have the higher discharge capacity and longer cycle life at big rate charge-discharge.Thus, it can be conclude that coated V₂O₅on the surface of LiMn₂O₄could obviouslyimprove the electrochemical performance of LiMn₂O₄materials.The solid-phase synthesis method used for preparing the LiMn₂O₄has advantagesin operation simple, rich raw materials and easy to industrial production. Noteworthy,when he covered the content of2.5%coated material is good rate performance and lifecycle.