| This dissertation is intending to investigate the modification of anti-fluorite Li5FeO4Cathode material for lithium-ion batteries by ion doping, so as to improve its electrochemical performance. Efforts were made to optimize the preparation condition of anti-fluorite Li5FeO4with solid-state method. Co-carbon nanotubes doping and Mn-carbon nanotubes doping methods were adopted to modify the anti-fluorite Li5FeO4cathode. Their effects on the anti-fluorite structure and electrochemical properties of the anti-fluorite Li5FeO4were studied respectively. The action mechanism of ion doping was also probed.The main experiments as follows:1. The optimization of anti-fluorite Li5FeO4preparation techniques was studied by means of FTIR, X-ray diffraction (XRD), SEM and electrochemical charge-discharge tests. LiOH·H2O and Fe(NO3)3·9H2O were used as the Li source and Fe source for the first time to synthesize anti-fluorite Li5FeO4, and the Li5FeO4were compared with which prepared from other Li sources and Fe sources. The optimal Li/Fe were inspected with LiOH·H2O and Fe(NO3)3·9H2O as the sources.2. A two-step solid-state process is attempted to prepare Li5Fe1-xCoxO4/CNT materials for Li-ion batteries. The process includes the following steps. A mixture containing Fe(NO3)3·9H2O, LiOH·H2O and Co(NO3)2·6H2O is thoroughly ground leading to a fine powder, and then this mixture is sintered at470℃for10h, followed at750℃for3h. To improve the conductivity of the obtained samples, carbon nanotubes (CNTs) are incorporated into the precursor, generating composite Li5Fe1-xCoxO4/CNTs. The obtained samples are featured by FTIR, X-ray diffraction (XRD), scanning electron microscope (SEM), and their electrochemical performances are investigated. It is revealed that the incorporation of CNTs can greatly enhance the electrochemical performance of Li5Fe1-xCoxO4. More interestingly, the phenomenon that the CNTs incorporation can significantly influence the particle size of obtained samples is observed in this study.3. A two-step solid-state process is proposed to prepare Li5Fe1-xMnxO4/carbon nanotubes (CNTs) materials for Li-ion batteries. The process includes the following steps. A mixture containing Fe(NO3)3·9H2O, LiOH·H2O and Mn(CH3COO)2·4H2O is thoroughly ground leading to a fine powder, and then this mixture is sintered at470℃for10h, followed at750℃for3h. To improve the conductivity of the obtained samples, carbon nanotubes (CNTs) are incorporated into the precursor, generating composite Li5Fe1-xCoxO4/CNTs. The obtained samples are featured by FTIR, X-ray diffraction (XRD), scanning electron microscope (SEM), and their electrochemical performances are investigated. It is revealed that the incorporation of CNTs can greatly enhance the electrochemical performance of Li5Fe1-xMnxO4. More interestingly, the phenomenon that the incorporation of CNTs can significantly influence the particle size of obtained samples is observed in this study.4. Li3V2(PO4)3/PANI materials as Cathode materilas for lithium-ion battery is attempted to prepare with High-temperature solid-gel method. Li3V2(PO4)3/PANI materials were prepared by homogeneously mixing LiOH·H2O, V2O5, NH4H2PO4and oxalic acid with a Li:V:P:oxalic acid molar ratio of3:2:3:2. The mixture was firstly dissolved by diluted hydrochloric acid,then joined different percentage of PANI (5%,7%,10%). Bluish-green solution of production was Generate in magnetic force at60℃and obtained the loose porous green gelatin at80℃after the evaporation, then burned the dry gel under300℃at atmosphere for4h in oder to remove NH3, CO2, H2O, and then used the carbon calcined method in800℃to burn the samples for4h, doped different quality score of PANI (5%,7%, and10%) into Li3V2(PO4)3, the preparation of Li3V2(PO4)3is as the mentioned aboved. In the experiment, the role of aniline was to act as a reductant, and madeV5+becomeV3+,PANI as conductive polymers could improve the conductivity of anode materials.。... |
